Convex-shaped clamp for direct tensile test

Abstract

The invention discloses a convex-shaped clamp for a direct tensile test. The convex-shaped clamp comprises a clamp body which comprises an upper clamp and a lower clamp, wherein the upper clamp and the lower clamp are symmetrically arranged and comprise bearing plates, fixed joints and convex-shaped chucks, one sides of the bearing plates are connected with the fixed joints through screws, and the fixed joints are connected to the bearing plates through threaded rods; and a rock sample is arranged between the upper clamp and the lower clamp. According to the convex-shaped clamp for the direct tensile test, a traditional convex-shaped chuck is replaced by virtue of the convex-shaped chucks, so that the stress concentration phenomenon in the test can be overcome, the stress is relatively uniform during a rock tensile test, and the result is relatively accurate; and by arranging the bearing plates and the fixed joints, the stress is relatively uniform, and the substantive characteristics of rock breaking are relatively accurately reflected.

Description

technical field [0001] The invention relates to a clamp, in particular to a convex-shaped clamp used for a direct tensile test, and belongs to the technical field of rock mechanics analysis and detection. Background technique [0002] Tensile strength is one of the basic mechanical parameters of brittle materials such as rock and concrete. Because it is far lower than the compressive strength, engineering design departments attach great importance to this parameter. Generally, the tensile strength parameter value can be obtained by direct tensile test. The processed test piece is bonded to the tensile fixture with AB glue, and then installed in the testing machine system for testing. In the current experiment, concave-shaped collets are usually used. However, it has been found through a large number of specific tests that there are some problems in this type of clamp. After using this kind of concave chuck, part of the sample is embedded in the chuck, and stress concentra...

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Problems solved by technology

However, through a large number of specific experiments, it was found that there are some problems in this form of fixture

After using this kind of concave chuck, part of the sample is embedded in the chuck, and stress concentration is easy to occur in the experiment, that is, the edge of the concave chuck is equivalent to a knife, cutting the root of the sample, Causes the specimen to fail at the bottom, this failure mode does not correctly reflect the failure characteristics of the rock under tensile loading

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