유한요소해석 기반 공차해석을 활용한차체 조립 공정의 로케이터 위치 최적설계

초록

Autobody consists of compliant sheet metal parts that are spot-welded in multiple stations. Since the compliant parts inevitably have geometric variations, they go through deformations caused by their contacts with fixtures and weld guns prior to welding. When they are released after the welding, they spring back, but still exhibit non-ideal geometry, thus resulting in geometric variations of the autobody with poor quality in both function and perception. These geometric variations occurring in the assembly process are greatly influenced by the position of the fixture. In this study, a methodology for determining the optimal locations of the part locators in such assembly process has been developed. It utilizes the method of influence coefficients for an effective tolerance analysis of flexible body assembly, and a genetic algorithm for optimization. In order to illustrate and verify the developed methodology, two sample problems have been solved, namely, a two-plate assembly problem exhibiting only out-of-plane deformations, and a real-world problem of wheel housing assembly involving three-dimensional deformations. This work is only a preliminary study, and future work is suggested in order to make the developed methodology more versatile and useful for the practical needs of the automotive industry.

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