Reliability-based design optimization for vehicle occupant protection system based on ensemble of metamodels

An Occupant Protection System (OPS) has very important applications in an automobile accident, which can save an occupant from fateful hurt or death. To provide a feasible framework for decreasing occupant injury degree, this paper presents a practical approach of the Reliability-based Design Optimization (RBDO) for vehicle OPS performance development based on the ensemble of metamodels. The weight factors of the ensemble associated with each metamodel are determined using a heuristic method. The comparative result shows that the prediction accuracies of the ensemble of metamodels exceed all individual one. Generally, the deterministic optimum designs without considering the uncertainty of design variables frequently push design constraints to the limit of boundaries and lead objective performance variation to largely fluctuate. So, the RBDO is presented and aims to maintain design feasibility at a desired reliability level. The First Order Reliability Method (FORM) and Second Order Reliability Method (SORM) are used to calculate the reliability index, and the results are checked by Monte Carlo (MC) simulation respectively, from which the failure probability of the OPS performance design is obtained. The result demonstrates that the reliability design is more reliable than the deterministic optimization in real engineering application. Finally, the reliability-based design optimization result is validated by the simulation result, which shows that the proposed RBDO approach is very effective in obtaining an optimum design.