Towards a Micromechanical Damage Model for Lightweight Materials in Vehicle Crash

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The 2012 U.S. Corporate Average Fuel Economy (CAFÉ) targets mandating a 50% cut in fuel consumption by 2025 have supercharged research and innovation within the automotive industry. To reach these targets without compromising occupant safety, next generation materials such as ultra high strength steels, high strength aluminum and magnesium alloys are being rapidly developed and implemented into a lightweight multi-material vehicle architecture. Although these materials offer tremendous potential for lightweighting, they also bring ever shrinking process design windows due to their complex material behaviour and fracture sensitivity. Consequently, advanced forming operations at elevated temperatures are required to avoid the low ductility of these materials at room temperature. To stay competitive in the high volume, low cost environment of automotive manufacturing, computer assisted engineering (CAE) is required to design the component, tooling, forming process and predict its performance in a vehicle crash. The complicated mechanical behaviour of these lightweight alloys coupled with the need for advanced forming operations far exceeds the capabilities of today's numerical models. The proposed research will address this critical shortfall in the CAE fracture models to capitalize on the potential of these emerging material systems for lightweighting. *** The long term goal of this research is the development of a comprehensive modeling platform for the simulation of product history, from manufacturing to in-service performance, to enable the design and commercialization of multi-material lightweight vehicle architectures. In the short term, the research program will develop innovative experimental and numerical methodologies to predict the behavior of anisotropic lightweight alloys in complex non-proportional loading conditions found in forming and crash events. Central to the research is the development of micromechanical void damage models that can replace the phenomenological damage models used by industry that have a limited physical basis. To optimize structural components and develop new alloys, it is imperative the material models can account for how a microstructure evolves across the process chain. *** The ability to design forming processes and components using advanced materials and manufacturing processes is critical for the innovation and global competitiveness of the automotive and manufacturing sectors in Canada. This research program is in direct alignment with Canada's 2014 Science and Technology Strategy for “Lightweight Materials and Technologies” to be a Research Focus within the new “Advanced Manufacturing” Research Priority. This research will provide Canadian automakers with a cutting edge research and design tool that can be used to design a component from its conception to crash and from the micro-to-macro-scale.