Structural-optimization-based design process for the body of a railway vehicle made from extruded aluminum panels

Abstract

The railway vehicle manufacturing industry faces increasing pressure to enhance performance and safety while minimizing weight, manufacturing cost and fuel consumption. Structural optimization is a very effective way to design the structure of the body of a railway vehicle so that it meets design requirements. There is a trend to manufacture the body of a vehicle using extruded aluminum. The design of a vehicle body to be built from extruded aluminum panels is considered in this paper. Each aluminum panel is made of sandwich panels that are welded together. The weight and stiffness of the structure are determined by changing the shape and thickness of the webs and ribs. A design process based on structural optimization is proposed to design the shape of the rib and the thickness distribution of the aluminum-based body. The design process is divided into three steps. First, topology optimization is performed to obtain the conceptual design of the ribs under given loading conditions while maximizing the stiffness of the structure. The results of the topology optimization are incorporated into the decision about the shape of the ribs that is performed in the next step. Second, the optimization technique for the shape of the ribs is developed using a design-of-experiments approach. An orthogonal array is used to obtain the optimum combination of the rib shapes. The shapes of the ribs are defined into four types. The characteristic function to find the optimum combination is defined by the maximum stress and the maximum displacement. Finally, size optimization is performed to reduce the weight of the structure while still meeting the design requirements. The thickness values of the webs and ribs are used as design variables. Design constraints are defined so that the maximum stress of the entire structure and the maximum displacement of the side sill are less than the allowable values. A systematic design process of an aluminum body for a railway vehicle is established that reduces its weight while maintaining sufficient strength, and new rib shapes are obtained.