Elastic materials, elastic units, and composite materials

Abstract

To provide an elastic material and an elastic unit having appropriate flexibility in a hardened state, and a composite material having both the strength of metal and the elasticity of elastomer. The composite material (1) comprises a shape memory alloy (11) having a compliant structure and an elastomer (10) connected to the shape memory alloy (11), and is stretchable.

Description

[Technical Field]

[0001] The present invention relates to an elastic material, an elastic unit, and a composite material. [Background technology]

[0002] Patent Document 1 discloses a medical fixation material that adheres closely to the surface of the human body while maintaining a shape that follows the shape of the surface of the human body to protect the surface. Patent Document 2 discloses a flap with a deforming wing shape. This flap is a so-called morphing wing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-199377 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-37155 Summary of the Invention [Problem to be solved by the invention]

[0004] The material disclosed in Patent Document 1 uses a thermoplastic resin that softens when heated above a certain temperature and hardens when cooled below that temperature. Therefore, the material disclosed in Patent Document 1 can be used as a cast that conforms to the surface of the affected area by heating it in a softened state, adhering it to the surface of the affected area, and then cooling it. The material disclosed in Patent Document 1 does not have flexibility in its hardened state. Therefore, if the material disclosed in Patent Document 1 is used as a cast across a joint, there is a concern that the hardened cast will restrict joint movement and cause the joint to stiffen. Therefore, a material for use in casts is desired that has adequate flexibility while maintaining the ability to immobilize the affected area.

[0005] The first and second inventions were made in consideration of the above-mentioned conventional situation, and the problem to be solved is to provide an elastic material that is flexible while protecting the object to which it is attached.

[0006] In the device disclosed in Patent Document 2, the upper and lower components of the morphing section of the flap can repeatedly deform in the vertical direction (thickness direction) using a built-in link mechanism. For example, if a morphing section and a non-deforming wing are adjacent to each other, when the morphing section deforms, it separates from the non-deforming wing, creating a gap and increasing the chance of turbulence. By preventing the formation of such gaps, it is possible to make the air flowing along the wing more laminar, thereby improving flight performance. For example, it is conceivable to connect the morphing section and the non-deforming wing with an elastic elastomer and suppress the formation of gaps by expanding and contracting the elastomer. However, it is difficult to ensure sufficient strength with elastomers. Furthermore, metal plates cannot expand and contract. For this reason, a composite material that combines the strength of metals with the flexibility of elastomers is desired. Here, elastomers are defined as polymeric materials with rubber-like elasticity.

[0007] The third invention was made in consideration of the above-mentioned conventional situation, and its problem to be solved is to provide a composite material that combines the strength of metal and the elasticity of elastomer. [Means for solving the problem]

[0008] The stretchable material of the first invention comprises a base body having a compliant structure, and the base body has slits formed therein that extend from the outer edge in a direction that intersects with the stretching direction.

[0009] When an external force is applied to the base body of this stretchable material so that it stretches in the stretching direction, the width of the slits expands in the stretching direction, making it easy to realize a configuration in which the base body can be stretched and deformed freely. Here, a compliant structure is a structure in which forces and deformations are transmitted by elastic deformation of continuous flexible members without using links.

[0010] The telescopic unit of the second invention is a telescopic unit having a plurality of telescopic materials of the first invention, each of which is stacked in the thickness direction, and the base of one of the telescopic materials is arranged so as not to overlap the base of another of the telescopic materials.

[0011] When an external force is applied to the base in the extension direction, the width of the slit expands in the extension direction, allowing the base to be deformed freely. Furthermore, since the base of one extension material is arranged so as not to overlap with the base of another extension material, it is possible to cover and conceal a wider area of ​​the surface of the attachment target.

[0012] The composite material of the third invention comprises a shape memory alloy having a compliant structure and an elastomer connected to the shape memory alloy, and is expandable and contractible.

[0013] This composite can be configured so that the elastomer deforms to follow the expansion and contraction of the shape memory alloy. This allows the composite to have both the strength of metal and the flexibility of elastomer. Here, a compliant structure is a structure that transmits force and deformation with elastic deformation. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view showing the shrinkable materials of Examples 1, 2, and 3. [Figure 2] FIG. 2 is an enlarged plan view showing the main parts of the first, second and third embodiments. [Figure 3] FIG. 2 is an enlarged plan view showing the main parts of Examples 1 and 2 in an enlarged state stretched in one direction. [Figure 4] 10 is a graph showing the elastic restoring force versus the stretched dimension when the shrinkable material of Example 2 is stretched and shrunk in one direction. [Figure 5] FIG. 10 is a perspective view showing a shrinkable material of Example 3. [Figure 6] 10 is a graph showing the elastic restoring force versus the compressed dimension when the shrinkable material of Example 3 is compressed in one direction. [Figure 7] FIG. 10 is a plan view showing a contraction unit according to a fourth embodiment. [Figure 8] FIG. 10 is a plan view showing the composite material of Example 5. [Figure 9] 9 is a cross-sectional view taken along the line AA in FIG. 8. [Figure 10] FIG. 10 is a plan view showing the composite material of Example 5 in a state stretched in one direction. [Figure 11] FIG. 10 is a plan view showing another embodiment in which the flat portion is formed in a band shape. [Figure 12] FIG. 10 is a plan view showing another embodiment in which slits are formed in the flat portion. [Figure 13] FIG. 10 is a side cross-sectional view showing another embodiment in which the through-hole is filled with elastomer. DETAILED DESCRIPTION OF THE INVENTION

[0015] A preferred embodiment of the present invention will now be described.

[0016] In the stretchable material of the first invention, the base may be flat, having a flat surface extending in the stretching direction. With this configuration, because the base is flat, when the stretchable material is attached to an object, it can be attached so as to cover the object, making it possible to realize a configuration that acts like armor to protect the object, for example.

[0017] The stretchable material of the first invention has connecting parts provided on both ends of the base body in the stretch direction, and the connecting parts can be connected so that multiple base bodies are lined up in the stretch direction. With this configuration, it is possible to increase the dimension that can be stretched in the stretch direction.

[0018] The base of the stretchable material of the first invention has a first outer edge and a second outer edge, and the slits include a first slit extending from the first outer edge and a second slit extending from the second outer edge, and the first slit and the second slit can be aligned in the stretch direction. With this configuration, the base can be stretched efficiently in the stretch direction.

[0019] In the stretchable material of the first invention, it is preferable that adjacent base bodies do not overlap when stretched in the stretch direction. With this configuration, the base bodies do not overlap, and the thickness of the stretchable material does not increase, making it easy to handle.

[0020] In the composite material of the third invention, the elastomer has elasticity and can be laminated on the shape memory alloy. This configuration allows the elastomer and the shape memory alloy to be bonded together well.

[0021] The compliant structure in the composite material of the third invention may have planar portions and connecting portions that extend in a direction intersecting the expansion / contraction direction and connect the plurality of planar portions. This configuration allows the plurality of planar portions to be connected by the connecting portions into a planar shape that expands in the expansion / contraction direction, and allows this plane to expand and contract in the expansion / contraction direction.

[0022] The planar portions of the composite material of the third invention may be configured not to overlap when stretched in the expansion / contraction direction. With this configuration, the composite material can be stretched in the expansion / contraction direction without increasing its thickness.

[0023] The elastomer in the composite material of the third invention may be a shape-memory resin. Shape-memory resins have the property of becoming deformable when an external force is applied while heated above their glass transition temperature, and retaining their deformed shape when cooled below their glass transition temperature. Therefore, according to this configuration, by heating the elastomer above its glass transition temperature, the elastomer can be easily deformed to follow the elongation of the shape-memory alloy. Then, by lowering the temperature of the elastomer below its glass transition temperature while maintaining the shape-memory alloy in its elongated state, the elastomer can be maintained in its shape while following the elongation of the shape-memory alloy.

[0024] In the composite material of the third invention, the temperature at which the shape memory alloy returns to its memorized shape can be higher than the glass transition temperature of the elastomer. With this configuration, when the shape memory alloy is heated to return from an elongated state to its memorized shape, the elastomer also softens, allowing it to smoothly contract to its original shape.

[0025] In the composite material of the third invention, the shape memory alloy can generate heat when electricity is passed through it. With this configuration, the shape memory alloy can be heated to a temperature at which it returns to its memorized shape by passing electricity through it without the need for a separate heater, and by heating the elastomer to a temperature above its glass transition temperature, the elastomer can be easily deformed to follow the elongation of the shape memory alloy.

[0026] Example 1 Next, a first embodiment of the stretchable material of the first invention will be described with reference to the drawings. As shown in Figure 1, stretchable material 300 of the first embodiment includes a plurality of bases 311, a plurality of connecting portions 311C, and a pair of holding portions 311P.

[0027] The stretchable material 300 is a shape memory alloy made by forming an alloy of Ni and Ti into a plate with a thickness of 0.03 mm. When a direct current is passed through the shape memory alloy, it generates heat according to the magnitude of the current. For example, the stretchable material 300 is placed in oil and formed by electrical discharge machining using wire cutting. This prevents the stretchable material 300 from being overheated during its manufacture, thereby preventing the stretchable material 300 from being altered by excessive heating.

[0028] Each base 311 has a flat triangular shape. As shown in FIG. 2, each base 311 has a first outer edge 311D, a second outer edge 311E that is shorter than the first outer edge 311D, and a third outer edge 311F that is shorter than the first outer edge 311D and the second outer edge 311E. That is, the outer shape of each base 311 is a scalene triangle. In Example 1, the dimension of the first outer edge 311D is approximately 26 mm, the dimension of the second outer edge 311E is approximately 18 mm, and the dimension of the third outer edge 311F is approximately 13 mm. Here, each base 311 has a first corner 311G where the first outer edge 311D and the second outer edge 311E are connected, a second corner 311H where the second outer edge 311E and the third outer edge 311F are connected, and a third corner 311J where the third outer edge 311F and the first outer edge 311D are connected.

[0029] Each of the connecting portions 311C is formed in a disk shape. Each of the connecting portions 311C is provided on both ends of a first outer edge 311D of the base 311. The bases 311 are arranged in a lattice pattern with their first outer edges 311D at right angles to each other (see FIG. 1), and are connected via the connecting portions 311C.

[0030] As shown in FIG. 1, focusing on the four bases 311 that form one lattice, the lattice formed by the first outer edges 311D includes two pairs of bases 311 (hereinafter simply referred to as pairs) whose first outer edges 311D are parallel. One of the two pairs is arranged so that the second corners 311H of the bases 311 approach each other (inside the lattice). The other of the two pairs is arranged so that the second corners 311H of the bases 311H move away from each other (outside the lattice). Furthermore, each of the four connecting portions 311C located at the corners of the lattice is connected to the second outer edge 311E and the third outer edge 311F of the adjacent bases 311.

[0031] As shown in FIG. 2, focusing on one connecting portion 311C, four bases 311 are connected to this connecting portion 311C. The first outer edges 311D of the four bases 311 are connected to each other so as to radiate outward from the connecting portion 311C. The first outer edges 311D of the two bases 311 arranged diametrically opposite each other across the connecting portion 311C are linearly arranged. First corners 311G and third corners 311J are connected to each connecting portion 311C so as to be alternately arranged in the circumferential direction around the connecting portion 311C. The second corners 311H of the four bases 311 face the first outer edges 311D of the bases 311 adjacent to each other in the circumferential direction around the connecting portion 311C. In one connecting portion 311C, the angle between the first outer edges 311D adjacent to each other in the circumferential direction around the connecting portion 311C is a right angle.

[0032] Each base 311 has two first slits 311K and two second slits 311L formed therein. The first slits 311K are continuous with the first outer edge 311D and extend toward the second outer edge 311E. The second slits 311L are continuous with the second outer edge 311E and extend toward the first outer edge 311D. One of the two first slits 311K extends toward the opening end where the second slit 311L is continuous with the second outer edge 311E. The other of the two first slits 311K extends toward the second corner 311H. The second slit 311L extends toward the opening end where the first slit 311K is continuous with the first outer edge 311D. The first slits 311K and the second slits 311L are arranged alternately in the direction in which the first outer edge 311D and the second outer edge 311E extend. Specifically, one of the two second slits 311L is arranged in a position closest to the first corner 311G. The extension lengths of the first slits 311K and the second slits 311L become longer as they move from the first corner 311G toward the third corner 311J.

[0033] Each base 311 has five planar portions 311M and four intra-base connecting portions 311N. The five planar portions 311M are formed by dividing the base 311 by the first slits 311K and the second slits 311L. The intra-base connecting portions 311N are formed in a circular shape. Adjacent planar portions 311M are connected via the intra-base connecting portions 311N. These planar portions 311M are arranged in a zigzag pattern. Of the five planar portions 311M, the planar portions 311M that form the first corner portions 311G have a triangular outer shape. The remaining four of the five planar portions 311M have a trapezoidal outer shape with the sides connecting to the two intra-base connecting portions 311N as their bases.

[0034] As shown in Figure 1, the pair of holding portions 311P are in the form of roughly rectangular flat plates. Each holding portion 311P is disposed at both ends in one direction D of the directions in which the stretchable material 300 expands. Each holding portion 311P is disposed so as to extend elongately in a direction perpendicular to the one direction D. A plurality of base bodies 311 are connected to each holding portion 311P via connecting portions 311C.

[0035] The first outer edge 311D of each base 311 extends at an angle of 45 degrees with respect to the direction D. The third outer edge 311F of each base 311 extends in a direction perpendicular to the direction D. Focusing on the base 311 adjacent to one of the holding portions 311P, each first outer edge 311D is connected in a zigzag shape in a direction perpendicular to the direction D. Of both end portions of each first outer edge 311D, the end closest to the holding portion 311P is connected to the holding portion 311P via a connecting portion 311C. In this way, the elastic material 300 is formed. The elastic material 300 memorizes the shape shown in FIG. 1 as its original shape.

[0036] For example, while holding the pair of holding portions 311P, an external force is applied to the pair of holding portions 311P in a direction in which they are pulled away from each other (direction D). As a result, as shown in FIG. 3, the open end sides of the first slits 311K and the second slits 311L in each base 311 expand. At this time, adjacent flat portions 311M in each base 311 deform so as to rotate around the intra-base connecting portion 311N. This increases the apparent dimension of the first outer edge 311D in each base 311, and increases the dimension between the first corner 311G and the third corner 311J. Thus, each base 311 expands in the direction in which the first outer edge 311D extends. The direction in which the first outer edge 311D extends is the expansion / contraction direction Ds. The expansion / contraction direction Ds is a direction that forms a 45-degree angle with the direction D (see FIG. 2). Adjacent bases 311 do not overlap when stretched in the stretching direction Ds.

[0037] Each flat surface 311M extends along the extension / contraction direction Ds. The first slits 311K and the second slits 311L extend from the first outer edge 311D and the second outer edge 311E, respectively, in a direction intersecting the extension / contraction direction Ds. The first slits 311K and the second slits 311L are arranged alternately in the extension / contraction direction Ds.

[0038] As each first outer edge 311D stretches, the dimension between the pair of holding portions 311P in direction D increases. When the application of external force is stopped, the stretchable material 300 maintains its stretched state in direction D. When a predetermined amount of external force (approximately 20 N) is applied to the pair of holding portions 311P in a direction in which they pull apart (direction D), the stretch rate of the stretchable material 300 in direction D is approximately 20%. Here, the stretch rate is the value obtained by dividing the stretched dimension of the stretchable material 300 in direction D by the dimension of the stretchable material 300 before stretching.

[0039] With the stretchable material 300 held in a stretched state in one direction D, the positive pole of a DC power supply unit P is connected to one of the pair of holding parts 311P, and the negative pole is connected to the other. A DC current is then passed between the pair of holding parts 311P. This causes the stretchable material 300 to generate heat. A DC current of about 2 A (amperes) is passed through the stretchable material 300, raising the temperature of the stretchable material 100 to about 90°C. The recovery temperature of the shape memory alloy of the stretchable material 300 is set to 85°C. The recovery temperature is the temperature at which a shape memory alloy begins to return to its memorized shape.

[0040] The temperature of the elastic material 300 exceeds the recovery temperature. As a result, the dimensions of the expanded opening ends of the first slits 311K and second slits 311L in each base 311 narrow. At this time, adjacent flat surfaces 311M in each base 311 deform so as to rotate around the intra-base connecting portions 311N. This causes the elongated first outer edge 311D to contract, and the first corner 311G and the third corner 311J approach the stretching direction Ds. Thus, the dimension between the pair of holding portions 311P returns to the dimension before the external force was applied (see FIG. 1). Each base 311 contracts in the direction in which the first outer edge 311D extends (stretching direction Ds). In this way, the elastic material 300 can repeatedly expand and contract in one direction D. In other words, base body 311 has a compliant structure in which force and deformation are transmitted by deformation of planar portions 311M that are connected by intra-base connecting portions 311N and arranged in a zigzag pattern.

[0041] According to the first embodiment configured as above, the following effects are achieved.

[0042] The stretchable material 300 includes a base 311 having a compliant structure, and the base 311 is formed with first slits 311K and second slits 311L that extend from the outer edge in a direction intersecting the stretch direction Ds. With this configuration, when an external force is applied to the base 311 so as to stretch it in the stretch direction Ds, the widths of the first slits 311K and second slits 311L expand in the stretch direction Ds, making it easy to realize a configuration in which the base 311 deforms stretchably.

[0043] In the stretchable material 300, the base 311 is flat and has a plurality of flat portions 311M that extend along the stretch direction Ds. With this configuration, because the base 311 is flat, when the stretchable material 300 is attached to an object, it can be attached so as to cover the object, making it possible to realize a configuration that acts like armor to protect the object, for example.

[0044] The stretchable material 300 has connecting portions 311C provided on both ends of the base body 311 in the stretch direction Ds, and the connecting portions 311C are connected so that multiple base bodies 311 are lined up in the stretch direction Ds. With this configuration, it is possible to increase the dimension that can be stretched in the stretch direction Ds.

[0045] The base 311 has a first outer edge 311D and a second outer edge 311E, the first slits 311K extend from the first outer edge 311D, the second slits 311L extend from the second outer edge 311E, and the first slits 311K and the second slits 311L are aligned in the extension / contraction direction Ds. This configuration allows the base 311 to be efficiently extended in the extension / contraction direction Ds.

[0046] Adjacent base bodies 311 do not overlap when stretched in the stretch direction Ds. With this configuration, the base bodies 311 do not overlap, and the thickness of the stretchable material 300 does not increase, making it easy to handle.

[0047] <Example 2> The stretchable material 400 according to Example 2 differs from Example 1 in that a synthetic resin is used instead of a shape memory alloy, and in the plate thickness dimensions, etc. In the following explanation, the same components as those in Example 1 are given the same reference numerals, and redundant explanations will be omitted. Since the external shape is the same as that of Example 1, the explanation will be made with reference to Figures 1 to 3.

[0048] The elastic material 400 can be produced using, for example, a known 3D printer. The material used for the elastic material 400 is nylon mixed with carbon fiber. The plate thickness of the elastic material 400 is approximately 1 mm. In Example 2, the dimensions of each of the first outer edge 311D, second outer edge 311E, and third outer edge 311F are approximately twice those of Example 1. The pair of holding portions 311P of the produced elastic material 400 are grasped, and an external force is applied in a direction that pulls them apart (direction D). As a result, as in Example 1, each base 311 stretches in the stretching direction Ds (see FIG. 3). At the same time, the pair of holding portions 311P move away from each other in direction D. At this time, the elastic material 400 generates an elastic restoring force that increases in proportion to the dimension stretched in direction D. The elastic restoring force at this time is a force that moves the pair of holding portions 311P toward direction D. Adjacent bases 311 do not overlap when stretched in the stretch direction Ds. When the application of external force is stopped, each base 311 elastically returns to its original position, and the first corner 311G and the third corner 311J approach each other in the stretch direction Ds. In this way, the dimension between the pair of holding portions 311P returns to the dimension before the external force was applied (see FIG. 1). In other words, the stretchable material 400 acts as a resin spring.

[0049] It was found that when the distance between the pair of holding portions 311P is increased by a fixed amount, the elastic restoring force generated in the stretchable material 400 increases in proportion to the stretched distance between the pair of holding portions 311P, as shown in Figure 4(A). Next, from a state in which the distance between the pair of holding portions 311P is separated (i.e., a state in which the stretchable material 400 is stretched), the pair of holding portions 311P is brought closer by a fixed amount. In this case, it was found that the degree to which the elastic restoring force decreases gradually from the start of contraction to the end of contraction, as shown in Figure 4(B).

[0050] Example 3 The elastic material 500 according to Example 3 differs from Example 2 in terms of plate thickness. In the following explanation, the same components as those in Example 2 are given the same reference numerals, and redundant explanations will be omitted. The external shape of the elastic material 500 as viewed in the plate thickness direction is the same as in Examples 1 and 2, and therefore will be explained with reference to Figures 1 and 2.

[0051] The plate thickness of the elastic material 500 is approximately 20 mm (see FIG. 5). The dimensions of the first outer edge 311D, the second outer edge 311E, and the third outer edge 311F are the same as in Example 2. A pair of holding portions 311P of the elastic material 500 are grasped, and an external force is applied in a direction in which they approach each other (direction D). In other words, an external force is applied so as to compress the elastic material 500 in direction D. The elastic material 500 has a thickness of approximately 20 mm. Therefore, each base 311 contracts in the expansion / contraction direction Ds without buckling. At this time, first, the dimensions on the open end sides of the first slits 311K and the second slits 311L narrow. Then, after the open ends of all the first slits 311K and the second slits 311L close, each base 311 is displaced so as to rotate, reducing its dimension in direction D. At this time, the stretchable material 500 generates an elastic restoring force that increases in accordance with the dimension contracted in the one direction D. The elastic restoring force at this time is a force in a direction that moves the pair of holding portions 311P apart in the one direction D.

[0052] When the application of the external force is stopped, each base 311 is displaced so as to rotate, and the dimension in one direction D returns to the dimension before compression. After that, the dimension on the open end side of all first slits 311K and second slits 311L returns to the dimension before compression. In this way, the elastic material 500 returns to the shape it had before the external force was applied. In other words, the elastic material 500 acts as a resin spring.

[0053] The distance between the pair of holding portions 311P was reduced at a constant rate. As a result, as shown in FIG. 6 , the elastic restoring force generated in the stretchable material 500 changed from start point S to end point E along path R1. Then, the distance between the pair of holding portions 311P was restored at a constant rate from a compressed state in one direction D. Then, the elastic restoring force generated in the stretchable material 500 changed from end point E to start point S along path R2. It was found that the slope of both paths R1 and R2 clearly changed at a predetermined compressed dimension between approximately 10 mm and 12 mm. Specifically, it was found that for both paths R1 and R2, the slope when the compressed dimension was below the predetermined dimension was smaller than the slope when the compressed dimension was above the predetermined dimension.

[0054] Example 4 Next, a fourth embodiment of the telescopic unit of the second invention will be described with reference to the drawings. The telescopic unit 600 of the fourth embodiment has a plurality of the telescopic materials 300 of the first embodiment (two in this embodiment) stacked in the thickness direction. Specifically, as shown in FIG. 7, one of the telescopic materials 300 (the gray one in FIG. 7) is inverted left-right or up-down and placed on top of the other telescopic material 300 (the white one in FIG. 7). As a result, the base 311 of one of the telescopic materials 300 is positioned so as not to overlap the base 311 of the other telescopic material 300. Specifically, the planar portion 311M of one of the telescopic materials 300 does not overlap the planar portion 311M of the other telescopic material 300. The first outer edge 311D of one of the telescopic materials 300 is adjacent to the first outer edge 311D of the other telescopic material 300. Focusing on the adjacent first outer edges 311D, the connecting portion 311C and the intra-base connecting portion 311N continuing to one first outer edge 311D overlap with the connecting portion 311C and the intra-base connecting portion 311N continuing to the other first outer edge 311D.

[0055] The extension unit 600 includes a plurality of extension materials 300, which are stacked in the thickness direction, and the base 311 of one extension material 300 is arranged so as not to overlap the base 311 of another extension material 300. With this configuration, when an external force is applied to the base 311 so as to stretch it in the extension direction Ds, the widths of the first slits 311K and the second slits 311L expand in the extension direction Ds, and the base 311 can be deformed to be elastic. Furthermore, the base 311 of one extension material 300 is arranged so as not to overlap the base 311 of another extension material 300. This allows the extension unit 600 to cover and conceal a wider area of ​​the surface of the object to which it is attached.

[0056] Next, a fifth embodiment of the composite material of the third invention will be described with reference to the drawings.

[0057] <Example 5> As shown in Figures 8 and 9, the composite material 1 of Example 5 includes a pair of elastomers 10 (see Figure 9) and a shape memory alloy 11. The pair of elastomers 10 are made of SMP (Shape Memory Polymer), which is a sheet-like shape memory resin. In this example, the material of the elastomer 10 is polyurethane, and the thickness thereof is 0.15 mm.

[0058] SMP has the property that when heated by an external heat source to a temperature higher than a predetermined temperature (glass transition temperature Tg), it becomes elastic, and when cooled below the predetermined temperature, it becomes rigid and not elastic. The glass transition temperature Tg of SMP can be freely set within a range of approximately -40°C to +120°C. In this embodiment, the glass transition temperature Tg of elastomer 10 was set to 25°C. When the SMP is heated to a temperature higher than the predetermined temperature, it is deformed by applying an external force, and then cooled below the predetermined temperature while maintaining the deformed state, and then it changes to a rigid state while retaining (memorizing) the deformed shape by the application of the external force.

[0059] When the SMP is heated to a temperature higher than a predetermined temperature, it returns to the shape it had before the external force was applied. When the SMP is cooled to a temperature lower than the predetermined temperature, it changes to a rigid, non-stretchable state, retaining the shape it had before the external force was applied. In other words, elastomer 10 is in a sheet form, and when an external force is applied while the elastomer is heated to a temperature higher than the glass transition temperature Tg, it becomes stretchable and deformable. When the temperature drops below the glass transition temperature Tg, it becomes rigid and non-stretchable.

[0060] As shown in FIG. 8, the shape memory alloy 11 has a flat plate shape with a plurality of through holes 11A formed therethrough in the plate thickness direction. In this embodiment, the plate thickness of the shape memory alloy 11 is 0.08 mm. In this embodiment, each through hole 11A is formed using a known water cutter. As a result, when manufacturing the shape memory alloy 11, no heat is applied to the shape memory alloy 11, and therefore, the shape memory alloy 11 can be manufactured without being altered by heat. The shape memory alloy 11 is formed, for example, from an alloy of Ni and Ti.

[0061] The shape memory alloy 11 has a plurality of flat portions 11B and a plurality of connecting portions 11C. The shape memory alloy 11 has a compliant structure constituted by the plurality of flat portions 11B and the plurality of connecting portions 11C. Each flat portion 11B is planar and has a roughly triangular shape. Specifically, each flat portion 11B is formed by a first side 11D and a second side 11E that are linear, and a third side 11F that curves outward in an arc.

[0062] Each connecting portion 11C has four connecting pieces 11K arranged in a cross shape, and each connecting piece 11K extends in a direction intersecting the plate thickness direction T (see FIG. 9). Four flat portions 11B are connected to each connecting portion 11C. Focusing on one connecting portion 11C, the connecting pieces 11K located opposite each other across the center of the connecting portion 11C are connected to each other at a corner where the first side 11D and the second side 11E of the flat portion 11B are joined. The remaining two connecting pieces 11K are connected to a corner where the first side 11D and the third side 11F of the flat portion 11B are joined. In one connecting portion 11C, the corner where the second side 11E and the third side 11F are joined is positioned so as to face the first side 11D of the adjacent flat portion 11B. In other words, in the plurality of flat portions 11B connected to one connecting portion 11C, the corners where the second sides 11E and the third sides 11F are joined do not face each other.

[0063] In one connecting portion 11C, the angle between adjacent connecting pieces 11K is set to 90°. The angle between the first sides 11D of the flat portion 11B connecting adjacent connecting pieces 11K is also set to 90°. The connecting portion 11C and the flat portion 11B memorize this shape as their original shape. For example, even if the connecting piece 11K is deformed so that the angle between adjacent connecting pieces 11K changes from 90° to a different angle, the deformed connecting piece 11K returns to its original shape by heating it above its recovery temperature, and the angle between adjacent connecting pieces 11K becomes 90°. Furthermore, the flat portion 11B connected to the connecting piece 11K also returns to its original shape by heating it above its recovery temperature, and the angle between adjacent first sides 11D becomes 90°. The recovery temperature of the shape memory alloy 11 used in this example was 85°C.

[0064] The shape memory alloy 11 further has a plurality of holding portions 11G. The holding portions 11G are formed in a flat, generally rectangular shape. Each holding portion 11G is arranged in connection with each connecting portion 11C located at both ends in one direction D of the directions in which the shape memory alloy 11 expands. Copper foil 11H is electrically connected to each holding portion 11G arranged on one side of the one direction and each holding portion 11G on the other side of the one direction. Specifically, each holding portion 11G is attached to the copper foil 11H using polyimide 11L (e.g., Kapton (registered trademark) by DuPont-Toray Co., Ltd.) with the copper foil 11H in contact with each holding portion 11G (see FIG. 9).

[0065] The shape memory alloy 11 thus formed is sandwiched between a pair of elastomers 10 in both directions in the plate thickness direction T, as shown in FIG. 9. Specifically, using a known hot press machine, the shape memory alloy 11 is crimped while sandwiched between the pair of elastomers 10. The elastomers 10 are stacked and connected to the shape memory alloy 11 in the plate thickness direction T. The pair of elastomers 10 are crimped to each other via the through holes 11A. The outer side of each copper foil 11H in one direction D is not covered by the elastomers 10 and is left exposed. In this way, the composite material 1 is formed.

[0066] A DC power supply unit P is connected to each of the pair of copper foils 11H (see Figure 8). When a DC current is passed from the DC power supply unit P to the shape memory alloy 11 via the pair of copper foils 11H, the shape memory alloy 11 generates heat. The degree of heat generation is greater in the connecting portion 11C than in the flat portion 11B. In this embodiment, when a DC current of 2 A (amperes) was passed through the shape memory alloy 11, the temperature of the connecting portion 11C rose to 50°C. As the shape memory alloy 11 generates heat and its temperature rises, the entire elastomer 10 is heated to a temperature above the glass transition temperature Tg (25°C in this embodiment).

[0067] [About the function of composite materials] For example, when no current is flowing through the shape memory alloy 11, the temperature of the composite 1 becomes lower than the glass transition temperature Tg (25°C). At this time, the elastomer 10 is in a hard state, so even if an external force is applied to the composite 1 outward in one direction D, the composite 1 does not elongate.

[0068] When a direct current is passed through the shape memory alloy 11, the shape memory alloy 11 generates heat. The heat generated by the shape memory alloy 11 then heats the elastomer 10. When the elastomer 10 is heated to a temperature equal to or higher than the glass transition temperature Tg, the elastomer 10 softens and changes to an elastic state. In this state, when an external force is applied outward in one direction D to the composite material 1, the composite material 1 stretches in the one direction D.

[0069] Before an external force is applied, the connecting piece 11K of the connecting portion 11C extends in a direction intersecting at approximately 45° with the direction D (stretching direction). When an external force is applied to the composite material 1 outward in the direction D, as shown in FIG. 10, the connecting piece 11K deforms so that its extension direction changes to be along the direction D. At the same time, the orientation of the planar portion 11B connected to the connecting piece 11K changes so that the first side 11D is oriented along the direction D. As a result, the composite material 1 stretches in the direction D. Adjacent planar portions 11B do not overlap when stretched in the stretching direction. The elongation rate of the composite material 1 when stretched in the direction D was approximately 17%. Here, the elongation rate is the value obtained by dividing the elongated dimension of the composite material 1 in the direction D by the dimension of the composite material 1 before it changed to an elongated state.

[0070] When the supply of current to the shape memory alloy 11 is stopped while the composite material 1 is stretched in the direction D, the composite material 1 maintains its shape in the stretched state stretched in the direction D. When a direct current is again passed through the shape memory alloy 11, the shape memory alloy 11 returns to its original shape (memorized shape) due to its own heat generation. Specifically, the connecting piece 11K of the connecting portion 11C deforms so as to return to an orientation intersecting the direction D at an angle of 45°. At the same time, the orientation of the flat portion 11B connected to the connecting piece 11K changes so that the first side 11D returns to an orientation intersecting the direction D at an angle of 45°.

[0071] Here, the temperature at which the shape memory alloy 11 returns to its memorized shape is set to be higher than the glass transition temperature Tg of the elastomer 10. Therefore, the elastomer 10 is heated to or above the glass transition temperature Tg by the heat generated by the shape memory alloy 11, softens, changes to a stretchable state, and returns to its original shape before being stretched. Then, the composite material 1 returns from the stretched state to the contracted state (see FIG. 8). In this way, the composite material 1 can repeatedly change between the stretched state and the contracted state.

[0072] According to the fifth embodiment configured as above, the following effects are achieved.

[0073] The composite material 1 comprises a shape memory alloy 11 having a compliant structure and an elastomer 10 connected to the shape memory alloy 11, and expands and contracts. This configuration allows the composite material 1 to be configured so that the elastomer 10 deforms to follow the expansion and contraction of the shape memory alloy 11. This allows the composite material 1 to be configured to have both the strength of the shape memory alloy 11 and the flexibility of the elastomer 10.

[0074] In the composite material 1, the elastomer 10 has elasticity and is laminated on the shape memory alloy 11. With this configuration, the elastomer 10 and the shape memory alloy 11 can be bonded together well.

[0075] The compliant structure of the composite material 1 has planar planar portions 11B and connecting portions 11C that extend in a direction intersecting the expansion / contraction direction at 45° and connect the plurality of planar portions 11B. This configuration enables the plurality of planar portions 11B to be connected by the connecting portions 11C in a planar shape that expands in the expansion / contraction direction, and enables the structure to expand and contract in the expansion / contraction direction while maintaining this planar expanding shape.

[0076] The planar portions 11B of the composite material 1 do not overlap when stretched in the expansion / contraction direction. With this configuration, the composite material 1 can expand in the expansion / contraction direction without increasing the plate thickness.

[0077] The elastomer 10 in the composite material 1 is a shape-memory resin. Shape-memory resins have the property of becoming deformable when an external force is applied while the resin is heated to a temperature equal to or higher than the glass transition temperature Tg, and retaining the deformed shape when the temperature drops below the glass transition temperature Tg. Therefore, with this configuration, by heating the elastomer 10 to a temperature equal to or higher than the glass transition temperature Tg, the elastomer 10 can be easily deformed to follow the elongation of the shape-memory alloy 11. Then, by lowering the temperature of the elastomer 10 below the glass transition temperature Tg while the shape-memory alloy 11 is maintained in an elongated state, the shape of the elastomer 10 can be maintained while following the elongation of the shape-memory alloy 11.

[0078] In the composite material 1, the temperature at which the shape memory alloy 11 returns to its memorized shape is higher than the glass transition temperature Tg of the elastomer 10. According to this configuration, when the shape memory alloy 11 is heated to return from an elongated state to its memorized shape, the elastomer 10 also softens, allowing it to smoothly return to its original shape.

[0079] In the composite material 1, the shape memory alloy 11 generates heat when electricity is applied. With this configuration, the shape memory alloy 11 can be heated to a temperature at which it returns to its memorized shape by applying electricity to the shape memory alloy 11 without the need for a separate heater, and by heating the elastomer 10 to a temperature above the glass transition temperature Tg, the elastomer 10 can be easily deformed to follow the contraction of the shape memory alloy 11.

[0080] The present invention is not limited to the first to fifth embodiments described above with reference to the drawings, and the following embodiments are also included within the technical scope of the present invention. (1) The shape of the flat portion may be different from that of Example 1. For example, as shown in Fig. 11, the flat portion 111B may be formed in a strip shape. Also, as shown in Fig. 12, a slit 211J may be formed in the flat portion 211B. This allows the flat portion 211B to have the ability to expand when an external force is applied. (2) The material of the shape memory alloy may be different from that used in the first and fifth embodiments. (3) Unlike the fifth embodiment, in the case of a laminated heater configuration, there is no need to energize the heater, so there is no need to provide copper foil. (4) Unlike in Example 5, the elastomer may be any material having elastic properties, and other materials such as synthetic rubber may be used instead of shape-memory resin. (5) Unlike Example 5, as shown in FIG. 13, a configuration may be adopted in which an elastomer 110 is filled into the through-hole 11A of the shape memory alloy 11. In this case, the elastomer and the shape memory alloy are connected to the inner surface of the through-hole 11A. This configuration also makes it possible to form a flat composite material. Alternatively, the shape memory alloy may be attached to a single piece of elastomer. Alternatively, the shape memory alloy and the elastomer may be connected by insert molding. (6) The thickness of the shape memory alloy and the elastomer is not limited to that in the fifth embodiment. (7) Unlike in Examples 1 and 2, the elastic material may be formed in a cylindrical or spherical shape instead of a flat shape. For example, if the elastic material is formed in a cylindrical shape, it can be configured to stretch in the axial or radial direction. Also, if the elastic material is formed in a spherical shape, it can be configured to stretch in the radial direction. (8) The shape-memory resin elastomer of Example 5 may be attached to the stretchable material of Example 1 or Example 2. (9) The stretchable material of Example 1 or Example 2, or the stretchable unit of Example 4 may be used to connect the surface of a movable part, such as a flap of an aircraft, to the surface of a non-movable part adjacent to the flap. (10) The elastic material of Example 1 or Example 2 or the elastic unit of Example 4 may be used in a bone fixation implant for children during their growth period. In this case, it can be extended in accordance with bone growth and does not hinder bone growth. (11) The stretchable material of Example 1 or Example 2, or the stretchable unit of Example 4 may be used as a protective sock to protect the protruding end of a prosthetic limb. In this case, it is preferable to form the base finely so that the spacing between adjacent bases is small, thereby preventing a large area of ​​the surface of the protruding end of the prosthetic limb from being exposed. (12) The elastic material of Example 1 or Example 2, or the extension unit of Example 4 may be used in a joint support device for elderly people. For example, the elastic material or extension unit may be attached along a joint to exert an assisting force that compensates for the muscle force that moves the joint when straightening a bent joint. (13) The elastic material of Example 3 may be used as a damper to absorb external impacts. For example, by incorporating an elastic material into a part of a hood, it is conceivable to absorb the collision energy when two cars collide or when a car collides with a person. Also, by incorporating an elastic material into the legs of a lander that makes a soft landing on a celestial body such as the moon or an asteroid, it is conceivable to absorb the collision energy when the lander makes a soft landing on the celestial body. (14) The metal spring may be replaced with the elastic material of Example 2 or Example 3, or the elastic unit of Example 4. (15) The elastic material of Example 1 may be used in a pantograph jack. Specifically, a stretched elastic material is attached instead of the threaded rod. Then, by heating the elastic material to a temperature above its recovery temperature, the elastic material contracts, deforming the arm so that the load receptacle is lifted. (16) The stretchable material of Example 1 may be used for a fishing net. Specifically, it is stretched according to the amount of fish caught. After the caught fish are removed, it is heated to a temperature above the recovery temperature to shrink it and make it easier to store. (17) The dimensions of the first outer edge, second outer edge, and third outer edge of the base are not limited to those in the above embodiment. The outer shape of the base may be a right-angled isosceles triangle in which the lengths of the second outer edge and the third outer edge are the same. When this stretchable material is used to form a stretchable unit, the gap between the bases of one stretchable material can be most efficiently closed by the bases of the other stretchable material. The outer shape of the base may also be set to a polygonal, circular, elliptical, or other shape. (18) The stretchable unit may be constructed by stacking the stretchable materials of Example 2. (19) The stretchable material of Example 2 may be molded by injection molding, or may be produced by cutting a flat plate-shaped material. (20) The number of each of the first slits and the second slits in one substrate may be one, or three or more. [Explanation of symbols]

[0081] 1: Composite material 10,110: Elastomer 11:Shape memory alloy 11B, 111B, 211B, 311M: Flat part 11C, 311C: Connection part D: One direction (stretch direction) Ds: Stretch direction 300, 400, 500: Contraction material 311: Base 311D: First outer edge 311E: Second outer edge 311K: First slit (slit) 311L: Second slit (slit) 600: Contraction unit

Claims

1. a substrate having a compliant structure; The base is a stretchable material having slits formed therein that extend from the outer edge in a direction that intersects with the stretch direction.

2. 2. The stretchable material according to claim 1, wherein the base body is in the form of a flat plate having a flat surface extending along the stretching direction.

3. The base body includes connecting portions provided at both ends in the extension / contraction direction, 3. The stretchable material according to claim 1, wherein the connecting portions are connected so that a plurality of the base bodies are aligned in the stretching direction.

4. the substrate has a first outer edge and a second outer edge; The slits include a first slit extending from the first outer edge and a second slit extending from the second outer edge, The stretchable material according to claim 1 or 2, wherein the first slit and the second slit are aligned in the stretch direction.

5. 4. The stretchable material according to claim 3, wherein adjacent base bodies do not overlap when stretched in the stretching direction.

6. An extension unit comprising a plurality of the extension materials according to claim 3, Each of the elastic materials is stacked in the thickness direction, The stretchable unit is arranged so that the base of one of the stretchable materials does not overlap the base of another of the stretchable materials.

7. a shape memory alloy having a compliant structure; an elastomer coupled to the shape memory alloy; Equipped with Stretchable composite material.

8. The composite material according to claim 7 , wherein the elastomer has elasticity and is laminated to the shape memory alloy.

9. The compliant structure comprises: a planar portion having a planar shape; a connecting portion extending in a direction intersecting the extension / contraction direction and connecting the plurality of planar portions; 9. The composite material according to claim 7 or claim 8, comprising:

10. The composite material according to claim 9 , wherein the planar portions do not overlap when stretched in the expansion / contraction direction.

11. 9. The composite material according to claim 7 or 8, wherein the elastomer is a shape memory resin.

12. 12. The composite of claim 11, wherein the temperature at which the shape memory alloy returns to the memorized shape is greater than the glass transition temperature of the elastomer.

13. 9. The composite material according to claim 7, wherein the shape memory alloy generates heat when an electric current is passed through it.

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