Design of an innovative chassis made in bio-composite

Abstract: The present master thesis concludes the Vehicle engineering program followed at KTH University in Sweden and my mechanical engineer formation at Arts & Métiers Paritech in France. The use of composites materials is nowadays widespread and no longer only restricted to high added value objects. They present indeed many advantages in term of diversity of use, strength, allowable shapes and weight. They are however using fossil resources, whose process to make them usable are heavy energy consuming. Moreover, on the opposite of metallic materials, it is hard to reprocess them. Those reasons make composites materials quite polluting. To remedy this problem, bio-composites materials are more and more considered but the obstacles for their systematic utilisation are still many. To that extend, VESO CONCEPT wants to value its panels and use them for structural parts. The objective of the master thesis is to replace the tubular steel chassis of the 4 wheeler named the PITCAR taken as reference by a bio composite chassis. To do so, the study of the vehicle and the literature has been realized in a first time. After defining the frame of the study, all the input data have been processed, open source software had been chosen (FEM analysis software, pre and post processing) and create the adapted simulation programs were designed for the composite chassis. Then, the definition of the architecture has been performed. A lot of different panel layouts have been tested to determine the best architecture, and a pre-sizing of the panels length and thickness has been realized. Once the architecture was defined, the fastening brackets linking the panels have been characterized. This link technology was a requirement from the company. A pre-design was made for their geometry and two different models allowed determining their number and position on the chassis. Finally, a 3D detailed design has been realised with the help of a CAD software in order to integrate every reference elements. Every integration has been defined: some elements only needed slight modifications but others needed to be re-study. The sizing and the verification of most of the elements have been performed, in function of the remaining time and importance. In parallel, a more detailed model for the FEM analysis has been developed in order to gather more precise results from simulations, and verify that the chassis being designed was strong enough regarding the considered solicitations. Solutions have been found to remedy the failing zones, and actions aiming at improving the performance/mass ratio have been taken.