An adaptive optimization procedure for spot-welded structures

The behavior of a spot welded structure under dynamic loads is strongly influenced by the number and locations of the resistance spot welds. The design problem requires the number and locations of spot welds to be optimized so as to obtain reasonable trade-offs between manufacturing cost and structural performance. An adaptive optimization procedure is proposed which iteratively adds and removes spot welds based on decision indicators in order to correct for the approximations made in the iterative process. In practice, it is possible that some spot welds may be defective or even missing when structure leaves the assembly line. Therefore, a simple robustness indicator is formulated to characterize the impact of the number of defective or missing spot welds on the system performance. This indicator provides a useful decision making tool for deciding both how many spot welds should be inspected following assembly as well as pointing to a small number of critical spot welds that should be reinforced. The proposed methodologies will be illustrated on a full body-in-white structure for a car.