Method for automatic measurement of elongation after uniaxial tension of metal plate specimens

Abstract

The invention discloses an automatic measurement method for the elongation rate of a metal plate sample after uniaxial tension, which belongs to the field of mechanical properties of metal materials. The method only needs to be measured and tested under the premise of known material elastic modulus and Poisson's ratio Record the gauge length elongation and load value at the moment of tensile fracture of the plate sample, and at the same time use optical methods to collect the distribution information of the outer contour of the plate sample in width and thickness, and obtain the uniaxial tension of the plate sample through elastic deformation analysis and calculation elongation after break. This method accurately deducts the elastic part, and automatically implements the displacement method without identifying the fracture position within the gauge length range, so as to accurately obtain the elongation after fracture. Compared with the existing manual measurement technology, it saves the cumbersome measurement links such as scribing and fixing the broken sample, and improves the measurement accuracy, which is of great significance for the mechanical performance test of metal materials.

Description

technical field [0001] The invention relates to the test of mechanical properties of metal materials, in particular to a method for automatically measuring the elongation rate of a metal plate sample after uniaxial tension. Background technique [0002] Among the mechanical properties of metal materials, the elongation after fracture is an important index reflecting the plasticity of metal materials. The larger the value, the better the plasticity of metal materials. There are two main ways to measure the elongation after fracture: manual and automatic. GB / T228.1-2010 stipulates the determination method of elongation after fracture. The manual measurement method is: carefully match the fracture parts of the tensile specimens together, so that the axes are on the same straight line, and ensure that the fractured part of the specimen is Measure the gauge length after fracture of the specimen after proper exposure u , the gauge distance after breaking l u and the original ga...

AI Technical Summary

Problems solved by technology

The automatic measurement method is simple and feasible, but the extensometer cannot automatically identify the fracture position of the sample

However, in the actual test process, most of the sample fracture positions are not at the extensometer gauge length l e In this case, the automatic measurement cannot be corrected by the displacement method like the manual measurement, and the measured elongation Δl will be smaller than the manual measurement

At the same time, due to the serious necking of the sample when it breaks, if the elastic deformation is calculated according to the uniform deformation when deducting the elastic part, the deducted elastic part is inaccurate

In view of the above two reasons, although the current automatic measurement of the elongation after fracture is simple and feasible, it has a large error. In practical applications, manual measurement is still mostly used.

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