Multi-Objective optimization and ring structure design for crashworthiness and lightweight performance of hybrid material A-pillar and front-end body structure

To enhance the crashworthiness and lightweight performance of the front body structure, while maintaining the occupant survival space within the passenger cabin, this study proposes a ring structure design and multi-objective optimization for a hybrid-material A-pillar assembly and front-end body structure. This study develops finite element models of the body-in-white (BIW). The BIW model's accuracy is validated via static tests. A full-vehicle simulation model for 100% frontal overlap impact is established and validated against physical crash tests. Using the original steel A-pillar assembly as a baseline, a carbon fiber composite layup is designed to replace the steel A-pillar reinforcement plate, resulting in a hybrid-material A-pillar assembly. A layup design and multi-level optimization were performed on the composite A-pillar reinforcement plate to obtain the optimal layup sequence for performance. Taking the hybrid-material front body structure as the research object, eight design variables were selected, and multi-objective optimization of the front-end ring structure was conducted using optimal Latin hypercube sampling, a radial basis function (RBF) surrogate model, and the non-dominated sorting genetic algorithm-II (NSGA-II). The results show that the optimized hybrid-material A-pillar assembly reduced mass by 21.70%, while total BIW mass decreased by 1.8%. Performance metrics such as the peak acceleration of the B-pillars on both sides during a head-on collision have also shown significant improvements. Both crashworthiness and lightweighting were significantly improved.