Multi-Functional Composite Design Concepts for Rail Vehicle Car Bodies

Abstract: Structures and material combinations, tailored for multiple purposes, are within the reach of vehicle manufacturers. Besides reducing the environmental impact of the transportation sector these multi-functional structures can reduce costs, such as development, manufacturing and maintenance, and at the same time offer improved comfort to the passengers. This thesis sets out to develop multi-functional design algorithms and evaluate concepts for future composite high speed train car bodies with the objective of optimising the amount of mass needed to fulfil all functions of the structure.In a first step complete composite car bodies were developed, optimised and evaluated based on global stiffness requirements and load cases. The knowledge gained in this step was used as requirements for the strength and stiffness of panels during the continued development of the multi-functional optimisation which, besides strength and stiffness, later also considers sound transmission, thermal insulation, geometric restrictions, manufacturability and fire safety. To be able to include fire safety in the analysis, a method for simulating the high temperature response of layered composite structures was needed, and developed.Significant weight reductions are proven when utilising carbon fibre in the load carrying structure of the vehicle, on component level as high as 60%. Structures can be made significantly thinner when using the algorithms developed in this thesis and wall thickness is reduced by 5-6 cm. Analysis carried out and extensive literature surveys also suggest significant cost savings in manufacturing, maintenance and use-phase, even thou the raw material cost can be significantly higher as compared to the conventional steel or aluminium alternatives.Results from drive cycle simulations showed that the benefit, with respect to reduced energy consumption, is in the range of 0.5-0.8% per reduced weight percentage, comparable to both automotive and air applications.The algorithms and methods established in this thesis can be directly applied for the development and analysis of future high speed train car bodies.