Method for predicting material equivalent stress-strain relation based on sphere and cone integrated pressure head

Abstract

The invention discloses a method for predicting a material equivalent stress-strain relation based on a sphere and cone integrated pressure head. The method includes the following steps that 1, a tested material is subjected to a quasi-static press-in text through the sphere and cone integrated pressure head, so that a continuous load-depth curve is obtained, wherein the lower portion of the pressure head is a spherical pressure head body, and the upper portion of the pressure head is of a conical structure; 2, a spherical loading curvature Cs (delta) and a spherical loading index m (delta) ofthe load-depth curve at a spherical pressure stage are obtained in consideration of displacement errors; 3, a loading curvature Cc of the load-depth curve at a conical pressure stage is obtained; 4,according to Cs (delta) and m (delta) obtained in the step 2 and Cc obtained in the step 3, constitutive parameters of the material are obtained, and the equivalent stress-strain relation is obtained.The method is simple, has universality, and can be used for performing mechanical effect analysis of equivalent stress-strain and related factors of the material under the loading conditions of creeping, impacting and others.

Description

technical field [0001] The invention relates to a method for testing the mechanical properties of materials, in particular to a method for predicting the equivalent stress-strain relationship of materials based on a ball-cone integrated indenter. Background technique [0002] Material equivalent stress-strain relationship is the core basis for mechanical analysis of materials or structures, and plays an important role in the integrity and safety evaluation of engineering components; traditionally, the method of obtaining material equivalent stress-strain relationship is from engineering A standard tensile sample of a certain size is cut out by machining on the component or the base material, and then the tensile test is carried out in the laboratory; with the miniaturization of the material size and the miniaturization of the structure, the traditional tensile method is limited by the size of the component, and it is difficult to sample and Effectively carry out tests; and, ...

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Problems solved by technology

[0018] In the formula: v * is the characteristic energy density and satisfies v * =E n σ y 1-n / (1+n), E is the elastic modulus of the material, σ y is the nominal yield stress, and n is the strain hardening exponent; this method still uses two conical indenters to press in respectively. In the test, it needs to be loaded twice, the position of the pressure point is not unique, and it is not sensitive to the problem of indentation. Therefore, there is a higher requirement for the test accuracy of the actual press-in equipment

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