Arc Backward Measurement Method for Uniaxial Tensile Stress-Strain of Metal Round Bar Specimen

Abstract

The present invention relates to the circular arc back-push measurement method of the uniaxial tensile stress and strain of metal round bar samples, and the technical field of testing the mechanical properties of metal materials. The circular arc rotating body model only needs to measure the elongation of the gauge length during the stretching process of the round bar sample, and extract the coordinate information of the outer contour curve of the broken test bar, and calculate the radius of the necking arc and the minimum necking at each moment by back-calculating The section radius is directly substituted into the Bridgman method to calculate the true stress and true strain at this moment. The invention omits the test and measurement link of the minimum section radius of the necking and the curvature radius of the outer contour in the existing method, and improves the measurement accuracy of the stress-strain curve in a large strain range, which is of great significance for the mechanical performance test of metal materials.

Description

technical field [0001] The invention belongs to the technical field of mechanical property testing of metal materials, and in particular relates to a method for measuring stress-strain curves in large strain ranges in uniaxial tensile tests of metal round bar samples. Background technique [0002] The uniaxial tensile test is a basic method for testing the mechanical properties of metal materials. Usually, the load-gauge length elongation curve of the material is obtained by the uniaxial tensile test, and then the load- The gauge elongation curve is converted to a stress-strain curve. However, the sample begins to shrink after the maximum load point, and the sample deforms unevenly within the gauge length range. Therefore, it is inaccurate to directly convert the load-instantaneous gauge length curve to the stress-strain curve after tensile instability, and the specimen gradually changes from the uniaxial stress state to the triaxial stress state after necking. Since the c...

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Problems solved by technology

[0003] Purpose of the present invention, in order to solve the difficult problem that the measurement of radius of curvature of minimum section radius of necking and necking outer contour curve at the minimum section place is loaded down with trivial details and error is big in Bridgman method at present, propose a kind of uniaxial tensile test of metal round bar sample Large strain range stress-strain curve measurement method does not need to directly measure the radius of curvature of the minimum section radius of the necking and the necking outer contour curve at the smallest section, but reverses by extracting the necking outer contour curve of the broken test rod

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