Fixture layout optimization for large thin-walled parts based on improved particle swarm optimization algorithm

Large thin-walled parts are generally featured with large in-plane dimension and thin thickness. This kind of parts deforms easily under the action of gravity due to their low out-of-plane stiffness in the assembly process. In order to reduce the part deformation, the “N-2–1” locating principle is used for large thin-walled parts. The part deformation leads to the assembly gap between two parts, which affects the assembly quality. In this paper, the influence of the fixture layout on the assembly gap is considered. The assembly gap is taken as the optimization objective to minimize by integrating the modified direct stiffness method (MDSM) and the improved particle swarm optimization (IPSO) algorithm. Then, the assembly of two ship parts is studied and the results show that the optimization method proposed in this paper can effectively reduce the assembly gap between two large thin-walled parts.