The Frontal Rail Optimization Design And Its Influence On The Frontal Impact

With the dramatic increasing number of car ownership in China, more and more people have private cars. The most common mode of transport is carrying millions of lives in the crowd streets. As the number of vehicles soaring, the streets being more crowded and the numbers of traffic accidents increasing dramatically, people began to pay more attention to the vehicle safety. According to the statistics, the frontal impact (including oblique impact) account for almost40%in all accidents. In the frontal impact, the front beam is the main energy absorbing and load-transmission component. How to improve the deformation form of the front beam, how to increase the energy absorbing in the impact, and how to reduce the peak load in the impact are the most important issues.Based on reading a large number of literatures concerned, the current vehicle crash regulations, the finite element simulation of thin-walled beam, and structural optimization design were summarized. Take the axial crushing characteristics of thin-walled beam into account, for a certain section of thin-walled beam, its shape, position, depth and width of the initiators’influence on the deformation characteristics, energy absorbing, the peak load on the section in the impact process were discussed and analyzed. The results show that in order to guide the thin-walled beam that occurring the axial deformation, the thin-walled beam should be set proper initiator; when it sets bead initiator, the initiator should be set in the half-wavelength of the thin-walled beam; the depth and width have a significant influence on its crash performance, the depth of the initiator should between5%and10%of the section dimension, the width should be shorter than the half-wavelength; when the initiator is too deep or too wide, thin-walled beam will occur directly bending deformation in the impact, which reduces its energy absorption values greatly.Orthogonal experimental design was used to select the sample points. A global optimization of the structure is performed based on the response surface methodology. In this methodology, the parameters are the position, the width and the depth, and the aim is to make the beam absorb more energy and perform better in the crash. The optimization results showed that, compared with the position and width, the depth had the most obvious influence on the energy-absorption and peak load, and the distance between the initiator should be half-wavelength and one quarter wavelength. Finally, the deformation and energy-absorption of the front rail were analyzed by using a vehicle model and the results of the one-initiator and two-initiator. The results showed that using the conclusions of the initiator have a certain influence on the crash performance.This paper proves the effectiveness of the analysis above, and provides a basis for the following design of the front rail in the frontal impact.