Multidisciplinary Design Optimisation Strategies for Lightweight Vehicle Structures

The future of automobiles will be driven by lightweight structures and highly efficient powertrains. The TARF-LCV EPSRC funded project (Towards Affordable, Closed-Loop Recyclable Future-Low Carbon Vehicle Structures) aims to provide a strong scientific and technological underpinning to future LCV development in areas of advanced materials, low carbon manufacturing technologies, holistic mass-optimised vehicle structure design and closed-loop recycling of End of life vehicles. The proposed paper investigates different optimisation strategies for the definition of material grade and subsequent panel size allocation throughout the vehicle architecture in order to meet EuroNCAP frontal, side and pole impact crash requirements. Higher grade materials are necessary in highly strained impact areas and have the possibility to compensate for the lower energy absorption offered by lower grade materials, consequently reducing the requirement of larger panel thickness, hence leading to an overall reduction in structural mass. Nevertheless, this method is not always adequate as reducing panel gauge will also have a negative influence on the vehicle’s durability performance. The research therefore investigates the application of optimisation tools and techniques (LS-OPT) for Multidisciplinary Design Optimisation (MDO) by coupling crashworthiness requirements to torsional stiffness in order to reduce structural mass without compromising static rigidity. The study will monitor vehicle accelerations and passenger compartment intrusions as means of assessing the suitability of the choice of optimisation technique. The computational time involved per method to find the optimum solution which meets the constraints is also investigated. The findings have shown that the MDO capabilities of LS-OPT can obtain a viable lightweight solution from a wide range of parameters and engineering constraints (crashworthiness and durability).