Calculation and detection methods for strength and index of metal material based on generalized Hosford yield function

Abstract

The invention discloses calculation and detection methods for strength and an index of a metal material based on a generalized Hosford yield function. The calculation method comprises the following steps of firstly, introducing a direction function and carrying out Taylor expansion to a six-order tensor form to improve the Hosford yield function; secondly, considering a microstructure of the material, researching a plastic parameter thereof and establishing an Hosford yield function of a cubic crystallite orthorhombic sheet under any stress state of a texture coefficient containing a constant term, a quadratic term, a quartic term and a sextic item based on a group theory and objectivity of the material; thirdly, combining a theory of plasticity to deduce yield strength of the metal sheet under the different angles and a relation between an anisotropic index q value and the texture coefficient; and lastly, detecting the yield strength of the orthorhombic metal sheet under the different angles and the anisotropic index q value according to the texture coefficient of the metal sheet. According to the methods, the destructive test on the material is avoided, and the necessary theoretical basis is provided for the research of sheet forming.

Description

technical field [0001] The invention belongs to the technical field of sheet metal forming and material processing, and relates to a method for calculating the yield strength and anisotropy index of sheet metal, specifically a method for establishing a new generalized Hosford orthogonal metal material yield function, and proposing a method for texture coefficient The invention relates to a method for calculating the yield strength and anisotropy index of a metal sheet, in particular to a method for detecting the strength and index of a metal material based on a generalized Hosford yield function. Background technique [0002] Metal sheet has the advantages of high strength, good elasticity, plasticity and plastic processing performance, strong corrosion resistance, good heat resistance and durability, and is widely used in many fields such as aerospace, automobile manufacturing, and mechanical design. The metal sheet is an aggregate of a large number of tiny crystal grains (...

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Problems solved by technology

However, since the metal sheet is relatively thin, it is difficult to accurately measure the strain in the thickness direction, and it is difficult to accurately obtain the anisotropy index q value of the sheet

[0004] Although Huang Mojia from the Engineering Mechanics Experimental Center of Nanchang University published a paper called "Gerneral Hosford yield functions so forthorhombic materials" in the journal "ARCHIVEOFAPPLIEDNECHANICS", in which he proposed a generalized Hosford yield function including three principal stresses and principal stress directions, but from the literature It can be seen from the figure that it fits the q value better for the plastic deformation of the orthogonal plate, but the error for the yield stress is relatively large, and it is difficult to meet the accuracy requirements

Therefore, there is no better calculation formula for the material texture coefficient in the prior art

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