Quick acquisition method of true stress strain curve in whole process of uniaxial drawing

A technology of uniaxial tension and strain curve, which is applied in the direction of applying stable tension/pressure to test the strength of materials, can solve the problems of unsuitable engineering stress-strain curve and parts deformation difference, and achieve the effect of easy operation and weakening influence

Active Publication Date: 2014-05-14
CHERY AUTOMOBILE CO LTD
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Problems solved by technology

[0009] 3) After the necking begins, the elongation is no longer uniformly distributed along the test gauge length, the necking area is very large, and the outside of the necking area is very small, the above formula is no longer applicable to the transformation from the engineering stress-strain cur

Method used

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  • Quick acquisition method of true stress strain curve in whole process of uniaxial drawing
  • Quick acquisition method of true stress strain curve in whole process of uniaxial drawing
  • Quick acquisition method of true stress strain curve in whole process of uniaxial drawing

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Experimental program
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Embodiment 1

[0041] 1. According to the uniaxial tensile national standard GB / T228, the load-displacement curve of the sample is measured by loading the extensometer, and the original size of the sample is measured to calculate the engineering stress-engineering strain curve. The elastic modulus is calculated by using the elastic deformation stage curve; in the uniform plastic deformation stage, the true stress-true strain curve is obtained by using formula (1) and formula (2).

[0042]2. Remove the elastic deformation stage from the obtained true stress-true strain curve in the uniform plastic deformation stage to obtain the plasticity curve of the material. For materials with a yield platform, the starting position of the plastic curve is selected from the starting position of the yield platform; for the curve without a yield platform, the starting position of the plastic curve is determined according to the engineering residual strain of 0.2%, and the corresponding true strain and true s...

Embodiment 2

[0048] Take a steel plate commonly used in automobiles (choose 2.0 thickness, see the shape of the sample figure 2 , sample size see Table 1) as an example

[0049] Table 1 Dimensions of uniaxial tension sample

[0050] Sample name

a 0

b 0

D

l 0

l

L

r

50 gauge length

plate thickness

25

30

50

75

≥180

25～40

[0051] The implementation method of indirectly obtaining the equivalent true stress-true strain curve of the whole stretching process through the combination of test and CAE is as follows.

[0052] 1. According to the metal material uniaxial tensile test standard GB / T228, the initial length of the extensometer is selected as 80mm, and the load-displacement curve of the sample is measured ( image 3 ). By measuring the original cross-sectional area of ​​the test, the engineering stress-engineering strain curve ( Figure 4 ).

[0053] 2. Use the elastic deformation stage curve to calculate th...

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Abstract

The invention relates to a quick acquisition method of a true stress strain curve in whole process of uniaxial drawing. The method comprises the steps of verifying the accuracy of a CAE (computer aided engineering) simulation model by a true stress-true strain curve at an even plastic deformation stage based on the static uniaxial drawing data, and indirectly predicting the true stress-true strain curve at a necking section through the CAE model to obtain the equivalent true stress-true strain curve in whole process of uniaxial drawing. The simple acquisition method of the true stress strain curve of the material in whole process of uniaxial drawing is easy and simple to operate, thus meeting the need of the CAE simulation in the engineering design. Furthermore, the quick acquisition method is in combination with a CAE technology, the influence of the grid effect to the CAE analysis accuracy can be weakened as much as possible.

Description

technical field [0001] The invention relates to the test of the mechanical properties of metal materials and the constitutive relationship of materials, in particular to a method for processing test data combined with CAE technology, and in particular to a method for quickly obtaining the full-range true stress-strain curve of uniaxial tension. Background technique [0002] In existing CAE simulation calculations, the plasticity curve of isotropic metal materials is obtained through uniaxial tensile tests. In engineering applications, there are usually two ways to deal with the true stress-strain curve in the necking stage: one is along the Extend along the tangent of the true stress curve in the uniform plastic deformation stage, and the CAE simulation software will automatically extend the extension according to the power function; another method is to set the true stress value after the necking starts to remain unchanged, that is, the true stress after the necking The str...

Claims

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Application Information

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IPC IPC(8): G01N3/08
Inventor 李军黄茁薛戬张磊陈云霞
Owner CHERY AUTOMOBILE CO LTD
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