Frontal Crash Oriented Robust Optimization of the Electric Bus Body Frame Considering Tolerance Design 2024-01-2459

For the design optimization of the electric bus body frame orienting frontal crash, considering the uncertainties that may affect the crashworthiness performance, a robust optimization scheme considering tolerance design is proposed, which maps the acceptable variations in objectives and feasibility into the parameter space, allowing for the analysis of robustness. Two contribution analysis methods, namely the entropy weight and TOPSIS method, along with the grey correlation calculations method, are adopted to screen all the design variables. Fifteen shape design variables with a relatively high impact are chosen for design optimization. A symmetric tolerance and interval model is used to depict the uncertainty associated with the 15 shape design variables of key components in the bus body frame to form an uncertainty optimization problem in the form of an interval, and a triple-objective robust optimization model is developed to optimize the shape design variables and tolerances simultaneously. The optimization problem is handled by the double-loop nested optimization algorithm, which combines the NSGA-III and the sequential quadratic programming (SQP) methods. The four sets of optimized crashworthiness midpoint values obtained from the optimization that meet the requirements of robustness and fluctuation range, as well as the tolerance evaluation coefficients, are analyzed, discussed, and compared with the measurements before optimization. The results demonstrate that the proposed robust optimization scheme, considering tolerances, effectively enhances the crashworthiness of the bus body frame under practical manufacturing conditions while ensuring the robustness of the optimization results.