Comparative Study And Multi-Objective Optimization Of Crash Performance Of Steel-Aluminium Double-Hat Bumper

In order to obtain a bumper with good crash performance and a high degree of light weight,a steel-aluminum double-hat bumper is proposed based on a new structural form and the use of lightweight materials,and the bumper beam is filled with aluminum foam,and two other foamfilled bumpers are derived on the basis of the steel-aluminum double-hat bumper: uniform foam-filled and functional gradient foam-filled steel-aluminum double-hat bumper.Establish the finite element model of pendulum collision for three bumpers and verify the validity of the simplified finite element model.A comparative analysis of the crash performance of the three bumpers was conducted,using the control variable method to analyze six crashworthiness indexes of the three base bumpers,including total energy absorption,specific energy absorption,intrusion,peak crash force,crash force efficiency and crash time.Firstly,the front and rear hat thicknesses of the bumpers were controlled to make a comparative analysis of the three base bumpers;secondly,the foam parameters of the filled foam were controlled to make a comparative analysis of two foam-filled bumpers with the same mass;finally,the front and rear hat thicknesses and foam parameters were controlled to make an analysis of the functional gradient foam-filled bumpers.The front and rear cap thicknesses and foam parameters have significant effects on the crash performance of bumpers,and there are differences in the effects on different bumpers.In order to get the specific design parameters of the bumper with superior performance,further design optimization analysis of the bumper is needed.A multi-objective optimal design was performed for three bumpers with maximum specific energy absorption,minimum intrusion and minimum peak crash force as optimization objectives and front and rear bumper hat thickness and foam parameters as design variables.The sampling points were sampled uniformly in the design space using the optimized Latinsquared experimental design method,and finite element analysis was performed on the sampling points.An approximate surrogate model of the optimization problem is constructed using a radial basis network model determined by error analysis,and the Pareto front is obtained by solving the approximate surrogate model using the MOPSO algorithm.The specific design parameters are obtained in the Pareto front using the minimum distance selection method and substituted into the bumper for finite element analysis,and the error between the simulated analysis values and the predicted values of the approximate surrogate model is small.The optimized bumper crash performance was substantially improved.The optimized three bumpers were assembled into the experimentally verified vehicle model for the whole-vehicle crash analysis,and the B-pillar acceleration,front fascia intrusion,door frame deformation and steering column runout of the whole-vehicle crash were analyzed in comparison with the original vehicle.It was found that the whole vehicle crash performance of the optimized bumper was improved and did not affect the other performance of the whole vehicle,so the bumper design and optimization work was effective.The article proposes unfilled,uniform foam-filled and functional gradient foam-filled steel and aluminum doublehat bumpers,which can provide some reference for bumper design research.