A device and method for measuring dynamic lateral strain of specimen based on shpb test system

Abstract

The invention discloses a test piece dynamic lateral strain measurement device and method based on an SHPB test system, and belongs to the field of testing the dynamic mechanical properties of brittle materials such as coal rocks by using the SHPB test system. The device includes a fixing system, an oil pressure system and a data acquisition system. The fixing system is used to fix the whole device on the SHPB test bench and adjust the height of the device; The volume change signal of the component is converted into the oil pressure change signal; the data acquisition system is used to capture the oil pressure change signal and obtain the time-history change curve of the lateral strain. The invention applies confining pressure to the test piece by using the oil pressure system, simulates the comprehensive loading of the confining pressure of the test piece, and cooperates with the axial force caused by the separate Hopkinson pressure bar device, so as to realize the complex stress state of the test piece simulation; the present invention obtains the relationship between the oil pressure and the lateral strain through the signal of the oil pressure change caused by the lateral strain, so as to calculate the lateral strain.

Description

technical field [0001] The invention relates to the technical field of testing the dynamic mechanical properties of brittle materials such as coal and rock by using a SHPB test system, in particular to a device and method for measuring dynamic lateral strain of a test piece based on the SHPB test system. Background technique [0002] Most materials exhibit some degree of loading rate or strain rate sensitivity in terms of mechanical properties such as strength. The strain rate effect on the mechanical properties of materials caused by high-amplitude short-time pulse dynamic loads is very important for the design and analysis of structures resistant to dynamic loads. The separate Hopkinson pressure bar (SHPB) test device is currently the main test method for testing the dynamic stress-strain response relationship of various engineering materials in the strain rate range from 100 / s to 10000 / s. The method is exquisite, the loading waveform is easy to control, and the like. Wh...

AI Technical Summary

Problems solved by technology

This method has certain limitations. First, for brittle materials such as coal and rock, due to the relatively rough surface, the strain gauges are not easy to stick, and the strain gauges are easy to fall off during the dynamic loading process, which affects the integrity of the experimental data; , the lateral strain of the specimen under dynamic load impact is often uneven, and the method of pasting the strain gauge can only measure the lateral strain of a certain point on the side of the specimen, so it is not accurate to represent the overall lateral strain of the specimen of

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