Method for determining yielding surface by crossed pre-stretching deformation and loading

Abstract

The invention discloses a method for determining a yielding surface by crossed pre-stretching deformation and loading. The method mainly comprises the following steps: determining an initial yielding surface and a subsequent yielding surface; determining the yielding surface by adopting a loading path of carrying out pre-stretching deformation in one direction and then carrying out stretching deformation in the other direction. In the step of determining the initial yielding surface, firstly, a crossed stretching test sample is stretched to selected different stress points along one direction to keep load and then is stretched until the test sample is broken from the other direction; the initial yielding surface is drawn according to obtained yielding strength value; in the step of determining the subsequent yielding surface, firstly, the crossed stretching test sample is stretched to a selected pre-stretching point along a rolling direction and then is unloaded to zero or is unloaded to the selected different stress points; then the next step of a loading manner is selected according to different unloading manners to obtain the corresponding yielding strength value for drawing the subsequent yielding surface. The method disclosed by the invention can be used for reflecting an evolution law of the yielding surface in biaxial loading of a sheet material very well and can be used for effectively characterizing anisotropic mechanical behaviors of plastic deformation of a metal material.

Description

technical field [0001] The invention belongs to the technical field of measuring the yield surface of a material mechanics experiment, and in particular relates to a method for measuring the yield surface by cross tension pre-deformation loading, and the method is especially suitable for measuring the yield surface of a metal sheet material. Background technique [0002] Many problems in engineering applications of metal materials involve the theory of plastic mechanics, and the forming process of sheet metal is a kind of plastic deformation behavior. In order to accurately predict the forming process and improve the forming process, it is necessary to construct an accurate constitutive model to characterize the plastic deformation process. However, the yield, plastic rheology and strengthening effects in the plastic deformation process of metal materials can be studied by the evolution of the yield surface, and the evolution law of the yield surface is an important theoretic...

AI Technical Summary

Problems solved by technology

At present, the mechanical experiments for plates generally use uniaxial loading and biaxial proportional loading along different directions. These loading methods cannot well reflect the actual stress state during the forming process of the plate. There are non-negligible errors in the lower forming process, which cannot meet the needs of the actual forming process, especially for metal materials with strong anisotropic behavior, such as magnesium alloys, titanium alloys, etc.

In summary, the existing yield surface determination methods cannot well characterize the anisotropy of metallic materials.

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