Use of unidirectional thermoplastic composite tapes to reduce mass & improve performance of a steel doorframe support on a commercial truck

A lightweighting study was conducted on a doorframe structural support for the storage bin on a commercial truck cab last year. Compression-molded composite laminates produced from unidirectional fiber-reinforced thermoplastic tapes were compared to incumbent stamped steel and shown to reduce mass 18 % while providing slightly better torsional resistance and significantly better wind-loading performance. This was accomplished despite the fact that it was not possible to modify the part design other than to allow slightly thicker wall stock and somewhat larger radii. A robust protocol was used to develop properties for material cards for use in an iterative series of analyses, which were conducted first to see what was possible with the composite laminates and then to meet thickness restrictions in carryover tooling from an earlier study. Once a final ply schedule was produced, it was passed to a second team in charge of conducting a novel process characterization study, which considered drape-ability in various orientations, quality of the laminate (via microscopic examination), and finally developed a temperature vs. time process chart from data obtained from thermocouples embedded at key locations in the laminate stack. Last, data from this study was used to optimize a 4-step semiautomated process that was capable of producing the doorframe support part in less than 90 sec (from preheating/consolidation through molding and de-molding). This supports the researchers' belief that the material/process combination could be translated to commercial vehicle production. Details of the study are provided in this report.