Optimisation of an off-road vehicle frame

A single seat off-road vehicle is designed for competing in the South African Mini-Baja competition where the static, dynamic and endurance capabilities of vehicles are compared. The frame has to comply with definite requirements concerning survival space inside the frame, load carrying capacity, terrain handling capability and safety. Since vehicle performance is inversely proportional to mass, a major consideration in frame optimisation is to minimize the vehicle mass. As a preliminary study, to verify an analysis procedure, the configuration of the roll cage of the vehicle frame is analysed. Circular hollow sections of various diameters and thickness are considered and optimised with respect to mass and cost subject to the requirements for local and overall buckling, local and overall stress constraints, and fatigue. The results indicate that optimisation can result in considerable mass and cost savings.