A Novel Rule-Based Method For Individualized Spot Welding Sequence Optimization With Respect to Geometrical Quality

Artikel i vetenskaplig tidskrift, 2019

Spot welding is the predominant joining process for sheet metal assemblies. The assemblies, during this process, are mainly bent and deformed. These deformations along with single part variations are the main sources of aesthetic and functional geometrical problems in an assembly. The sequence of welding has a considerable effect on the geometrical variation of the final assembly. Finding the optimal weld sequence for geometrical quality can be categorized as a Hamiltonian graph search problem which is of combinatorial non-deterministic polynomial acceptable problems. Exhaustive search to find the optimum, using the FEM simulations in computer-aided tolerancing tools, is a time-consuming and thereby infeasible task. Applying the genetic algorithm to this problem can considerably reduce the search time but finding the global optimum is not guaranteed and still, a large number of sequences need to be evaluated. The effectiveness of these type of algorithms is dependent on the quality of the initial solutions. Previous studies have attempted to solve this problem by random initiation of the population in the genetic algorithm. In this paper, a rule-based approach for initiating the genetic algorithm for spot-weld sequencing is introduced. The optimization approach is applied to three automotive sheet metal assemblies for evaluation. The results show that the proposed method improves the computation time and effectiveness of the genetic algorithm.