关键词: 薄壁结构, 材料替代, 车身结构, 轻量化设计, 应变能分析

Abstract: An approximate analytical expression for the calculation of the stiffness of thin-walled structures of different materials is developed on the basis of bending and membrane strain energy analysis of shell finite elements. The analytical expression combining with finite element analysis gives an analysis method for lightweight material substitution design of thin-walled structures with equal stiffness. The lightweight effect of material substitution can be estimated by using material density and thickness of the two structures, and an equal-stiffness curve with respect to the ratio of shell bending strain energy to the total strain energy  of structure is presented to show the lightweight effect and to guide the lightweight design of thin-walled structures. It is also shown that the influence of material substitution on structural stiffness is related not only to the material properties and shell thickness but also the ratio . For design problems of substituting aluminum structures for equal-stiffness steel ones, lightweight benefit increases quickly with the ratio increasing. Two aluminum substitution designs, with equal-stiffness requirement, for a curved thin-walled steel beam and a typical car body joint are discussed, and the lightweight effects are analyzed, which demonstrates the effectiveness of the proposed design and analysis method and related conclusions.

Key words: Automotive body structure, Lightweight design, Material substitution, Strain energy analysis, Thin-walled structure