Lightweight Design And Optimization On Bumper Beam Of Fiber Enhanced Composite

Along with the shortage of resources and environmental pollution problems have become increasingly serious. In order to reduce the impact of cars on the environment, lightweight of automobile is becoming an increasingly popular field of research. Lightweight materials is one of the important ways to realize auto lightweight, in which the fiber enhanced composite material as a new type of lightweight materials, due to its good mechanical properties and great potential for weight reduction has been widely favored. Based on the requirements of regulation GB17354-1998, Long Glass Fiber Thermoplastic(LGFT) and Carbon Fiber Reinforced Plastics(CFRP) composite materials are applied to the car bumper beam have been researched in this paper, which can be described as follow:First of all, LGFT and CFRP specimens for tensile and three-point bending experiment are made, mechanical properties tests of two fiber composites have been carried out, Young’s modulus and fracture strain and other parameters are obtained. Finite element model of tensile and three-point bending test are been established to obtain their testing parameters.Secondly, Aluminum alloy of the original bumper beam is replaced by LGFT and CFRP composite materials by the method of equivalent stiffness to evaluate the performance of crashworthiness and lightweight according to the rules of low-speed impact. At the same time, the cost of three kinds of materials has been contrasted. The results show that, on the premise of meeting the performance of crashworthiness, LGFT can decrease the bumper mass by 11.2% and CFRP can decrease the bumper mass by 46.1%, the lightweight effect of both composite materials is obviously. The cost of LFGT decreases significantly, but the cost of CFRP increases markedly.Further, analysis of the energy absorption characteristics of CFRP laminates. Angle optimization plies of CFRP bumper has been executed with Genetic Algorithm(GA),the optimization models are constructed with the minimal impact peak force as the goal and the intrusion of the impactor as the constraint, and the optimal ply orientation angle is [0/-45/90/45/45/90/-45/0]. Finite element simulation of bumper beams ply angle before and after optimization were compared, the peak force of CFRP bumper beam is reduced significantly after ply angle optimized.Finally, in according to the mechanical behavior of the automotive bumper beam and facilitate LGFT material manufacturing processes, a continuously variable thickness design method is been carried out. The thickness is selected as variable, the RSM models for the peak force of the and the mass of the bumper beam are constructed. Then Pointer is applied to search the global optimal designs. The results show that the tolerance between the impact index of optimization model and simulation model are controlled within 10%,and the performance of lightweight and crashworthiness have varying degrees of improvement.This study has a significant effect for improving the lightweight effect and low-speed bumper car collision performance, and for fiber enhanced composite material application in automobile as well.