Method for determining forming limit of high-strength aluminum alloy sheet

Abstract

The invention discloses a method for determining a forming limit of a high-strength aluminum alloy sheet. The method comprises the following steps of preparing a plurality of high-strength aluminum alloy sheet samples; carrying out a tensile test on the samples to obtain a tensile displacement curve of each sample, elastic modulus and power function hardening model parameters; carrying out simulation on a tensile process by adopting finite element software; determining stress triaxiality change data and Lode parameter change data of each sample according to the tensile displacement curve and asimulation result; solving by adopting an analytic expression of an Lou-Huh ductile fracture criterion in order to obtain a plurality of groups of fracture parameter values; determining a predictionerror of each group of fracture parameter values to each sample; and computing a forming limit diagram of the high-strength aluminum alloy sheet by adopting a principal strain space function in a principal strain space according to the plurality of groups of fracture parameter values of which the prediction error is smaller than a set threshold value. According to the method, on the basis of preferred selection, the ductile fracture criterion is applied to obtain the forming limit curves in order to form a fracture judgement ribbon area, and a judgement result is more reliable.

Description

technical field [0001] The invention relates to the field of plate deformation analysis, in particular to a method for determining the forming limit of high-strength aluminum alloy plates. Background technique [0002] With the continuous development of lightweight in the automobile industry, high-strength aluminum alloy sheets with advantages such as low density and high strength are widely used in automobile manufacturing. However, high-strength aluminum alloy sheets have low plasticity and poor formability. Improving the formability of this type of material is a problem that needs to be solved. At the same time, accurately predicting the forming limit of this type of material is also an important problem that needs to be solved. [0003] The forming limit diagram can predict and judge the cracking phenomenon in the sheet metal forming process, and is an important tool for analyzing the sheet metal forming performance. There are usually experimental methods and theoretica...

AI Technical Summary

Problems solved by technology

There are two problems in this process. First, the stress triaxiality and Lode parameters of the notched sample change during the tensile process of the sample. Therefore, the average stress triaxiality η is often used to solve the equations ave and the average Lode parameter L ave (see formula (4) for the mathematical expression) to replace η and L in the analytical expression

Second, there are many types of notched specimens given by existing research, and there is no clear answer on how to select specimens to solve the fracture parameters

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