Advanced Material Modelling for Failure Prediction of ISOFIX Anchorages

ISOFIX anchorage plays a critical role in restraining child occupants during crashes. Effective design of ISOFIX anchorages is essential for achieving controlled child occupant kinematics. CAE simulations are extensively used for the development of ISOFIX anchorages. Comprehensive material characterization of ISOFIX wires play a vital role for achieving desired prediction accuracy. This paper covers the detailed process of ISOFIX material characterization for material failure prediction. ISOFIX wires are case hardened to exhibit required strength characteristics. Due to its material characteristics, the conventional material models don't give desired prediction accuracy for failure prediction. Therefore, advanced material models are developed in LS Dyna environment, which can accurately predict plastic and fracture behavior of ISOFIX wires. Extensive coupon level material testing was done to achieve the material hardening and failure characteristic in Tension, Compression, Shear, and Bending and combine loadings. A series of simulations were carried out to correlate these tests and development of LS Dyna executable material model. This material model includes, yield locus definition considering state of loading, strain hardening data covering quasi static and dynamic strain rates and failure limit curves considering Instability, ductile normal fracture and ductile shear fracture criteria. This material model is validated with component level physical tests. The developed material model can predict the accurate plastic deformation and failure behavior of ISOFIX anchorages. The detailed process for new material model development and its validation through series of digital and physical tests presented in this paper