Speaker
Description
Recent developments aimed at reducing cumulative CO2 emissions in the energy sector and e-mobility are leading to an increase in the production volumes of formed components made from thin metallic foils used for alternative energy supply concepts. Thus, components such as bipolar plates in fuel cells and a variety of parts in e-motors and batteries are being manufactured in ever higher quantities and thinner material thicknesses. As a consequence, this leads to increased challenges regarding the feasibility and robustness of required production processes. FE-simulations represent a useful tool in this context to predict and to optimize the results of forming processes at an early stage of development. The prediction accuracy of such simulations thereby significantly depends on the modeling of the material behavior, which is derived from material characterization methods. However, classical approaches to material characterization usually tend to fail in case of thin metallic foils, especially when the structural stability of the specimen becomes an important factor for the validity of the characterization test. The cyclic shear test, for example, is used to determine the hardening behavior of the material to be characterized, but is unsuitable for metallic foils unless a special anti-wrinkling device is used. Current anti-wrinkling devices proposed in literature must be attached directly to the deforming area of the specimen, apply pressure to the specimen surface, and must also be transparent to allow optical measurement of the deformation. Attaching such devices to prevent the specimen from wrinkling requires extreme skills to avoid deforming of the specimen even before testing. Against this background, this paper presents a novel experimental setup, which increases the structural stability of the cyclic shear specimen and thus prevents wrinkling without the use of an additional device in the measurement area during the test procedure. Structural stability is enhanced by curving the gauge area of the specimen to drastically suppress the tendency to wrinkle. As a proof of concept FE-simulations with LS-Dyna were performed in this study to verify this novel idea and to design the experimental setup.