Strength Analysis And Lightweight Optimization Study On Special Heavy Vehicle Frame

This paper summarizes the present research situation in lightweight structure using in vehicles, analyzes the development trend of the technology using in this area, and discusses the deficiency of this kind research work in domestic vehicles. On the basis of those, an idea of using Finite Element Method (FEM) and modern optimization technology to analyze and optimize the frame of the special vehicle is presented.Subsequently, according to the demand of the client and the vehicle structure, the all-shell-element model of the frame and the balanced-suspension model which can simulate the real one well are build. Before the analysis of the frame, the analysis of the performance of balanced-suspension including balance effect and pass capability is made first. In this course, a new process to verify the movement of the suspensionwan compare to maditional way, this process is more complex,but it's more credible and more accurate.On basis of the using situation of the vehicle, various load cases are determined, and the stress and displacement of the frame is calculated under these load cases, the carrying capacity of the frame is then quantificationally accounted.Because of the high stress concentration in some small areas, the stress of these areas is high as a result, some improvement are made to reduce the high stress, and make the nearby structure are more reasonable, at the mean time, the whole structure is not influenced.The FEM and the mathematical programming are taken to obtain the lightweight optimized frame structure.Firstly, not changing the topological layout of the frame, just set the section size of the longerons as the design variables, set the max stress as the state variables, and set the volume of the frame as the target. A result of reducing weight 12.94% is get, with the strength and the stiffness keeping almost the same as the origin.As the advanced optimization method, a topological optimization is studied, on the basis of keeping the weight of the frame from changing, the result greatly increase the torsion stiffness of frame, and torsion deformation of the frame is accordingly more concordant. And at the same time, the stress of frame is lower as well, then the more weight of frame can be reduced, a further section size optimization is taken to get that effect. The final optimized frame structure with satisfying the need of the strength and stiffness reduce 20.23% weight compare to the origin.All the studies in this paper offer a valuable analysis method to balanced_ suspensions, and a fine, available optimization method to such large frame structure.