Experimental and Numerical Assessment of Anisotropy in S600MC Sheet: Charpy Impact Testing in Different Rolling Directions and Applications to Automotive Seatbelt Support

The present study examines the influence of rolling direction on the impact response of S600MC thermo-mechanically rolled steel sheet. Charpy V-notch tests were performed on sub-size specimens extracted at 0°, 45°, and 90° relative to the rolling direction. The results showed a consistent orientation-dependent trend in absorbed energy, with the lowest values obtained for the transverse direction. An explicit finite element model of the Charpy test was developed in Altair Radioss using /MAT/PLAS_JOHNS and the /FAIL/BIQUAD ductile failure criterion. The Charpy simulations were used for specimen-level calibration of the failure parameter by comparing the numerically predicted absorbed energy with the experimentally measured final absorbed energy. To assess the engineering relevance of the calibrated model, impact simulations were performed on an automotive seatbelt support. The cold-forming process was simulated separately in Altair Inspire Form using a Barlat anisotropic sheet-metal model, and the resulting plastic strain and thickness variation were mapped onto the Radioss component model. Component-level simulations were compared with pendulum impact tests. Including forming history improved the prediction of peak force, absorbed energy, and deformation pattern. The results show that combining directional material characterization with forming-history mapping improves the predictive capability of dynamic simulations for cold-formed S600MC sheet components, while the approach remains limited by the neglect of strain-rate effects and residual stress transfer.