Test piece dynamic lateral strain measurement device and method based on SHPB test system

Abstract

The invention discloses a test piece dynamic lateral strain measuring device and method based on an SHPB test system, and belongs to the field of dynamic mechanical property testing of brittle materials such as coal rock by adopting the SHPB test system. The device comprises a fixing system, an oil pressure system and a data acquisition system; the fixing system is used for fixing the whole deviceon an SHPB test bed and adjusting the height of the device; the oil pressure system is used for applying required confining pressure to the test piece and converting a volume change signal of the test piece into an oil pressure change signal; the data acquisition system is used for capturing signals of oil pressure changes and obtaining a time-history change curve of lateral strain. The confiningpressure is applied to the test piece by utilizing the oil pressure system, comprehensive confining pressure loading of the test piece is simulated, and the comprehensive confining pressure loading and axial acting force caused by the split Hopkinson pressure bar device act together, so that simulation of a complex stress state of the test piece is realized; the relation between oil pressure andlateral strain is obtained through signals of oil pressure changes 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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