Abstract: The research and technology evolution of lightweight car body are reviewed, including the application of various new type steel and aluminum alloys, aluminum space frame in car body structure, components arrangement & integration, structural optimization, and new manufacturing process and forming techniques. Based on the incorporation of the advanced framework structure and the light material substitution, the steel-aluminum hybrid structure is presented. The substituting aluminum alloys for some steel in the traditional steel framework structure and optimizing the structural combination will implement the integrated load-supporting with the hybrid structure. It can develop the advantages of aluminum alloy sheets in weight reduction and increased strength and rigidity and result in the whole body structural optimization. The research contents, the key technologies, and the feasible schemes, approaches and precise computer aided engineering (CAE) modeling for self-development of the hybrid structure body are expressed. The research contents mainly include determining the ratio of steel and aluminum, the substitution position of aluminum to steel, the structural members dimension, the optimal components layout, and research on the joining mechanism of steel and aluminum and forming theory of aluminum alloy, and analyzing the influences of these factors on the whole car performances such as the joining strength, rigidity, vibration, noise, reliability, ride performance and handling stability. As a result, the whole car development criterion of the steel-aluminum hybrid structure is proposed. The key technologies include the new forming technology, topological structure optimization, joining technology, electrochemical corrosion and lightweight car body based on required safety.

Key words: Car body, Lightweight, Steel-aluminum