Research On The Crashworthiness Analysis And Lightweight Of Front Bumper

As the rapid growth of auto sales in China, various vehicle collision accidents have been continually raising, causing great damage to people. As the body part that firstly impacts the collision objects, front bumper plays a key role in the crashworthiness of a vehicle and its crashworthiness need to be thoroughly studied. Meanwhile, the degree of automobiles lightening can be further promoted by reasonably using light materials and optimizing structures, including decrease the weight of bumper system.In this study, research situation at home and abroad of automotive crash safety and carbon fiber for vehicle are introduced in detail. A front bumper of a car as research object, using VPG to establish the collision model, LS-DYNA is used as the simulation platform. The crashworthiness and deformation process of the bumper under low speed collision are emulated and analyzed in detail. A bumper structure that consists of a double bumper and crash box is presented for the disadvantages of the former one. The new bumper is made of carbon fiber while the crash box is made of aluminium alloy. The results of the simulated analysis of several shapes of crash box prove that the best form of the crash box is folded thin-walled tube, and the thickness of the crash box that lead to the best crashworthiness of the new bumper system is confirmed afterwards.Combining the common forms of carbon fiber materials, several layer forms of the new bumper are presented. The most optimal layer form is reached through analyzing of the simulation result. Multi-objective optimization is used in the thickness optimization of several parts of the new bumper, and the response surface method is applied. The objective function is fitted out through the least square method and the optimum value is obtained. Compared with the new bumper that without optimization, the new bumper is lighter, and its compromise degree of energy absorption and acceleration controlling is much better. Furthermore, the biggest stress value of the bumper under low speed collision is significantly reduced. Compared with the original bumper, the new bumper system dramatically increased the crashworthiness under low speed collision and reduced the weight.The difference of the crashworthiness under high speed collision between the former and the optimized car is compared through the establishment of the collision model of full vehicle. The simulation results show that under high speed collision, the new bumper system signally raises the degree of the car’s passive safety as well.