Characterization of the wrinkling limit curve using in-plane compression tests

Abstract

Abstract. The global need for a green economy and the ongoing challenge of climate change have spurred demand for lightweight construction in various industries. This transition involves redesigning components with intricate geometries and advanced materials to reduce sheet metal thickness and the overall part weight. However, this pursuit of lightweight structures introduces challenges, particularly in wrinkling, raising the need to develop accurate methodologies for determining formability limits by wrinkling. This paper focuses on in-plane compression tests, specifically addressing the compression stress state associated with wrinkling in the flange area in deep drawing or a strip during flexible roll forming. Three physically-based methodologies (A, B, and C) are proposed to detect the onset of wrinkling and characterize the wrinkling limit curve (WLC) through experimental tests. Methodology A involves the analysis of the Z displacement, methodology B focuses on the in-plane minor strain rate evolution, and methodology C employs the analysis of the force-displacement evolution. The experimental work involves the mechanical characterization of AA1050-O aluminum sheets and the in-plane compression tests of rectangular specimens with different lengths. The results reveal distinct behaviors in wrinkling initiation for the different specimen lengths. The critical strain pairs obtained from each methodology are utilized to construct the WLCs in the principal strain space, providing insights into the formability limits by wrinkling.