| As one of the critical areas for automotive quality control, dimensional quality of automotive body is deeply rooted in the product, process and tooling design. The limitations of existing methods are due to the lack of understanding of the impacts of the non-rigid sheet metal product and assembly process, and the difficulty of dealing with the large number of the components and potential assembly sequences for the dimensional variation analysis and evaluation.; The two aspects of dimensional integrity for automotive body, the variation and mean deviation, are extensively studied in this dissertation. The interaction between two components and the variation/deviation propagation among components for automotive body assemblies are investigated. Based on the findings of the variation propagation among multiple-component assembly, an adaptive product and process design (APPD) strategy is proposed to eliminate or significantly reduce the dimensional influence from components and tooling without tightening the component tolerance. For dimensional mean deviation, the sources of the problem are classified and studied. An adaptive tooling design strategy is proposed to improve the functionality for some “rigid” dimensions.; Two matrixes, DCM (Dual-number Connection Matrix) and CCM (Connection Contact Matrix) are proposed to represent the complicated relationships among the large number of components for automotive body assemblies. The matrixes can be used for connection pattern recognition, structure complexity evaluation and assembly sequence generation. Procedures are developed to analyze and search for optimal assembly process (sequence) and optimal modules/subassemblies by using the matrixes and the APPD strategy.; The research investigations will enhance the understanding on the dimensional integrity of automotive body assemblies and provide methods to analyze and evaluate the product and process (assembly sequence) design of automotive body assemblies. The design strategy is implemented on the designs of a new vehicle and the comparison between the old and new vehicles shows significant improvement on the dimensional quality. |
