Method for automatically acquiring volume and strain cloud diagram of cylindrical test piece in loading process

Abstract

The invention provides a method for automatically acquiring the volume and a strain cloud diagram of a cylindrical test piece in loading process. According to the method, a mark point matrix which canbe identified by software only needs to be arranged on the surface of a rubber film for wrapping the cylindrical test piece, a photogrammetry method is used for obtaining the three-dimensional positions of all marked points before, during and at the end of an experiment, and through the initial position analysis of the mark point matrix before the experiment, a triangular mesh is automatically established and further calculation is performed to obtain the volume and the strain cloud diagram of the test piece in different forms. The method has the main advantages of low cost, simple operation,clear logic, high accuracy and high efficiency. According to the method, the problem of deformation measurement of the test piece of the stress-strain test experiment is solved, and a reliable and effective tool is provided for in-depth analysis of the uneven deformation of the test piece and the effect of the uneven deformation on the stress-strain characteristics of materials.

Description

technical field [0001] The invention relates to the technical field of material stress-strain performance testing, in particular to a method for automatically acquiring volume and strain nephograms of cylindrical specimens during loading. Background technique [0002] Stress-strain characteristic testing (including uniaxial and triaxial) is a commonly used method for evaluating material properties. The traditional stress-strain characteristic testing process needs to calculate the applied stress and the strain of the specimen to obtain the corresponding stress-strain curve. In order to calculate the stress and strain of the specimen, the test process needs to monitor the axial deformation and the overall volume change of the specimen. Based on the assumption of uniform axial deformation, the average cross-sectional area of ​​the specimen and the average strain can be calculated according to the overall volume and the height change of the specimen; further, combined with the...

AI Technical Summary

Problems solved by technology

The above methods are all based on image analysis technology, and the calculation of volume and strain introduces assumptions about the shape and deformation characteristics of the sample, so the degree of automation is low, the measurement efficiency is not high, and the accuracy is low

At present, in the field of stress-strain performance testing technology, there is still a lack of efficient and accurate methods to obtain the strain nephogram of cylindrical specimens during stress-strain characteristic testing.

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