KR20230131473A - Composites and Structures - Google Patents

Abstract

Described herein are details for designing and manufacturing helicoidal layups with enhanced impact resistance by combining nanomaterials, variable pitch and partial helices, thin unidirectional fiber plies, hybrid materials, and/or curved fibers within the plies. do. This helicoidal structure, created by a given method, can be tuned and pitched to a desired wavelength to attenuate propagating shock waves initiated by ballistics, impact forces, or foreign object impacts, and can be used to attenuate fractures, including catastrophic fractures. Transmission can be prevented. These improvements enable helicoid technology to be used in consumer products, protective armor, sports equipment, crash protection devices, wind turbine blades, cryogenic tanks, pressure vessels, battery cases, automotive/aerospace components, structural materials, and other composite products. It can be used for the same purposes.

Description

Composites and Structures

Cross-reference to related applications

This application claims the benefit of U.S. Patent Application Serial No. 17/247,603, filed December 17, 2020, and U.S. Patent Application Serial No. 17/304,902, filed June 28, 2021. All of the foregoing patent applications are hereby incorporated by reference in their entirety for all purposes.

Statement of Government Interest

The disclosed embodiments are not pursuant to any government grant or contract. The government has no rights to this invention.

This disclosure relates to impact-resistant structures. In particular, the present disclosure relates to embodiments of materials having a helicoidal architecture.

U.S. Patent No. 6,641,893 and U.S. Patent No. 9,452,587, which are incorporated herein by reference in their entirety, state that individual layers are rotated at a predefined angle relative to adjacent layers along a longitudinal axis or A method of ply laying up fiber-reinforced elastic composites to create a single fiber-oriented stack (i.e., laminate) is described. This helicoidal clocking can be selected to produce a specific helical pitch or circular polarization. Helices formed from aggregates of fibers of this pitch can be tuned to specific wavelengths to attenuate propagating shock waves initiated by ballistics, striking forces, or foreign object impacts; Can have matrix additives to inhibit and arrest the propagation of catastrophic fractures; The difference in elastic modulus between the fiber and the matrix resin can be used to prevent breakage from blunt or sharp impacts.

The present disclosure provides impact-resistant structures with thin ply unidirectional (TPUD), thin ply woven (TPW), quasi unidirectional woven (QUDW) and hybrid fiber reinforced helicoid materials arranged as stacks of, for example, polymer-based composite materials. Details for design and manufacturing are explained. Also described are devices containing the proposed structures, such as consumer products, protective armor, sports equipment, crash protection devices, wind turbine blades, cryogenic tanks, automotive/aerospace components, structural materials, and other composite products. .

Accordingly, to describe the present invention in general terms, reference will be made to the accompanying drawings, which are not necessarily drawn to scale, and some of which may represent background art, at least unless otherwise specified.

1 is an illustration of an example of a helicoidal geometry.
2A and 2B illustrate an example of a matrix resin molecular structure.
Figure 3 illustrates a stack of fiber layers arranged in a helicoidal pattern according to an embodiment of the invention.
4A and 4B illustrate discontinuous and continuous material morphologies.
5A-5H illustrate unidirectional material configurations and other material configurations.
Figure 6 illustrates fiber crimping caused by interlacing.
7A illustrates a helicoidal preform with straight fibers placed over a 3D curved shape according to an embodiment of the present invention.
7B illustrates a helicoidal preform with curved fibers disposed over a 2D shape according to an embodiment of the present invention.
Figure 8 is an exemplary diagram of an MX textile machine.
9 is an exemplary diagram of a fiber metal laminate.
10A and 10B are exemplary diagrams of composite sandwich structures.
Figure 11 shows an example of a helicoid laminate stack.
Figure 12 shows the lamina inner region and the interlaminar zone.
Figure 13 shows an example of contact length between laminae of individual fibers according to an embodiment of the present invention.
Figures 14A-14C show impact damage of a typical composite.
Figures 15 (a) to (c) show a typical composite material in which nanomaterials fill the gaps and cracks between fibers.
Figure 16 shows a stepped cloaking helicoid assembly according to an embodiment of the present invention.
Figure 17 shows an example of fiber placement steering.
18A-18C are schematic diagrams of a structure including both impact resistance and load-bearing strength according to an embodiment of the present invention.
Figure 19 shows spread tow fabric and light-tow fabric.
Figures 20(a)-(c) illustrate initial crack formation in a fabric composite according to an embodiment of the present invention.
Figures 21(a)-(c) show QUDW fabrics according to embodiments of the present invention.
Figures 22 (a) and (b) show QUDW fabrics with different included angles between plies according to an embodiment of the present invention.
Figure 23(a) shows the ply orientation of a helicoid layup according to an embodiment of the present invention.
Figure 23(b) shows the ply orientation of a conventional thin ply biaxial layup.
Figure 24 shows force versus displacement for various plies and arrangements according to embodiments of the present invention.

Hereinafter, the present invention will be described more completely with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the present invention. Indeed, these inventions may be embodied in many different forms, and should not be construed as limited to the embodiments described herein, but rather, these embodiments are provided so that the disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

The present disclosure improves helicoid material design and manufacturing methods by changing the helical pitch and structure over prior art embodiments, and expands and improves the mechanics related to impact resistance. The helicoid geometry is shown in Figure 1. As used herein, the term "helicoid" refers to a ply that defines a direction of orientation of the fibers of at least one ply with respect to the direction of orientation of the fibers of an adjacent ply and provides an included angle of greater than 0° and less than about 30°. Refers to the stacked arrangement of plies of fiber. The stack arrangement may include adjacent plies defining included angles outside this range, and the stack arrangement may include less than a full 360° rotation, or may include more than one rotation. The direction of fiber orientation of one or more plies may be straight or curved.

The range of new enhancements described herein include helicoid materials, which can be (a) nanomaterials, (b) variable pitch and partial helix, (c) TPUD layup, and (d) hybrid. Materials, (e) curved fibers within plies, (f) automated placement of fibers or tapes or patches for 2D or 3D preforms, (g) uncrimped fabrics, (h) 3D fabrics, (i) 3D printed materials. , and (j) filament winding material, (l) TPW layup, (m) QUDW layup. These helicoid materials can be laid up by hand, installed directly on automated machines, or stacked using weaving/braiding/stitching equipment (e.g., non-crimped fabric machines). Can be pre-assembled. Additive (e.g., 3D printing) manufacturing techniques can be used to vary and mix types of materials. For example, when manufacturing a helicoid stack, a combination of polymer fibers and metal fibers printed using additive manufacturing techniques can be used. These improvements can improve the tunability of composite helicoid materials and expand their applicability to a wider range of product types.

Impact behavior of composite structures is a complex dynamic phenomenon involving elastic deformation, matrix resin cracking, fiber fracture and finally delamination within and/or between plies. Part failure can occur at free ends, areas of concentrated bearing loads, or at points of maximum stress caused by the impact of external objects. Impact damage is often more severe on the side opposite to the blow and may not be noticeable, necessitating extensive non-destructive testing (e.g., handheld ultrasound). Therefore, impact resistance and damage resistance are often design limitations. Impact damage can reduce or limit in-plane load bearing capacity and require the product to be removed from service for repairs or, if damage is extensive, to be discarded and replaced. A number of materials and design methods have been considered to increase the impact resistance of composite parts and/or limit the severity of impact damage. In general, these designs aim to improve the laminate's ability to absorb or dissipate strain energy. Unfortunately, most of these approaches include foreign substances that alter the fiber structure and/or adversely affect other properties such as tensile and compressive strengths. Several of the more common approaches are described below:

Resin Material: The molecular structure of the matrix resin in the composite consists of a backbone structure (polymer chains) with many different types of crosslinks (i.e. network structure). See Figures 2A and 2B. Conventional thermosets (composites that reach their final form through a phase change curing reaction) typically have a rigid, highly cross-linked, glassy polymer structure. This molecular arrangement can make the composite susceptible to matrix cracking and/or delamination upon impact. Conventional approaches to avoid these drawbacks include: a) thermoplastics (resins that melt rather than harden, typically have higher molecular weight, a lower degree of cross-linking, and/or are amorphous rather than crystalline); (b) toughening of thermosets through network modifications (e.g., lowering monomer functionality, increasing backbone molecular weight, or introducing flexible subgroups), (c) separate rubbers, or Toughening of the elastomer by introduction of thermoplastic particles, and (d) interlaminar strengthening between thermoset plies (introduction of a thin thermoplastic veil, typically 0.001 inch). Resin toughening is well known and used in industry. Resin toughening can improve impact resistance, but may adversely affect other physical properties such as glass transition temperature, hot-cold or dry-wet performance, and chemical resistance. Embodiments of the present invention may also use vitrimer, a reprocessable thermoset resin, in addition to or instead of a non-reprocessable thermoset or thermoplastic resin.

In composite materials, the introduction of microspheres and micropores within a helicoid laminate is used, as in the fiber structure illustrated in Figure 3. However, according to the present disclosure, it is further contemplated that nanovoids (eg, formed by a laser or other mechanism) may be employed to impede crack propagation during fracture mode. Additionally, it is possible to provide voids larger than this as well as voids of various shapes. For example, voids or areas of weakness may have a directional component to cause catastrophic failure at a desired location and/or along a desired direction. Voids may have, for example, any desired average dimension (average transverse dimension) ranging from 0.1 nanometers to 500 microns, or any increment of 0.1 nanometers between these dimensions, or any increment ranging from 10 nanometers to 50 microns. Subranges may be present, such as 10 nanometers, 25 nanometers, 50 nanometers, 80 nanometers, 100 nanometers, 150 nanometers, 250 nanometers, 500 nanometers, etc.

Nanomaterials: Incorporation of elongated nanofibers, such as nanoparticles (e.g., carbon nanotubes (CNTs) and graphene) or in the form of fibers with an average diameter of less than 100 nm, into a matrix resin that may be combined with fiber reinforcement. These improvements can improve mechanical properties and impact resistance compared to conventional composite laminates of the same thickness. These improvements are due to whiskering (i.e., nanoscale whiskers interacting with the fibers to alter transverse and shear properties within the lamina). improved).

Fiber materials: Fibers provide strength and rigidity to composites. Fibers can be continuous or discontinuous depending on the application and manufacturing process. Fibers can also be steered (placed in a preferred orientation for use). Most common in the industry is for the plies to be clocked every 45° using orientations of 0, +45, -45, and 90°. For cost, manufacturing and performance reasons, the type and amount of fiber reinforcement within the composite may vary. Certain fiber types (i.e. carbon and graphite) have high specific strength (properties such as tensile and compression divided by density) but are inherently brittle, while others, such as glass fiber, have better impact strength but lower specific strength. lower due to high density. Aramid (aromatic polyamide) fibers have excellent toughness, bullet resistance, and impact resistance, but their performance deteriorates with temperature changes, they are easily affected by ultraviolet rays, and they tend to absorb moisture. To have the option of using fiber types that offer the best combination of strength and impact properties, you can choose from carbon, fiberglass, aramid, basalt, ultra-high molecular weight polyethylene (UHMWPE), ultra-high molecular weight polypropylene (UHMWPP) (e.g. Innegra® ), self-reinforcing polymer fibers (e.g. Pure®, Tegris®, Curv®), natural fibers (e.g. flax or hemp), metal fibers, quartz fibers, ceramic fibers and any of these types of recycled fibers, etc. Helicoidal structures can be created using a variety of known fiber types.

Material type: As with the choice of resins and fibers, material type is generally selected by application, cost, and manufacturing process. Broadly speaking, the material form may include discontinuous or continuous fibers with random or oriented orientation, as illustrated in FIGS. 4A and 4B.

In general, continuous/oriented fiber forms have excellent structural properties, but the manufacture of discontinuous fiber forms requires manual or special methods (automated material placement (AMP) or weaving, braiding, fly stitching) for plastic injection and compression molding of common compounds. , 3D printing or winding equipment), so manufacturing costs are higher. The two main categories of continuous material forming are unidirectional (UD) forming and fabric forming (including 3D weaving and braiding). Figure 5A illustrates unidirectional manufacturing and Figure 5B illustrates the fabric structure. Figure 5C shows an example of a non-crimped multiaxial fabric, and Figure 5D shows the preform in its final shape. Figure 5E shows a schematic diagram of a 3D fabric, Figure 5F shows an example of filament winding, Figure 5G shows an example of fiber patch placement, and Figure 5H shows an example of braiding.

UD tapes generally offer better in-plane structural properties than fabrics because there is no fiber crimp (fibers moving in and out of the plain during interlacing). It will be understood that the drawings are not necessarily to scale. Weaving can create z-directional fibers and interlocked non-planar fiber bundles, thereby dispersing point loads and retarding or inhibiting matrix cracking and laminate delamination. However, weaving requires large, complex machinery, which can be expensive and limits its size. Additionally, in-plane properties are typically degraded due to fiber crimp when compared to UD composites. Transverse stitching was used to create z-direction load-carrying capacity in UD composites and as a means of crack arrest. This approach is expensive and its value is questionable because the amount of stitching required to improve impact performance deforms the fibers in-plane and reduces core properties such as tensile, compressive and fatigue strengths. This disclosure expands on helicoid uses/designs to help overcome the shortcomings and limitations of current impact resistant composite designs, including certain materials (most commonly TPUD tape, TPW, and QUDW), glass, carbon, aramid fibers, etc. It includes new fiber angle cloaking combinations that give , and skins for sandwich applications where helicoid layups were not considered due to lack of design space for reproduction of a complete helicoid stack.

Manufacturing Methods: Several common methods for placing continuous composite materials using dry or pre-impregnated fibers include: (a) hand layup, (b) automated material placement (as well as continuous fiber placement). (c) weaving/braiding/fly stitching machines (e.g. multi-axial non-crimped textile machines where bundles of fibers are bound into knitting yarns); (d) filament winding and pulling; Pull winding, (e) 3D weaving, (f) 3D printing, (g) heat press compaction of organosheet. AMP adds material onto the ply using any type of fiber (slit tape). and can be dropped and clocked at any pre-programmed angle, and thus has the ability to be used to position stacks of near net-shape. Helicoid stacks require high-precision clocking. AMP is an exemplary low-cost method for deploying near-net shaped two-dimensional (2D) and three-dimensional (3D) preforms (primarily dry fiber layups that can later be infused with resin) using UD tape or multidirectional tape. (plies bound using powder binder, nonwoven veil between plies, and/or stitching), pre-impregnated tape (typically 1 ½ inches to 24 inches wide), slit tape (typically 1/8 inch to 1 ½ inches wide), or "towpreg" can be used on AMP equipment (e.g., contoured tape laminating machine (CTLM), automated fiber placement (AFP) Alternatively, it can be laid down to be molded directly on a contoured tool using robotic fiber placement (RFP) and then cured in an oven or autoclave.

AFP fabricates near-net shaped helicoidal preforms with modifiable angles and an unlimited number of plies or patches and provides significant flexibility to create any desired helicoidal preform stacking sequence. These helicoid materials give the part a near net shape. 2D or 3D preform structures can be manufactured from dry fibers or UD tapes or multidirectional tapes, which form a plurality of plies held together by a powder binder, a non-woven thermoplastic veil between the plies, needle or pneumatic air punching. “Towpreg”, or any type of pre-impregnated fiber, UD tape, multi-directional tape or slit tape of thermoplastic matrix and fibers can be deposited with a robotic fiber placement head to pre-impregnate as shown in Figures 7A and 7B. 2D or 3D preforms with helicoidal near net shapes can be manufactured. Figure 7a illustrates a helicoid preform made by placing straight fibers in a 3D curved shape, and Figure 7b illustrates a helicoid preform made by placing curved fibers in a 2D shape. Continuous tow shear (CTS) can be used to create an in-plane curved fiber orientation.

Industry-standard MX fabric machines, such as those from Karl Mayer GMBH (see, for example, Figure 8), can produce non-crimped fabric (NCF) with one ply per adjustable directional arm, typically five plies. limited to: 0° ply, defined as the winding direction of the roll + 4 off-axis with angles exceeding 20° to limit the length of the directional arm at a shallow angle and avoid reducing the machine's output. Fly. The plies are typically stitched, but may be joined by a powder binder or a thermoplastic nonwoven veil between the plies that is slightly melted.

This technique is used for helicoidal multiaxial (HMX) fabric rolls (e.g. [0°, 22.5°, 45°, 67.5°, 90°] or [80°,60°,40°,20°,0] or It is suitable for mass production of [39.4°, 28.2°, 16.9°, 5.6°]). However, a larger number of helicoids can be achieved by using additional adjustable arms and/or by manufacturing a plurality of rolls individually and then assembling these layers to form a helicoid sequence of a larger number of plies. Manufacturing coiled plies can be much more cost-effective. In one exemplary embodiment, a roll of five helicoid plies can be made to form a helicoid multiaxial (HMX) fabric [0°, 22.5°, 45°, 67.5°, 90°]. Next, fold this roll by dividing its width into two around the 0° axis, or simply combine it with another identical roll turned over to form 10 ply HMX [-90°,-67.5°,-45°,- 22.5°, 0°, 0°, 22.5°, 45°, 67.5°, 90°] can be formed. In another embodiment, a first helicoid MX fabric (e.g., [56°,79°,-79°,-56°]) is taken from a large continuous roll and rotated 90° (e.g., [-34°,-11°,11°,34°]) overlapping each other to form 8 ply HMX fabrics (e.g. 8 ply [56°,79°,-79°,-56°, -34°]). °, -11°, 11°, 34°] can be manufactured. As with individual plies, two HMX stacks can be joined using stitching or powder binders or heat laminated thermoplastic nonwoven veils or any other suitable known technique (e.g., air punch or needle punch).

This is an efficient and innovative method that proposes HMX with eight or more helicoid plies embedded within one HMX fabric roll to overcome the mechanical limitations commonly found in the composite industry. These HMX rolls can be pre-impregnated.

Hybrid structures: Composite parts have been manufactured incorporating non-polymeric and/or sandwich materials that can improve properties such as support, stiffness and impact resistance. An example of a hybrid design is provided below:

Metals: Composites typically have limited elastic ability to dissipate energy and therefore fail catastrophically when subjected to loads that exceed their ultimate capacity. Instead, the metal can plastically deform and dissipate the impact energy. Metal foils, meshes, and fibers (e.g., aluminum, titanium, and steel) are optionally incorporated within the laminate to provide fracture toughness, improved impact resistance, lightning protection, and reduction of surface erosion (see Figure 9). Impact resistance can be provided by introducing shape memory alloy (SMA). Typical fiber metal laminate (FML) types in use in industry include: ARAL (aramid/aluminum), GLARE (glass fiber/aluminum), CARALL (carbon/aluminum), and TiGr (titanium/graphite). The introduction of metals typically requires weight-increasing adhesive operations (in the form of additional adhesives), expensive and hazardous metal surface treatment techniques (e.g. steam degreasing, alkali cleaning and etching or anodizing). in need. Additional drawbacks of metal/composite hybrids include the following: (a) metals may not have suitable coefficients of thermal expansion when incorporated into polymer-based composites, and (b) metal foils, meshes and fibers can be shaped into complex contours. It is difficult to place, and (c) the metal is denser than the composite material it replaces.

Sandwich Structure: Placing a material comprising, for example, a polymer layer or foam material on a honeycomb core, between the face sheets of a composite laminate, as shown in FIGS. 10A and 10B, causes the face sheets to form A synergistic structural configuration is created in which the sandwich material provides bending rigidity and also provides shear stiffness and buckling resistance. Compared to monolithic laminate composites, sandwich panels can demonstrate improved strength-to-weight ratio, acoustic properties, fatigue capacity, thermal insulation, and impact/damage resistance. The impact performance of a sandwich panel is such that some of the energy associated with the blow can be dissipated as elastic deformation instead of damage to the matrix and/or fibers, and/or the core can relieve the inertial load while the face sheet absorbs the energy. Therefore, it can be superior to laminate. The composition, core type/structural properties and boundary conditions of the laminate face sheet control the impact behavior. Typically, in a sandwich design the face sheet is relatively thin, and the core is bonded to the face sheet using an adhesive. Structural failure mechanisms that make sandwiches unsuitable for some applications include: a) limited bonding area and strength, which may lead to premature separation of the face sheet from the core upon impact; and b) the face sheet may be separated from the core by an equivalent laminate. Because it is thinner than designed, fiber fracture, fiber matrix debonding and laminate delamination can begin at lower impact levels, c) the core can be crushed or sheared, and d) replacing laminate plies with sandwich materials can cause compression, tension and , in-plane structural properties such as strength and rigidity may be reduced.

Thin plies: Composite laminates made from TPUD stacks have shown better mechanical properties and improved resistance to microcracks, delamination, and impact when compared to parts of the same thickness made using thick plies. Typically, aerospace UD carbon/epoxy (C/E) prepreg is grade 190 (0.0073 inch/ply) or grade 145 (0.0056 inch/ply). TPUD is typically grade 75 (.003 inch/ply) or lower. The grade specifies the nominal areal weight of the carbon fibers in the UD prepreg in g/m ² . TPUD laminates allow for reduced minimum gauge and/or lighter equivalent performance structures. To avoid warping during cure cooling, conventional layups require balanced ply stacks (i.e., the laminate must have equal numbers of plus- and minus-oriented plies) and symmetry (i.e., above the midplane of the layup). It is required that each ply present must have an identical ply (same material, thickness and orientation) at the same distance below the midplane.

Fiber orientation controls load-bearing capacity. Therefore, it is best to extend most of the fibers in the direction of the main load. The rules of balance/symmetry and the rules of minimum orientation to protect against accidental loading (no more than 10% of the fibers in any one direction) limit the freedom of stacking and, in many cases, to accommodate a given load. Requires a thicker layup than is significantly needed. This limitation is particularly problematic when tapering (dropping the ply) in areas of reduced load.

TPUD plies allow for lighter/thinner laminate options, either as a whole or in combination with conventional thickness plies. Unfortunately, TPUD can be more difficult and more expensive to prepreg slit and re-roll than conventional thick prepreg tapes, and can be more difficult to lay down to part shape using automated fiber placement equipment. It may be more defective, more difficult, and/or more expensive. In other applications, TPUD tape takes more time to lay down to part shape than conventional thick prepreg tape due to the greater number of plies placed.

Depending on the environment, composite structures may be subject to low-velocity and/or high-velocity impacts such as deliberate strikes, impacts, hail, rain, birds, falling tools, ballistics, random fragments, shock waves, lightning, or aerial fluttering. A fiber-reinforced elastic composite ply lamination method in which individual layers are rotated along their longitudinal or x-axis relative to adjacent layers to create a helicoidal fiber-oriented stack in the z-direction is shown in Figure 11. The diagram on the left uses a single line to represent each ply layer (lamina), with the resulting z-direction helicoid helix highlighted. The diagram on the right shows the structural layers of a helicoid layup more realistically using fiber bundles (tows typically consisting of 3000 to 50,000 or more fibers). The enlarged view that follows shows how a helicoid laminate stack is formed with individual laminar layers formed from uniformly dispersed fiber tow and resin.

Helicoidal cloaking can be chosen to create circularly z-oriented fibers or a particular helical pitch close enough to show significant intra-lamina direct load sharing between fibers within the lamina. Industry standard 0°, ±45°, 90° composite laminates (Note: in some cases 22.5°, 30°, and 60° angles may be used, but large cloaking angles and symmetry/balance rules are still typical) Compared to , these helices of left- and right-handed chirality (non-superimposable structures distinguishable from mirror images) are novel. When laminating laminae with greatly different angles of 0°, ±45°, and 90°, a resin-rich layer is created between each ply, so that load sharing between fibers depends on shear between the laminae through the matrix resin (Figure 12). For example, in conventional layup cloaking, when two adjacent plies differ by 90° and individual fibers have a diameter of 0.0003 inches (which is typical in the industry), overlap/direct contact between adjacent interlaminar fibers occurs. is 9 x10-8 in ² . And when the fibers differ by 45°, they have only 0.000424 inches of direct contact (see Figure 13). Because all of these contact areas are minimal, most load transfer between laminae must occur through resin shear. In contrast, larger contact areas are obtained with helicoid layups: (a) 30° - 0.0006 inches, (b) 22.5° - 0.000784 inches, (c) 15° - 0.00116 inches, (d) 5° - 0.00344 inches. inch. These helicoid values (1.5 to 10 times larger than standard 0°, ±45°, 90° layups) are sufficiently large to allow direct fiber load sharing to occur.

The ability of the fibers to share load directly between the laminar plies contributes significantly to the helicoid laminate's ability to absorb and dissipate impact forces more efficiently than conventional composite layups and to minimize the effects of impact fatigue. Additionally, helices formed from aggregates of fibers of these pitches can be tuned to specific wave lengths to attenuate propagating shock waves initiated by ballistics, striking forces, or foreign object impacts; It can be filled with a matrix containing microspheres or toughening particles to further inhibit or impede the propagation of catastrophic fractures, taking advantage of the difference in elastic modulus between the fiber and the resin to further impede fractures produced from blunt or sharp impacts. can do.

The dynamic performance under load of composite structures exposed to shock or shock waves is complex and difficult to predict even using the latest technology, fine-grid finite element analysis (FEA). The degree of plastic deformation, matrix cracking, fiber fracture and ultimate delamination resulting from extraneous object impact (planned or unplanned) can only be ascertained with some degree of certainty through controlled structural testing and post-failure evaluation. The present disclosure extends the scope and capabilities of the helicoid stack to a broader range of industrial applications (e.g., wind turbine blades, cryogenic tanks, hydrogen pressure vessels, aerospace primary structures, sporting goods, automotive components, consumer products, defense/space). Additional design and manufacturing options are detailed, extending to vehicles, soft or hard armor, structural materials, and other composite products. Specific disclosed enhancements include helicoid materials, which include (a) nanomaterials, (b) variable pitch and partial helices, (c) TPUD plies, (d) hybrid materials, and (e) Curved fibers in plies, (f) automated fiber or tape or patch placement for 2D or 3D preforms, (g) uncrimped fabrics, (h) 3D fabrics, (i) 3D printed materials, and (j) filament winding. Includes parts, (l) TPW layup, (m) QUDW layup. Dry and/or prepreg helicoid layups can be placed manually, ply by ply, directly on contoured tools using automated fiber placement machines, and/or weaving/braiding. They can be pre-knitted into stacks using ding/UD ply and fabric stitching equipment (e.g., non-crimped fabric machines).

Helicoid materials, including nanomaterials: Nanomaterials are property-enhancing particles with dimensions ranging from 1 to 1000 nanometers (10 ^-9 meters). Examples include carbon nanofibers (CNFs), carbon nanotubes (CNTs), single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs), graphite platelets/graphene, organic spherical particles; copolymers, inorganic clays; Included are silica, silicon carbide, alumina, metal oxides, and other known and as yet undeveloped nanomaterials. It is shown that introducing nanomaterials into the resin in combination with fiber reinforcement improves mechanical properties and impact resistance compared to conventional composite laminates of the same thickness. In some embodiments, nanofibers (fibers with a diameter of less than 100 nm) may be incorporated into the material.

Figures 14A-14C show different types of impact damage (i.e. deformation, interlaminar resin cracking, interlaminar resin cracking, fiber breakage and delamination) resulting from different impact levels (low, medium and high). In the case of nanomaterials, the impact improvement is believed to be due to whiskering (i.e., improved transverse and interlaminar shear properties by nanoscale bridging between fibers). Figures 15(a)-(c) show that nanoscale bridging (also called stitching) can be achieved by forming co-oriented or similarly oriented fibers (i.e., fibers within a co-oriented lamina, such as the 5° helicoid example shown in Figure 13). or closely oriented lamina fibers). In these cases, nanomaterials can reduce or even eliminate resin cracking caused by low- and mid-level impacts. Because the plies of a helicoid layup are cloaked at a shallow angle (e.g., 5 to 30°), the length of direct contact between individual interlaminar fibers can be up to 10 degrees longer than in a standard 0°, ±45°, 90° layup. It's twice as long. This long contact length makes nanocomposite additives more effective in helicoidal layups than industry standard layups separated by 45 or 90°. Helicoid layup using nano additives not only reduces/elimination of vertical/horizontal resin cracks within the lamina, but also reduces/elimination of resin cracks between the lamina in the horizontal direction under moderate impact, as shown in Figure 14b. , may also show resistance to delamination (full ply separation). Nanomaterials can be added uniformly within the resin during pre-pregging, attached directly to the fibers, or added to the interlaminar layer between ply stacks.

Variable Pitch and Partial Helicoid Structure: The pitch of a helicoid layup depends on the thickness of the lamina per ply and the angle at which the plies are cloaked/laminated. The resulting helicoid can be tuned to a particular wavelength or intensity in anticipation of the expected impact type/level and/or required intensity. To avoid deformation during cure cooling, conventional layups (those using 0°, ±45°, and 90° plies) require balanced and symmetrical ply stacks. Some prior art confirms that helicoid layups can be left-handed, right-handed or bi-helical. As originally conceived, the helicoid stack contains a constant angular offset throughout the entire layup. Examples of balanced and symmetrical 18° offset helicoidal layups include (0°, 18°, 36°, 54°, 72°, 90°, -72°, -54°, -36°, -18°, 0°, -18°, -36°, -54°, -72°, 90°, 72°, 54°, 36°, 18°, 0°). Helicoidal layups with shallow cloaking angles (e.g., 30° or less) have less tendency to deform than the industry standard 0°, ±45°, 90° layups, even if they are not balanced and/or symmetrical. This ability to create non-standard helicoidal layups allows for unique thinner laminate options that can be further tailored for specific applications. This disclosure describes additional helicoid cloaking options:

1. Layup with variable cloaking angles of 5, 10, 15 and 30° in a single laminate. One example is (0°, 5°, 15°, 30, 45°, 75°, -75°, -45°, 30 -15°, -5°, 0°). This type of layup is excellent for tuning across multiple wavelengths, arresting/dissipating impact forces in a region/depth within the layup, and/or balancing impact capability with overall laminate strength.

2. A layup with tight cloaking on (a) the outside, (b) middle, or (c) middle and outside of the layup and wider cloaking on the remainder of the layup. (0°, 5°, 10°, 15°, 45°, 75°, -75°, -45°, -15°, -10°, -5°, 0°) are the middle and outer surfaces of the laminate. This is an example of a layup with tight cloaking. This type of layup is excellent at dissipating impact loads within a specific thickness of the laminate while allowing freedom to orient the different plies for strength in the load bearing direction.

3. (0°, 30°, 60°, 90°, -60°, -30°, 0°) and (0°, -30°, -60°, 90°, 60°, 30°, 0° ) Asymmetric and/or unbalanced layups that are left-handed and right-handed helices, etc. These layups allow helicoid cloaking, or impact capability, to be utilized without the need to manufacture thick balanced/symmetric layups. Because tighter helicoidal cloaking angles are used (rather than the traditional 0°, ±45°, or 90°), these layups are less prone to deformation. Additionally, the tendency to deform can often be overcome by the geometry of the part or local reinforcement.

4. (0°, 5°, 10°, 15°, 90°, 90°, 15°, 10°, 5°, 0°) or (-35°, -25°, -15°, -5° , 5°, 15°, 25°, 35°), etc. A layup that is only partially spiral and does not cloak through the entire 360°. This layup can isolate the impact benefits of helicoidal placement in certain laminate areas while optimizing load-bearing fibers in other areas. This cloaking can be directional to predict the nature and direction of impact during use.

TPUD Helicoid Material: Industry-typical grades of UD carbon/epoxy (C/E) prepreg include 190 (0.0073 inch/ply) and 145 (0.0056 inch/ply). Thin ply prepreg is typically grade 60 (0.0023 inch/ply) or less. Figure 16 shows how stepped helices of various heights and widths are created by the thickness and cloaking of helicoid plies. For example, Grade 145 UD helicoid layup has about 15 to 20 carbon fibers per ply, resulting in a vertical step of 0.0056 inches. = Using a standard offset of a = 0.064 inches at a cloaking angle of approximately 5°, the horizontal step difference is calculated as b = 0.0056 inches, resulting in an almost 1 to 1 (1:1) helix. These 1:1 narrowly cloaked helices with short interlaminar resin shear zones and significant fiber-to-fiber direct contact form the core of the helicoid layup's impact resistance, crack arresting, and interlaminar load-sharing capabilities. A Grade 190 (0.0073 inch/ply) helicoid layup with the same 5° clocking would have an approximately 2:1 stepped step. A typical Grade 145 industry standard layup with 45° cloaking has a vertical resin step of 0.056 inches, forming a relatively long 1:10 helix. This long resin shear zone limits the direct fiber load sharing between the laminas when compared to helicoid layups and, in some cases, can cause reduced impact resistance. At 90° cloaking, the step difference between laminae becomes infinite (i.e., the resin area between laminae is undisturbed).

In summary, and continuing to refer to Figure 16, it can be noted that the narrower the "spiral step" the better the potential impact resistance, all other criteria being similar. However, very shallow angles in the range of 1° to 5° can be expected to promote the dominant failure mechanism described as helical matrix cracking, while larger shallow angles in the range of 15° to 30° result in intra-ply delamination and inter-ply delamination. It can be expected to promote the dominant failure mechanism described as delamination and fiber fracture. Applicants have recognized that, for a given fiber type and ply thickness, there is a portion of the preferred range of angle values at which both of the above-described failure mechanisms cooperate to maximize impact energy dissipation and impact strength. This preferred range, and any optimum within that range, may depend on many variables, including resin properties, fiber properties, tow size, and interlaminar resin thickness in addition to the cloaking angle of the fiber layer. TPUD layups showed improved strength and impact performance when compared to conventional layups of similar thickness.

In a new embodiment described by this disclosure, a TPUD grade 60 (0.0023 inch/ply) helicoid layup with 5° clocking produces an exemplary ½:1 stepped step. This prepreg cloaking arrangement has been shown to have an impact improvement of up to 50% over conventional (thickness and cloaking) layups. Additionally, thin ply layups have been shown to have strength improvements of up to 30% when compared to conventional layups of finite total thickness and orientation. Additionally, it should be noted that even when the cloaking angle is small, adjacent plies are still divergent enough to help resist vertical resin cracking within the lamina. Conversely, when two or more plies of the same orientation are stacked, it has been found that cracks within the lamina extend relatively easily from one ply into an adjacent ply. Microcracks within the resin lamina can also occur in environments with extremely low temperatures (e.g., -200°F to -415°F) (e.g., space and cryogenic tanks). According to the present disclosure, when constructed with TPUD prepreg, improvement in impact and microcrack prevention results can be expected for any previously known helicoid structure. Microcrack arrest not only helps maintain load bearing capacity but also reduces the permeation of liquids and/or gases within the containment vessel. The following TPUD variants are excellent embodiments of the art:

1. TPUD helicoid stacks demonstrate improvements in strength, impact and interlaminar microcrack arrest compared to conventional cloaked layups of standard ply thickness . These capabilities can be attributed to the smaller aspect ratio helix and the resulting improved inter-laminar load sharing.

2. TPUD helicoidal stacks of continuously cloaked helicoids have greater strength than highly oriented conventional stacks (with additional plies in the primary load bearing direction) while also improving impact properties. This is due to the fact that although the helicoid layup has a lower total number of fibers in the primary load direction, the thinner ply and slightly cloaked off-angle fibers promote efficient inter-laminar load sharing. Additionally, in a helicoid stack, fibers of the same angle are not directly stacked, so the propagation of vertical resin microcracks between laminae during high loads and/or upon impact and/or in low temperature environments is reduced. Microcrack arrest not only helps maintain load bearing capacity but also reduces the permeation of liquids and/or gases within the containment vessel.

3. TPUD helicoid stacks of smaller total thickness can have impact strengths similar to or better than thicker conventional laminates . Therefore, using TPUD helicoid stacks, thinner and lighter laminates can be produced than using the industry's standard balanced, symmetrical and minimally oriented laminates, which are non-helicoidal.

4. Thinner minimum gauge TPUD helicoidal stacks can retain the desired properties while complying with traditional layup symmetry, balance and minimum orientation rules. For example, the aircraft skin has the standard 0°, ±45°, 90° layup rule (0°, +45°, -45°, 90°, 90°, -45°, +45°, 0°) If used, you may need 8-ply grade 190 UD tape or a total thickness of 0.058 inches to protect against hail strikes. However, for the same application, TPUD helicoid layup (using 0.0023 inch plies or less) can meet the impact requirements and layup rules using 16-ply 0.037 inch laminate.

5. Helicoid stacks combine TPUD and thick plies to produce uniquely tuned strength/impact laminates that are superior to conventional layups. One drawback of TPUD is that because more layers are required, the layup of the laminate may require more time compared to thick ply material parts. This defect can be partially prevented by using a combination of thin and thick plies. In an exemplary case that this disclosure addresses, thin helicoid plies can be used for portions of the layup to adjust the layup and increase overall impact capacity, while thick plies can be used to reduce layup time and It can also increase overall strength. In one preferred embodiment, helicoid plies may be used near the exterior surface of the laminate to improve impact strength, and thicker plies may be used on the remainder or middle portion of the layup as the primary load bearing mechanism. For example, in the example of a wind turbine blade, one may have a thick inner layer using unidirectional fibers, which may be surrounded by or encapsulated within a layer of helicoid material. As a further example, helicoid materials can be used in the inner layer of a pressure vessel to prevent propagation of cracks to the outer layer of the pressure vessel. If desired, helicoid materials may be used in the middle or outer layers of the pressure vessel in addition to or instead of the inner layer of the pressure vessel.

An example of this is shown in Figures 18A-18C, which show schematic diagrams of ply arrangements of fiber reinforced composite structures 10 according to embodiments of the present invention. Figure 18b shows a cross-sectional view of the structure shown in perspective in Figures 18a and 18c. The composite structure 10 has a first plurality of plies 11 of reinforcing fibers defining a first region of the fiber reinforced composite structure, the ply comprising parallel fibers, the plies providing load bearing properties to the reinforced composite structure. It is placed to provide strength. In the illustrated embodiment, the first plurality of plies 11 includes five plies. The bottom 2 plies are positioned at +80°/-80°, and the top 3 plies are positioned at 0°. In this embodiment, the 0° ply is placed along the axis of an axisymmetric part, such as a tubular structure, and imparts strength in the direction of the primary load. The +80°/-80° ply serves to reinforce the 0° ply and to resist buckling of axisymmetric parts, which is advantageous for long, thin tubular structures.

A second plurality of plies 12 of reinforcing fibers define a second region of the fiber reinforced composite structure and are arranged in helicoidal relationship, with the inclusion angle between the orientation directions of at least two adjacent plies being in the reinforced composite structure. Greater than 0° to less than about 30° to provide impact resistance. In the illustrated embodiment, the plies are positioned (from top to bottom) at 70°, 65°, 60°, 55°, 50°, 45°, 40°, 30°, 20°, and 10°. As described elsewhere herein, this helicoid relationship provides impact resistance to the substructure.

The third plurality of plies of reinforcing fibers may be disposed on opposite sides of the second plurality of plies of reinforcing fibers to provide impact resistance to both sides of the first plurality of plies located midway between the second ply and the third ply. The second plurality of helicoid plies are shown as TPUD plies and the other plies as thicker plies which are advantageous in terms of impact resistance, primary load carrying capacity and reduced layup time, but the thickness of the plies varies for each ply. You can do the same for

6. TPUD helicoid stacks can be manufactured with variable cloaking to create uniquely tuned laminates that possess superior strength and impact properties than conventional layups. For example, instead of using the standard cloaking of 45° and 90°, which is typical of the industry, or the consistent 5° cloaking that can be implemented in a basic helicoid layup, the cloaking may vary by a few degrees for each subsequent lamina. A helicoid layup can be created. The resulting laminate can possess any pitch and tuning that independently meets the needs of the product environment (e.g., thermal, impact and strength requirements) while minimizing the weight of the part.

7. Helicoid layouts created using tight cloaking and thin plies showed less tendency to deform than conventional layups using standard cloaking and standard ply thickness. Additionally, residual strain in the TPUD asymmetric/unbalanced stack can often be overcome by component geometry or local reinforcement effects. Accordingly, the left-hand only and right-hand only TPUD helicoid layup allows the helicoid TPUD layup to include exemplary strength and impact properties while having the smallest gauge and the lowest possible weight.

8. Helicoidal stacks combining TPUD and thick plies can be manufactured with variable cloaking to create laminates with independently tuned strength/impact capabilities that are superior to conventional layups. Accordingly, layup costs can be minimized using thin and thick plies, while also optimizing strength/helix tunability, while variable cloaking pitch can be used to maximize higher or variable properties. For example, the selection of thin and thick plies may be driven primarily from a layup cost perspective, while variable cloaking may be selected to resist resin microcracks within the vertical lamina. Other combinations of cost-to-strength, cost-to-impact resistance, and cost-to-weight adjustments may be considered to improve cost performance.

One of the main advantages of composite parts is that they can be tuned by adding and deleting plies, thus increasing strength and impact resistance in higher load areas while maintaining minimum thickness and weight in other areas. In many cases, components provide localized reinforcement and/or load-bearing and/or structural support around openings in structures, such as fastener locations and conduit passages, or bicycle rims around spoke attachment points or aerospace structural assemblies using rivets. Pads are added to the bonding area to improve strength. Other cases include thickening areas where high impacts are expected, such as the leading edges of wings or wind turbine blades, golf clubs, striking areas of bats and clubs, protective helmets, etc. In other cases, one area can be manufactured flexible and another area rigid, as in the case of fishing rods, golf clubs, pole vaulting poles, sailing masts, skis and snowboards, and sneakers. As another special case described in this disclosure, the pad-up region of the component may consist of any of the helicoidal modifications described in this disclosure. This pad-up can be introduced into a base conventional layup or a base helicoid layup of the same or different structure. As detailed in the eight example examples listed above, TPUD helicoid laminates allow for structures with better or equivalent performance with reduced minimum gauge and/or lighter weight. Rules of minimum orientation to protect against accidental loading (e.g. any one direction The rules of balance/symmetry (not laying out more than 10% of the fibers) are less used in TPUD helicoidal structures or can be ignored in some cases.

Hybrid Materials Helicoid Structures: Helicoid laminates comprising nanomaterials, variable pitch and partial helix, and TPUD can be used as hybrid materials (e.g., textile composites, non-polymers, metals, foams, sandwich materials, and/or industrial applications). It can be combined with other materials (known or later developed) to improve properties such as overall weight, manufacturing cost, bearing capacity, stiffness, and impact resistance. These combinations can be used either holistically (e.g. combining nanomaterials throughout the matrix resin) or smartly (e.g. thin helicoids) to control specific strength and impact properties while minimizing cost, weight and/or thickness. This can be implemented (by placing a layer of titanium foil instead of four plies of prepreg of conventional thickness) in a helicoidal and thick helicoid helix. Specific exemplary embodiments of hybrid helicoid structures are as follows:

1. Helicoidal structures with woven composite plies distributed within the stack or on the inner and outer surfaces can be created with unique cloaking arrangements selected to improve impact performance. Fabric plies can be usefully used on the inner and outer surfaces to minimize fiber protrusion when perforating or trimming. Within the layup, the fabric can be used to create a unique combination of cloaking/spiralization and coordination, which helps absorb and dissipate impact forces and also minimize the effects of impact fatigue. The fabric ply may also contain metal foils, fibers or mesh to help dissipate lightning strikes, conduct electrical current, shield electrical components or alter thermal conductivity.

2. Helicoidal structures can be created with metal foils on the inner and outer surfaces to improve erosion and impact capabilities. Accordingly, the metal foil can prevent bearing failure, reduce or delay erosion, and/or yield under impact while keeping the helicoid structure intact to improve impact resistance and load bearing.

3. Placing a layer of cushioning foam or sandwich material at the center of the helicoid stack can increase shear stiffness, cushion inertial loads, dissipate impact energy, and/or improve buckling resistance. These structures can improve component strength-to-weight ratio, noise properties, fatigue capacity, thermal insulation, and impact/damage resistance.

4. 2-axis (e.g. [+x°/-x°]), 3-axis (e.g. [0°,+x°,-x°]) or 4-axis (e.g. [0°, ±45°, 90°]), or the through-thickness impact strength of the skin can be improved by using a helicoidal TPUD skin in a sandwich structure instead of a conventional skin structure made of fabric. Skin buckling can be delayed under in-plane compression. This is due to the smaller angle between the plies and the higher number of plies, which leads to weight reduction. In this structure, helicoidal laminates provide greater through-thickness impact strength and compensate for and offset the weaknesses in out-of-plane strength typical of thin ply laminates. Therefore, helicoidal lamination of thin plies can improve the in-plane properties of thin plies to enhance weight reduction.

5. By introducing nanomaterials into the matrix resin, it is possible to improve the bond between the helicoid ply itself and the hybrid material (e.g. metal and sandwich), thus improving the inter-laminar strength and properties dependent on this (e.g. , strength shear, bending tension, compression and impact) can be improved.

For sandwich structures, the advantages mentioned above can be achieved by using a face sheet or skin along with the core. However, conventional wisdom in the composites field is to form composite layups that are balanced and symmetrical. The minimum thickness of the skin is therefore relatively large to accommodate all the ply layers needed to provide balance and symmetry. It is known to use unbalanced layups for certain applications, but this is limited to impact resistance aspects. Embodiments of the invention herein provide an impact-resistant composite skin sandwich structure wherein at least one of the skins includes a plurality of plies of reinforcing fibers arranged in a helicoidal relationship that is not necessarily balanced and/or symmetrical. do.

The thickness or weight of the skin may be related to the final intended use of this sandwich structure. For example, according to embodiments of the invention, the total textile fiber areal weight of the skin is less than about 1,600 gsm. This fabric weight can be used for surfboards, for example. In another example according to an embodiment of the present invention, the total fabric fiber areal weight of the skin is less than about 5,000 gsm. This fabric weight can be used, for example, for wind turbine blades made of E-glass fiber. According to embodiments, the thickness of the epidermis is less than about 4 mm. For carbon fiber, the weight of the skin may be less than about 3,000 gsm, according to embodiments. The skin of the composite sandwich structure can have a partially directional (or quasi-isotropic) strength profile and also improve impact resistance.

Additionally, the helicoidal arrangement of the epidermis has excellent in-plane compression resistance. For multiaxial laminated skins of conventional sandwich structures under compression, the off-axis plies (i.e., plies whose fiber directions are not aligned along the loading direction) typically fail first with the formation of matrix cracks. These matrix cracks in many cases occur in a direction parallel to the off-axis ply and are aligned within and/or adjacent to the toe of the off-axis ply. From here, matrix cracks propagate into the interply interface damage, which can cause delamination and lead to premature catastrophic failure. This is particularly noticeable in conventional skins with off-axis plies that are oriented away from the major orientation, for example ±30°, ±45° and ±60° and 90°.

The presence of the helicoidal fiber arrangement results in better redistribution of the load along the off-axis plies and makes the formation and propagation of cracks more difficult. This is due to one or both of at least two reasons. First, helicoid fiber arrangements typically have fewer off-axis plies compared to conventional skins and/or the off-axis plies are placed at a smaller angle to the reference direction (0°), thereby reducing the number of sites at which matrix cracks occur. It becomes less.

Second, the propagation of interlaminar cracks at the interface between two plies is determined at least in part by the interlaminar shear stress, which is caused at least in part by the difference in directional elasticity from one ply to the next. . The greater the difference in elasticity from one ply to the next along a common reference direction, the more likely it is that interlaminar matrix cracking will occur. In a helicoid structure, the fiber orientation between adjacent plies transitions smoothly, so the difference in elasticity from one ply to the next is smaller (compared to a conventional skin), resulting in lower interlaminar stress at the interface between plies. is reduced, and crack propagation and delamination are delayed even when compressive load increases. These detachments can locally reduce the rigidity of the epidermis, which can cause premature buckling of the epidermis. Therefore, in the case of helicoidal fiber arrangement, even if matrix cracks occur in the off-axis plies, the formation of delamination is delayed and leads to an improvement in compressive strength.

The bending or flexural resistance of composite structures (as determined by the three-point bend test, known in the industry) is often limited by the skin of the sandwich under compressive loading (as opposed to the opposing skin under tensile loading), so Helico The in-plane compression resistance of the id skin is particularly advantageous in sandwich structures.

According to embodiments of the invention, the sandwich structure may have a three-layer structure comprising two helicoid skins and a core material between them. However, embodiments of the invention also include three-layer structures where only one of the skins is a helicoid skin and the opposite skin may comprise, for example, a conventional composite material. This structure is suitable for a design environment in which the sandwich structure is subject to bending forces in only one direction, and/or in a design environment in which only one surface of the sandwich structure is expected to receive impact forces. Likewise, the core may include two or more layers of material and/or may be formed from two or more types of core material. Additional layers of composite material may also be included to provide rigidity or other structural properties.

Curved fibers within the ply can be created using conventional or robotic fiber placement equipment. In this case, relatively narrow strips of slit tape or tow (e.g., ¼ inch) can be simultaneously placed side by side within a wider band (e.g., 4 inches). The placing head can vary the heat, placement pressure, and angular shear laydown forces so that the band can be placed in an arc (e.g., radius of 200 mm), s-shaped, or arbitrary shape instead of the conventional straight orientation used when placing most composites. It can be adjusted to the desired contour (see Figure 17). This curvature can add more degrees of freedom to the helicoid stack and can be used with any of the alternative designs discussed in this disclosure. In-plane curvature in 2D or 3D shapes combined with helicoidal ply lamination can further increase wavelength tuning and impact capabilities.

Thin ply fabrics (TPW) are a new class of high-performance fiber-reinforced materials that offer high strength and abrasion resistance. TPW fabrics typically take two forms, as shown in Figure 19: 1) Spread tow fabrics, where the tow is spread into thin, flat, one-way tapes (with fiber areal weights similar to TPUD) and then the various tapes are wrapped around the fabric. woven into shapes); and 2) fabrics manufactured using light tow. Lightweight tow is defined herein as tow having 1k-12k filaments per tow for carbon filaments and tow having a weight of less than about 300 tex for glass. Lightweight tow TPW fibers according to embodiments of the invention generally include natural fibers (up to 320 tex), aramid fibers (up to 300 tex), UHMWPE fibers (up to 300 tex), polypropylene fibers (up to 200 tex), and composites. Other typical fibers used and mixtures thereof may also be included.

According to embodiments of the present invention, TPW fabrics are laid up helicoidally and provide superior impact performance compared to conventional thick tows. As used herein, a helicoid layup of fabric (including both TPW and QUDW) is a helicoid where the included angle between the two corresponding toe directions of the contacting fabric layers is offset by the helicoid angle. Refers to a layup. For example, the warp tow of two overlapping fabrics is [0°/5°/?? to define the placement] can be offset by 5°, and thus the weft tow is offset by 90° [in the 90°/95°/... direction].

The superior impact performance of the helicoid TPW layup disclosed herein is due to the ability of subcritical matrix splitting (impact-induced) to grow more gradually and to nest within the laminate in a spiral crack pattern. It is in When any textile composite is impacted, failure mechanisms initiate splitting in the (isolated) matrix, which typically has a lower tensile strength than the fiber material. This division may begin in a portion of the matrix between the tows, as shown in Figures 20(a)-(c), or may begin through the tow (and parallel to its fiber orientation direction). Figure 20(a) shows a two-layer conventional fabric with alternating warp tow and weft tow, Figure 20(b) shows a two-layer spread tow TPW fabric, and Figure 20(c) ) shows two layers of light tow TPW fabric. However, in order for the split to proceed and absorb more shock, the split needs to traverse the fibers of the next tow in the splitting direction. For fabrics, this next tow is approximately perpendicular to the split tow, so this split separates the fibers of the next tow (as shown in layers 1 and 2 in Figure 20(a)-(c)). It needs to be broken (in the direction of tension).

In fiber-reinforced composites, translaminar fracture toughness increases with ply thickness. However, contrary to expectations, through-lamina fracture toughness does not increase linearly with increasing ply thickness. As an example, doubling the thickness of the plies or the number of toes would more than double the energy required for crack propagation. This involves the activation of additional energy dissipation mechanisms such as splitting, delamination, kink band (compression) and fiber drawing (tension), which contribute to the energy dissipation process.

If the energy released upon fracture through the lamina of orthogonal tows is too high to arrest fracture at the interface with adjacent fabric layers, this can lead to unstable crack propagation and resulting catastrophic failure. The use of TPW fabrics with lower tow counts and/or spread tow layers significantly reduces the amount of energy required for fracture of the (relatively) thin tow/spread tow of the weft, thereby facilitating the failure mechanism of the helicoid structure. Can be activated without instability. In an exemplary embodiment, composite structures with TPW fabric layers laminated in a helicoidal arrangement may exhibit helical cracking patterns and thus exhibit superior impact resistance compared to conventional thick ply fabric composites, which may fail in an unstable manner. there is. Use cases for TPW fabric composites include sporting goods, automotive/motorsports components (including wings, splitters, diffusers, and body panels) and marine components (including hulls, masts, and decks). Other use cases include consumer products such as suitcases and luggage. Suitcases and travel bags made from polypropylene fibers according to embodiments of the present invention provide impact protection and toughness at a reasonable cost.

According to embodiments of the present invention, quasi-unidirectional woven (QUDW) fabrics can be provided in standard, thick, and thin fabrics and can be helicoidally arranged to enhance impact performance. QUDW fabrics are highly unbalanced fabrics where more than 80% of the fibers are aligned along the warp direction and the remainder (less than 20%) are aligned along the weft direction, as shown in Figure 21 (a) to (c). and has the function of providing stability and drapability of the fabric. The fibers of the weft may differ from those of the warp to maximize the difference in elastic properties from the warp fibers (i.e., load-bearing fibers). This difference in elastic properties can be useful in creating fabrics with orthogonal elastic properties similar to those of a unidirectional ply, where the elastic properties orthogonal to the fiber direction are dominated by the matrix properties. In other embodiments, the fibers along the warp direction (greater than 80%), and thus forming the majority of the fabric, may be glass fibers to provide most of the stiffness and strength of the ply using a relatively inexpensive fiber type. can be manufactured. The fibers (less than 20%) of the weft tow can be made of carbon fiber, which is more expensive and performs better than glass to provide a stiffening effect in the direction perpendicular to the warp yarn.

When the QUDW fabric is arranged in a helicoid shape to achieve the failure mechanism of the helicoid layup according to an embodiment of the present invention, the imbalance of the fabric and the relative spacing between the dispersed weft yarns achieve enhanced impact performance. It is advantageous to As explained above with respect to TPW fabrics, matrix splits that form along the warp yarns can propagate in neighboring ply fabrics without being stopped by the weft yarns crossing over the warp yarns. Therefore, there is no need for the fibers to be fractured to allow the formation and growth of helicoid cracks to utilize the helicoid layup failure mechanism.

As shown in Figures 22 (a) and (b), embodiments of the present invention include larger included angles for the QUDW fabric. Areas where the weft yarns of two adjacent plies overlap produce higher resistance to propagation of helicoidal cracks because the energy required for the crack to propagate helicoidally is required to fracture the fibers of the weft yarns. This could lead to destabilizing and catastrophic destruction.

By increasing the frequency (reducing the spacing) between the weft yarns, the laminate becomes more balanced. Figure 22(a) shows two QUDW plies with 95% warp fibers and 5% weft fibers, while Figure 22(b) shows 75% warp fibers and 25% weft fibers. Shows two QUDW plies provided. Reducing the spacing of weft yarns increases the total area of overlap of adjacent weft yarns in small narrow-angle layups. However, for larger narrow angle layups, the total area of overlapping weft yarns can be more smoothly increased by reducing the spacing of the weft yarns. Therefore, for larger pitch angle helicoidal laminates, the number/frequency of weft yarns can be increased (thus improving the balance) without resulting in an excessive increase in overlapping weft yarns. As a result, the length of the split is shortened compared to the helicoidal QUDW laminate with a smaller pitch angle. This promotes nesting of cracks and propagation of damage and makes the fracture process more stable.

QUDW fabrics can be made from carbon fiber, and fiber types typically used in composites. According to embodiments of the invention, the warp yarn and/or weft yarn may be formed from glass fibers. Examples of uses for QUDW fabric composites include sporting goods, automotive/motorsports components (including body panels, chassis components, battery cases, and skid plates), wind turbine blades, tubes, and marine components (including hulls, masts, and decks). Included.

Accordingly, the present disclosure details a variety of new helicoid design and enhancements over the prior art. The present disclosure relates to (a) nanomaterials, (b) variable pitch and partial helix, (c) TPUD, (d) hybrid materials, (e) curved fibers in plies, (f) automated fibers for 2D or 3D preforms, or Helical pitch and structural materials including tape placement, (g) non-crimped fabric, (h) 3D fabric, (i) 3D printed material, and (j) filament wound part, (l) TPW, and (m) QUDW. /Instructs specific changes to substitutes.

Accordingly, in accordance with the present disclosure, the following examples illustrate aspects of the present invention. However, it will be understood that these examples are intended to be illustrative and non-limiting.

Example 1 : CNFs, CNTs, SWNTs, MWNTs, graphite platelets/graphene, organic spherical particles, copolymers, inorganic clays, silica, silicon carbide, alumina, metal oxides, and other known or later developed nanomaterials. Helicoidal structures containing nanomaterials including but not limited to. It is shown that introducing nanomaterials into the resin in combination with fiber reinforcement improves mechanical properties and impact resistance compared to conventional composite laminates of the same thickness. If desired, nanofibers (fibers with a diameter of less than 100 nm) can be introduced into the material. Nanomaterial whiskering between fibers can improve transverse and intra-lamina shear properties and reduce or eliminate resin cracking resulting from low- and medium-level impacts. Helicoidal layups with shallow cloaking angles that increase the length of direct contact between the interlaminar fibers can improve the whiskering effect. This extended contact length due to tight helicoid cloaking makes nanocomposite additives more effective when incorporated into helicoid layups than when used in industry standard layups. Helicoid layup using nano additives not only reduces/eliminates vertical/horizontal resin cracks within the lamina, but also reduces/eliminates resin cracks between laminas in the horizontal direction, and preemptively suppresses the occurrence of delamination. You can.

Example 2: TPUD helicoid structures produce tightly cloaked helicoids with short interlaminar resin shear zones and substantial direct fiber-to-fiber contact. This layup is impact resistant, resists cracking (both from impact and cold temperatures), and improves load sharing between the laminae. TPUD helicoid laminates can reduce minimum gauge and/or enable better or equivalent performance structures that are lighter. Rules of minimum orientation to protect against accidental loading (e.g. any one direction The rules of balance/symmetry (not laying out more than 10% of the fibers) are less used in TPUD helicoidal structures or can be ignored in some cases. Specific variations of this embodiment include:

1. Helicoid stack with all layers being TPUD ply.

2. TPUD helicoid stack of sequentially cloaked helicoids.

3. TPUD helicoid stacks that are thinner than conventional layups but adhere to industry standard rules of balance, symmetry, and minimal orientation with similar or better strength and impact.

4. Thinner minimum gauge TPUD helicoidal stacks that retain the desired properties while complying with traditional layup symmetry, balance and minimum orientation rules.

5. Helicoid stack, which combines TPUD and thick plies to create a uniquely tuned strength/impact laminate that is superior to conventional layups. For example, thin helicoid plies can be used as part of a layup to adjust the layup and also increase overall impact capacity, while thicker plies can be used to shorten layup time and increase overall strength. there is.

6. TPUD helicoidal stack with variable cloaking to create a uniquely tuned laminate, which still has superior strength and impact properties than conventional layups.

7. Helicoid stacks using tight cloaking and thin plies that are less prone to deformation than conventional layups using standard cloaking and standard ply thicknesses. This allows helicoid TPUD layups to include exemplary strength and impact properties while having the smallest gauge and lowest possible weight.

8. Helicoid stacks combining TPUD and thick plies can produce independently tuned strength/impact superior to conventional layups by using variable cloaking. For example, the selection of thin and thick plies may be driven primarily from a layup cost perspective, while variable cloaking may be selected to resist resin microcracks within the vertical lamina.

9. The pad-up area of the part may include any of the helicoid variations described in this disclosure. This pad-up can be introduced into a base conventional layup or a base helicoid layup of the same or different structure.

Example 3 : Helicoidal structures of hybrid materials combine any of the previously mentioned nanomaterials, variable pitch and partial helices, and TPUD plies with hybrid materials (e.g., non-polymers, metals, foams, and/or sandwich materials). By using it in combination with , strength, durability, rigidity, and impact resistance can be improved. These combinations can be implemented globally or in selected areas to control specific strength and impact properties while minimizing cost, weight and/or thickness. Specific variations of this embodiment include:

1. Heli distributed fabric composite plies within the stack or on the inner and outer surfaces to create a unique cloaking arrangement selected to absorb and dissipate impact forces, minimize fiber protrusion when drilling or trimming, and improve erosion capacity. Coid variant example. The fabric ply may also contain metal foils, fibers or mesh to help dissipate lightning strikes, conduct electrical current, shield electrical components or alter thermal conductivity.

2. Helicoid modification with improved erosion and impact capabilities by providing metal foil on the inner and outer surfaces.

3. Helicoid variants that increase shear stiffness, cushion inertial loads, dissipate impact energy, and/or improve buckling resistance by placing a cushioning foam or sandwich material in the center of the layup. This also improves component strength-to-weight ratio, noise properties, fatigue capacity, thermal insulation, and impact/damage resistance.

4. Helicoid materials can be manufactured using thin ply unidirectional (TPUD) materials assembled into a sandwich structure instead of conventional skin structures made of non-crimped fabrics or fabrics. This structure can improve impact strength and also delay skin buckling under in-plane compression. In this structure, helicoid TPUD lamination is expected to be able to realize relatively high impact strength in the thickness direction and to complement and offset the weakness of the out-of-plane strength of thin ply laminates. Therefore, in this embodiment, helicoidal lamination of TPUD can enhance the in-plane properties of the thin ply, ultimately reducing the weight of the part.

5. Use of nanomaterials in the resin to improve the bond between the helicoid ply itself and the hybrid material (e.g. metal and sandwich), thus improving the interlaminar strength and properties dependent on this (e.g. strength shear). , helicoidal modifications to improve bending, tension, compression and impact).

Example 4 : Using automated material placement equipment to deposit continuous fibers, tapes or fiber patches to create any of the previously mentioned helicoid designs with the additional reinforcement of bending the fibers within a given ply. can do. These curvatures can add more degrees of freedom to helicoidal stacks in 2D or 3D shapes and can be used to further increase wavelength tuning and impact capabilities.

Example 5 : Helicoidal multiaxial (HMX) non-crimped fabric [0°, 22.5°, 45°, 67.5°, 90°] can be manufactured. Next, fold this roll by dividing its width into two around the 0° axis, or simply combine it with another identical roll turned over to form 10 ply HMX [-90°,-67.5°,-45°,- 22.5°, 0°, 0°, 22.5°, 45°, 67.5°, 90°] can be formed. In another embodiment, a first helicoid MX fabric (e.g., [56°,79°,-79°,-56°]) is taken from a large continuous roll and rotated 90° (e.g., [-34°,-11°,11°,34°]) overlapping each other to form 8 ply HMX fabrics (e.g. 8 ply [56°,79°,-79°,-56°, -34°]). °, -11°, 11°, 34°] can be manufactured. As with individual plies, two HMX stacks can be joined using stitching or powder binders or heat laminated thermoplastic nonwoven veils or any other suitable known technique (e.g., air punch or needle punch).

This is an efficient and innovative method that proposes HMX with eight or more helicoid plies embedded within one HMX fabric roll to overcome the mechanical limitations commonly found in the composite industry. These HMX rolls can be pre-impregnated.

Example 6 . Structures based on helicoid architecture for a variety of axisymmetric parts such as pipes, tapered tubes, tanks and pressure vessels (typically spherical or cylindrical, which may have domes on one or both ends) using filament winding. can be created. For some applications, these filament winding components (such as hydrogen pressure vessels in the form of vehicle fuel tanks) must be highly resistant to external shocks, withstand large impacts, and undergo crash and drop tests to avoid explosions. These structures can be manufactured using full or partial helicoid laminates to increase impact strength and also have more diffuse crack propagation to avoid gas leaks and extend operating life.

Using filament winding techniques, helicoidally formed unidirectional fiber bands or tapes can be interlaced, for example, by winding them from one end to the other on a mandrel. This interlaced helicoidal pattern (e.g., illustrated in Figure 5h) can complete the covering of the mandrel with a two-angled +X°/-X° bilayer. This angle can be measured from the mandrel axis of rotation, which is the 0° angle reference. In this technique, the relative angle between two adjacent plies within this double layer is 2X° for X<45° (e.g., 14° for X=7°) or In the case of 45°, it may be 180°-2X° (for example, -10° in the case of X=85°). Therefore, this filament winding technique produces continuous interlaced helicoidal bilayers with small, shallow cloaking angles (e.g., 5° to 10°) between the helicoidal bilayers around a 0° or 90° orientation. It is possible. Around the 45° direction, the fibers intersect at almost right angles.

In a further embodiment, structures with filament wound helicoid architecture can be manufactured by winding layers of fibers that all have the same angle or have varying angles within the layer/ply. This can be achieved by programming the robotic filament winding machine to wind the desired pattern or by adjusting the settings of the roving dispenser. This technique allows complete winding of multiple surface plies of fiber by slightly varying the cloaking angle between plies to take advantage of the helicoid architecture. As an example, winding continuous plies circumferentially at relative angles close to 90° (88°, 84°, 80°, 76°, 72°, etc. in 4° increments) results in much higher impact strength and more diffusive ply. A pressure vessel-resistant product with crack propagation can be obtained. This helicoid architecture can also be used as an inner layer to increase the safety factor regarding gas leakage through cracks within a partially damaged laminate structure. The full winding process can further increase resistance to transverse loads by combining the pultrusion of a profile with a main direction of fiber reinforcement of 0° and wound fibers or tapes. These wound plies can also realize higher lateral impact resistance properties by adjoining them with a slight change in their angle from a structure with a helicoid architecture.

Example 7. Braided and skewed fabric. Braids manufactured using 2D or 3D techniques offer an interesting property called diameter variation related to changes in fiber angle. The fibers can slip within the tubular braids, thereby expanding or contracting the diameter of these braids. These properties allow multiple layers to effectively slide against each other to gradually enlarge the diameter of the structure and slightly change the fiber angles between and/or along the layers, creating a very small change in cloaking angle between two adjacent braided layers. It may be advantageous to create a structure with a sleeved helicoid architecture. This braided fiber reinforced structure can be provided in the form of a flat braided tape obtained from a tubular braid that is cut along its length and then opened and flattened. The angular orientation of the fibers also depends on the width of the tape. These braided tapes can also be used to create structures with a helicoidal architecture by stacking different layers of the same tape with slightly different fiber angles. This property can also be found in fabrics that have been skewed to change the initial 90° angle between the warp and weft yarns, resulting in small angle changes from one fabric layer to the next (90°, 85°, 80°, It can be adjusted to create a series of warp/weft angles (such as a cloaking angle of 5° to arrange the layers at 75°, etc.) to create a structure with a helicoid architecture.

Example 8 : Additive Manufacturing. Many of the techniques described above utilize existing sets of fabrics, prepregs, etc. In this embodiment, an alternative method for forming a helicoid architecture is provided. Additive manufacturing includes stereolithography (SLA), which uses a laser to cure photopolymer resin layer by layer; melt deposition modeling (FDM), which uses a 3D printer to deposit thermoplastic materials, and printer heads that deposit the material in three dimensions. There are multiple routes, including multijet modeling (MJM), which can deposit materials, and selective laser sintering (SLS), which uses high-power lasers to fuse small polymer, metal, or ceramic/glass particles. All of the above-mentioned techniques allow the construction of helicoid structures. The method used depends in part on the materials used and the length scale of the features required for the particular application. Therefore, this offers many opportunities not only for fabricating helicoid materials, but also to enable their multifunctionalization by printing, z-pinned structures, etc. of materials that are not available in fiber or prepreg form. .

In one embodiment, multijet modeling (MJM) uses multiple printer jets to simultaneously print two or more materials that have a helicoidal structure and are offset by a certain angle (e.g., double helicoids). Alternatively, two or more materials can be printed simultaneously, with one material acting as an in-plane helicoid and the other material printing out-of-plane acting as a z-pinned structure. Moreover, the material does not have to be printed in solid fiber form. For example, during printing, a “core-shell” print head can be used to print core-shell material, where the shell is the desired final material and the core serves as a sacrificial template. do. In one embodiment, a hydrophobic polymer such as polypropylene (PP) can be printed with polyvinyl alcohol (PVA) as the core. After printing, the structure is placed in an aqueous bath to remove the PVA, resulting in hollow PP fibers/tubes. In other embodiments, the material need not be printed as a polymer, but can be printed as a ceramic-based precursor (eg, SiC, B ₄ C, etc.). Here, a ceramic precursor (for example, polycarbosilane, a precursor of SiC) as a shell can be printed with PVA as a core. When annealed at low temperature (e.g. 200°C), the ceramic precursor solidifies (not yet transformed to SiC). Thereafter, the PVA can be safely removed without collapsing the tube, and then the obtained structure can be annealed to completely transform the ceramic precursor into a specific material (e.g., SiC). The resulting fibers can be microtubes or nanotubes that can serve as transport channels for fluids (air, water, self-healing resins, thermal cooling materials, etc.).

Many additive manufacturing methods allow real-time adjustments in which printing material to use, allowing gradient structures to be built precisely. This can be applied in a variety of ways, including but not limited to the following.

1. The stiffness or hardness of the deposited material (or any other material property depending on material composition, particle size, etc.) can be varied stepwise by continuously varying the material in the print reservoir.

2. By further adjusting the rotation angle of the helicoid, It is possible to form graded helicoid composites that can yield additional mechanical advantages.

In another implementation, an existing template structure can be placed as a scaffold or sacrificial structure on the printing stage to achieve an architecture that exceeds the helicoid architecture. For example, a 2D or 3D array of fins, tubes, or other structures (e.g., composed of multiple types of materials that can be retained or dissolved) can be placed on the build plate of an SLA printer. You can. A helicoid architecture can be printed around this scaffold and then removed by removing the scaffold, retaining the helicoidal structure while retaining its impact resistance but providing additional benefits (e.g. mechanical advantages such as z-peening and thermal cooling). Obtain a multi-structure with a coid architecture. In another implementation, curved structures can be easily printed using this 3D printing technology. In this case, a simple CAD model can be built to allow (for example) an FDM printer to place the fibers in a helicoidal array, but as curved macrostructure parts.

Example 9: Helicoidal structure of TPW and QUDW fabrics combines the superior impact resistance benefits of helicoid architecture with the benefits of a class of fabrics for improved drapability, reduced layup time, improved wear and appearance. This layup is impact resistant, resists cracking (both from impact and cold temperatures), and improves load sharing between the laminae. TPW and QUDW helicoid laminates enable lightweight structures by improving the impact performance of conventional fabric laminates while reducing the manufacturing cost of helicoid structures. The presence of weft and warp fibers eliminates the problem of using balanced/unbalanced layups and enables a helicoid solution with a larger design space. Specific variations of this embodiment include:

1. Helicoid stack with all layers being TPW ply.

2. Helicoidal stack with all layers QUDW ply.

3. TPW helicoid stack of sequentially cloaked helicoids.

4. QUDW helicoid stack of sequentially cloaked helicoids.

5. TPW and/or QUDW helicoid stacks combining TPUD, thick plies and thick fabric plies to create a uniquely tuned strength/impact laminate that is superior to conventional layups. For example, TPW helicoid ply is used on top of the layup to locally improve wear resistance, appearance and impact resistance, according to embodiments of the invention, and TPUD or thick UD ply is used for adjusted stiffness and in-plane strength. Can be used to provide.

6. TPW and/or QUDW helicoid stacks with variable cloaking to create a uniquely tuned laminate that still has superior strength and impact properties than conventional layups.

7. Helicoid stacks combining TPW and/or QUDW thick fabric, TPUD and thick UD plies with variable cloaking to create a uniquely tuned strength/impact laminate superior to conventional layups.

Example 10: Conventional lightweight sandwich structures include cores, typically PVC, EPS, honeycomb, aramid fiber honeycomb, shear thickening foam cores (D3O®), and metamaterial cores (MetaCORE ^™ , MetaCORE-LD). ^TM , MetaTHERM ^TM ), etc., provide stiffness, acoustic impedance, weight reduction and other structural and mechanical properties. Lightweight fiber reinforced composite skins having a total fiber areal weight of 5000 gsm or less and/or a skin thickness of 4 mm or less are used to provide strength and stiffness to sandwich structures in lightweight sandwich applications. The use of TPUD, QUDW, TPW, NCF, and UD as single materials or as hybrids with thick plies and standard fabric layers allows helicoid skins to be used in applications where a limited number of layers can be used to create a helicoid layup. can be introduced.

In one exemplary embodiment shown in Figure 23(a), the sandwich application includes a skin of 200 gsm for application to a 5 mm thick PVC core. The skin is arranged so that the parallel fibers of each ply have the same orientation as [-15/-25/-35/-45/-60/60/45/35/25/15], creating a helicoid relationship. It is formed using 10 layers of 20gsm carbon filament TPUD. On the other hand, (b) of Figure 23 shows the conventional TPUD 2 axis of the [+45/-45] ₅ relationship.

Figure 24 shows the results of a three-point bend bend test according to ASTM D7249. Compared to an equivalent TPUD biaxial [+45/-45] ₅ , this helicoid TPUD layup, when tested along the longitudinal (0°) and transverse (90°) directions, was 88% and 54% more efficient, respectively. showed an improvement in bending strength (in the conventional two-axis, the 0° and 90° characteristics are expected to be the same). Compared to a biaxial [+45°/-45°] layer of equivalent standard thickness of equivalent weight, the helicoid TPUD layup according to this example had a 118% reduction when tested along the longitudinal and transverse directions, respectively. and showed an increase in flexural strength of 77%. The resulting innovative sandwich with an oriented helicoid skin therefore has excellent compressive strength of the skin in both the longitudinal and orthogonal loading directions. In fact, considering the orientation of the helicoidal fiber arrangement, it is expected to achieve higher compressive strengths along the longitudinal direction. However, the helicoid arrangement achieves higher stiffness and strength also along orthogonal directions, characterized by a lower percentage of fiber components aligned for load than in the helicoid [+45/-45].

Other embodiments include:

1. Helicoid skin where all layers are TPW ply, or QUDW ply, or TPUD, or NCF, or UD ply.

2. TPW or QUDW or TPUD or NCF or UD helicoid skin of sequentially cloaked helicoids.

3. TPW or QUDW or TPUD or NCF or UD helicoid stack, which is a partially cloaked helix with continuous or variable pitch angle.

4. TPW or QUDW or TPUD or NCF or UD helicoid skins that combine TPUD, NCF, thick plies and thick fabric plies to create a uniquely tuned strength/impact skin that is superior to conventional skins. For example, one layer of TPW can be used as the top skin to improve visual appearance and abrasion resistance, while TPUD helicoid ply can be used for the remainder of the skin to provide tailored impact resistance, stiffness, and in-plane strength. .

5. Sandwich applications with only the upper (impact facing) helicoid skin. This is intended to provide an impact-resistant mechanism where overall rigidity is provided by the geometric features of the structure, such as in applications involving double curvature or complex shapes. This architecture further improves impact performance by imparting higher stress redistribution upon impact.

6. Sandwich applications comprising both an upper (impact facing) helicoid skin and a lower helicoid skin.

7. Sandwich applications where either the upper or lower skin is a helicoid layup or a partial helicoid layup.

8. For sandwich applications where the upper and lower skins are symmetrical.

9. Sandwich application with asymmetric upper and lower helicoid skins.

10. Sandwich applications where the upper skin is helicoid and the lower skin is non-helical, and the upper and lower skins may have similar or different weights. For example, the thick upper helicoid skin provides compressive strength and impact resistance while the lower non-helicaloid skin provides flexural tensile strength and stiffness.

Those skilled in the art will understand that virtually any fabric, whether carbon fiber or other material, can be used and assembled into a helicoidal structure. The methods, systems and products of the present disclosure, as described above and shown in the figures, provide, among other things, improved composite materials and methods for forming them. It will be apparent to those skilled in the art that various modifications and variations may be made in the devices and methods of the present disclosure without departing from the spirit or scope of the disclosure. Accordingly, this disclosure is intended to cover modifications and variations that come within the scope of the disclosure and equivalents of the subject matter.

The following aspects of the invention characterize the invention according to the embodiments of the invention described above:

1. Specifying multiple plies to create a z-direction fiber arrangement that attenuates and absorbs the propagation of shock waves, dissipates strain energy, minimizes the effects of impact fatigue, and minimizes and/or arrests impact-related damage. Helicoid composite ply cloaking/lamination design and method for lamination into dense helical bodies at a pitch of .

2. Aspect 1, wherein the helicoid system is laid up by hand, placed directly on an automated machine, and/or stacked using a weaving/braiding/stitching facility (e.g., a non-crimped fabric machine). Pre-knitted, helicoid system. If laid out as a pre-knitted stack (e.g., 4, 6, 10, or more specifically helicoid plies selected for strength and impact resistance), the stack is dried and later liquid molded or made from prepreg. It can be. This stack can be the entire part, or it can be specific areas of the part selected for helicoid reinforcement using any of the variations disclosed in this disclosure.

3. The helicoid system of Aspect 1, wherein the fibers are bent within a given ply using automated placement equipment.

4. The helicoid system of Aspect 1, wherein the pitched fibers are tuned to a specific wavelength to attenuate propagating shock waves initiated by ballistics, striking forces, or foreign object impacts.

5. The helicoid system of Aspect 1, wherein the cloaking is selected to produce a specific helical pitch or circular z-orientation, and the fibers are sufficiently close together to demonstrate direct load sharing within the significant lamina between the plies.

6. The method of Aspect 1, wherein matrix resin modifications (e.g., lowering monomer functionality, increasing backbone molecular weight, or introducing flexible subgroups) and/or additives (e.g., microspheres, discrete rubber, thermoplastic particles) or veil) is used to strengthen the laminate and prevent the propagation of catastrophic fracture.

7. The helicoid system of Aspect 1, wherein the resin and fibers are specifically selected to take advantage of the difference in elastic modulus between the fibers and the resin.

8. For Aspect 1, the type, amount, and form of fiber reinforcement (e.g., carbon, glass fiber, aramid, ultra-high molecular weight polyolefin fiber, PBO fiber, and natural fiber (such as flax and hemp)), amount, and form depend on cost, manufacturing, and Helicoid system, selected to best suit performance requirements.

9. The method of Aspect 1, wherein the pad-up region of the part comprises any of the helicoid variants described in this disclosure with a base conventional layup or a base helicoid layup of the same or different structure. Helicoid system that can do it.

10. The method of Aspects 1 to 7, wherein nanomaterials (e.g., CNFs, CNTs, SWNTs, MWNTs, graphite platelets/graphene, organic spherical particles, copolymers, inorganic clays, silica, silicon carbide, alumina, metals) oxides, and other known or later developed nanomaterials) are added within the resin, attached directly to the fibers, or disposed as a laminar interlayer. Here, the resulting helicoid/nanomaterial hybrid has nanoscale whiskers/connections, which enable bridging and sharing between fibers, improving the mechanical properties of the overall laminate, improving impact resistance, and It has crack-stopping properties.

11. In embodiment 8, the shear properties in the transverse direction and within the lamina are improved with respect to the helicoid cloaking angle by the addition of nanomaterials (i.e., tighter cloaking angles result in longer contact lengths and fiber-to-fiber contact). greater interaction), helicoid system.

12. The method of Aspect 8, wherein the helicoid/nanomaterial hybrid, when subjected to impact, (a) cracks the resin vertically and/or horizontally within the lamina, (b) cracks the resin between the laminae horizontally, and/or (c) a helicoid system that demonstrates reduction and/or elimination of delamination.

13. The method of Aspect 1 to Aspect 7, wherein the variable pitch and/or portion is adjusted to a specific wavelength and/or orientation in anticipation of the type, level and source of expected impact and/or adjusted to meet specific load requirements. Helicoid system, containing a helix.

14. The method of Aspect 11, wherein a variable cloaking angle (i.e. 5°, 10°, 15°), helicoid system.

15. The method of Aspect 11, wherein the layup is subjected to tight cloaking (i.e., 5°) on one or more of (a) the exterior, (b) the middle, (c) the interior, or (d) the interior, the middle, and the exterior. and a helicoid system, which implements wider cloaking in the remainder of the layup to dissipate impact loads within a specific thickness area of the laminate while still allowing freedom to orient most of the plies for in-plane strength. .

16. The helicoid system of aspect 11, comprising asymmetric and/or unbalanced ply stacking, which may be, for example, only a left-handed helix or only a right-handed helix. These layups can take advantage of helicoidal cloaking without the need to increase thickness to adhere to rules of thumb for balance and symmetry. Parts manufactured with a shallow helicoid clocking angle are less prone to deformation than traditional 0°, ±45°, or 90° layups. Additionally, any tendency to deform can often be overcome by the geometry of the part or local reinforcing effects.

17. The helicoid system of aspect 11, wherein the layup is only partially helical and not cloaked through all 360 degrees. This layup isolates the impact benefits of the helicoid structure in certain laminate areas while optimizing the load-bearing fibers in other areas.

17.1 The helicoid system of Aspects 1 through 7 using TPW and/or QUDW plies disposed within a helicoid helical body. The specific structure of these fabrics is characterized by the low through-lamina fracture toughness of the weft yarns (TPW), and the large spacing between the weft yarns (QUDW) activates the highly dissipative fracture mechanism of the helicoid structure and strengthens the fracture toughness. It can be adjusted to achieve impact performance. The use of fabric can improve the drapeability of helicoid stacks into complex shapes and reduce layup costs.

18. The helicoid system of aspects 1 to 7, using TPUD plies (typically 0.0023 inches/ply or less) disposed within a helicoid helical body. The resulting tightly cloaked helicoid helicoid has a relatively short interlaminar resin shear zone, resulting in greater direct fiber-to-fiber contact/load sharing (i.e., smaller aspect ratio) and thus higher impact resistance and crack arresting capabilities. . Additionally, the TPUD layup showed improved strength when compared to a conventional layup of similar thickness.

19. The laminae of Aspect 16, which has excellent ability to resist resin cracking from impact as well as extreme environments such as those that may be experienced in space and cryogenic tank applications (e.g., temperatures from -200 to 415°F). Helicoid system, which shows the ability to minimize intra- and interlaminar cracking.

20. The helicoid system of Aspect 16, wherein the continuously cloaked helicoids exhibit strength over a highly oriented conventional stack (with additional plies in the primary load bearing direction) while providing improved impact properties. In these applications, even if the helicoid layup has a lower total number of fibers in the primary load direction, the combination of thinner plies and slightly cloaked, off-angle fibers provides efficient interlaminar load sharing, resulting in superior strength. Ability is gained.

21. The helicoid system of Aspect 16, wherein the total thickness may be less than that of an equivalent conventional Raman spectrum, but the strength and impact capacity may be equivalent or greater. Therefore, thinner and lighter TPUD helicoid laminates can be manufactured while complying with industry standard rules of balance, symmetry, and minimum orientation.

22. Aspect 16 of a thinner or smaller gauge (which can be taken in the case of significant loads such as hail or bird strikes) while having the desired properties and also complying with the symmetry, balance and minimum orientation rules of a conventional layup. thickness), helicoid system.

23. The helicoid system of aspect 16, wherein TPUD and thick ply can be combined to create a part of independently tuned strength and impact capacity. For example, thin helicoid plies can be used as part of a layup to adjust the layup and also increase impact capacity, while thicker plies can be used to shorten layup time and increase overall in-plane strength. there is.

24. The helicoid system of Aspect 16, involving variable cloaking to create a uniquely tuned laminate that still has strength and impact properties superior to conventional layups.

25. The helicoid system of Aspect 16, using tight cloaking and thin plies and having less tendency to deform than a conventional layup using standard cloaking and standard ply thickness. Therefore, helicoid TPUD asymmetric/unbalanced stacks can have minimal gauge and light weight.

26. The helicoid system of aspect 16, wherein helicoid stacking combining TPUD and thick plies and variable cloaking creates a uniquely tuned strength/impact laminate that is superior to conventional layups. Therefore, layup costs can be minimized using thin and thick plies, strength/helix tuning parameters can be optimized to some extent, and properties can be optimized using variable cloaking pitch.

27. The method of Aspect 16, wherein the pad-up area of the component is any of the TPUD variants described in Aspects 17-24 with a conventional layup as a base or a helicoidal layup of the same or different structure as a base. A helicoid system, which may include:

28. The helicoid system of aspects 1 to 25, wherein the helicoid system is combined with a hybrid material (e.g., non-polymeric, metal, foam and/or sandwich material) to improve strength, bearing capacity, stiffness and/or impact resistance. . These combinations may be used globally (e.g., nanomaterials combined throughout a matrix resin) or selectively (e.g., nanomaterials combined throughout a matrix resin) to meet specific strength, erosion, and impact properties while minimizing cost, weight, and/or thickness. layer of titanium foil) can be carried out.

29. Aspect 26, wherein nanomaterials are introduced into the resin to improve the bond between the helicoid plies and the hybrid materials (e.g. metals and sandwiches), thereby improving the inter-laminar strength and properties dependent thereon (e.g. Helicoid systems, which improve strength (e.g., strength, shear, bending, tension, compression, and impact).

30. The helicoid system of Aspect 26, wherein the fabric composite plies are selectively placed within the stack or on the inner and outer surfaces to create a unique cloaking arrangement specifically selected for absorption and dissipation of impact forces. Additionally, if plies are used on the outside, fiber protrusion is minimized during drilling or trimming. The fabric ply may also contain metal foils, fibers or mesh to help dissipate lightning strikes, conduct electrical current, shield electrical components or alter thermal conductivity.

31. The helicoid system of aspect 26, comprising metal foil on the inner and outer surfaces to improve strength, erosion, bearing capacity and impact capacity. In the case of this helicoid/hybrid, upon impact the metal foil can yield and the helicoid ply can absorb/dissipate energy.

32. Aspect 17 and Aspect 18, wherein a cushioning foam or sandwich material is placed in the center of the helicoid stack to increase shear stiffness, cushion inertial loads, dissipate impact energy, and/or improve buckling resistance. , helicoid system.

33. The method of Aspects 1 through 30, wherein shock wave propagation is achieved by introducing consumer products, protective gloves, sports equipment, crash protection devices, wind turbine blades, automotive/aerospace components, hydrogen pressure vessels, structural materials, and other composite products. A helicoid system that attenuates and absorbs, minimizes the effects of impact fatigue, dissipates strain energy, and minimizes and/or arrests impact-related cracking and damage.

34. The method of Aspects 1 to 30, wherein the effects of low energy impacts, medium energy impacts and high energy impacts from planned strikes, impacts, hail, tool drops, ballistics, random fragments, shock waves, lightning strikes, cavitation and airborne fluttering. A helicoid system, which is introduced within a composite structure to minimize

35. Method for manufacturing helicoid structures from non-crimped fabric using a multi-axial fabric machine.

36. The method of Aspect 35, wherein the plurality of helicoid plies are manufactured by manufacturing a plurality of rolls of material and aggregating layers of the rolls of material to form a helicoid sequence of a larger number of plies. method.

37. The method of Aspect 36, wherein a multiaxial helicoidal non-crimped fabric (HMX) (e.g., H-NCF12°:[48°,60°,72°,84°] or H-NCF22.5°:[0 , 22.5, 45, 67.5, 90]), wherein a roll of 4 or 5 helicoidal plies is produced.

38. The method of Aspect 36, wherein the material is inverted from the roll of material to produce material HMX (e.g., H-NCF12°: [48°,60°,72°,84°,-84°,-72°,-60 °,-48°] or H-NCF22.5°:[90,-67.5,-45,-22.5,0,0,22.5, 45, 67.5,90]) forming 8 or 10 ply rolls. Method, including more.

39. In embodiment 38, fold the material from the roll of material about the 0° axis of the roll of material and divide its width by 2 to form the material HMX (e.g., H-NCF12°: [48°, 60°, 72°) ,84°,-84°,-72°,-60°,-48°] or H-NCF22.5°:[90,-67.5,-45,-22.5,0,0,22.5, 45, 67.5, 90]), further comprising forming 8 or 10 ply rolls.

40. The method of Aspect 38, wherein the material is rotated ±90° from the roll of material to rotate the material HMX (e.g., [56.3°,78.8°,-78.8°,-56.3°] by -90°: [-33.8°) ,-11.3°,11.3°,33.8°] to form H-NCF22.5°:[56.3°,78.8°,-78.8°,-56.3°,-33.8°,-11.3°,11.3°,33.8 °]), the method further comprising forming 8 or 10 ply rolls.

41. The method of Aspects 38-40, wherein an operation combining reversal, folding, and rotation of the initial HMX roll can produce a much larger number of fly rolls involving continuous helicoids.

42. The method of aspects 35 to 41, wherein the layers of fabric are combined by a stitching machine or a heat laminated thermoplastic veil, a powder binder or an air punch or needle punch.

43. The method of aspects 35 to 42, wherein a variable cloaking angle as described in aspects 13 to 15 is applied.

Claims (28)

A composite skin sandwich structure, comprising:
The composite skin sandwich structure is:
a core formed from at least one core material, and
comprising at least one epidermis attached to the core,
The epidermis is,
comprising a plurality of plies of reinforcing fibers arranged in a helicoidal relationship, wherein the plies include parallel fibers defining an orientation direction, and between the orientation directions of at least two adjacent plies. A composite skin sandwich structure, wherein the included angle is greater than 0° and less than about 30°. According to claim 1,
A composite skin sandwich structure, wherein the plies arranged in helicoidal relationship are partially helical. According to claim 1,
The composite skin sandwich structure further comprising at least one second skin attached to an opposite side of the core from the at least one skin. According to claim 3,
The at least one second epidermis:
A plurality of plies of reinforcing fibers arranged in a helicoidal relationship, wherein the plies include parallel fibers defining an orientation direction, and wherein the inclusion angle between the orientation directions of at least two adjacent plies is greater than 0° to about 0°. Composite skin sandwich structure, less than 30°. According to claim 1,
A composite skin sandwich structure, wherein the core material comprises PVC foam. According to claim 1,
A composite skin sandwich structure, wherein the core material comprises a honeycomb structure. According to claim 1,
A composite skin sandwich structure, wherein the sandwich structure is arranged to form the shape of an aerospace structure including wind turbine blades, automotive components and wings. According to claim 1,
A composite skin sandwich structure, wherein the sandwich structure is arranged to form the shape of a sporting article. According to claim 1,
A composite skin sandwich structure, wherein the at least one skin comprises carbon fiber and has a weight of less than about 3,000 gsm. According to claim 1,
A composite skin sandwich structure, wherein the at least one skin comprises glass fibers and has a weight of less than about 5,000 gsm. According to claim 2,
The composite skin sandwich structure, wherein the plies are arranged as [-15°/-25°/-35°/-45°/-60°/60°/45°/35°/25°/15°]. According to claim 1,
The composite skin sandwich structure of claim 1, wherein the plurality of plies include at least one of UD tow, TPUD tow, QUDW fabric, TPW fabric, and NCF fabric. According to claim 1,
The plurality of plies of reinforcing fibers arranged in helicoidal relationship further include at least a third ply, the third ply including parallel fibers defining an orientation direction, and the third ply and at least one adjacent ply. wherein the included angle between the orientation directions is greater than 0° and less than about 30°. A fiber-reinforced composite material with impact resistance,
The composite material:
a first TPW fabric layer, the first TPW fabric layer comprising a plurality of weft tows and a plurality of warp tows, at least one of the plurality of tows defining an orientation direction, and
comprising a second TPW fabric layer, wherein the second TPW fabric layer includes a plurality of weft tows and a plurality of warp tows, at least one of the plurality of tows defining an orientation direction,
The first TPW fabric layer and the second TPW fabric layer are arranged in a helicoidal relationship, and the included angle between the orientation direction of the tow of the first TPW fabric layer and the orientation direction of the tow of the second TPW fabric layer is: A fiber reinforced composite material having impact resistance greater than 0° and less than about 30° to provide impact resistance to the fiber reinforced composite material. According to claim 14,
At least one of the TPW fabric layers comprises a spread warp tow and/or a spread weft tow. According to claim 14,
At least one of the TPW fabric layers comprises a light warp tow and/or a light weft tow. According to claim 14,
At least one tow of the at least one TPW fabric layer comprises carbon fiber. According to claim 14,
Wherein at least one tow of the at least one TPW fabric layer comprises glass fiber. According to claim 14,
At least one tow of the at least one TPW fabric layer comprises aramid fibers. According to claim 14,
At least one tow of the at least one TPW fabric layer comprises UHMWPE fibers. According to claim 14,
At least one tow of the at least one TPW fabric layer comprises polypropylene fibers. According to claim 14,
A fiber-reinforced composite material with impact resistance, wherein the fiber-reinforced composite material is formed into the shape of at least one of sporting goods, automobile/motorsports parts, consumer products including luggage, and marine parts. A fiber-reinforced composite material with impact resistance,
The composite material:
a first QUDW fabric layer, the first QUDW fabric layer comprising a plurality of weft tows and a plurality of warp tows, the plurality of warp tows defining an orientation direction, and
comprising a second QUDW fabric layer, the second QUDW fabric layer comprising a plurality of weft tows and a plurality of warp tows, the plurality of warp tows defining an orientation direction;
The first QUDW fabric layer and the second QUDW fabric layer are arranged in a helicoidal relationship, and an included angle between the orientation direction of the warp tow of the first QUDW fabric layer and the orientation direction of the warp tow of the second TPW fabric layer. is greater than 0° and less than about 30° to provide impact resistance to the fiber reinforced composite material. According to claim 23,
A fiber-reinforced composite material with impact resistance, wherein an amount greater than 80% of the fibers of the composite material are disposed in the warp tow. According to claim 23,
An impact-resistant, fiber-reinforced composite material, wherein at least one tow of the at least one QUDW fabric layer comprises carbon fiber. According to claim 23,
An impact-resistant, fiber-reinforced composite material, wherein at least one tow of at least one QUDW fabric layer comprises glass fibers. According to claim 23,
An impact-resistant, fiber-reinforced composite material, wherein the warp tow of at least one QUDW fabric layer comprises glass fibers, and the weft tow of the at least one QUDW fabric layer comprises carbon fibers. According to claim 23,
A fiber-reinforced composite material with impact resistance, wherein the fiber-reinforced composite material is formed into the shape of at least one of sporting goods, automobile/motorsports parts, consumer products including luggage, and marine parts.