Research On Collision Energy Decay Characteristic For Automobile And Design For Magnetorheological Bumper Energy Absorption Device

With the rapid development of highway transportation in our country and the improvement of the quality of people’s living standard, total car ownership is increasing sharply, however, the car has brought convenience to people, also brought serious safety problems at the same time. Many experts and scholars have done a lot of research on the cushion energy-absorbing bumpers, and have made a lot of achievement on the connection of bumper with body, the structure design of energy-absorbing device, the choice of materials and lightweight, etc., but these are passive cushion energy-absorbing devices, and have a poor adaptability of different impact speeds and different impact weight. Magnetorheological fluid as a new smart material with properties of magnetorheological effect, shorter response time, lower power consumption, larger intensity of shear yield and controllable and so on, thus which based on magnetorheological technology, buffers or dampers have been rapid development in the impact field.Combined with the characteristics of the cushion energy absorbing bumpers can transform single wave kinetic energy generated in car collision into the multiple impact condition, this paper presents a MRF bumper energy absorption device as a car bumper energy absorption component. Based on the collision dynamics theory, this paper has established the mathematical model of the decay of car collision energy, and obtained the decay characteristics of car collision energy by car simulation crash experiments, and done what about magnetic circuit design, structure design, structure parameter optimization for the magnetorheological damper and conducted research on vehicle crash simulation based on magnetorheological damper, and realized the reasonable dissipation of the collision energy, having great significance to improve the performance of vehicle passive safety. The main research work are as follows:(1) Based on the collision dynamics theory, the high-speed car collision dynamics modeling is established, and utilize the finite element software Hypermesh and LS-DYNA to establish a finite element model of the vehicle with the traditional energy-absorbing bumper, and do the vehicle frontal crash simulation under different speed, obtaining the collision energy decay characteristics curves of the vehicle under different impact velocities, the limited nature of the collision energy of the traditional bumper absorbing under the high speed.(2) Applications of parallel plate flow theory, the dynamic model of magnetorheological damper is deduced, and on this basis design the magnetorheological damper structure and magnetic circuit and use MALAB genetic algorithm tool for structural parameters optimization.(3) Build a finite element model of the vehicle with the traditional energy-absorbing bumper by Hypermesh and LS-DYNA software and do the high speed(50 km/h) collision simulation experiment, simulation results show that the magnetorheological damper can significantly improve the passive safety performance of automobile collision at high speed.