Multi-material and multi-joint topology optimization for automotive lightweight design

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With new government regulations on fuel efficiency and C02 emissions, automotive manufacturers are under tremendous pressure to reduce vehicle mass drastically. As an example, OEMs have to significantly improve vehicle mileage through a series of steps beginning in 2016 through to 2025 due to the mandated Corporate Average Fuel Economy (CAFE). The fuel economy requirements will transform the way in which vehicles are designed and manufactured as automakers are looking at every possible means to reduce weight. Topology optimization determines the optimum layout or distribution of material that minimizes weight while maintaining important performance characteristics; and this is one of the most effective and promising design techniques for reducing vehicle weight. The use of various lightweight materials in vehicle development is rapidly increasing, and this raises a new design challenge: "What are the optimum use and distribution of multiple materials and the optimum joining methods?" Conventional optimization approaches are ill equipped for this challenge, and it is imperative to develop an effective approach that can determine the optimum use of the multiple, dissimilar materials and their joining methods. The objectives of this research are (1) to determine optimum designs of next generation vehicle chassis joining strategies which utilize mixed materials and various joining methods (2) by developing advanced topology optimization approaches for multiple material joint designs and joining methods. By developing new techniques for multi-material and multi-joint topology optimization, optimized designs will be determined for the ladder chassis frame of a light-duty truck by General Motors of Canada. A total weight savings of 30% is targeted, without sacrificing the strength or stiffness of the frame. The final deliverables for the project are production ready designs for next generation ladder frame assemblies as well as optimization-software modules for use by GM Canada in its early vehicle architecture development stage.