ITMO20070270A1 - FABRIC OR REINFORCEMENT TAPE IN PSEUDOELASTIC MATERIAL FOR DAMPING VIBRATIONS IN ELEMENTS OF SUBJECTS - Google Patents

Abstract

Stiffening fabric or band in pseudoelastic material to damp vibration in elements subject to it, comprising a layer of material of thread(s) of pseudoelastic material, or SMA, with thread(s) arranged in the plane of the layer; characterised by the fact that the thread(s) in pseudoelastic material are arranged in strips of volutes, orientated with the pitches (L) of the volutes in the direction of the warp (O) and the amplitude of the volute (F) in the direction of the weft (T). Advantageously the fabric or band has at least one layer of support material and the volute strips, advantageously placed in the plane, are produced with different threads and the volutes are separate from each other.

Description

Patent application for invention entitled: PSEUDOELASTIC MATERIAL REINFORCEMENT FABRIC OR TAPE TO DAMPEN VIBRATIONS IN ELEMENTS SUBJECT TO THEM

DESCRIPTION

Field of application

The invention relates to: a reinforcing fabric or tape in pseudoelastic material to dampen vibrations in elements subject to them, that is a fabric or tape in which a pseudoelastic material is housed which, due to the particular arrangement and application in an element of an object subjected to vibrations, it allows internal damping, making the object more advantageously usable in the specific construction or intended use.

Known art

In the state of the art, more or less rigid materials are known that oppose the internal vibration in the thickness of the material itself and respond to the laws of elasticity and known coefficients such as the specific elastic modulus of each material, including composite.

In technological development, design levels have been reached such in which construction elements of the object are subjected to tensions and stresses that determine the application of vibrations to the object itself, so as to require an in-depth study and resolution of the way to dampen these vibrations without for this to dimension the element differently: design road, known from the analysis of stresses and deformations from construction science, which leads to the use of the most diverse materials, multilayer, impregnated with internal mechanical reinforcement elements applied externally to the element or products with the element itself.

Therefore the effect of damping vibrations is known with the use of reinforcement layers in rigid material mainly impregnated and applied with thermosetting resins, so the rigid material and the always rigid resin determine a variable elastic modulus inside the element so as not to allow adequate damping of vibrations; on the other hand, the higher the stiffness of the material (high elastic modulus), the higher the natural vibration frequency of the element itself, so that the element may be subject to higher resonance frequencies.

In the state of the art, the so-called "shape memory" materials known with the acronym of SMA or also with "superelasticity" or "pseudoelesticity" are known, that is metal alloys in which the components determine a martensitic structural transformation. austenitic at temperatures close to room temperature, exploiting its characteristic snap transformation both in the transition from martensite to austenite, with heating, and in the opposite transformation from austenite into martensite, with cooling.

The best known of these alloys is NiTiNOL which has made it possible to create the so-called shape memory materials used in the most various technologies, including that of surgical prosthesis devices, as well as to create devices in which the stress induces deformations of the object controlled at the maximum value allowed for that object so as to exploit the elastic return, or rather pseudo-elastic, which recovers the shape of the object itself to avoid excessive deformations and prevent breakage.

Finally, materials or application elements specifically designed for the damping of vibrations are known in the art which use said pseudoelastic materials where SMA wires have been arranged longitudinally to the direction of the stress and deformation (stress-strain) which present high quantities of SMA wire, even up to 10% by weight of the weight of the support material, i.e. in considerable quantities to have a significant damping response.

This state of the art is susceptible of considerable progress with the definition of materials using components in such pseudoelastic alloys which can be advantageously used to dampen vibrations in elements subject to them, when such materials are intimately connected to said elements subject to vibrations.

From the foregoing derives the need to solve the technical problem, which is the basis of the present invention, to provide an arrangement of the component element, the tape or fabric in pseudoelastic alloy, which allows to control and direct the known pseudoelastic effect that it tape or fabric can transmit to the element of the object subjected to vibrations with the main purpose of containing and / or canceling said vibrations.

Another purpose of the invention is to provide an arrangement of the pseudoelastic alloy element in the tape or fabric that allows you to control the intensity and directionality of the vibration damping intervention, using limited quantities of pseudoelastic material.

A further and not least purpose of the present invention is to control the frequency of intervention in the damping of vibrations, linked or not linked to the required value of the vibration damping intensity.

Summary of the invention

The invention solves the aforementioned technical problem by adopting a reinforcing fabric or tape in pseudoelastic material to dampen vibrations in elements subject to them, comprising: a layer of pseudoelastic material or SMA wire / s, with wire / s arranged / i in the plane of the layer; characterized in that the yarn (s) in pseudoelastic material conformed to strips of scrolls, oriented with the pitch of the scrolls in the direction of the warp and with the width of the scrolls in the direction of the weft.

In an advantageous constructive solution: at least one layer of support material is present to reinforce the fabric or tape; in addition, the strips of volutes placed side by side on the top can be made with different threads and separated from each other volute.

Further embodiments of the invention are summarized in the dependent claims.

More still, advantageously, the fabric or tape has the scroll strips with a volute pitch or wavelength between 2 and 20 mm. Furthermore, the volute strips have a volute width (F) between 3 and 20 mm.

Furthermore, the aforesaid fabric or tape has the thread or threads made of pseudoelastic material, or SMA, constituting the scrolls having a diameter between 0.050 and 0.250 mm.

In a further advantageous constructive embodiment, the invention comprises a composite band, with a layer of reinforcing material to resist the vibrations of the application element, in which there is a thread or threads made of pseudoelastic material, or SMA, arranged / i in the plane / s of the layer; characterized in that it has the wire (s) in pseudoelastic material shaped in strips of volutes, uniformly oriented to each other in the plane (s) of the layer. Advantageously, the composite band has the thread or threads made of pseudoelastic material, or SMA, arranged in the plane (s) of the layer by means of a fabric or tape.

Finally, in another advantageous constructional embodiment, the invention comprises a composite structural element, with a layer of reinforcing material to resist vibrations in the machine device for which it is intended, in which there is a wire or wires made of pseudoelastic material , or SMA, arranged in the plane / s of the layer; characterized in that it has the thread (s) in pseudoelastic material shaped in strips of volutes, uniformly oriented to each other in the plane (s) of the layer. Advantageously, the composite structural element has the thread or threads made of pseudoelastic material, or SMA, arranged in the plane (s) of the layer by means of a fabric or tape.

The characteristics and advantages of the present invention, in the realization of a reinforcing fabric or tape, with components in pseudo-elastic material, to dampen vibrations in elements subject to them, will result from the description given below of an example of embodiment given as an indication and not limitative with reference to the attached drawing tables.

Brief description of the drawings

One way to implement the invention is illustrated, purely by way of example, in the five attached drawing tables in which:

- Figure 1 is a limited schematic representation of a tape or fabric, according to the invention, in which the material with pseudoelastic properties and the way of fixing it to the other components of the tape are highlighted;

- Figure 2 is the schematic plan view of a wire volute made of pseudoelastic material;

- Figure 3 is a schematic perspective view of a belt according to the invention in pseudoleastic material;

- Figure 4 is the schematic view of a first arrangement of strips of scrolls placed side by side in a plane of the fabric or ribbon according to the invention;

Figure 5 is the schematic view of a second arrangement of strips of volutes offset by a quarter of a volute and slightly superimposed in a plane of the fabric or ribbon according to the invention;

- Figure 6 is the schematic view of a third arrangement of half-volute staggered volute strips, aligned and slightly overlapping in a plane of the fabric or ribbon according to the invention;

- Figure 7 is the schematic view of a fourth arrangement of strips of juxtaposed scrolls, divided into two superimposed planes, each with the arrangement of Figure 4; the volutes on the two levels are offset by a quarter of a volute and slightly overlapping; these planes of swirl strips being inserted facing each other in an internal plane of the fabric or ribbon according to the invention;

Figure 8 is the schematic view of a fifth arrangement of strips of juxtaposed volutes, divided into two superimposed planes, each with the arrangement of Figure 4; the volutes on the two floors result in staggered rows of half volutes and aligned with each other; these planes of swirl strips being inserted facing each other in an internal plane of the fabric or ribbon according to the invention;

- Figure 9 is the schematic view of a sixth arrangement of strips of spirals placed side by side on two superimposed planes, each with the arrangement of Figure 4; the volutes on the two floors are offset from each other by an eighth of a volute; they planes of volute strips being inserted facing each other in an internal plane of the fabric or ribbon according to the invention;

- Figure 10 is the schematic view of a seventh arrangement of strips of juxtaposed scrolls, divided into three superimposed planes, each with the arrangement of Figure 4; the volutes on the three levels are offset from each other by a third of the volute and slightly overlapping; they planes of volute strips being inserted facing each other in an internal plane of the fabric or ribbon according to the invention;

- Figure 11 is the representation in a schematic diagram of the structural transformation of the alloy formation lattice into pseudoelastic material, in which the snap deformation between two slightly different stresses and the corresponding large deformation due to this known phenomenon for the aforementioned alloy is visible .

Detailed description of a preferred embodiment In Figure 1 you can see: a tape 1, according to the invention, on which three strips 2 of volutes 3 with thread in pseudoelastic material are arranged; each strip is tied in the position of formation of the scrolls 3 with a simple chain stitch 4, to keep the scrolls 3 positioned during the production of the web 1. The warp O indicates the direction of construction of the web / fabric, while the direction T of the weft indicates the direction of stress of the tensions in the web / fabric and of the consequent deformations.

In Figure 2, in which a single volute 3 of a strip 2 is represented, the pitch is indicated by L and the width of the volute obtained by bending the thread in pseudo-elastic material with F.

Figure 3 shows the layers of the tape / fabric on which the volute strips of Figure 1 are applied. The layers consist of a first layer 4 of reinforcing fibers longitudinally to the warp; a second layer 5 of reinforcing fibers in the sense of the weft is applied to the previous one; to complete the web / fabric, there may be a further layer or core 6, which in the case of direct construction of a composite material may not be used.

In Figures 4 to 10 the various forms of arrangement of strips 2 of volutes 3 are differentiated by the quantity and partial overlapping of the strips and / or volutes.

In fact, Figure 4 represents a pattern of strips 2 with scrolls 3 like the one shown in Figures 1 and 3.

Furthermore, in Figure 5 two rows of side-by-side strips 7 are offset by Q, ie by a quarter of the volute pitch L.

Furthermore, in Figure 6, two rows of side-by-side strips 8 are offset by M, that is, by a half volute pitch L.

Furthermore, in Figure 7 two rows of strips 9a in one plane and 9b in the other are offset by Q, i.e. by a quarter of the volute pitch L.

Similarly to Figure 6, in Figure 8 two rows of strips 10a in one plane and 10b in the other are offset by M, that is, by a half volute pitch L.

Similarly to Figure 7, in Figure 9 two rows of strips 11 a in one plane and 11 b in the other are offset by V, that is, by an eighth of the volute pitch L.

Similarly to the previous Figures, in Figure 9 three rows of strips 12a in one plane, 12b in a second plane and 12c in a third plane are offset by Z, i.e. by a third of the volute pitch L.

Finally, the diagram of Figure 11 shows the loading diagram of the metal wire of the scrolls. During the load, from o to σ ', the tension in the wire of pseudoelastic material varies little, while the strain ε' is much larger than ε. During the variation of the tensions, typical of fatigue stresses with vibrations, the material is subjected to continuous tensioning and loosening, so the metal wire must perform several cycles, equal to the frequency of the vibration, and at each cycle it dissipates in the transformation of phase l energy stored in the deformation, thus drastically reducing their amplitude.

The tape / fabric according to the invention is produced by "superimposing" the metallic thread in pseudoelastic material on other reinforcing fibers (glass, carbon, aramides, etc.) arranged in a longitudinal direction and blocked there with the aid of other threads which are inserted transversely (without top-bottom crossing or crimp between the wires). In the realization of a composite, the direction of the fibers is generally that of the maximum effort (in compression or traction) and it follows that the volutes 3 are aligned in the same direction T, which can, mainly, be the optimal one to maximize the absorption of the vibrations that are produced.

However, it must be said that the arrangement similar to the sinusoidal depicted (in reality less precise than what is visible in the Figures), covers the entire surface of the fabric or tape in a way that is close to the "isotropic" and, therefore, the aforementioned negative aspects are minimized.

In the tests carried out, the diameter of the wire was found to be advantageous if between 0.050 and 0.250 mm, while the scrolls were formed with an amplitude (F) between 3 and 20 mm and a wavelength (L) between 2 and 20 mm.

The production of fabrics or ribbons can take place with a width from 3 to 1600 mm and (theoretically) infinite length.

Normally thermosetting resins (epoxy, polyester, vinylester, furanic, etc.) are used to impregnate the tape or fabric and make it cooperate with the object in which it is to be applied.

The resin impregnation can take place either by direct manual application (brush, roller etc.) or by infusion or by extrusion with traction of the same, thus obtaining a rigid strip that will subsequently be glued to the final object. The tape or the fabric can be inserted as such or with other reinforcing fabrics in the structure of the article or object on which it is intended to dampen vibrations, and then impregnated with resin as said.

In another possibility of application, the tape or fabric can be inserted as such or with other reinforcing fabrics between sheets of thermoplastic material and then printed until the product or object within which it is intended to dampen vibrations is obtained.

The greatest advantages in damping vibrations are obtainable with thermosetting materials (high modulus) which transfer energy well to the pseudoelastic material wire, allowing dissipation, while with thermoplastic materials (low modulus of elasticity) they have been tested and have not ensured an effect. of similar damping, as if the pseudoelastic material wire was not adequately stressed.

In an application test, the tape was used in the production of a pair of skis, inserting it both on the traction axis and on the compression axis of the tensions longitudinally to the ski. The results obtained were comforting and, subjected to laboratory tests, the testers highlighted the absence of vibrations, moreover, in the test on the track, also a remarkable stability in the holes that form near the doors.

The advantages obtained by this invention are: the tape / fabric 1, according to the invention, having the threads in pseudoelastic metal material organized and arranged in strips of oriented scrolls, almost completely exploits the characteristic of the material used, making it work in the hysteresis field marked between tensions and deformations, dissipating energy during stresses and decreasing the consequent elastic response typical of materials with a high elastic modulus, which notoriously also have good mechanical characteristics in response to stresses. This is a great advantage with respect to the use of wires arranged only longitudinally to the prevailing tension / deformation direction known in the art. The deformation prior to the composition of the tape / fabric or composite material leads to the introduction into the yarn itself that stress that is exploited in the pseudo-sinusoidal structure, to bring the material to work and dissipate energy in the optimal area of the tension / deformation graph. (or Stress / Strain).

The ribbon / fabric is produced with the technique of chain knitting (advantageously with the technology of crochet machines) which allows to produce fabrics in which the various layers are not intertwined as in a traditional fabric, but simply placed on each other and then linked together by a chain thread. This effect is advantageous, since, in the field of composite materials, the absence of crimp (intertwining) between layers reduces the de-lamination phenomena of the composite.

In the practical implementation, the materials, the dimensions, the executive details may be different from those indicated, but technically equivalent to them, without thereby departing from the legal domain of the present invention.

Claims (1)

CLAIMS 1- Reinforcing fabric or tape in pseudoelastic material to dampen vibrations in elements subject to them, comprising: a layer of wire / s material in pseudoelastic material, or SMA, with wire / s arranged in the plane of the layer; characterized in that it has the thread (s) in pseudoelastic material shaped in strips of scrolls, oriented with the pitch (L) of the scrolls in the direction of the warp (O) and with the width of the scrolls (F) in the direction of the plot (T). 2- Fabric or tape, according to claim 1, wherein at least one layer of support material is present to reinforce the fabric or tape. 3- Fabric or ribbon, according to one of claims 1, 2, in which the strips of spirals placed side by side are made with different and separate threads from each other. 4- Fabric or ribbon, according to one of claims 1, 2, 3, in which the scroll strips in the plane are penetrated in the respective scroll vertices between adjacent strips. 5- Fabric or tape, according to one of claims 1, 2, 3, in which the scroll strips in the plane are superimposed in the respective scroll vertices between adjacent strips. 6- Fabric or ribbon, according to one of claims 1, 2, 3, in which the scroll strips in the plane are superimposed and offset in the respective scroll vertices between adjacent strips. 7- Fabric or ribbon, according to one of claims 1, 2, 3, in which the scroll strips in the plane are interpenetrated, superimposed and offset in the respective scroll vertices between adjacent strips. 8- Fabric or tape, according to one of claims 1, 2, 3, in which the swirl strips divided on two levels are interpenetrated and offset, with respect to those of the other plane, in the respective volute vertices between adjacent strips. 9- Fabric or tape, according to one of claims 1, 2, 3, in which the swirl strips divided on two levels are interpenetrated, overlapped and offset, with respect to those of the other plane, in the respective volute vertices between adjacent strips. 10- Fabric or ribbon, according to one of claims 1, 2, 3, in which the scroll strips divided into three or more planes are interpenetrated, superimposed and offset, with respect to those of the other planes, in the respective volute vertices between adjacent strips . 11- Fabric or tape, according to one of the preceding claims from 6 to 10, in which the scrolls are offset from each other by a quarter (Q) of the scroll pitch (L). 12- Fabric or tape, according to one of the preceding claims from 6 to 10, in which the scrolls are offset from each other by half (M) of the scroll pitch (L). 13- Fabric or tape, according to one of the preceding claims from 6 to 10, in which the scrolls are offset from each other by one third (Z) of the scroll pitch (L). 14- Fabric or tape, according to one of the preceding claims from 6 to 10, in which the scrolls are offset from each other by one eighth (V) of the scroll pitch (L). 15- Fabric or tape, according to one of claims 1, 2, 3, in which the scroll strips have a volute pitch or wavelength (L) between 2 and 20 mm. 16- Fabric or tape, according to one of claims 1, 2, 3, wherein the scroll strips have a scroll width (F) comprised between 3 and 20 mm. 17- Fabric or tape, according to one of the preceding claims, in which the pseudoelastic material or SMA thread or threads constituting the scrolls have a diameter of between 0.050 and 0.250 mm. 18- Composite band, with a layer of reinforcing material to resist the vibrations of the application element, in which there is a wire or wires in pseudoelastic material, or SMA, arranged in the plane / s of the layer, according to one of the preceding claims; characterized in that it has the wire (s) in pseudoelastic material shaped in strips of volutes, uniformly oriented to each other in the plane (s) of the layer. 19- Composite band, according to the preceding claim 18, in which the thread or threads made of pseudoelastic material, or SMA, is / are arranged in the plane (s) of the layer by means of a fabric or tape. 20- Composite structural element, with a layer of reinforcing material to resist vibrations in the machine device for which it is intended, in which there is a wire or wires in pseudoelastic material, or SMA, arranged in the plane / s of the layer, according to one of the preceding claims; characterized in that it has the thread (s) in pseudoelastic material shaped in strips of volutes, uniformly oriented to each other in the plane (s) of the layer. 21- Composite structural element, according to the preceding claim 20, in which the thread or threads made of pseudoelastic material, or SMA, is / are arranged in the plane (s) of the layer by means of a fabric or tape.