Oblique Crashworthiness Analysis And Design Optimization Of Vehicle Frontal Thin-walled Structures

Safety design is the key step in the process of modern automobile design. It has become a hot issue that how to improve vehicle crashworthiness. Thin-walled structures are widely used in the fields of automobile, ship, space craft and aircraft because of its high energy absorption capacity. It can effectively improve vehicle crash performance, through the research and optimization design on the crashworthiness of thin-walled structures used on vehicles. In the actual collision, the condition is very complex and the loading is varied. As the typical structures of the vehicle body, thin-walled tubes show significant effect in the vehicle. A lot of researches on thin-walled tubes crashworthiness mainly focus ed on axial impact. It shows great significance to research on the crashworthiness of thin-walled tubes under oblique impact, since oblique impact is more common in real accidents.In this paper, the structural and material parameters of thin-walled tubes which affect the energy absorption under oblique impact were analyzed and optimized, by using methods of the finite element numercial simula tion and metamodel technology. Firstly, the crash performance under oblique impact affected by structural parameters of thin-walled tubes was investgated. It provided the reference for further oblique crashworthiness optimization. Some research showed that tapered thin-walled tubes have better bending resitance compared with common stright tubes. So this kind of thin-walled tubes was used as initial structure for further crashworthiness design. The crashworthiness of aluminum foam-filled thin-walled tubes with different foam density and filling types were compared and re searched. A new type of functionally graded foam filling tubes was proposed. Through impact simulation test of this kind thin-walled tube, it was found that the functionally graded foam-filled tubes gained good performance under axial and olique impact.Then further investigation focus on the multi-cell tubes crashworthiness. Studies showed that multi-cell tubes has more stable deformation mode under axial impact. In this paper, seven kinds of multi-cell tubes were investigated under oblique impact and the type with best energy absorption potential was chosen for further study. The tube’s parameters were optimized by using metamodel technology and tragerring mechanism. The optimized structure had good axial crashworthiness and oblique crashworthiness was significantly improved.According to Federal Motor Vehicle Safety Standards NO.208 front 30 degree oblique impact, the vehicle crash finite element model was simulated for crashworthiness analysis. Based on the research conclusion of thin-walled tubes oblique crashworthiness, the key parts on the vehicle were strengthened by using aluminum foam filling and high-tensile steel. The vehicle performance under 30 degree oblique impact was obviously developed. It was proved that the method and conclusion of this study could be significant reference to practical engineering design.