This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

Welding is an essential part of any automotive assembly but determining the proper placement of welds can be a time consuming and difficult process. At the same time, there is a strong need to decrease the overall number of welds in automotive assemblies to reduce manufacturing cost and time without sacrificing structural integrity. The current spotweld optimization procedures used today involve much trial and error and are typically limited in capabilities. Optim Welds, a multidisciplinary FEA spotweld optimization tool developed by BETA CAE Systems, USA allows engineers to efficiently optimize the locations of spotwelds, including non-uniform weld distribution, on an assembly while also saving time and resources compared to current optimization approaches. Starting with a running FEA model, Optim Welds guides the user through the entire optimization procedure. Tools are provided to easily create and parameterize spotweld lines, while an optimization workflow is automatically generated according to user inputs. The resulting optimization is capable of handling multiple loadcases, disciplines, and solvers simultaneously, with the user being able to freely choose their preferred finite element weld representations. Non-uniform weld distribution is achieved through flagging critical welds in the model according to a user-specified threshold criterion, which are then carried over to subsequent designs automatically. Weld lines are parameterized in groups, leading to a reduction in the number of design variables and total optimization time. At the same time, the use of critical welds strategically places welds in important locations. Model symmetry can be defined to ensure weld placement is feasible for production. A case study with a simplified vehicle model using frontal and side crash loadcases was performed. Results after 77 designs showed a reduction of 270 welds (4%) while still meeting performance targets.