Clamp for testing shear performance of composite material

Abstract

The invention discloses a clamp for testing the shear performance of a composite material. The clamp can be used for effectively loading a V-shaped slotted sample. An upper grooved cavity and a lower grooved cavity are used for placing the first end and the second end of the V-shaped grooved sample and respectively comprise an upper groove, a lower groove, an upper connecting hole and a lower connecting hole, the first side and the fifth side, adjacent to the shearing surface of the sample, of the upper groove and the lower groove in the first direction are open sides, and the upper connecting hole and the lower connecting hole penetrate through the upper grooved cavity from the second side opposite to the first side and the fifth side in the first direction; the upper and lower wedge blocks are used for being plugged between the first and second ends and the upper and lower surfaces of the upper and lower grooves, so that the first and second ends in the upper and lower grooves are wedged tightly; the upper connecting piece and the lower connecting piece are connected with the upper wedge block and the lower wedge block, penetrate out of the upper connecting hole and the lower connecting hole and are used for applying pulling force to the upper wedge block and the lower wedge block so that the upper wedge block and the lower wedge block can move in the wedging direction.

Description

technical field [0001] The invention relates to a fixture for testing the shear performance of composite materials. Background technique [0002] At present, there are many methods for testing the shear performance of materials at home and abroad, such as double-track shearing method, three-track shearing method, ±45° vertical and horizontal shearing method, 10° off-axis tensile method, cross-beam bending method, etc. Commonly used is the V-groove specimen shear performance test method, the shear test method is easy to operate, the sample shape is simple, easy to process, and can measure the shear strength and shear modulus at the same time, the test has obvious shear properties. It has good shear failure characteristics and good repeatability of test results, so it is widely used in shear tests of various materials. This test method has formed a relevant standard, such as ASTM D5379. This standard applies a fixture for the shear test of V-shaped notched specimens. The fix...

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Problems solved by technology

[0003] (1) The debugging process of the jig is very complicated, and multiple adjustments are required to make the V-shaped groove section flush with the axis of the loading force;

[0004] (2) When the loading force is relatively large, various parts on the fixture will bend, causing the V-shaped notched specimen to bear the shear load and bending load at the same time, and then the friction between the chuck and the support column increases, have a great influence on the test results;

[0005] (3) When the V-shaped grooved sample is thin, the test becomes very difficult, and it is necessary to paste reinforcement sheets at both ends of the sample, which greatly increases the workload of the test

[0007] (1) The use of this fixture requires the V-notch beam sample to be drilled. The shear performance of the sample after drilling will be different from the shear performance before drilling, which will have a great impact on the test results;

[0008] (2) Several bolts need to be debugged multiple times to ensure that the center line of the loading force is consistent with the V-notch center line of the V-notch beam sample, and the debugging process is complicated;

[0009] (3) Stress concentration is prone to occur at the place where the bolt is fixed, resulting in unnecessary bending moment and friction

However, the structure of the fixture is complicated, the process of disassembling and assembling the sample is cumbersome, and it is difficult to observe the test situation when the specimen is in the fixture, which has great limitations.

[0011] EP3073244B1 discloses a device, which includes a shearing direction, including an upper body and a lower body, the upper body and the lower body are configured to move up and down relative to the shearing direction, but it is not suitable for V Effective loading of the type notched specimen, especially to achieve reliable fatigue reciprocating loading function under large loads

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