Necking failure limiting strain detection method based on DIC

Abstract

The invention provides a necking failure limiting strain detection method based on DIC. The method comprises the following steps: S1, based on a DIC technique, selecting data points in a plurality ofsections vertical to a crack direction to draw a curve of primary and secondary strains varying along with time; S2, determining the limiting primary strain and the limiting secondary strain of the sections vertical to the crack direction based on the curve of primary and secondary strains varying along with time; and S3, based on the limiting primary strain and the limiting secondary strain of the sections vertical to the crack direction, drawing the limiting primary strain and the limiting secondary strain as vertical axis and cross axis in a coordinate map to obtain a formed limiting curveof a metal panel material, wherein necking failure limiting strain detection of the metal panel material is achieved. The method is quick, direct, concise and effective, and has very good universality.

Description

technical field [0001] The invention relates to the technical field of plate formability testing, in particular to a DIC-based necking failure limit strain detection method, especially a rapid detection method. Background technique [0002] When sheet metal is formed, the deformation process includes several stages of uniform deformation, diffusive instability, concentrated instability, and fracture failure. Among them, diffuse instability and concentrated instability can also be called dispersed necking and local necking respectively. Sheet metal forming must exceed the elastic limit, but not beyond the necking stage, especially the local necking stage. Because once the deformation exceeds this stage, the strength of the material cannot be guaranteed, and a slight force may cause rupture and failure in the subsequent process or during use. Therefore, although the desired shape can be obtained by large deformation, necking of the sheet must be avoided in the actual process...

AI Technical Summary

Problems solved by technology

Although the forming limit curves obtained by this method and other existing time-correlation detection methods are relatively accurate, differential operations are generally required, which have high requirements for data continuity and smoothness, and filtering is required when necessary. processing, the follow-up analysis work introduces more mathematical processing, and the whole process is lengthy, cumbersome and complicated, which is not conducive to engineering applications

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