Lightweight Hybrid Electrical Vehicle Structural Topology Optimisation Investigation Focusing on Crashworthiness

As focus on the world climate rises, so does the demand for ever more environmentally friendly technologies. The response from the automotive industry includes vehicles whose primary propulsion systems are not based upon fossil fuels. On this basis a Low Carbon Vehicle Technology Project, partly funded by the European Regional Development Fund, is currently under way; part of this project involves designing a lightweight Body In White (BIW). This has been specifically tailored to suit the drive train and general packaging requirements associated with a Hybrid Electric Vehicle (HEV). The future opportunities for new lightweight vehicle architecture have been investigated using a technique entitled topology optimisation, which extracts the idealised load paths for a given loading. The topology optimisation includes equivalent NCAP dynamic impact loading conditions, as well as torsional rigidity performance. Initially a total of 7 loading scenarios are applied on a structure comprising of various battery and range extender layouts. Two different optimisation modelling techniques have been undertaken comparing conventional boundary conditions against inertia relief, as well as studying the sensitivity of the BIW topology against the influence of load case direction and battery box stiffness. Optimal locations for the two components having the highest mass, i.e. a single battery pack and a combined range extender and fuel tank have been studied focusing upon the effects of the location of their Centre of Mass. It has been assumed that advances in battery technology will reduce the external dimensions of the battery package, thereby enabling an increased number of possible locations within the BIW.