The performance and design criteria for seat systems require that the seat be lighter for reduced fuel consumption while still meeting the safety requirements specified by legislation. The safety requirements for seats include headrests, seat back static and dynamic structural performance, seat belt anchorage, luggage retention capability, child seat anchorage and top tether requirements as defined by pertinent regulation. The interior space constraints require that the seat be thinner. The seat design is expected to address the growing concern for environmental friendliness. In addition to these main criteria, various additional features such as adjustable and stow-able design are required for customer delight. All these design objectives should be met within a given cost target.
Conventional seating systems include a steel frame, with springs attached to provide support and flexibility to foam cushions. The steel frame is made up of several parts welded together. Weight of the seating system in comparison with the overall vehicle weight is typically about 3% for a small car and it could be as high as 5% for a SUV type vehicle.
This paper deals with plastic rear seat design that provides more than 20% weight reduction in the seat structure. Lighter seat improves vehicle fuel efficiency, reducing CO2 emissions. The material of construction includes recyclable plastics and “green” polyurethane foam, making this design eco-friendly. Low cycle time of molding, reduced part count and assembly time, optimized contours for comfort and reduced material consumption lead to cost competitive design. The optimized structural properties and processibility of PC/ ABS offer good stiffness and impact properties at fast cycle times. The combination of ease of processing, excellent mechanical behavior, good finish, dimensional stability and a wide operating temperature window make these materials a suitable choice for construction of seat systems.
Various implicit and explicit finite element analysis codes are used to simulate the process, structural and crash behavior in order to optimize the design, minimizing weight while meeting various regulatory requirements. This paper describes the design, process, materials and the development methodology for plastic seats to meet various regulations and help to fulfill the environmental demands on emissions and fuel consumption.