车用复合材料螺旋弹簧的设计与优化

A major problem in designing automotive structures is how to make full use of the flexible designability of composites and light weight of polymer matrix, and also consider the close connection among the material, structure and properties. Since the helical spring is one of the major load-bearing parts of suspension and subjected to complex loads, it is generally manufactured by spring steel with ultra-high performance. If replaced by lightweight composites, both safety and light weight should be satisfied, which makes the design of composite helical spring rather difficult. In this paper, an integrated materials-structure-performance design method of composite helical spring is proposed. According to the stress distribution on the cross section of spring under compression, carbon fiber reinforce polymer (CFRP) material with ±45° ply sequence is selected. Under the constraint conditions of stiffness, strength and installation space, the initial geometric parameters of helical spring are derived by analytical models based on spring stiffness and strength and composite material mechanics. Furthermore, the initial result is verified numerically by finite element simulation. Combining the design of orthogonal experiment with numerical simulation, the response surface model of stiffness and strength of helical spring to its geometric parameters is established. Finally, the optimal design of helical spring satisfying both required performance and weight reduction is obtained by genetic optimization algorithm. Compared with the metal helical spring, the CFRP one reduces the mass by 34.4%. As a representative product development case, it has demonstrated that the proposed method is a feasible integrated solution for design of automotive structural components with composite materials.