The Structure Optimization Research On Front Rail Of Vehicles Based On The Frontal Crash

With the rapid development of Chinese economy, the number of cars' ownership is sharp increasing, which resulting in the increases of the probability of automobiles collision accidents. Among many forms of automobiles collision accidents,the frontal crash due to the largest number of casualties, and the highest rate of occurrence, got the attention of researchers and scholars from domestic and foreign.As the most important energy-absorbing elements of the forward portion in vehicle body,the front rail mainly through the folds in the deformation process of the collision, absorb the kinetic energy of the collision as much as possible, in order to achieve the purpose of protecting the occupants. Thus, without changing the structure of automobiles body and other conditions of the situation, by optimizing the structure of the front rail, make it has better crash performance,to improve the safety of vehicle crash,has a very important practical significance.Firstly,after understanding the evaluation methods of automobiles passive safety and the research status of the front rail in domestic and foreign, the thesis based on the explicit nonlinear finite element theory, introduced the nonlinear characteristics during the vehicle crash, analysed and studied during the process of the vehicle crash simulation, used different shell elements algorithm, selected the element size of different size, meshed density situations,different spotweld analog mode, hourglass control settings and the contact settings, these main control parameters affect the accuracy of the simulation, lay the theoretical foundation to establish the finite element model of vehicle frontal crash.Then, according to the study of the factors, which effect the accuracy of collision simulation, selected a domestic car models to study, used finite element modeling methods,which is on the basis of three-dimensional CAD model, established the finite element model of car frontal crash a rigid wall,according to the rules of C-NCAP,selected the initial speed of 50km/h(13.89m/s) in car collision with the rigid wall, analysed the situation of whole vehicle frontal crash simulation, and evaluated the safety of the frontal crash from the crash acceleration, rigid wall reaction force, the main energy-absorbing components.By evaluating the safety of the vehicle collision, we can got a conclusion that during the process of the frontal crash, the collision performance of the front rail has a direct impact on the safety of the frontal crash. Thus, extracted the single component from the vehicle finite element model - the front rail, to study its frontal crash performance. Through maximum impact load and total energy absorbed during the collision to evaluate the crash safety of the front rail.Finally, focus on the thickness of the front rail, with the target to minimize the maximum impact load and maximum the total energy absorbed during the collision of the front rail,optimized the structure of the front rail, studied the changes of the thickness for the influence on its crash safety, and applied the optimized front rail to the whole vehicle, verified the effectiveness of the optimized front rail.