A MODULAR AUTOMOTIVE ROOF SYSTEM DESIGN CONCEPT BASED ON POLYURETHANE COMPOSITE TECHNOLOGY

摘要

There is a growing trend in the automotive industry to offer more "non-traditional" roof configurations to the consumer. In many cases the non-traditional roof contains glass, guides, drives and other hardware that increase the cost and weight of the vehicle. Consequently, suppliers are being challenged to offer designs that use lightweight materials, integrate or eliminate components, while maintaining or improving overall structural and dimensional performance of the vehicle. Based on a standard "body in white" roof structure, the innovative concepts described in this paper use molded polymers and composite materials that allow a vehicle to be fitted with a wide variety of roof "modules", each having customized performance, content and value. The modules are designed to integrate components, eliminate post painting, increasing vehicle rigidity, and reduce weight. Conceptual designs illustrated in this paper will include two different vehicle architectures and two different roof module constructions. Three different composite materials will be reviewed for their suitability in the roof module. Detailed section views are included to illustrate important part design features, attachment methods, performance considerations, and general composite "know-how". The concept's value proposition is examined in four areas: cost, weight, safety and assembly. Technical and economic benefits to the value proposition include weight reduction, design and styling freedom, in-mold features, attachment points, color options, fixed or moveable window design, and improved roll-over safety due to the lowered center of gravity. Since the modular roof system starts with a component that is ready to assemble it offers a path forward for the supply chain, which enables OEMs to decrease capital expenditures and reduce labor hours required to manufacture a vehicle. The backbone of the value proposition is a recently conducted case study, comparing a traditional vehicle to the same vehicle fitted with a composite polyurethane roof module. The two piece roof module examined in the case study is constructed using long fiber technology, and results in a vehicle that is lighter, stiffer, has a lower center of gravity, while offering greater design freedom and integration flexibility than traditional roof materials and design solutions. In addition to polyurethane composites, the paper includes references to adhesives, coatings, co-extruded polycarbonate and polycarbonate/acrylonitrile film, and polycarbonate thermoplastic glazing.