Design and development of a long fiber thermoplastic bus seat

Long fiber thermoplastics (LFTs) are increasingly being used in automotive applications for front-ends, bumper beams, dashboards, and under body shields. They have a significant potential for mass-transit applications in buses, trucks, and railroad vehicles. The LFTs are processed with a thermoplastic matrix such as polypropylene (PP) or polyamide (PAI) reinforced with long glass (or carbon, aramid, etc.) fibers, with starting fiber lengths >12 mm, through a pultrusion processing method. The LFT components are typically produced using extrusion-compression molding. In the present work, a bus seat was chosen as a candidate component to assess the viability of LFT technology to reduce weight and cost, without compromising performance over presently used designs. A conservative estimate of 43% weight reduction and 18% cost reduction per seat was predicted over presently implemented seat designs that contain a circumferential steel frame. Cadpress-Thermoplastic (EXPRESS) compression molding software for LFTs was utilized for the process modeling. Flow simulation during the compression molding of E-glass/PP LFT was conducted. Finite element stress analysis was conducted to verify mechanical properties developed as a result of fiber orientation and distribution after flow simulation. This article covers the design, process modeling, component verification, and manufacturing studies conducted for the LFT bus seat.