Method for determining annular thickness anisotropy coefficient of anisotropic pipe
A technique of thick anisotropy and determination method, which is applied in the direction of applying stable tension/pressure to test the strength of materials, etc., which can solve the problem that the deformation performance of anisotropic pipes cannot be fully and accurately described, and the hoop thickness anisotropy coefficient of pipes cannot be accurately determined. And other issues
Active Publication Date: 2020-02-07
DALIAN UNIV OF TECH
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Problems solved by technology
[0006] The present invention aims to solve the problem that the existing methods cannot accurately determine the anisotropy coefficient in the circumferential direction of the pipe material, and thus cannot comprehensively and accurately describe the deformation performance of the anisotropic pipe material, and proposes an anisotropy coefficient in the circumferential direction of the anisotropic pipe material method of determination
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[0062] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.
[0063] Take the IF cold-rolled coil welded steel pipe with an outer diameter of 46mm and a wall thickness of 0.7mm as an example, combined with Figure 1 ~ Figure 3 with Figure 7 The implementation process of the present invention is described:
[0064] Step 1. Cut the pipe to be tested into a length of 200 mm, and conduct two sets of controllable bidirectional loading experiments on the pipe under different stress ratios, as shown in image 3 As shown, the stress and strain experimental data under the two-way stress state of the pipe are obtained;
[0065] The pipe bidirectional loading experiment is carried out on a special pipe bidirectional loading experiment test device (refer to patent CN105300802B), applying a tensile or compressive load to the end of the pipe, and applying a pressure medium inside the pipe to make the pipe in the set st...
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Abstract
The invention discloses a method for determining an annular thickness anisotropy coefficient of an anisotropic pipe, and belongs to the field of pipe performance testing. The method comprises the following steps: 1, acquiring stress and strain experimental data of a pipe sample in a bidirectional stress state under different loading paths through an experiment; 2, performing regression on discretestress-strain experimental data under each loading path, and expressing flow stress-strain curves in two directions as a continuous function form; 3, selecting equivalent strengthening state parameters, and selecting flow stress in an axial uniaxial stress state as equivalent stress; 4, calculating stress and strain data corresponding to different stress paths under the same equivalent strengthening state parameter by utilizing a regression curve; 5, selecting an appropriate yield function f; 6, determining an undetermined coefficient matrix of the yield function f; and 7, further calculatingby utilizing a plastic flow criterion through the yield function f to obtain the annular thickness anisotropy coefficient of the pipe. According to the method, the annular thickness anisotropy coefficients of various anisotropic pipes can be accurately determined.
Description
technical field [0001] The invention belongs to the field of performance testing of pipes, and in particular relates to a method for determining the anisotropy coefficient of anisotropic pipes in the circumferential direction. Background technique [0002] Internal high pressure forming of pipes is an advanced forming method for the production of hollow variable cross-section complex parts. Because the parts manufactured by it have excellent comprehensive mechanical properties such as high strength and large flexural modulus, it is widely used in automobiles, aviation, aerospace and sports cars. and other fields are increasingly widely used. However, the pipes used in internal high pressure forming are usually rolled and welded after extrusion or rolling, and have obvious anisotropy along the axial and circumferential directions of the pipes, and are prone to instability wrinkling or excessive local thinning in the process of plastic deformation. Defects such as large crack...
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IPC IPC(8): G01N3/08
CPCG01N3/08
Inventor 林艳丽何祝斌胡馨予朱海辉苑世剑
Owner DALIAN UNIV OF TECH