A New Method for Fitting Car Doors Allowing for the Thermal Effects of Welding

Abstract

Gap evenness and flushness between car doors and body-in-white (BIW) openings are appropriate quality criteria. They affect not only the car's functional value such as in door-closing effectiveness, rattle, wind noise, and water leakage, but also the vehicle's aesthetic value to customers. They have a direct and crucial influence on the dimensional integrity and quality of the car door. With the aim of improving these complex processes, a new fitting quality evaluation model is built, in which the directed Hausdorff distance (DHD) from graphics recognition and matching is adopted to measure the degree to which the door and body opening profiles match by high fitting resolution and quick fitting computation. Also, the door-welding multiple physical fields coupled finite element method (FEM) model and simulation are presented allowing for the thermal effects of welding. Furthermore, a new systematical car-door-fitting method is proposed, integrating and compensating variation from the thermal effects of welding. Genetic algorithm (GA) is applied to search global optimization of fitting variables quickly and effectively. Finally, a software prototype is developed under a MATLAB environment. A case study of certain door-fitting designs shows that the proposed method can effectively improve fitting quality and accuracy.