A systematic and optimal design method for replacing steel backrest in automotive seat with carbon fiber-reinforced polymer composites

Carbon fiber-reinforced polymer composites (CFRPC) are extensively utilized in the lightweight design of automobiles due to their superior material properties. This study focuses on the automotive seat backrest as the subject of research. To address the challenge of achieving both lightweight and performance optimization in CFRPC, subsequent to replacing the steel backrest in automotive seat, a systematic optimization design method is proposed. Firstly, the experimentally validated finite element analysis model of a steel seat, subjected to four typical working conditions, is redesigned for the CFRPC backrest in automotive seat. Building upon this foundation, the optimization design of the CFRPC backrest is segmented into two phases: optimization of layup size and optimization of layup sequence. During the optimization of layup size, a sophisticated optimization strategy is employed. This strategy combines many-objective optimization and multi-criteria decision-making. It integrates the modified extensible lattice sequence experimental design, the hybrid surrogate model utilizes the global response search method in conjunction with weighted prediction error lowering, the non-dominated sorting genetic algorithm-III, the improved double combination weighting model of game theory, and the improved VIsekriterijumsko KOmpromisno Rangiranje method, which incorporates Euclidean distance and gray relational analysis (IVIKOR-ED&GRA). This approach is utilized to ascertain the optimal count and thickness of the number of layers required for each specific angle. The simulation results demonstrate that the optimized CFRPC backrest, featuring refined layup dimensions, not only fulfills regulatory requirements but also enhances a majority of performance metrics, accompanied by a substantial weight reduction of 38.66%. Ultimately, the OptiStruct optimization technique of layup sequence is employed to further enhance the performance of the CFRPC backrest seat. This is achieved by modifying the layup stacking sequence, while maintaining the original material’s weight and the number of layups for each angle unchanged.