Research On The Crashworthiness Of Car Bumper System Crash In Low Speed

With the increasing of the world automobile inventory and the ever-growing of the highway traffic injury, how to improve the passive safety and reduce the cost of repairing have become important tasks for automobile makers. According to the request of the RCAR laws and the features of the bumper system crash in low speed, the paper is carried out the research on the crashworthiness performance of the low speed crash by explict finite element method, and makes it meet the evaluation indexes by optimization.First of all, according to the characteristic of the car bumper system crash in low speed, the detailed evaluation indexes is constituted to the impact simulation course. The evalution parameters include energy-absorbing performance, the peak of the impact force, the average impact force, compressed displacement and the impact stationarity.Secondly, according to the RCAR laws, the paper establishes the 3D geometric model of the car bumper system using the software of Pro/E, mainly including the bumper beam, crash-box, the front longitudinal beam, the vehicle under-frame, the wheels and so on. The geometric model of the car bumper system is transformed to the finite element basic model using finite element method. The course of establishing finite element model is carried though in the finite element software HyperMesh, including that the 3D geometric model is cleared and modified, the size of the element is chosen, mesh is generated, mesh quality is checked, material is defined, boundary condition is defined, interface is defined, hourglass is controlled and so on. And at the end of the course, the Key files of the LS-DYNA3D format are exported.And then, the finite element model is calculated using the software of LS-DYNA3D. The basic finite element model of the car bumper system is simulated and analyzed in the software of HyperView. From the analysis of the energy curve and the impact force-displacement curve, the simulated results are exact. According to the evaluation index of the car bumper beam, the peak of the impact force and the impact stationarity of the basic model cannot meet the request of the evaluation indexes. So the crash-box should be improved.At last, according to the reasonal deformation pattern of the crash-box, the crashbox is improved by setting beads in truns, the improved finite element model is simulated and analyzed. The designed car bumper system meets the design request at last though the method of improvement-simulation-analysis-improve -ment once more. The final improved model improves the crashworthiness and the crash safety.