Design and Evaluatoin of a Carbon Fibre Bus Body

Abstract: The automotive industry is in constant development and in recent years the environmental legislations have been getting tougher. The need for lighter and stronger materials has increased according to these changes and composite materials such as carbon fibre reinforced polymers is showing potential of being a solution due to their high specific properties. This thesis is an investigation and design proposal for one way of making a carbon fibre bus body wall structure by the use of pultruded beam elements and a certain number of standardised node elements. This is done to increase the possibility of mass production and possibly lower the manufacturing cost for a carbon fibre structure. The methodology is based on a product development process where a market research as well as a literary study was conducted initially to see what work had been done in the area. Needs were investigated and formulated to a product specification from which concepts was generated using brainstorming methods as well as discussions with bus design engineers at Scania. A number of materials and manufacturing methods was analysed for the node elements and after comparing and scoring different concepts, a carbon fibre node element was chosen. Dimensioning calculations were made based on standardised tests which simulates different driving scenarios. The concept was then designed in 3D-cad and the final weight of the concept was measured to 194 kg. A comparison of the concept with a steel bus was made by the use of the life cycle analysis tool in CES Edupack 2017 which resulted in a difference of 47 tonnes carbon dioxide released for a diesel driven light goods vehicle during the first six years of the lifetime. The overall results show that a carbon fibre bus body might be economically beneficial during the entire lifetime of a bus even though the purchase price is higher.