Car body concept modeling for NVH optimization in the early design phase at BMW: a critical review and new advanced solutions

The car body concept modeling is a well established design process at BMW. The process is based on the FE "Beams and Shells” concept model, with arbitrary beam cross sections, used for early concept phase car body structural optimization with a special focus on the NVH performance [1] [2] [3]. The aim of the investigations is to evaluate the potential of different structural topological solutions in order to achieve premium NVH performance with minimum weight and construction space, while matching a complete set of vehicle customer relevant functional requirements, also including basic requirements for ride, handling and crash. A general description and a critical review of the car body design and optimization process will be presented. The focus will be on the latest modeling solutions, introduced to increase the robustness and the accuracy of the modeling process. More details will be given on the new joint modeling approach based on hybrid structures, whereby one-dimensional FE elements are coupled with three-dimensional joint structures and morphing techniques are applied to the three-dimensional parts in order to realize a full- body geometrical optimization process. The challenges related to stress calculation, connections of FE dissimilar elements and the set-up of the hybrid design model will be highlighted, a study case showing the benefits of the new approach will be presented.