A Study On Theory And Method In Vehicle Side Structure Crashworthiness Design Under Pole Side Impact

Due to the rapid development of automotive industry, the automobile production and sales in China have been ranking the first in the world for several years, meanwhile the traffic safety situation of China is more and more serious. According to relevant data statistics, side impact, which includes pole side impact, is the second most popular vehicle impact scenario after frontal impact. Due to high rigidity of pole structure, high impact speed, limited impact zone and weak stiffness of vehic le structure, pole side impact would lead to high risk of serious injury to occupants, which poses a great challenge to crashworthiness design of vehicle side structures.In view of the above problems, the kinematic process and structure stress of vehicle body under pole side impact were first analyzed through theoretical approach. The energy conversion and the injury mechanism of dummy were obtained to lay down theoretical basis for further vehicle structural design. The finite element model of pole side impact was established and the accuracy of model was validated.Then the crashworthiness indices such as vehicle body crushing deformation, energy absorption of vehicle parts, acceleration of vehicle body, t ransferring path of impact force and intrusion of side structures were analyzed based on simulation results. The direction and principle of vehicle crashworthiness design were obtained. Then the improving scheme for important load carrying parts such as rocker, B pillar, roof reinforce beam and seat cross beam were carried out, and the crashworthiness of vehicle under pole side impact was consequently improved. A vehicle crashworthiness design strategy combining structural topological optimization and multi-objective parameter optimization method was proposed and applied in crashworthiness design of vehicle door under pole impact. The dynamics problem in door pole impact and stiffness experiment was transferred into statics problem through mechanical calculation. The best material distribution was obtained through structural topological optimization, and two new side door beams were constructed through chosing correct cross section. After multi-objective parameter optimization, the side door bea m had the best crashworthiness in pole impact and the biggest structural stiffness with lightest weight. A material matching design strategy based on orthogonal experiment sensitivity analysis method was proposed and applied in material matching of important vehicle side structural components. After analyzing the sensitivity of structural energy absorption and material cost to components material replacement, the adaptive components were chosen to replace material, thus the c onfiguration of materials with different range of strength level was accomplished.The results showed that the crashworthiness of vehicle in pole side impact could be effectively improved through employment of appropriate structural optimization design method and material matching method. The structural improvement scheme of vehicle body proposed in this paper can effectively improve the stiffness of vehicle side structures and reduce vehicle deformation and intrusion of rigid pole in pole side impact. The research methods and results can be referred in pole side impact crashworthiness design of other automobile type.