Two improved assembly deviation analysis methods based on Jacobian–Torsor matrix and skin model shapes with contact deformation effort

Assembly deviation analysis methods, which have been studied and improved over the past 30 years, are necessary and effective for checking functional requirements before manufacturing. Contact deformation was not negligible and significantly affected the final assembly deviation, which prevented the application of the current assembly deviation analysis methods. Considering the contact deformation, we aimed to improve the precision of the 3D deviation analysis methods, which are based on the Jacobian-Torsor matrix and skin model shape (SMS), respectively. In this study, the contact deformation was quantified based on the Hertzian contact theory. The unified Jacobian-Torsor matrix is modified with the location points and contact deformation to increase the precision of the stack-up assembly deviation. In the SMS-based method, the assembly components are represented as non-nominal SMS models. The final posture of each component and stack-up assembly deviation were solved by iteratively mimicking the physical assembly process. The practicality of the improved deviation analysis method was successfully demonstrated through two case studies. The modified Jacobian-Torsor matrix-based method is efficient. However, the improved SMS-based method can provide more precise results by mimicking tight fitting on mating surfaces.