Method for measuring coefficient of normal anisortopy and yield stress of pipe in any direction

Abstract

The invention provides a method for measuring a coefficient of normal anisortopy and a yield stress of a pipe in any direction, and belongs to the field of pipe performance test. The method comprisesthe following steps of step 1, carrying out a bidirectional pipe loading experiment to obtain stress and strain experimental data of the pipe under a plurality of bidirectional stress states; step 2,preparing a pipe shear sample, and acquiring shear stress and strain experimental data under a pipe pure shear stress state; step 3, calculating a stress value and / or a plastic strain increment ratioof the pipe under different stress states of a bidirectional loading and pure shear experiment when the same plastic work is reached, and determining all coefficients in a yield function and a plasticpotential function of the pipe; step 4, establishing an expression for measuring the yield stress of the pipe direction and the coefficient of normal anisotropy; step 5, giving an angle, and obtaining values of the yield stress and the coefficient of normal anisotropy of the pipe direction; and step 6, changing the angle to obtain the values of the yield stress and the coefficient of normal anisotropy of the pipe in any direction. The method provided by the invention is used for measuring the coefficient of normal anisotropy and the yield stress of the pipe in any direction.

Description

technical field [0001] The invention belongs to the field of performance testing of pipes, and in particular relates to a method for measuring the thickness anisotropy coefficient and yield stress of pipes in any direction. Background technique [0002] Tubes are often used to form tubular components with various shapes. Commonly used pipes are aluminum alloy, steel, titanium alloy, magnesium alloy, etc. Pipes often produce anisotropic features during the fabrication process. For tubing with anisotropic characteristics, different mechanical properties in different directions. It is generally manifested as the difference in yield stress and plastic flow behavior in different directions, and the thickness anisotropy coefficient and yield stress in different directions are often used to characterize this anisotropy feature. This anisotropic feature directly affects the deformation behavior of the pipe, and then affects the formulation of the pipe forming process parameters. ...

AI Technical Summary

Problems solved by technology

[0006] The present invention aims to solve the problem that the existing pipe material experimental test method cannot or cannot accurately measure the anisotropic characteristic parameters of the pipe material, and proposes a method for measuring the thickness anisotropy coefficient and yield stress of the pipe material in any direction

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