A design process for a railway-car body with aluminium extrusion panels using structural optimization

Abstract

The railway vehicle industry faces increasing pressure to enhance performance and safety while minimizing weight, manufacturing cost and fuel consumption. The cost can also be increased when satisfying various safety requirements. Structural optimization can be a very effective method to design the structure of a railway-car body. In recent years, there have been many applications that design the structure of a vehicle body with aluminum material. The aluminum railway-car body consists of sandwich panels, and a sandwich panel is made of units which are placed side by side and welded along the edges of facing plates. A unit is fabricated from an extrusion process and constructed with webs and ribs. The mass and stiffness of the structure can be determined by changing the shape and thickness of the webs and ribs. In this research, a design process based on structural optimization is proposed to design the rib shape of each unit and the entire thickness distribution of an aluminum railway-car 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 and to maximize the stiffness of the structure with specific mass constraints. The results of topology optimization are reflected in the decision of rib shape in the next step. Second, the optimization technique for rib shape is developed employing design of experiments (DOE). An orthogonal array is used to obtain the optimum combination for the rib shape of each unit. Each unit has four types of rib shape. The characteristic function to find an optimum combination of design parameters is defined by the maximum stress and the maximum displacement. Finally, size optimization is performed to reduce the structural mass while the design requirements are satisfied. The thickness of the webs and ribs are defined as the design variables. Design constraints are defined as that the maximum stress of the entire structure and the maximum displacement of the side sill should be less than the allowable values. The process for a systematic design of an aluminum railway-car body is established to reduce the weight while sufficient strength is kept, and new rib shapes are obtained. © Civil-Comp Press, 2012.