Cross-shaped test piece biaxial tensile test based yield criterion evaluation method

A biaxial stretching, cross-shaped technology, applied in the direction of applying stable tension/pressure to test the strength of materials, measuring devices, instruments, etc., can solve the problems of not being able to analyze the yield criterion well, predicting accuracy, poor continuity, etc.

CN108844816AInactive Publication Date: 2018-11-20SOUTHEAST UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2018-11-20
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention provides a cross-shaped test piece biaxial tensile test based yield criterion evaluation method. According to the relation of the real stress in a rolling direction and plastic strain, the relation of biaxial directional stress and equivalent stress can be deduced by adopting a yield criterion, the relation of plastic strain in a biaxial direction and equivalent plastic strain can bededuced, the relation of biaxial directional strain and the equivalent plastic strain can be obtained, and therefore, the relation of stress and strain in the biaxial direction can be obtained; dataof the equivalent stress and the equivalent plastic strain can be measured by a test, so that data of elastic and plastic stages in the biaxial direction can be obtained; the expressions of two curvescan be obtained through curve fitting, contrast can be performed on the biaxial directional data measured by the test and the expressions, and the prediction precision of the deformational behavior of a material corresponding to the yield criterion can be evaluated. The contrast of the difference between the relation of stress and strain in the biaxial direction obtained by the test and the yieldcriterion in the whole plastic stage can be realized; and the limitation that traditional methods can only compare the difference between a test yield point and the yield criterion under a certain equivalent plastic strain can be overcome.
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Description

technical field

[0001] The invention relates to a biaxial tensile strength analysis method, in particular to a yield criterion evaluation method. Background technique

[0002] In many engineering fields such as aviation, aerospace, machinery, etc., components often bear loads in multiple directions during work. Under complex stress conditions, the mechanical behavior of metal materials presents very complex characteristics. Only relying on uniaxial tensile tests is The yield characteristics of components and materials cannot be accurately analyzed. Therefore, in order to study the deformation behavior and constitutive relationship of metal materials more accurately, it is necessary to study the mechanical behavior of materials under different loading paths.

[0003] At this stage, biaxial tensile tests are mostly used to realize different loading paths. Most of the specimens in biaxial tensile tests are cross-shaped specimens, which can effectively improve the uniformity of...

Examples

Embodiment Construction

[0059] The technical solutions of the present invention will be described in detail below, but the protection scope of the present invention is not limited to the embodiments.

[0060] Evaluate the prediction accuracy of Hill48 yield criterion with a kind of yield criterion evaluation method based on cross-shaped specimen biaxial tensile test of the present invention, the method steps are as follows:

[0061] Step 1: Prepare as figure 1 For the cross-shaped test piece shown, the rolling direction coincides with one of the axial directions; the unidirectional tensile test is carried out on the test piece along the rolling direction, and the relationship between the real stress and the real strain in this direction is obtained, as shown in figure 2 shown. Obtaining the stress-strain relationship in the rolling direction of the specimen includes the following steps:

[0062] Step 1.1: Clamp the cross-shaped specimen on the biaxial tensile testing machine, and clamp the extenso...