Load pad and load device

Abstract

To suppress a reduction in load resistant by reducing local concentration of stress.SOLUTION: A load applying pad to be mounted to a sample for applying a load to the sample, includes a back skin to be applied with the load, an elastic body provided between the back skin and the sample, and an insertion member provided between the elastic body and the sample. The back skin, the elastic body and the insertion member are integrally joined, and the insertion member is lower in rigidity than the sample, and higher in rigidity than the elastic body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a load application pad and a load application device for applying a load to a specimen.

Background Art

[0002] Conventionally, as a load application pad, a tension pad for a structural strength test having a back skin for applying a load to a specimen and a low elastic body provided between the specimen and the back skin and adhered to the specimen and the back skin is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the specimen and the back skin are hard members, and the structure is such that a low elastic body is adhered between the hard members. In such a structure, since the rigidity change between the members becomes large, a large local stress is generated in the adhesive layer at the boundary between the specimen and the low elastic body and the adhesive layer at the boundary between the low elastic body and the back skin, and as a result, the load-bearing capacity of the load application pad is reduced.

[0005] Therefore, an object of the present disclosure is to provide a load application pad and a load application device that can relieve local stress concentration and suppress a decrease in load-bearing capacity.

Means for Solving the Problems

[0006] The load application pad of the present disclosure is a load application pad that is attached to a specimen to apply a load to the specimen, and includes a backskin to which the load is applied, an elastic body provided between the backskin and the specimen, and an insertion member provided between the elastic body and the specimen. The backskin, the elastic body, and the insertion member are integrally joined. The insertion member has a lower rigidity than the specimen and a higher rigidity than the elastic body.

[0007] The load application device of the present disclosure includes a load application jig including the above load application pad, a connection jig for connecting a plurality of the load application pads, and an actuator for applying a load to the specimen via the load application pad and the connection jig.

Effect of the Invention

[0008] According to the present disclosure, local stress concentration can be alleviated, and a decrease in load resistance can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited by these embodiments. Also, the components in the following embodiments include those that can be easily replaced by those skilled in the art or are substantially the same. Furthermore, the components described below can be combined as appropriate, and when there are multiple embodiments, it is also possible to combine each embodiment.

[0011] [Embodiment 1] (Load Loading Device) The load loading device 10 including the load pad 31 according to Embodiment 1 is a device that loads a tensile load on the specimen 5. As the specimen 5, for example, it is a wing body such as the main wing or tail wing of an aircraft.

[0012] FIG. 1 is an explanatory diagram schematically showing the load loading device according to Embodiment 1. FIG. 2 is a side view of the load pad according to Embodiment 1. FIGS. 3 to 5 are side views of another example of the load pad according to Embodiment 1.

[0013] As shown in FIG. 1, in the case of taking the tensile load loading as an example, the load loading device 10 includes an actuator 11 attached to the support portion 8, a connection jig 32 connected to the actuator 11, and a plurality of load pads 31 attached to the connection jig 32.

[0014] Actuator 11 applies a tensile load to the specimen 5 via the connecting jig 32 and the load pad 31. The actuator 11 is, for example, a hydraulic actuator and is provided by being suspended from the support portion 8. The actuator 11 includes a cylinder 21 and a piston 22 that linearly moves with respect to the cylinder 21. The cylinder 21 is attached to the support portion 8. The piston 22 expands and contracts with respect to the cylinder 21, and a connecting jig 32 is attached to the tip of the piston 22.

[0015] The connecting jig 32 is formed by connecting one actuator 11 and a plurality of load pads 31. The connecting jig 32 is, for example, a jig formed in a tournament shape using a steel material. That is, the connecting jig 32 has a shape that branches into a plurality from one actuator 11 toward a plurality of load pads 31.

[0016] The load pad 31 is a jig that is attached to the specimen 5 by being adhered to the specimen 5 using an adhesive, and is detachable from the specimen 5. As shown in FIG. 2, a tensile load is applied to the load pad 31 as a load.

[0017] The load pad 31 has a backskin 41, an elastic body 42, and an insertion member 43, and they are stacked in the thickness direction and integrally joined using an adhesive.

[0018] The backskin 41 includes a connected portion 41a connected to the connecting jig 32 and a plate portion 41b joined to the elastic body 42. The connected portion 41a is formed, for example, as a handle portion having an arc shape, and a tensile load is applied via the connecting jig 32. The plate portion 41b has a rectangular shape in plan view and is formed using, for example, a metal material. The surface of the plate portion 41b facing the elastic body 42 is a joining surface, and it is joined to the elastic body 42 using an adhesive. Note that the plate portion 41b may have a rectangular shape or a circular shape, and may have any shape.

[0019] The elastic body 42 is provided between the back skin 41 and the insertion member 43. The elastic body 42 is made of, for example, rubber or the like, and is deformable following the relative displacement between the specimen 5 and the back skin 41. The surface of the elastic body 42 facing the insertion member 43 serves as a joint surface, and it is joined to the insertion member 43 using an adhesive.

[0020] The insertion member 43 is provided between the elastic body 42 and the specimen 5. The insertion member 43 is made of, for example, resin or the like. The insertion member 43 has a complementary shape with respect to the space formed by the specimen 5 and the elastic body 42. In FIG. 2, since the surfaces of the specimen 5 and the elastic body 42 facing each other are parallel surfaces, the insertion member 43 has a flat plate shape. The surface of the insertion member 43 facing the specimen 5 serves as a joint surface, and it is joined to the specimen 5 using an adhesive.

[0021] Here, the insertion member 43 has a lower rigidity than the specimen 5 and a higher rigidity than the elastic body 42. That is, the rigidity of the load-bearing pad 31 decreases from the specimen 5 toward the elastic body 42.

[0022] Specifically, the Young's modulus of the insertion member 43 is lower than that of the specimen 5 and higher than that of the elastic body 42. When the specimen 5 is made of a metal material containing, for example, aluminum, its Young's modulus is about 70 GPa, and when it is made of a metal material containing iron, its Young's modulus is about 200 GPa. Also, when the elastic body 42 is made of an elastic material containing, for example, chloroprene rubber, its Young's modulus is about 5 MPa. In this case, the Young's modulus of the insertion member 43 is in the range of 1 GPa to 10 GPa.

[0023] Next, with reference to FIGS. 3 and 4, another example of the insertion member 43 will be described. FIG. 3 shows a specimen 5 to which the insertion member 43 is joined, having a curved joint surface, and FIG. 4 shows a specimen 5 to which the insertion member 43 is joined, having a stepped portion on the joint surface. As described above, the insertion member 43 has a shape complementary to the space formed by the specimen 5 and the elastic body 42. For this reason, in FIG. 3, the insertion member 43 is formed in a shape such that the surface facing the specimen 5 is curved. Further, in FIG. 4, the insertion member 43 is formed in a shape such that the surface facing the specimen 5 has a stepped portion 45. Note that the insertion member 43 may be formed using a three-dimensional modeling device. In this case, even when the shape of the insertion member 43 is a complicated shape, the insertion member 43 can be easily formed.

[0024] Next, with reference to FIG. 5, another example of the load application pad 31 will be described. The load application pad 31 shown in FIG. 5 further includes an insertion member 43 provided between the backskin 41 and the elastic body 42. That is, the load application pad 31 includes a first insertion member 43a provided between the specimen 5 and the elastic body 42, and a second insertion member 43c provided between the backskin 41 and the elastic body 42. The first insertion member 43a is the same as the above-described insertion member 43. The second insertion member 43b has a lower rigidity than the backskin 41 and a higher rigidity than the elastic body 42. That is, the rigidity of the load application pad 31 decreases from the backskin 41 toward the elastic body 42. Note that the material and Young's modulus of the second insertion member 43b may be the same as those of the first insertion member 43a.

[0025] The load application device 10 provided with the load application pad 31 as described above applies a tensile load to the load application pad 31 from the actuator 11 via the connecting jig 32. Then, a load is applied to the load application pad 31 in a direction away from the specimen 5. At this time, the load application pad 31 can make the change in rigidity gentler from the specimen 5 toward the elastic body 42 when the insertion member 43 is interposed and joined between the specimen 5 and the elastic body 42 as compared with the case where the load application pad 31 is joined to the specimen 5 and the elastic body 42. For this reason, the load application pad 31 can relieve local stress concentration in the adhesive layer at the boundary between the specimen 5 and the elastic body 42, and a load resistance against the tensile load can be obtained. In the above description, the tensile load is described as the main acting force, but it goes without saying that the same effect can be obtained even when a load in the shear direction or the compression direction acts.

[0026] [Embodiment 2] Next, referring to FIGS. 6 to 10, Embodiment 2 will be described. In Embodiment 2, in order to avoid redundant description, parts different from Embodiment 1 will be described, and parts having the same configuration as in Embodiment 1 will be described with the same reference numerals. FIG. 6 is a perspective view of the load application pad according to Embodiment 2. FIG. 7 is a perspective view of another example of the load application pad according to Embodiment 2. FIG. 8 is a side view of the load application pad according to Embodiment 2. FIGS. 9 and 10 are side views of another example of the load application pad according to Embodiment 2.

[0027] The load-bearing pad 51 of Embodiment 2 is formed by creating a void 55 in the insertion member 43 of Embodiment 1. Specifically, the insertion member 53 of Embodiment 2 has a plurality of voids 55 formed therethrough in the thickness direction. That is, the insertion member 53 is a porous member. The plurality of voids 55 are formed in the shapes shown in FIGS. 6 and 7. The insertion member 53a shown on the left side of FIG. 6 is formed in a rectangular shape in plan view, and the void 55 is also formed in a rectangular shape in plan view. That is, the insertion member 53a is formed in a square frame shape. The insertion member 53b shown on the right side of FIG. 6 is formed in a rectangular shape in plan view, similar to the left side of FIG. 6, and the void 55 is also formed in a rectangular shape in plan view. Here, the void 55 on the left side of FIG. 6 is smaller than the void 55 on the right side of FIG. 6.

[0028] The insertion member 53c shown in FIG. 7 is formed in a rectangular shape in plan view, and the void 55 is formed in a polygonal shape (e.g., hexagonal shape) in plan view. That is, the insertion member 53c is formed in a honeycomb structure.

[0029] Here, if the ratio of the area of the void 55 per unit area as viewed from the thickness direction is defined as the porosity, the porosity of the insertion member 53 shown in FIGS. 6 and 7 is in the range of 70% to 90%. Also, the insertion member 53a on the left side of FIG. 6 and the insertion member 53b on the right side of FIG. 6 have different sizes of voids 55, and the void 55 of the insertion member 53a on the left side of FIG. 6 is larger than the void 55 of the insertion member 53b on the right side of FIG. 6. For this reason, the porosity of the insertion member 53a is larger than the porosity of the insertion member 53b.

[0030] As shown in FIG. 8, in the cross section of the insertion member 53 cut along the thickness direction, a void 55 is formed between the specimen 5 and the elastic body 42. And when the specimen 5, the insertion member 53, and the elastic body 42 are joined, the void 55 is filled with an adhesive. That is, in the void 55 portion, the specimen 5 and the elastic body 42 are joined via an adhesive.

[0031] Further, as shown in FIGS. 9 and 10, the insertion member 53 of Embodiment 2 may further include a flat plate 58 joined to one surface in the thickness direction. The insertion member 53d shown in FIG. 9 includes a member body 57 provided with a gap 55 and a flat plate 58 joined to the elastic body 42 side of the member body 57. The member body 57 is the same as the insertion member 53 of Embodiment 2. The flat plate 58 is made of the same material as the member body 57 and is integrally joined to the member body 57. The insertion member 53e shown in FIG. 10 includes a member body 57 provided with a gap 55 and a flat plate 58 joined to the specimen 5 side of the member body 57. The member body 57 is the same as the member body 57 in FIG. 9, and the flat plate 58 is also the same as the flat plate 58 in FIG. 9. Note that the rigidity of the insertion member 53 on the side where the flat plate 58 is provided is increased. Therefore, the insertion member 53 in FIG. 10 has a higher rigidity on the specimen 5 side and a lower rigidity on the elastic body 42 side, so that the rigidity decreases from the specimen 5 toward the elastic body 42.

[0032] [Embodiment 3] Next, referring to FIG. 11, Embodiment 3 will be described. In Embodiment 3, in order to avoid redundant descriptions, differences from Embodiments 1 and 2 will be described, and parts having the same configuration as those in Embodiments 1 and 2 will be described with the same reference numerals. FIG. 11 is a side view of the load-bearing pad according to Embodiment 3.

[0033] The load-bearing pad 61 of Embodiment 3 includes an adhesive layer 65 formed by bonding using an adhesive, and the adhesive layer 65 includes an impregnated film body 66. The adhesive layer 65 is formed between the back skin 41 and the elastic body 42, and between the elastic body 42 and the insertion member 43. The adhesive layer 65 includes an adhesive and an impregnated film body 66 impregnated with the adhesive. The impregnated film body 66 is, for example, a fiber such as a woven fabric, and a glass cloth or the like is applicable. Such an adhesive layer 65 can absorb unevenness by the impregnated film body 66 containing the adhesive even when the surface to be bonded has unevenness.

[0034] As described above, the load-bearing pads 31, 51, 61 and the load-bearing device 10 described in the present embodiment can be understood as follows, for example.

[0035] The load pads 31, 51, 61 according to the first aspect are load pads 31, 51, 61 that are attached to the specimen 5 in order to apply a load to the specimen 5. The load pads 31, 51, 61 include a back skin 41 to which the load is applied, an elastic body 42 provided between the back skin 41 and the specimen 5, and an insertion member 43 provided between the elastic body 42 and the specimen 5. The back skin 41, the elastic body 42, and the insertion member 43 are integrally joined. The insertion member 43 has a lower rigidity than the specimen 5 and a higher rigidity than the elastic body 42.

[0036] According to this configuration, by providing the insertion member 43 between the specimen 5 and the elastic body 42, it is possible to reduce the change in rigidity between the specimen 5 and the elastic body 42. Therefore, in the adhesive layer at the boundary between the specimen 5 and the insertion member 43 and the adhesive layer at the boundary between the insertion member 43 and the elastic body 42, local stress concentration can be alleviated, and a decrease in load resistance can be suppressed.

[0037] As a second aspect, the Young's modulus of the insertion member 43 is lower than the Young's modulus of the specimen 5 and higher than the Young's modulus of the elastic body 42.

[0038] According to this configuration, by making the Young's modulus of the insertion member 43 different from that of the specimen 5 and the elastic body 42, the material of the insertion member 43 can be made different from the materials of the specimen 5 and the elastic body 42. Therefore, the rigidity of the insertion member 53 can be easily adjusted.

[0039] As a third aspect, the Young's modulus of the insertion member 43 is in the range of 1 GPa to 10 GPa.

[0040] According to this configuration, a resin material or the like can be applied as the insertion member 43.

[0041] As a fourth aspect, the insertion member 43 is a first insertion member 43a, and further includes a second insertion member 43c provided between the back skin 41 and the elastic body 42.

[0042] According to this configuration, even between the backskin 41 and the elastic body 42, local stress concentration can be alleviated, and a decrease in load-bearing capacity can be suppressed.

[0043] As a fifth aspect, the insertion member 53 has a member body 57 in which a gap 55 penetrating in the thickness direction, which is the direction in which the elastic body 42 and the specimen 5 face each other, is formed.

[0044] According to this configuration, the rigidity of the insertion member 53 can be easily adjusted by the gap 55.

[0045] As a sixth aspect, when the ratio of the area of the gap 55 per unit area viewed from the thickness direction is defined as the porosity, the porosity of the insertion member 53 is in the range of 70% to 90%.

[0046] According to this configuration, an appropriate porosity considering the durability of the insertion member 53 can be achieved.

[0047] As a seventh aspect, the insertion member 53 further has a flat plate 58 joined to one surface of the member body 57 in the thickness direction.

[0048] According to this configuration, the rigidity of the insertion member 53 on the side where the flat plate 58 is provided can be increased. Therefore, the rigidity can also be changed in the insertion member 53. Thereby, for example, in the insertion member 53, if the rigidity on the side of the specimen 5 is increased and the rigidity on the side of the elastic body 42 is decreased, it becomes possible to make the change in rigidity between the specimen 5 and the elastic body 42 smaller.

[0049] As an eighth aspect, an adhesive layer 65 formed by joining using an adhesive is provided between the backskin 41 and the elastic body 42, and between the elastic body 42 and the insertion member 43, and the adhesive layer 65 includes the adhesive and an impregnated film body 66 impregnated with the adhesive.

[0050] According to this configuration, even if the surface to be adhered has unevenness, the unevenness can be absorbed by the impregnated film body 66 containing the adhesive. Therefore, the adhesive strength can be increased.

[0051] The load applying device 10 according to the ninth aspect includes the above load applying pads 31, 51, 61, a connecting jig 32 that connects a plurality of the load applying pads 31, 51, 61, and an actuator 11 that applies a load to the specimen 5 via the load applying pads 31, 51, 61 and the connecting jig 32.

[0052] According to this configuration, it is possible to appropriately apply a load to the specimen 5 while suppressing a decrease in load resistance.

Explanation of Reference Numerals

[0053] 5 Specimen 10 Load applying device 11 Actuator 21 Cylinder 22 Piston 31 Load applying pad 32 Connecting jig 41 Back skin 42 Elastic body 43 Insertion member 51 Load applying pad 53 Insertion member 55 Gap 57 Member body 58 Flat plate 61 Load applying pad 65 Adhesive layer 66 Impregnated film body

Claims

1. In a load-bearing pad that is attached to a specimen in order to apply a load to the specimen, a back skin to which the load is applied, an elastic body provided between the back skin and the specimen, and an insertion member provided between the elastic body and the specimen, wherein the back skin, the elastic body, and the insertion member are integrally joined, the insertion member has a lower rigidity than the specimen and a higher rigidity than the elastic body, and is a load-bearing pad.

2. The load-bearing pad according to claim 1, wherein the Young's modulus of the insertion member is lower than the Young's modulus of the specimen and higher than the Young's modulus of the elastic body.

3. The load-bearing pad according to claim 2, wherein the Young's modulus of the insertion member is in the range of 1 GPa to 10 GPa.

4. The insertion member is a first insertion member, and the load-bearing pad according to any one of claims 1 to 3, further comprising a second insertion member provided between the back skin and the elastic body.

5. The load-bearing pad according to any one of claims 1 to 4, wherein the insertion member has a member body in which a void is formed that penetrates in the thickness direction, which is the direction in which the elastic body and the specimen face each other.

6. When the ratio of the area of the voids per unit area as viewed from the thickness direction is defined as the porosity, the load-bearing pad according to claim 5, wherein the porosity of the insertion member is in the range of 70% to 90%.

7. The insertion member The load-bearing pad according to claim 5 or 6, further having a flat plate joined to one surface of the member body in the thickness direction.

8. An adhesive layer formed by joining using an adhesive is provided between the back skin and the elastic body and between the elastic body and the insertion member, The load-bearing pad according to any one of claims 1 to 7, wherein the adhesive layer includes the adhesive and an impregnated film body impregnated with the adhesive.

9. A load-bearing device comprising the load-bearing pad according to any one of claims 1 to 8, a connecting jig for connecting a plurality of the load-bearing pads, and an actuator for applying a load to the specimen via the load-bearing pad and the connecting jig.

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