A Case Study in Structural Optimization of an Automotive Body-In-White Design

A process for simultaneously optimizing the mechanical performance and minimizing the weight of an automotive body-in-white will be developed herein. The process begins with appropriate load path definition though calculation of an optimized topology. Load paths are then converted to sheet metal, and initial critical cross sections are sized and shaped based on packaging, engineering judgment, and stress and stiffness approximations. As a general direction of design, section requirements are based on an overall vehicle “design for stiffness first” philosophy. Design for impact and durability requirements, which generally call for strength rather than stiffness, are then addressed by judicious application of the most recently developed automotive grade advanced high strength steels. Sheet metal gages, including tailored blanks design, are selected via experience and topometry optimization studies. Full-vehicle CAE analysis of the stiffness, durability and impact performance are then used to further refine the sheet metal design. In the next round of iteration, individual components of the body-in-white, such as the shock towers, are optimized using the aforementioned optimization tools and process. In all, using a generic mid-sized SUV body as a test case, it is demonstrated that in using this process, there exists the opportunity to reliably reduce the mass of a body-in-white structure by between 6 and 15 percent while still meeting stiffness, durability and impact goals.