Spring thrust down clamp of direct tensile test

Abstract

A spring-supported lower clamp for direct tensile test, comprising a lower joint connected with the base of a testing machine, a lower end cap for fixing the sample, a lower chain connecting the lower joint and the lower end cap, and a sample damaged by the tensile test. The support member of the lower end cap, the lower end cap is composed of a sample fixing groove and a connecting section, and the supporting member is a compression coil spring; during the tensile test, one end of the compression coil spring is connected or contacted with the sample fixing groove of the lower end cap, compressing The other end of the coil spring is connected or in contact with the base of the testing machine, the connecting section of the lower end cap, the lower chain and the lower joint are sheathed in the compression coil spring, one end of the lower chain is connected with the connecting section of the lower end cap, and the other end is connected with the lower joint. During the whole test process, the sample, the lower end cap and the lower chain are always supported by the compression coil spring, which can prevent the sudden failure of the sample due to the influence of gravity when the peak tensile stress is reached, so the mechanical effect test after the peak stress can be directly carried out.

Description

technical field [0001] The invention belongs to a fixture used for direct tension test on brittle materials, in particular to a fixture used for fixing samples in direct tension test of rocks. Background technique [0002] Tensile strength is an important mechanical property of brittle materials such as rocks. At present, in the tensile test for directly measuring the tensile strength of rock, the structure of the sample fixing fixture matched with the testing machine is as follows: figure 1 As shown, it consists of an upper fixture and a lower fixture. Both the upper clamp and the lower clamp include a joint connected to the tensile testing machine, an end cap for fixing the sample, and a chain connecting the joint and the end cap. The lower fixture also includes a supporting member composed of a rigid sleeve 4 and a backing plate 6 because it is required to bear part of the sample and the lower end cap destroyed by the tensile test. During the tensile test, since there ...

AI Technical Summary

Problems solved by technology

During the tensile test, since there is a certain gap between the backing plate 6 and the sample fixing groove of the lower end cap 7, the rigid sleeve 4 cannot effectively support the weight of the sample 8 and the lower end cap 7 during the entire test process. When the tensile stress of the sample reaches the peak value, under the action of gravity on the sample below the failure surface, the lower end cap and the lower chain, the sample suddenly fails, and the mechanical effect test after the peak stress cannot be carried out.

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