Hopkinson rod stress wave measurement system and measurement method using flexoelectric effect

Abstract

Hopkinson rod stress wave measurement system and measurement method using flexoelectric effect, the system includes bullet, laser velocimeter, input rod, output rod, absorption rod and damper, respectively attached to the input rod and output rod on the first rod 1. The second strain gradient sensor, a tachometer circuit optically connected to the laser velocimeter, and a dual-channel charge amplifier electrically connected to the first and second strain gradient sensors, wherein the output terminals of the tachometer circuit and the dual-channel charge amplifier are associated with signal processing , display, and storage modules are electrically connected; when measuring stress waves, fix the specimen between the input rod and the output rod, place the absorption rod and damper after the output rod in turn, and place the bullet and the input rod on the laser velocimeter respectively. Both ends are on the same horizontal plane; the present invention sets a passive strain gradient sensor based on the flexoelectric principle, which can measure the first-order derivative of the real waveform, and then directly integrate the waveform to obtain the waveform of the stress wave more realistically. Improve measurement accuracy.

Description

technical field [0001] The invention relates to the technical field of tests based on Hopkinson rods, in particular to a Hopkinson rod stress wave measurement system and a measurement method utilizing flexoelectric effect. Background technique [0002] In the field of military science such as shock and explosion, high strain rate is widely used in the research of various materials as a loading method to simulate the real environment. Due to the special loading method of high strain rate, the most widely used experimental platforms are based on Hopkinson rods. In short, the material to be tested is fixed between two long straight metal rods, and the left end of the input rod is struck by a bullet (metal block) at a certain initial speed, and a stress wave is generated on the input rod, which is the strain on the input rod. The plate detects the strain signal caused by the stress wave and sends it to the strain circuit; after the stress wave passes through the material to be ...

AI Technical Summary

Problems solved by technology

[0006] Taking the half-sine wave with a duration of 100μs as an example, its real waveform and measured waveform are as follows: figure 2 As shown: It can be clearly seen that there is a big difference between the actual waveform and the measured waveform at the beginning and end of the waveform, and the waveform maintenance time is elongated, and there is a certain waveform distortion

This phenomenon is more distorted in waveforms with steeper fronts and shorter durations

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