WO2019131893A1 - Composite material, layered structure, aircraft wing, and composite material manufacturing method - Google Patents

Abstract

Provided is a composite material that achieves weight reduction and separation prevention. The composite material comprises: a body section 16A in which fibers 16C are aligned in a matrix in a first direction X; and a stress relief section 16B which is integrally provided connected to an end of the body section 16A in the first direction X, and in which fibers 16C are aligned in a second direction X1 that forms an acute angle with the first direction X, such fibers being continuous with the fibers of the body section 16A.

Description

Composite material, laminated structure, wing of aircraft, and method of manufacturing composite material

The present invention relates to composite materials, laminated structures, aircraft wings and methods of making composite materials.

Composite materials are widely used in structures such as aircrafts and satellites because they are lightweight, have high strength, and can be freely designed to have strength and rigidity depending on applications. The load or external force acting on such a structure is not uniform depending on the position on the structure. For this reason, according to the position on a structure, the weight reduction can be achieved, securing rigidity required for the position by changing the number of sheets of the composite material to laminate | stack.

U.S. Pat. No. 5,956,015 describes a composite laminate that reduces the weight of the wing skin without sacrificing flexural strength, flexural rigidity and damage tolerance.

Specifically, it comprises a first plurality of plies comprising longitudinally oriented reinforcing fibers with respect to the main loading direction, and reinforcing fibers oriented at an angle of between 15 degrees and 35 degrees to the main loading direction. A laminate of the second plurality of plies is described.

JP, 2015-214027, A

However, when the thickness is changed by changing the number of laminated layers, if the taper is made sharp with emphasis on weight reduction, a bending stress due to the eccentricity is generated, and thus cracking and peeling are likely to occur. As described in Patent Document 1, even if plies having different fiber orientations are laminated, cracks and peeling still occur from the end of the zero layer in which the fibers are oriented in the longitudinal direction.

On the other hand, if the thickness is changed so as to form a gentle taper, the waste of material increases and the weight of the structure increases. For example, providing a gradual taper of 1:50 to 1: 100 may result in a weight gain of 30% or more as compared to a steep taper of 1: 5.

An object of the present invention is to provide a composite material, a laminated structure, a wing of an aircraft, and a method of manufacturing the composite material, which can achieve both suppression of delamination and weight reduction.

The composite material according to one aspect of the present invention is integrally connected to the main body in which the first fibers are oriented in the first direction and the end of the main body in the first direction in the matrix. It is equipped with a stress relieving portion provided. The second fibers of the stress relieving portion continuous with the first fibers of the main body portion are oriented along a second direction which forms an acute angle with the first direction.

According to this aspect, since the main body portion in which the first fiber is oriented in the first direction is provided, while maintaining the elastic modulus in the first direction, the second direction having an acute angle with the first direction In addition, since the second fiber continuous with the first fiber is provided with the stress relaxation portion, the elastic modulus in the first direction at the end becomes small. For this reason, when laminating such a composite material, for example, stress concentration occurring at the end can be alleviated and peeling can be suppressed due to the high elastic modulus of the end. . In addition, since the first and second fibers are continuous, stress concentration at this boundary is also avoided.

Furthermore, it also becomes possible to relieve the residual stress generated due to the heat molding, the temperature change of the environment and the like.

The composite material according to another aspect of the present invention is connected to the first main body portion in which the first fibers are oriented in the first direction, and the one end portion of the first main body portion in the first direction. And a stress relaxation portion in which a second fiber continuous to the first fiber is oriented along a curve including a straight line directed in a third direction perpendicular to the first direction as a tangent. .

According to this aspect, since the stress relaxation portion in which the second fiber continuous to the first fiber is oriented is provided along the curve including, as a tangent, a straight line directed in the third direction perpendicular to the first direction, While maintaining the elastic modulus with respect to the first direction in one direction, the elastic modulus in multiple directions including the first direction in the stress relaxation portion decreases. For this reason, when laminating such a composite material, for example, the stress concentration generated in the portion corresponding to the stress relaxation portion is alleviated due to the high elastic modulus, and the peeling is suppressed. It becomes possible.

Furthermore, a third fiber continuous to the second fiber is oriented along a fourth direction toward the other end in the first direction of the first main body portion, integrally connected to the stress relieving portion, You may further provide the 2nd main-body part laminated | stacked on a 1st main-body part.

Alternatively, in the first body portion, the third fibers continuous with the second fibers may be oriented in the fourth direction.

According to these aspects, it is also possible to maintain the elastic modulus in the fourth direction. The fourth direction may form an acute angle with the first direction, or may be parallel to the first direction.

The curve indicating the orientation of the second fiber in the stress relieving portion may be a circular arc, an ellipse, or any other curve, but it is possible to continuously and smoothly connect the first fiber and the third fiber preferable. However, a partially linear portion (for example, a curve having a large radius of curvature) may be included.

In addition, a laminated structure according to another aspect of the present invention includes a second composite material that is longer than the composite material in the first direction, and the composite material stacked on the second composite material.

According to this aspect, since the composite material provided with the above-described stress relaxation portion can be used as the composite material laminated on the second composite material, it is possible to reduce the stress concentration generated at the end. As a result, it is possible to suppress exfoliation between the second composite material.

The fibers included in the second composite material may not necessarily be oriented in the first direction, and may be oriented in different directions (for example, 90 degrees or ± 45 degrees).

Also, a composite material comprising fibers oriented in different directions may be further laminated in the gap with the composite material or above and below. For example, another composite material comprising fibers oriented at +45 degrees, yet another composite material comprising fibers oriented at -45 degrees, further comprising fibers oriented at 90 degrees above the composite material. The composite materials of the above may be laminated in order.

The fibers may be made of the same material among the composite materials. For example, glass fibers or carbon reinforced fibers can be used as the fibers. Further, as to the resin, the same material may be used among the composite materials, and for example, an epoxy resin or a carbon resin can be used as the resin.

In addition, an aircraft wing according to another aspect of the present invention includes the above-described laminated structure.

Another aspect of the present invention is a method of producing a composite material. Then, preparing a composite material in which fibers are oriented in a first direction into the matrix, and shearing the end of the composite material in a direction perpendicular to the first direction, And a body portion in which the first fibers are oriented along the direction, and an end portion of the body portion in the first direction, integrally provided, along a second direction forming an acute angle with the first direction Providing a stress relieving portion in which the second fibers continuous with the first fibers are oriented.

In addition, even after shear deformation, a part of the stress relaxation portion is cut in a direction perpendicular to the first direction so that the end face of the second fiber is not in the second direction but in the first direction. Good.

In the method of manufacturing a composite material according to another aspect of the present invention, a step of preparing a composite material in which fibers are oriented in a first direction in a base material, and bending an intermediate portion in the first direction of the base material A first main body portion in which the first fibers are oriented in the first direction, and one end of the first main body portion in the first direction are integrally provided in the base material, in the first direction; A stress relieving portion in which a second fiber continuous to the first fiber is oriented and a stress relieving portion connected integrally along a curve including a straight line directed in a vertical third direction as a tangent; A second main body portion in which a third fiber continuous to the second fiber is oriented along a fourth direction toward the other end in the first direction of the first main body portion, and is stacked on the first main body portion; Providing
including.

According to this aspect, it is possible to provide a stress relaxation portion in which the second fiber continuous to the first fiber is oriented along a curve including, as a tangent, a straight line directed in the third direction perpendicular to the first direction. Thus, while maintaining the elastic modulus in the first direction in the first direction, the elastic modulus in the first direction in the stress relaxation portion decreases. For this reason, when laminating such a composite material, for example, the stress concentration generated in the portion corresponding to the stress relaxation portion is alleviated due to the high elastic modulus, and the peeling is suppressed. It is possible to produce composite materials.

In addition, a middle part means the part which is not an edge part, and it is not restricted to the part which bisects the both ends of a base material. Therefore, the length in the first direction of the first main body and the length in the first direction of the second main body may be different. Also, the portion to be bent may not necessarily be perpendicular to the first direction. It is also possible to adjust the fourth direction by bending the first direction at an acute angle. After that, if necessary, the composite material can be cut to obtain a composite material having a desired shape.

The third direction may be a stacking direction, but may be an in-plane direction perpendicular to the first direction. The base material is preferably in the form of a layer, but is not limited thereto.

According to the present invention, it is possible to provide a composite material, a laminated structure, a wing of an aircraft, and a method of manufacturing the composite material, which can achieve both suppression of delamination and weight reduction.

Plan view of the laminated structure 10 according to the first embodiment Front view of laminated structure 10 according to the first embodiment Top view of laminated structure 100 according to comparative example Front view of a laminated structure 100 according to a comparative example Front view of a laminated structure 200 according to a comparative example to be subjected to a tensile test Front view of a laminated structure 300 according to a comparative example to be subjected to a tensile test Front view of a laminated structure 20 according to the present invention to be subjected to a tensile test Front view of a laminated structure 30 according to the present invention to be subjected to a tensile test Partially Expanded View of Laminated Structure 200 A partially enlarged view of the laminated structure 300 A partially enlarged view of the laminated structure 20 Partially enlarged view of laminated structure 30 Graph showing experimental results of tensile test The perspective view of the laminated structure 60 which concerns on the modification 5 Plan view of the laminated structure 70 according to the second embodiment Front view of a laminated structure 70 according to a second embodiment Fiber shape 74C1 'according to a modification of the second embodiment Fiber shape 74C2 'according to a modification of the second embodiment Fiber shape 74C3 'according to a modification of the second embodiment Fiber shape 74C4 'according to a modification of the second embodiment Explanatory drawing of the manufacturing process of the composite material which concerns on 2nd Embodiment Explanatory drawing of the manufacturing process of the composite material which concerns on 2nd Embodiment Explanatory drawing of the manufacturing process of the composite material which concerns on 2nd Embodiment A view of the manufactured laminated structure 70 'viewed from the depth direction

First Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. In addition, the following embodiments are exemplifications for describing the present invention, and the present invention is not limited to the embodiments. Furthermore, the present invention can be variously modified without departing from the scope of the invention.

FIG. 1A is a plan view conceptually showing a laminated structure 10 according to the first embodiment of the present invention, and FIG. 1B is a front view of the laminated structure 10. FIG. 2A is a plan view conceptually showing the laminated structure 100 of the comparative example, and FIG. 2B is a front view of the laminated structure 100. As shown in FIG.

As shown in FIGS. 1A and 1B, the laminated structure 10 includes a base ply 12 (an example of a “second composite material”) and a ply 14 (“composite material”) laminated on the ply 12. And a ply 16 (an example of a “base material” made of a “composite material”) laminated on the ply 14. Each ply 12, the ply 14 and the ply 16 have a sheet-like layer structure made of CFRP (Carbon Fiber Reinforced Plastic), and are provided with fibers oriented in a predetermined direction in a resin. Each ply of the laminated structure 10 is integrally molded by being heated and pressurized in an autoclave. The laminated structure 10 does not have to be a double layer of the ply 14 and the ply 16, and may be only the ply 14 or the ply 16. Furthermore, other plies may be laminated.

In addition, the material and content of the resin and fibers of the ply 12, the ply 14 and the ply 16 of the laminated structure 10 can be appropriately set without changing the gist of the present invention. The resin may be thermoplastic or thermosetting, and the fibers may be carbon fibers or glass fibers and the like.

Further, the thickness and shape of the layer structure of the ply 12, the ply 14 and the ply 16 can be appropriately set according to the purpose and the like. Further, the ply 12, the ply 14 and the ply 16 do not have to be made of the same material, and for example, the materials of the resins contained in the ply 12 and the ply 14 may be made different. Furthermore, as described in detail later, plies having the same or different fiber orientations may be further stacked between each ply 12, ply 14 and ply 16 or up and down. Furthermore, a cover ply may be provided.

The orientation direction of the fibers 16C of the ply 16 is shown in FIG. 1A. As shown in the figure, from one end (right end in the drawing) of the ply 16 to the vicinity of the other end is an example of a longitudinal direction X ("first direction" and is referred to as "longitudinal direction X" or "0 degree direction" Each fiber 16C is oriented in parallel to. A region in which the fibers 16C are oriented along the longitudinal direction X is referred to as a main portion 16A (an example of a “main portion”).

In addition, each fiber 16C of the ply 16 is bent in the vicinity of the end on the other end side in the longitudinal direction X, and in a direction X1 (an example of “second direction”) forming an acute angle with the longitudinal direction X in plan view. It is oriented in parallel. In the present embodiment, the angle of the direction X1 with respect to the longitudinal direction X is +45 degrees. A region in which the fibers 16C are oriented along the direction X1 is referred to as a stress relaxation portion 16B (an example of a "stress relaxation portion").

In the present embodiment, in the longitudinal direction X, the length of the stress relaxation portion 16B is, for example, 5 mm, and the length of the main body portion 16A has a length of 10 times or more.

The lower ply 14 of the ply 16 also has a similar structure. Specifically, the fibers of the ply 14 are oriented parallel to the longitudinal direction X from one end of the ply 14 to the vicinity of the other end, bent near the end, and oriented parallel to the direction X1. For this reason, the ply 14 also includes the main body portion 14A and the stress relief portion 14B at substantially the same position as the ply 16 in the longitudinal direction X.

The length of the ply 14 in the first direction may be longer than that of the ply 16 so that the thickness of the stacked structure 10 in the stacking direction Z may be different. Furthermore, a plurality of plies having different lengths in the first direction may be stacked on the ply 16 as well.

Although FRP (Fiber Reinforced Plastic) represented by CFRP has a high elastic modulus in the fiber orientation direction, the elastic modulus in the direction different from the orientation direction is greatly reduced. For example, in the case of a typical CFRP, the elastic modulus in the direction different by 20 degrees from the orientation direction drops to about half of the elastic modulus in the orientation direction. Also in the present embodiment, the elastic modulus of the main body portion 16A and the main body portion 14A in the longitudinal direction X is about 200 GPa, and the elastic modulus of the stress relaxation portion 16B and the stress relaxation portion 14B is 50 GPa or less.

In addition, it is preferable to further stack plies oriented in different directions above and below the ply 14 and the ply 16 in order to respond to external forces from various directions. For example, a ply containing fibers oriented in the depth direction Y (or “90 degree direction”) perpendicular to the longitudinal direction X and the stacking direction Z on the ply 16, +45 degrees from the longitudinal direction X and the depth direction Y A ply containing fibers oriented in a direction, and a ply containing fibers oriented in the direction of −45 degrees from the longitudinal direction X and the depth direction Y can be laminated repeatedly in random order.

Similarly, with regard to the base ply, a plurality of plies in which fibers are oriented in the 0 degree direction, +45 degree direction, -45 degree direction, and 90 degree direction can be repeatedly laminated. For example, the fibers of the ply 12 disposed below the ply 14 may be oriented in the 0 degree direction from one end of the longitudinal direction X to the other end.

The ply 12 is formed to be longer than the plies 16 and 14 in the longitudinal direction X. Unlike the plies 16 and 14, the fibers of the ply 12 are not oriented parallel to the direction X1 at the ends. However, it is not limited to this. For example, when the ply 12 is further laminated on another ply, the end of the fiber of the ply 12 whose thickness in the laminating direction changes is bent and oriented parallel to the direction X1 forming an acute angle with the longitudinal direction X It may be configured as follows. In that case, the ply 12 also has a body portion and a stress relief portion.

In the present embodiment, the fibers of the ply 12, the ply 14 and the ply 16 are not oriented in the stacking direction Z of the ply 12, the ply 14 and the ply 16. However, it is not limited to this.

FIG. 2A is a plan view of the laminated structure 100 according to the comparative example, and FIG. 2B is a front view of the laminated structure 100. The laminated structure 100 includes a base ply 120, a ply 140 stacked on the ply 120, and a ply 160 stacked on the ply 140. Each ply 120, the ply 140 and the ply 160 have a sheet-like layer structure made of CFRP.

However, unlike the laminate structure 10, the fibers 160C of the ply 160 of the laminate structure 100 and the fibers of the ply 140 are oriented parallel to the longitudinal direction X over the entire area from one end to the other in the longitudinal direction X. There is.

Here, the difference in the effect at the time of applying tensile load to the longitudinal direction X to the laminated structure 10 which concerns on this embodiment, and the laminated structure 100 which concerns on a comparative example, respectively is demonstrated.

In the case of the laminated structure 100, since the elastic modulus in the longitudinal direction X of the ply 140 is uniformly high, a large stress is generated for a predetermined strain. As a result, stress is concentrated at the end portion of the ply 140 whose thickness is changed, and a large peel stress and shear stress which cause peeling from the lower ply 120 occur. Further, in the laminated structure 100, since the elastic modulus also changes in the laminating direction as the thickness changes, the neutral axis of the cross section shifts to the ply 140 side, and a secondary bending deformation also occurs due to the tensile load. Do. As a result, a large bending moment is generated in the vicinity of the end of the ply 140, which causes a crack to occur and progress.

On the other hand, in the case of the laminated structure 10, since the elastic modulus in the longitudinal direction X of the stress relaxation portion 14B of the ply 14 is not more than half the elastic modulus of the main body portion 14A, the stress generated for a predetermined strain is also relative As small as As a result, it is possible to suppress the stress concentration in the stress relieving portion 14B and the generation of a crack associated therewith. Further, since the stress relaxation portion 14B is provided, the change in elastic modulus in the stacking direction is also smaller than that in the stacked structure 100. Therefore, the neutral axis of the cross section does not change significantly, and secondary bending deformation due to tensile load is suppressed. As a result, the bending moment in the vicinity of the end portion of the ply 14 is reduced, so that it is possible to suppress the occurrence and progress of the crack as compared with the laminated structure 100.

Furthermore, in addition to the ply 14 and the ply 16 of the laminated structure 10, when the ply in which the fibers are oriented in the +45 degree direction, the -45 degree direction, and the 90 degree direction is small. Even in this case, the elastic modulus of the region where stress relaxation portions 14B and 16B exist in the longitudinal direction X is still kept low, so that the generation and progress of cracks can be suppressed.

Below, the result of the tension fatigue test of the laminated structure which concerns on this invention, and the laminated structure which concerns on a comparative example is demonstrated.

FIG. 3A is a front view of the laminated structure 200 according to the comparative example, FIG. 3B is a front view of the laminated structure 300 according to the comparative example, FIG. 3C is a front view of the laminated structure 20 according to the present invention, FIG. These show the front view of the laminated structure 30 which concerns on this invention.

4A is an enlarged view of a portion where the thickness direction of the laminated structure 200 changes, FIG. 4B is an enlarged view of the laminated structure 300, and FIG. 4C is an enlarged view of the laminated structure 20, FIG. These show the same enlarged view of the laminated structure 30. FIG.

Each of the laminated structures 200, 300, 20 and 30 is a structure in which a plurality of plies made of T700SC / 2592 are laminated, and the length in the longitudinal direction X is 180 mm, and the length in the depth direction Y is , 10 mm. Both ends in the longitudinal direction X form thick portions where the thickness in the stacking direction Z is large, and 16 plies each having a thickness of about 100 μm (for example, 125 μm) are stacked. The central portion forms a thin portion having a small thickness in the stacking direction Z, and eight plies are stacked.

The fibers of each ply of the laminated structure 200 are uniformly oriented in the 0 degree direction, that is, in the longitudinal direction X from one end to the other end.

The fibers of each ply of the laminated structure 300 are also uniformly oriented in the 0 degree direction, that is, in the longitudinal direction X from one end to the other end. However, as shown in FIG. 4B, in the stacked structure 300, the variation in the stacking direction Z is gentler than that of the stacked structure 200 in the 10: 1 taper (ie, 1 mm variation in the stacking direction). A laminated structure in which the length of the upper eight plies in the longitudinal direction X is adjusted to form a fluctuation of 10 mm in X, but the taper is hardly formed and the lamination direction Z fluctuates sharply Different from body 200.

In the laminated structure 20, a lower ply portion 22 in which eight plies are laminated and a ply portion 24 in which eight plies are laminated and laminated on the ply portion 22 (an example of a “composite material”)
Equipped with The fibers of each ply of the ply portion 22 are oriented in the 0 degree direction. The ply portion 24 includes a main portion 24A in which the fibers of each ply are oriented in the 0 degree direction, and a stress relaxation portion 24B in which the fibers are bent and oriented in the +45 degree direction. The length of the stress relaxation portion 24B in the longitudinal direction X is 5 mm. Since each ply of the ply portion 24 is laminated after providing the stress relieving portion 24B by in-plane shear deformation, the thickness in the laminating direction Z is larger than that of the main portion 24A.

In the laminated structure 30, a lower ply portion 32 in which eight plies are laminated and a ply portion 34 in which eight plies are laminated and laminated on the ply portion 32 (an example of a “composite material”)
Equipped with The fibers of each ply of the ply portion 32 are oriented in the 0 degree direction. The ply portion 34 is integrally provided by connecting the body portion in which the fibers are oriented in the 0 ° direction and the end portion of the body portion, and the fibers connected to the fibers in the body portion are oriented in the + 45 ° direction A ply having a stress relaxation portion, a main portion in which fibers are oriented in the 0 degree direction, and an end portion of the main portion are integrally provided, and fibers continuous to the fibers in the main portion are in the -45 degree direction It is formed by alternately laminating plies having stress relieving portions oriented. Therefore, the ply portion 34 has a main portion 34A in which the fibers of each ply are oriented in the 0 degree direction and a stress relaxation portion 34B in which the fibers are bent and alternately oriented in the +45 degree direction or -45 degree direction. Have. The length of the stress relaxation portion 34B in the longitudinal direction X is 5 mm.

A tensile fatigue test was performed on such a laminated structure 200, 300, 20, and 30 under the conditions of a maximum load of 4000 N, a load ratio of 0.1, and a test frequency of 8 Hz.

FIG. 5 shows the test results of the laminated structures 200, 300 and 20. The horizontal axis represents the number of cycles at which the maximum load is applied at the test frequency, and the vertical axis represents the delamination length.

As shown in this figure, the laminated structure 200 is shown to have exfoliation occurring from 2000 to 3000 times. After the occurrence of peeling, peeling progressed in proportion to the number of times of load application, and when a load of about 10,000 times was applied, peeling of 40 mm or more was formed.

It is shown that peeling occurs in the laminated structure 300 from 9000 times to 10000 times. And after 12000 times, peeling progressed in proportion to the number of times of load application, and when load of about 17000 times was applied, peeling of 50 mm or more was formed.

In addition, it was confirmed also about the laminated structure 30 that the advancing of peeling is suppressed rather than the laminated structure 200 and 300. FIG. Specifically, even when a total of 12000 loads were applied, the progress of peeling remained within 5 mm, that is, in the stress relaxation portion 34B.

The laminated structure 20 was significantly superior to the other laminated structures 30, 200, and 300 in that peeling occurred at 28,000 times to 29,000 times. Thereafter, the progress of peeling is suppressed, and it is shown that the progress of peeling is within 5 mm, that is, in the stress relaxation portion 24B even when a load of 6000 times (34000 times in total) is applied after the peeling occurs. It was done. Peeling progressed to the same extent as laminated structure 300 after 35000 times after that.

As described above, according to the laminated structures 10, 20 and 30 according to the present embodiment, since the main body portions 16A, 24A and 34A are provided, it is possible to withstand the load in the longitudinal direction X, and the stress relieving portion 16B. , 24B and 34B, it is possible to suppress the occurrence and progress of peeling.

The method of manufacturing such laminated structures 10, 20 and 30 using a prepreg will be described below. In addition, the following is only one aspect of a manufacturing method, and laminated structure 10, 20 and 30 can also be manufactured by a different method. For example, after laminating using dry fibers, the resin may be impregnated and molded. In addition, the composite according to the present invention using a known manufacturing technology (RTM (Resin Transfer Molding), RFI (Resin Film Infusion), CPM (Compression Press Molding), FW (Filament Winding), LFT (Long Fiber Thermoplastic), etc.) Materials and laminate structures can be manufactured.

First, a sheet-like prepreg in which fibers are oriented in a predetermined direction is prepared. For example, a CFRP prepreg can be used as a base material.

Then, the end portion of such a prepreg (for example, a region within 5 mm to 10 mm from the end surface of the prepreg) is sheared in an in-plane direction perpendicular to the fiber orientation to correspond to the main portion and the stress relaxation portion Provide an area. As a method for shear deformation, for example, a region corresponding to the main body maintaining the orientation direction of the fiber constant is gripped and fixed, and an end portion to be a free end is gripped to be in a plane perpendicular to the fiber orientation direction. By moving in the direction, the end of the prepreg can be sheared and deformed. By changing the amount of movement in the shearing direction, it is possible to adjust the orientation direction of the fibers. For example, when a region within 10 mm from the end face of the prepreg is sheared, the orientation direction can be changed in the 45 ° direction by moving approximately 10 mm in the in-plane direction perpendicular to the orientation direction of the fibers. As means for such shear deformation, it is possible to use a robot provided in the automatic stacking apparatus, or it may be deformed manually while being heated.

As described above, while the composite material exerts a large elastic modulus in the fiber orientation direction, the elastic modulus rapidly decreases in the direction different from the orientation direction. For example, there is also a composite material in which the elastic modulus is halved when it deviates 20 degrees from the orientation direction, and a nearly constant low elastic modulus is maintained when it deviates by 45 degrees or more. For this reason, depending on the application, it is not always necessary to bend the fibers in the correct orientation direction. In addition, even within the same prepreg, in some cases, variation in orientation between fibers can be tolerated.

By passing through the process as described above, a portion corresponding to the main body portion in which the fiber orientation direction is constant and an end portion in the fiber orientation direction of the main body portion are integrally provided to be bent, As a result, for example, it is possible to provide a prepreg including a portion corresponding to the stress relaxation portion in which the fibers are oriented along the 45 ° direction.

Thereafter, such a prepreg is cut into a desired shape. At this time, by cutting a part of the stress relaxation portion of the prepreg (for example, a portion 5 mm away from the end face) in a direction perpendicular to the orientation direction of the main body, the end face of each fiber is not 45 degrees It can align so that it may turn to the 0 degree direction which is an orientation direction of textiles in a main part.

Each fiber itself has a high elastic modulus in the axial direction, for example, in the stress relaxation portion whose orientation direction is changed in the 45-degree direction, the axis of the fiber, not the 45-degree direction perpendicular to the axial direction of the fibers By providing the end face inclined 45 degrees from the direction, relaxation of stress concentration can be promoted for each fiber. However, the present invention is not limited to this, and shear deformation may be performed after the shape is adjusted by cutting or the like. The fiber may be bent to change the orientation direction by means other than shear deformation.

Then, along with such a prepreg, a plurality of prepregs in which fibers are respectively oriented in the +45 degree direction, the -45 degree direction, and the 90 degree direction are repeatedly laminated.

Thereafter, by applying pressure and heat with an autoclave, the laminated structure including the main body portion and the stress relieving portion can be integrally formed.

Such a laminated structure can be applied to transportation devices such as aircraft fuselages and wings, artificial satellites, automobiles, ships and the like.

For example, the bottom of the skin of an aircraft wing is provided with a plurality of inspection openings called access holes. Since a large load is applied to the peripheral portion of the access hole, it is necessary to increase the thickness of the composite material. On the other hand, it is necessary to reduce the thickness of the composite material and achieve weight reduction at a position away from the peripheral portion and not subjected to a large load. By applying the laminated structure according to the present embodiment to such a portion, it is possible to achieve both suppression of delamination and weight reduction. In addition, when a part of the structure is broken due to lightning strike or the like, it is necessary to peel off the broken laminated structure and attach a new laminated structure for repair, but the laminated structure according to the present embodiment By using the above, it is possible to suppress the easy peeling of the laminated structure attached. In addition, the laminated structure which concerns on this embodiment is applicable also to the structure of other parts, such as a fuselage | body of an aircraft, and other transport devices, such as a ship.

Below, the modification of the laminated structure which concerns on the said embodiment is demonstrated.

[Modification 1]
The length in the longitudinal direction X of the composite material according to the above embodiment is, for example, several tens of mm or more, but each composite material and the fibers contained therein may be shorter.

For example, it is known that CFRP can be cut by using a short pulse laser such as a femtosecond laser.

Therefore, the laser is used to cut in a brick shape so that the length in the longitudinal direction is 5 to 10 mm or less, and each particle has a fixed fiber orientation direction while maintaining the aligned state of each particle A composite material can be formed that includes a body portion and a stress relaxation portion in which the orientation direction of these fibers is bent. Under the present circumstances, it may be made a structure which can absorb energy by filling between each particle | grains formed by cutting | disconnection with a small rigid substance and a flexible substance.

Although such a composite material has a problem that brittle fracture occurs from the end due to fatigue, a stress relaxation portion is provided at the end of each particle to reduce stress concentration by reducing the elastic modulus in the longitudinal direction. Since it is possible, it becomes possible to control the brittle fracture from the end.

[Modification 2]
In each ply (for example, the ply 14) constituting the composite material according to the above embodiment, the height in the stacking direction Z was constant.

However, the configuration is such that the height in the stacking direction Z gradually increases from the end face of the stress relaxation portion 16B toward the main body portion 16A by chamfering (in other words, the length in the longitudinal direction X It is good also as composition which becomes small. With such a configuration, it is possible to further reduce the elastic modulus in the longitudinal direction X of the stress relaxation portion 16B.

[Modification 3]
The laminated structures 10, 20, and 30 according to the above embodiments may include one or more cover plies. By providing such a cover ply and covering the upper surface facing in the stacking direction Z with the cover ply, it is possible to further suppress delamination.

Under the present circumstances, you may make it provide a stress relaxation part in the area | region where the inclination of a cover ply changes.

For example, when a cover ply is provided in the laminated structure of FIG. 1, the fiber orientation in the longitudinal direction X in the horizontal portion of the cover ply to be laminated on the main body portion 16A and the stress relaxation portion 16B is stress relaxation portion. From 16B, for the portion where the inclination varies toward the ply 12, the fiber orientation is in the direction X1, and then for the tapered portion toward the ply 12 while maintaining the inclination, the fiber orientation is again in the longitudinal direction X, The fiber orientation is in the direction X1 for the part reaching the ply 12 and the inclination is changed again in the horizontal direction, and for the horizontal part along the upper surface of the ply 12 in the longitudinal direction X. It can be structured as

As described above, by providing the stress relaxation portion having a low elastic modulus in the portion where the stress is discontinuous, it becomes possible to suppress the occurrence of peeling due to the concentration of the stress in that portion.

[Modification 4]
Although the composite material which concerns on the said embodiment was made into one of the objective in suppressing peeling from another composite material, it is not restricted to this. For example, when the composite material and the different material are integrally configured, the present invention can be applied to suppress the separation of the composite material from the different material.

For example, in a structure in which plies made of CFRP or the like are stacked, another CFRP is obliquely disposed so as to straddle each ply, so that a structure that suppresses the progress of a crack traveling parallel to the layer is obtained. Are known. Due to such a structure, the boundary between the upper layer ply and the area between the diagonally arranged CFRPs narrows as the diagonally arranged CFRP approaches the upper layer ply. And since stress concentrates in the tip part which tapers, exfoliation with CFRP arranged diagonally may occur.

Therefore, by bending the fibers at the tapered end of the lower layer ply and changing the orientation direction to a direction different from the longitudinal direction, which is the orientation direction of the main portion, stress concentration at the end is alleviated, thus peeling off. It becomes possible to suppress.

Similarly, by bending the fibers at the tip of the CFRP disposed diagonally and changing the orientation direction to a direction different from the orientation direction of the main body, the stress concentration at the tip of the CFRP disposed diagonally Can be relaxed.

[Modification 5]
FIG. 6 is a perspective view of a laminated structure 60 according to a fifth modification.

The laminated structure described above has an object of alleviating stress concentration generated at an end in the longitudinal direction X, which is a direction in which a load is applied.

However, when a tensile load acts in the longitudinal direction X, a stress that tends to shrink in the depth direction Y acts due to the Poisson effect. At this time, if there is a ply containing fibers oriented in the depth direction Y, that is, 90 degrees in the laminated structure, high interlayer stress occurs near the free end to prevent deformation in the depth direction Y, Peeling is likely to occur.

In addition to tensile load, also when thermal stress acts to shrink in the depth direction Y due to thermal stress, high interlayer stress is generated near the free end, and peeling tends to occur.

Therefore, in the laminated structure 60, the stress relaxation portion 62B is provided at the free end of the depth direction Y end of the ply 62 including the fibers oriented in the 90 ° direction. Specifically, the ply 62 is integrally connected to the end of the main portion 62A in which the first fibers 62C are oriented in the depth direction Y and the end of the main portion 62A in the depth direction Y in the base material. And a stress relaxation portion 62B in which the first fibers 62C are oriented along a direction (for example, the X1 direction) forming an acute angle with the depth direction Y.

Another layer of the laminated structure 60 may be provided with a stress relaxation portion which relieves stress concentration generated at the end in the longitudinal direction X. For example, in the ply 64, a body portion in which fibers are oriented along the longitudinal direction X, and a tip portion continuous to the fibers along a direction (for example, X1 direction) forming an acute angle with the longitudinal direction X The stress relieving portion may be provided.

Second Embodiment
Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to an element the same as that of 1st Embodiment, or same, and the overlapping description is abbreviate | omitted. Moreover, description is abbreviate | omitted or simplified about the effect exhibited similarly to 1st Embodiment.

FIG. 7A is a plan view of the laminated structure 70 according to the second embodiment, and FIG. 7B is a front view of the laminated structure 70.

As shown in this figure, the laminated structure 70 comprises at least a ply 12 and a ply 74 laminated on the ply 12. However, as in the first embodiment, it is preferable to provide the laminated structure 70 by further laminating a plurality of plies in which the fibers are oriented in a plurality of directions.

The ply 74 has a structure in which the central portion is folded and laminated. Specifically, it is connected to a first main portion 74A1 in which fibers 74C1 (an example of "first fibers") are oriented along the longitudinal direction X, and one end in the longitudinal direction X of the first main portion 74A1. The stress relieving portion 74B (one example of “second fibers”) integrally provided and continuous to the fiber 74C1 is curvilinearly oriented, and the stress relieving part 74B (one example of “intermediate part”) An example of a fiber 74C3 ("third fiber") continuous with the fiber 74C2 along the longitudinal direction X (an example of the "fourth direction") which is integrally provided and connected to the other end of the first main body 74A1 ) Is provided, and the second main body 74A2 is provided.

FIG. 7A also shows the orientation direction of the fibers 74C3 in the second main portion 74A2 that is the lower layer of the first main portion 74A1 in order to easily show the orientation direction of the fibers 74C.

As shown in FIG. 7A, in a plan view seen from the stacking direction Z, the fibers 74C1 and the fibers 74C3 are oriented along the longitudinal direction X in parallel with each other, slightly separated in the depth direction Y. The fibers 74C1 and the fibers 74C3 connected to the fibers 74C3 are smoothly bent so as to form an arc-shaped curve having a diameter larger than the distance between the fibers 74C1 and the fibers 74C3 in a plan view. As a result, in the fiber 74C2, two tangents (L11 and L21 in FIG. 8) at both ends in the depth direction Y are directed in the longitudinal direction X and a tangent at one end in the longitudinal direction X (L31 in FIG. An example of “a straight line facing in the direction” faces in the depth direction Y.

Further, as shown in FIG. 7B, when viewed in the depth direction Y, the fibers 74C1 and the fibers 74C3 are slightly separated in the stacking direction Z and oriented parallel to one another along the longitudinal direction X. Further, the fibers 74C2 are connected to the fibers 74C1 and the fibers 74C3 by drawing a gentle curve. For this reason, a tangent at one end of the longitudinal direction X of the fiber 74C2 (an example of “a straight line facing the third direction”) faces the stacking direction Z.

Accordingly, the fibers 74C2 in the stress relieving portion 74B are spirally bent so as to advance in the stacking direction Z while drawing a loop.

In such a stress relieving portion 74B, since the fiber 74C2 forms a curve, the elastic modulus of the stress relieving portion 74B is not only in the longitudinal direction X but also in any direction, the longitudinal direction X of the main body portion 74A1. Have a relatively small value (eg, less than half) as compared to the elastic modulus of Therefore, for example, even in the case of receiving a load from another direction such as a load in the direction X1, it is possible to relieve the stress concentration.

FIG. 8 shows a modification of the shape of the fibers 74C as viewed in the stacking direction Z.

FIG. 8A shows the shape of the fibers 74C1 '. When viewed in the stacking direction Z, the fibers 74C1 'have the same shape as the fibers 74C. That is, the fibers 74C11 'and the fibers 74C31' are oriented parallel to each other and in the longitudinal direction X while being slightly separated from each other in the depth direction Y, and the fibers 74C21 'are more than the distance between the fibers 74C11' and 74C31 '. It is smoothly curved to form an arc-shaped curve having a wide diameter. As a result, in the fiber 74C21 ′, the two tangents L11 and L21 at both ends in the depth direction Y are in the longitudinal direction X, and the tangent L31 at one end in the longitudinal direction X (a straight line facing the third direction) ) Is facing in the depth direction Y.

However, while the fiber 74C shown in FIG. 7 is provided over the laminated structure of the main body 74A1 and the main body 74A2 by bending the ply 74, the fiber 74C1 ′ shown in FIG. 8A consists of a single layer It is provided in the ply. In other words, a single main body including fibers 74C11 'oriented along the longitudinal direction X and fibers 74C31' oriented along the longitudinal direction X, and one end in the longitudinal direction of the main body The stress relieving portion is integrally provided, and a fiber 74C21 'continuous to the fiber 74C11' and the fiber 74C31 'is oriented along a curve.

Even in such a configuration, the elastic modulus of the stress relaxation portion is relatively small not only in the longitudinal direction X but also in any direction (for example, not more than half the elastic modulus in the longitudinal direction X of the main body 74A1) Have. Therefore, for example, even when a load in the direction X1 is received, it is possible to relieve the stress concentration.

As shown in FIG. 7A, the fibers 74C21 'of the stress relaxation portion of two adjacent fibers 74C1' may be arranged to overlap.

FIG. 8B also shows the shape of the fibers 74C2 '. As shown in this figure, the fibers 74C22 'may have an elliptical curve whose minor axis is the distance between the fibers 74C12' and the fibers 74C32 '. Of the fibers 74C22 ', a tangent L32 (an example of a "straight line pointing in the third direction") at one end in the longitudinal direction X is directed in the depth direction Y.

The curve of the fiber 74C12 'connecting the fiber 74C12' and the fiber 74C32 'may be an ellipse, an arc, another higher order curve, or a combination of two or more thereof, and the curvature is partially small. It may include a portion that looks straight. Further, the fibers 74C12 'and the fibers 74C32' may be provided in the same main body, or may be provided in different main bodies by being bent.

FIG. 8C also shows the shape of the fiber 74C3 '. As shown in this figure, the fibers 74C13 'and the fibers 74C33' are bent at the stress relieving portion provided with the fibers 74C23 'so as to substantially overlap when viewed in the stacking direction Z. Even in such a shape, the tangent L33 at one end of the longitudinal direction X of the fiber 74C23 'is directed in the depth direction Y.

FIG. 8D also shows the shape of the fibers 74C4 '. As shown in this figure, the fibers 74C14 'are oriented in the longitudinal direction X, and the fibers 74C34' are in the direction X2 ("fourth direction") forming an acute angle (eg 45 degrees) with the longitudinal direction X (Example) oriented. Also in this modification, the fibers 74C24 'are bent at the stress relieving portion provided. Even in such a shape, the tangent L34 at one end of the longitudinal direction X of the fiber 74C24 'is directed in the depth direction Y. Further, tangents L14 and L24 at both ends in the depth direction Y are in the longitudinal direction X.

In the configuration as described above, the elastic modulus of each of the stress relaxation portions provided with the fibers 74C21 'to 74C24' is smaller than the elastic modulus in the longitudinal direction X of the main body portion 74A1 in any direction (for example, , Half or less). Therefore, for example, even when a load in the direction X1 is received, it is possible to relieve the stress concentration.

Furthermore, the composite material shown in FIG. 8D has a high elastic modulus not only in the longitudinal direction X but also in the direction X2. For this reason, it is possible to suitably use a composite material in which a fiber 74C4 'as shown in FIG. 8D is provided at a place where it is known that a strong load is applied in two directions (longitudinal direction X and direction X2). Become. When the shapes of the fibers 74C3 'and 74C4' in FIGS. 8C and 8D are adopted as the composite material, the position at which the base material is bent does not necessarily have to be the central portion in the longitudinal direction X. For example, the base material may be bent at a position deviated from the central portion in the longitudinal direction X so that the length in the longitudinal direction X of the first body portion and the length in the longitudinal direction X of the second body portion are different. .

FIG. 9 is a view for explaining an example of a process of bending a base material performed by the automatic laminating apparatus M in order to produce the composite material as described above. As described above, the composite material and the laminated structure according to the present invention can be manufactured by various methods. For example, a dry fiber is bent to form a desired laminated structure, and then the resin is impregnated. You may do so.

As shown in FIG. 9, the automatic laminating apparatus M includes two adjacent cylindrical rollers R1 and R2 and a stage S.

First, a layered prepreg sheet P in which fibers are oriented in a predetermined direction in a base material is prepared.

Next, the prepreg sheet P is passed using the roller R1 while passing the prepreg sheet P through the gap between the roller R1 and the roller R2 so that the orientation direction of the fibers of the prepreg sheet P and the moving direction by rotation of the roller R1 coincide. It is pressed against the stage S. As a result, a prepreg sheet P in which the fibers are oriented in the same direction as the moving direction of the roller R1 is disposed on the stage S.

FIG. 9B shows a state in which the prepreg sheet P is disposed on the stage S while the roller R1 and the roller R2 move in the right direction in the drawing by rotating.

Thereafter, the roller R1 and the roller R2 are rotated in the opposite direction, and the prepreg sheet P is pressed against the prepreg sheet P disposed on the stage S using the roller R1 using the roller R2, so that the base material is intermediate A process of folding the part and laminating the base material is performed.

FIG. 9C shows a state in which the prepreg sheet P is laminated while the roller R1 and the roller R2 move to the left in the drawing respectively by rotating in the opposite direction.

After the above-described process, different prepreg sheets are further laminated, and thereafter, heating and pressure are applied in an autoclave, whereby an integrally formed laminated structure can be provided.

FIG. 10 shows the manufactured laminated structure 70 '. The laminated structure 70 ′ comprises a ply 12 and four plies 74 ′ laminated on the ply 12. Here, each ply 74 ′ has the same configuration as the ply 74. Specifically, the first main body portion in the upper layer, the second main body portion in the lower layer, and a stress relaxation portion (an example of an “intermediate portion”) connecting these are provided.

In addition, the four plies 74 'are provided such that the length in the longitudinal direction X becomes smaller as the upper layer becomes. Therefore, as a result of the position in the longitudinal direction X of the stress relieving portions 74B 'of each ply 74' being different, the laminated structure 70 'has a tapered shape as shown in FIG. Furthermore, a cover ply CP is provided above the stacking direction Z of the four plies 74 'so as to cover the stress relieving portion 74B'.

Each of the laminated structure 70 ′ and the standard test piece was subjected to a tensile test, and the number of cycles when broken was measured.

Since the ply 74 'has a thickness of 8 plies, the standard test piece is provided with the cover ply CP after laminating 8 plies so as to have a taper of 5: 1 equivalent to the ply 74'. It has a structure.

As a result of the test, the standard test piece was broken in about 30,000 cycles.

On the other hand, in the laminated structure 70 ′, even a crack was not found even at 1,000,000 cycles (one million cycles).

The embodiments described above are for the purpose of facilitating the understanding of the present invention, and are not for the purpose of limiting the present invention. The elements included in the embodiment and the arrangement, the material, the conditions, the shape, the size, and the like of the elements are not limited to those illustrated, and can be changed as appropriate. In addition, configurations shown in different embodiments can be partially substituted or combined with each other.

12 ply 14 ply 14A body portion 14B stress relaxation portion 16 ply 16A body portion 16B stress relaxation portion 16C fiber 20 laminated structure 22 ply portion 24 ... Ply part, 24A ... body part, 24B ... stress relaxation part, 30 ... laminated structure, 32 ... ply part, 34 ... ply part, 34A ... body part, 34B ... stress relaxation part, 40 ... laminated structure, 60 ... Laminated structure, 62: ply, 62A: main body portion, 62B: stress relieving portion, 62C: fiber, 64: ply, 70: laminated structure, 74: ply, 74A1: main body portion, 74A2: main body portion, 74B: stress Relief part, 74C ... fiber, 74C1, 74C1 'to 74C4' ... fiber, 100 ... laminated structure, 120 ... ply, 140 ... ply, 160 ... ply, 160C ... fiber, 200 ... laminated structure, 300 Laminated structure, AR: arrow, CP: cover ply, M: automatic laminating device, P: prepreg sheet, R1: roller, R2: roller, S: stage, X: longitudinal direction, X1, X2: direction, Y: depth Direction, Z: Stacking direction

Claims (16)

1. A composite material,
   A body portion in which a first fiber is oriented in a matrix along a first direction;
   A second fiber continuous with the first fiber is oriented along a second direction which is integrally connected to an end of the main body in the first direction and which forms an acute angle with the first direction. Stress relieving part,
   Composite material comprising:
2. The composite material according to claim 1, wherein an angle formed by the first direction and the second direction is 20 degrees or more.
3. The composite material according to claim 1 or 2, wherein the rigidity of the stress relieving portion in the first direction is equal to or less than half the rigidity of the main body portion in the first direction.
4. The composite material according to any one of claims 1 to 3, wherein the first fiber and the second fiber contain carbon.
5. The composite material according to any one of claims 1 to 4, wherein an end face of the second fiber faces the first direction.
6. A composite material,
   In the base material,
   A first body portion in which a first fiber is oriented along a first direction;
   The first fiber is provided integrally with one end of the first body portion in the first direction, along a curve including, as a tangent, a straight line directed in a third direction perpendicular to the first direction. A stress relief section in which the continuous second fibers are oriented;
   Composite material comprising:
7. In the first main body portion, third fibers continuous to the second fibers are oriented in a fourth direction toward the other end of the first main body portion in the first direction. The composite material according to claim 6.
8. The composite material according to claim 6, wherein the curve includes a straight line directed in the first direction as a tangent.
9. The base material is
   A third fiber connected to the stress relieving portion is integrally provided, and a third fiber connected to the second fiber is oriented along a fourth direction toward the other end of the first body portion in the first direction. The composite material according to claim 6, further comprising: a second body portion stacked on the first body portion.
10. The composite material according to claim 7, wherein the first direction and the fourth direction are parallel.
11. A second composite material that is longer than the composite material in the first direction;
    11. A composite according to any one of the preceding claims, laminated on this second composite.
    Laminated structure.
12. The laminated structure according to claim 11, wherein the length in the first direction of the composite material decreases with distance from the second composite material.
13. An aircraft wing comprising the laminated structure according to claim 11 or 12.
14. A method of manufacturing a composite material,
    Preparing a composite material in which the fibers are oriented in a first direction in the matrix;
    An end portion of the base material is sheared in a direction perpendicular to the first direction, and a main body portion in which first fibers are oriented in the first direction in the base material, and the main body portion Stress relaxation in which a second fiber connected to the first fiber is oriented along a second direction which is integrally provided at an end in the first direction and which forms an acute angle with the first direction. Providing a unit;
    A method of producing a composite material comprising:
15. After the shear deformation, cutting a part of the stress relieving portion in a direction perpendicular to the first direction to provide the second fiber with an end surface facing the first direction;
    The method for producing a composite material according to claim 14, further comprising
16. A method of manufacturing a composite material,
    Providing a composite material in which the fibers are oriented in a first direction in a layered matrix;
    The first body portion in which the first fiber is oriented in the matrix along the first direction by bending the middle portion of the matrix, and one end of the first body portion in the first direction Stress relieving portion in which a second fiber connected to the first fiber is oriented along a curve including a straight line directed in a third direction perpendicular to the first direction as a tangent line. And a third fiber connected to the stress relieving portion and integrally provided, and a third fiber connected to the second fiber is oriented along a fourth direction toward the other end of the first main body in the first direction. The second main body, and the first main body including the first main body and the second main body, and the third direction is stacked on the first layer with the stacking direction A second layer portion and the stress relieving portion, and an end portion and a front portion of the first layer portion in the first direction Providing at an intermediate portion integrally provided by connecting the end portion in the first direction of the second layer portion,
    A method of producing a composite material comprising:

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