Structure configuration/connection impact and design gaps for compliant body assemblies

Abstract

For compliant body assemblies such as automotive and aircraft bodies, design gaps are often given at certain areas in design to avoid interference or to offset potential mean-deviation stack-up. The location, the size and the necessity of design gaps for body assembly are usually based on engineers' experience or the outcomes of previous models. In this paper, the sources for deviations are discussed and the structure-induced deviation, due to the peak contact in parallel connection/contact among the components, is identified. It is discovered that the parallel contacts would result in mean shifting and the resulting variations shrinking. To reduce or eliminate these deviations, it is to either consider the impact from product and assembly process design, or specify design gaps if they are necessary. Principle and estimations/calculations of the amounts of design gaps are developed. The study shows that the design gaps are highly related to the structure/connection, contact, assembly process and datum schemes. The work provides insights and practical ways for design engineers to better understand assembly processes and specify design gaps.