Stretching-twisting combined loading clamp for tensile testing machine

Abstract

The invention discloses a tensile-torsion combined loading clamp for a tensile testing machine, which comprises a gland, the gland is provided with a through hole, and the end part of a to-be-tested sample can extend into the gland from the through hole; the turntable is connected with the gland, a wedge-shaped chuck is arranged between the turntable and the gland, the bottom of the wedge-shaped chuck is in plane contact with the top of the turntable, and the wedge-shaped chuck is used for clamping the end part of a to-be-tested piece; a sliding groove is formed in the rotating disc. The base is provided with a clamping end and can be clamped by a testing machine, a positioning hole is formed in the base, the first connecting piece penetrates through the sliding groove to be arranged in the positioning hole, and when the rotating disc rotates under the action of external force, the first connecting piece slides in the sliding groove, so that the base is movably connected with the rotating disc. The loading clamp is simple in structure and low in processing cost, and the uniaxial testing machine is a common mechanical testing instrument.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical property testing, and particularly to a tensile-torsion combined loading fixture for a tensile testing machine. Background Art

[0002] Material mechanics experiments are a class of experimental methods for studying the mechanical behavior and properties of materials under the action of external forces. The main purpose is to obtain mechanical property data of materials, such as strength, stiffness, toughness, hardness, etc., to provide a scientific basis for engineering design, structural optimization, material selection and application. In engineering design and material selection, many structures and components are not only subjected to a single axial load. Especially in the fields of composite materials, aerospace, automotive and civil engineering, materials often bear complex multiaxial mechanical environments. Taking the composite material blade in an aircraft as an example, the blade is subjected to tensile and torsional loads during operation. The combined load applied to the material in actual applications can be simulated by a multiaxial testing machine, but the high price of the multiaxial testing machine limits its application in scientific research and engineering practice.

[0003] The patent with the application number CN201910909150.7 provides a tensile-torsion combined fixture based on a positive and negative thread structure, which can reliably clamp a specimen in a material testing experiment with a tensile-torsion combined load under quasi-static and high-frequency dynamic conditions, and the high-frequency dynamic loading includes but is not limited to zero-crossing loading. It includes a fixture housing part, a clamping part and a tightening part. The rear end of the fixture cup seat in the housing part is connected to the tensile-torsion combined sensor through a flange; the clamping part consists of two nuts with different diameters and opposite helix directions, and is connected to the fixture cup seat through a flat key pair and a tightening part; the tightening part is used to adjust the locking degree of the inner-end nut. The advantages are as follows: It can clamp the specimen in a mechanical connection manner under the conditions of tensile-torsion combined load under quasi-static and high-frequency dynamic conditions. It has good versatility, low cost and convenient maintenance, and has an important prospect of application in extremely high temperature, extremely low temperature environments and limited spaces.

[0004] The patent with the application number CN202310674358.1 provides a wedge-shaped fixture for tensile-torsional composite loading tests, which includes an annular locking outer cover, wedge-shaped clamping pairs, and a circular fixture bottom plate; there are grooves with the same configuration as the end of the specimen inside the wedge-shaped clamping pairs. After clamping the upper specimen, it can be embedded into the inner wedge-shaped groove of the annular locking outer cover. The circular fixture bottom plate and the annular locking outer cover are locked by four T-shaped screws. Axial pressure is applied to the wedge-shaped clamping pairs through the central disc of the circular fixture bottom plate, prompting the two inclined surfaces of the inner wedge-shaped groove of the annular locking outer cover to apply an inward pre-tightening force to the wedge-shaped clamping pairs, ensuring that the specimen can be firmly clamped before the start of monotonic tension, monotonic torsion, and tensile-torsional composite loading. The advantages are simple structure, convenient clamping, strong clamping force, good centering, and can adapt to specimens with various cross-sectional shapes, having good application prospects in tensile-torsional composite loading tests.

[0005] Two fixtures of the prior art cannot rotate by themselves. To apply torsional load, another fixture is needed, which is costly and prone to loss if not properly stored, and it is impossible to achieve clamping for tensile-torsional loading with one fixture. Summary of the Invention

[0006] Aiming at the problems existing in the technology of this field, this application provides a simple tensile-torsional composite loading fixture that can be used in a uniaxial testing machine to realize the tensile-torsional coupling mechanical properties of materials tested on a tensile testing machine. The fixture has a simple structure, low processing cost, and the uniaxial testing machine is a common mechanical testing instrument. This solution is beneficial to scientific research and engineering practice applications.

[0007] The present invention adopts the following technical solutions:

[0008] A tensile-torsional composite loading fixture for a tensile testing machine, comprising:

[0009] A gland, with a through hole provided on the gland, and the end of the specimen to be tested can extend into the gland through the through hole;

[0010] A turntable, connected to the gland, with a wedge-shaped chuck provided between the turntable and the gland. The bottom of the wedge-shaped chuck is in contact with the top plane of the turntable, and the wedge-shaped chuck is used to clamp the end of the specimen to be tested; a chute is provided on the turntable;

[0011] A base, having a clamping end that can be clamped by the testing machine, with a positioning hole provided on the base. A first connecting member passes through the chute and is arranged in the positioning hole. When the turntable rotates under an external force, the first connecting member slides in the chute, thereby realizing the movable connection between the base and the turntable.

[0012] In this application, the wedge chuck can hold the end of the specimen to be tested. Using a turntable can facilitate the uniaxial testing machine to complete torsional loading. That is to say, using one kind of fixture can meet two loading requirements, with a simple, compact structure and reasonable processing cost.

[0013] Further, a turntable positioning tooth is provided on one side of the turntable facing the base, and a turntable positioning member is provided on the base. The turntable positioning member is slidably arranged at the turntable positioning tooth. When the turntable rotates under an external force, the turntable positioning member slides past the turntable positioning tooth in sequence, realizing multi-stage limiting of the turntable and the base. When the turntable rotates, the turntable positioning member radially inserts into the turntable positioning tooth, which can realize limiting at multiple positions, facilitating multi-angle torsion, so as to complete tensile-torsion combined loading.

[0014] Further, a notch is provided on the base, and the turntable positioning member is arranged at the notch. The turntable positioning member and the base are of a split structure, which is convenient for replacing them with various shapes.

[0015] Further, the positioning hole is located at the notch. A perforation adapted to the first connecting member is provided on the turntable positioning member. The perforation and the positioning hole are in a position-adapted relationship. The first connecting member passes through the perforation and the positioning hole to realize the movable connection between the base and the turntable. The perforation on the turntable positioning member and the positioning hole on the base are on the same axis, which is convenient for the connection of the first connecting member.

[0016] Further, the wedge chuck can extend out of the through hole. When the gland is locked, it is in direct contact with the outer wall of the wedge chuck, which is beneficial for subsequent disassembly. The wedge chuck has a limiting groove, and the shape of the limiting groove is adapted to the shape of the end of the specimen to be clamped. The depth of the limiting groove is not greater than half of the thickness of the end of the specimen to be clamped. The limiting groove has the same shape as the specimen clamping end, and the depth of the groove is not greater than half of the thickness of the specimen clamping end, which can ensure that the wedge chuck clamps the specimen before applying the axial load.

[0017] Further, the side wall of the limiting groove is in a shape of expanding diameter from the small end to the large end of the wedge chuck. This setting can prevent the specimen clamping end from slipping out of the wedge chuck.

[0018] Further, the bottom of the limiting groove is a damping surface, preferably a serrated surface, to increase damping to prevent the specimen from directly slipping out of the wedge chuck during loading.

[0019] Further, a second connecting member is provided on the turntable. The second connecting member has a thread. A connecting hole is provided on the gland. The second connecting member passes through the connecting hole and is connected to a nut to realize the connection between the gland and the turntable.

[0020] Further, the through hole is a trapezoidal notch with a large end and a small end, and the end of the through hole facing the turntable is the large end of the trapezoidal notch. The small end of the trapezoidal notch of the gland should be large enough to ensure that the top of the wedge chuck can pass through the top of the gland after clamping the specimen. The trapezoidal notch is provided to facilitate further clamping after the wedge fixture extends from the through hole, applying a large clamping force to ensure that the clamping end of the specimen to be tested is clamped.

[0021] Further, a positioning groove is provided on the turntable, and a driving member is arranged at the positioning groove so as to drive the turntable to rotate by applying a force to the driving member. The setting of the driving member facilitates the application of an external force, can provide a more reasonable torque, and reduces the force applied during torsion.

[0022] Advantages of the present invention:

[0023] 1. The use of a wedge chuck can meet the requirement of continuous tightening of the specimen during the loading process, and specific dimensional designs of the groove of the wedge chuck and the gland can enable a pair of chucks to clamp specimens of different thicknesses. Changing the shape of the internal groove of the chuck can adapt to different specimens without replacing other parts.

[0024] 2. The rotation mode of the turntable is manually completed by operating a lever. The positioning depends on the cooperation of the toothed groove on the turntable and the positioning teeth of the turntable, and the axial connection relies on standard parts such as bolts and nuts.

[0025] 3. The torsional load is measured by a quantitative torsional deformation angle, realizing tensile-torsional combined loading on a uniaxial tensile testing machine. Compared with a multi-axial loading testing machine, the present invention greatly reduces the cost of studying the tensile-torsional coupling mechanical properties of materials. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application;

[0027] Figure 2 It is a schematic diagram of the assembly structure of an embodiment of the present application;

[0028] Figure 3 It is a schematic diagram of the internal structure of an embodiment of the present application;

[0029] Figure 4 It is a schematic diagram of the structure of the turntable;

[0030] Figure 5 It is a schematic diagram of the structure of the wedge chuck;

[0031] In the figure: 1 - nut; 2 - gland; 21 - through hole; 22 - connection hole; 3 - wedge chuck; 31 - limit groove; 32 - damping surface; 4 - driving part; 5 - second connecting part; 6 - first connecting part; 7 - turntable; 71 - chute; 72 - turntable positioning teeth; 73 - positioning groove; 8 - turntable positioning part; 81 - perforation; 9 - base; 91 - positioning hole; 10 - base nut; 11 - specimen to be tested. Detailed implementation mode

[0032] The technical solution of the present invention will be elaborated in detail and clearly below in combination with the accompanying drawings in the embodiments of the present invention. It should be emphasized that the described embodiments are only partial examples of the present invention and do not exhaust all possible implementation manners. The schematic examples of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0033] This embodiment provides a tensile-torsional composite loading fixture for a tensile testing machine, as Figures 1 to 5 shown, a tensile-torsional composite loading fixture for a tensile testing machine, comprising:

[0034] A gland 2, on which a through hole 21 is provided, and the end of the specimen to be tested 11 can extend into the gland 2 from the through hole 21;

[0035] A turntable 7, connected to the gland 2, between the turntable 7 and the gland 2 there is a wedge chuck 3, the bottom of the wedge chuck 3 is in contact with the top plane of the turntable 7, and the wedge chuck 3 is used to clamp the end of the specimen to be tested; a chute 71 is provided on the turntable 7;

[0036] A base 9, which has a clamping end and can be clamped by a testing machine, and a positioning hole 91 is provided on the base 9. The first connecting part 6 passes through the chute 71 and is arranged in the positioning hole 91. When the turntable 7 rotates under an external force, the first connecting part 6 slides in the chute 71, thereby realizing the movable connection between the base 9 and the turntable 7.

[0037] In this application, the wedge chuck 3 can clamp the end of the specimen to be tested 11, and the turntable 7 can be used to facilitate the uniaxial testing machine to complete torsional loading. That is to say, using one fixture can realize the clamping of two kinds of loads, with a simple, compact structure and reasonable processing cost.

[0038] On one side of the turntable 7 facing the base 9, there are turntable positioning teeth 72. On the base 9, there is a turntable positioning member 8. The turntable positioning member 8 is slidably arranged at the turntable positioning teeth 72. The turntable 7 rotates under the action of an external force, causing the turntable positioning member 8 to slide past the turntable positioning teeth 72 in sequence, realizing multi-stage limiting of the turntable 7 and the base 9. When the turntable 7 rotates, the turntable positioning member 8 is inserted into the turntable positioning teeth 72 radially, which can realize limiting at multiple positions, facilitating multi-angle torsion to complete tensile-torsional composite loading.

[0039] There is a notch on the base 9, and the turntable positioning member 8 is arranged at the notch. The turntable positioning member 8 and the base 9 are of a split structure, which is convenient for replacing with various shapes. The positioning hole 91 is located at the notch. There is a perforation 81 on the turntable positioning member 8 adapted to the first connecting member 6. The perforation 81 and the positioning hole 91 are in position adaptation. The first connecting member 6 passes through the perforation 81 and the positioning hole 91 to realize the movable connection between the base 9 and the turntable 7. The perforation 81 on the turntable positioning member 8 and the positioning hole 91 on the base 9 are on the same axis, which is convenient for the connection of the first connecting member 6.

[0040] The wedge chuck 3 can extend out of the through hole 21 to facilitate the removal of the wedge chuck 3 after the test is completed. The wedge chuck 3 has a limit groove 31. The shape of the limit groove 31 is adapted to the shape of the end of the specimen to be clamped. The depth of the limit groove 31 is not greater than half of the thickness of the end of the specimen to be clamped. The limit groove 31 has the same shape as the specimen clamping end, and the depth of the groove is not greater than half of the thickness of the specimen clamping end, which can ensure that the wedge chuck 3 clamps the specimen before applying the axial load. The side wall of the limit groove 31 is in a shape of expanding diameter from the small end to the large end of the wedge chuck 3. This setting can prevent the specimen clamping end from slipping out of the wedge chuck 3. The bottom of the limit groove 31 is a damping surface 32, preferably a serrated surface, to increase damping to avoid the specimen slipping directly out of the wedge chuck 3 during loading.

[0041] There is a second connecting member 5 on the turntable 7. The second connecting member 5 has a thread. There is a connecting hole 22 on the gland 2. The second connecting member 5 passes through the connecting hole 22 and is connected to the nut 1 to realize the connection between the gland 2 and the turntable 7.

[0042] The through hole 21 is a trapezoidal notch with a large end at one side and a small end at the other side. The end of the through hole 21 facing the turntable 7 is the large end of the trapezoidal notch. The small end of the trapezoidal notch of the gland 2 should be large enough to ensure that the top of the wedge chuck 3 can pass through the top of the gland 2 after clamping the specimen. The setting of the trapezoidal notch is convenient for the wedge fixture to further tighten after extending out of the through hole 21, applying a large clamping force to ensure that the clamping end of the specimen 11 to be tested is clamped.

[0043] The turntable 7 is provided with a positioning groove 73, and the driving member 4 is arranged at the positioning groove 73 so as to drive the turntable 7 to rotate by applying a force to the driving member 4. Arranging the driving member 4 facilitates the application of an external force, can provide a relatively reasonable torque, and reduces the force applied during torsion.

[0044] The specimen is clamped by the top chuck of the tensile testing machine and the wedge chuck 3 of the fixture. The transition curve of the groove shape of the wedge chuck 3 is an arc to avoid stress concentration, which is the same as the shape of the specimen clamping end, and the depth of the groove is not greater than half of the thickness of the specimen clamping end. The groove is provided with a diamond serrated pattern to ensure that the wedge chuck 3 clamps the specimen when a load is applied. The gland 2 has a trapezoidal notch, and the slope of the trapezoidal notch is about 10° to match the wedge chuck 3. After clamping, the wedge chuck 3 can be embedded in the trapezoidal groove of the gland 2 and the end of the chuck passes through the top of the gland 2. The bottom of the wedge chuck 3 contacts the top plane of the turntable 7. The gland 2 and the turntable 7 are connected by the second connecting member 5 and the nut 1. The locking force in the axial direction provided acts on the outer wall of the wedge chuck 3, and then the wedge chuck 3 applies a clamping force to the specimen to complete the clamping of the specimen before the start of the tensile-torsion experiment. After the experiment starts, the tensile load provided by the tensile testing machine results in a greater bolt locking force, which further clamps the specimen by the wedge chuck 3.

[0045] The driving member 4 can cooperate with the positioning groove 73. Under the above connection relationship, the torsion of the specimen can be realized through the driving member 4. The main structure of the base 9 is a combination of a frustum of a cone and a cuboid. The cuboid part is clamped and fixed by the bottom chuck of the tensile testing machine, and at the same time, the frustum of the cone part supports the turntable 7. The main structure of the turntable 7 is a double-layer circular boss, with a larger radius in the upper layer and a smaller radius in the lower layer. The upper frustum of the cone provides a through groove required for bolt connection, and the lower frustum of the cone provides a toothed groove for torsion positioning. The circular groove of the base 9 can accommodate the lower frustum of the cone of the turntable 7. The depth of the groove is 2 mm larger than the height of the lower frustum of the cone of the turntable 7 and does not directly contact the lower frustum of the cone of the turntable 7 to facilitate the rotation of the turntable 7. The cross section of the turntable positioning member 8 is a combination of a triangle and a sector, enabling it to cooperate with the turntable positioning teeth 72 of the turntable 7 and the notch of the base 9.

Claims

1. A tensile-torsional composite loading fixture for a tensile testing machine, characterized in that, Comprising: A gland (2), a through hole (21) is provided on the gland (2), and the end of the specimen to be tested (11) can extend into the gland (2) through the through hole (21); A turntable (7), connected to the gland (2), a wedge chuck (3) is provided between the turntable (7) and the gland (2), and the wedge chuck (3) is used for clamping the end of the specimen to be tested; a chute (71) is provided on the turntable (7); A base (9), a positioning hole (91) is provided on the base (9), a first connecting member (6) is arranged in the positioning hole (91) through the chute (71), when the turntable (7) rotates under the action of an external force, the first connecting member (6) slides in the chute (71), thereby realizing the movable connection between the base (9) and the turntable (7).

2. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 1, characterized in that, A turntable positioning tooth (72) is provided on one side of the turntable (7) facing the base (9), a turntable positioning member (8) is provided on the base (9), the turntable positioning member (8) is slidably arranged at the turntable positioning tooth (72), and the turntable (7) rotates under the action of an external force to make the turntable positioning member (8) slide over the turntable positioning tooth (72) in sequence, realizing the multi-stage limit between the turntable (7) and the base (9).

3. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 2, wherein A notch is provided on the base (9), and the turntable positioning member (8) is arranged at the notch.

4. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 3, characterized in that, The positioning hole (91) is located at the notch, a through hole (81) adapted to the first connecting member (6) is provided on the turntable positioning member (8), the through hole (81) is adapted to the position of the positioning hole (91), and the first connecting member (6) passes through the through hole (81) and the positioning hole (91) to realize the movable connection between the base (9) and the turntable (7).

5. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 1, wherein The wedge chuck (3) can extend out of the through hole (21), the wedge chuck (3) has a limit groove (31), the shape of the limit groove (31) is adapted to the shape of the end of the specimen to be tested being clamped, and the depth of the limit groove (31) is not greater than half of the thickness of the end of the specimen to be tested being clamped.

6. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 5, characterized in that The side wall of the limit groove (31) is in a shape of expanding diameter from the small end to the large end of the wedge chuck (3).

7. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 5, characterized in that, The bottom of the limit groove (31) is a damping surface (32).

8. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 1, characterized in that, A second connecting member (5) is provided on the turntable (7), the second connecting member (5) has a thread, a connecting hole (22) is provided on the gland (2), the second connecting member (5) passes through the connecting hole (22) and is connected to a nut (1) to realize the connection between the gland (2) and the turntable (7).

9. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 1 or 5, characterized in that, The through hole (21) is a trapezoidal notch with one end large and the other end small, and the end of the through hole (21) facing the turntable (7) is the large end of the trapezoidal notch.

10. The tensile-torsional composite loading fixture for a tensile testing machine according to claim 1, wherein A positioning groove (73) is provided on the turntable (7), a driving member (4) is arranged at the positioning groove (73) so as to drive the turntable (7) to rotate by applying a force to the driving member (4).

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