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2014
Conference Paper
Titel
Process efficiency improvements for a structural doorframe support panel molded from unidirectional E-glass/polypropylene composite tapes
Abstract
To help transportation OEMs meet pending fuel efficiency and emissions standards and become more comfortable with composites and use them in higher volume vehicles on more structure-critical applications where these materials can have the greatest impact on mass reduction and hence fuel efficiency/emissions, the automotive supply community must demonstrate the accuracy of its predictive engineering tools, the reliability of faster production processes, and the ability of molded parts to maintain long-term performance. One such study that concluded last year evaluated the use of thermostamped 70-wt% unidirectional (UD) fiberglass-reinforced polypropylene (PP) composite tape in a structural-composite doorframe support for a storage door on a commercial truck cab. The study involved structural simulation and performance validation loops to optimize ply layup and fiber orientations; a process study that evaluated different layup schedules on fiber movement in the same geometry, a microscopy study to see if and where fibers twisted or broke along the part's length, and a temperature study where thermocouples were inserted into the ply stack to identify the correct processing window for the material to avoid glass breakage due to attempts to mold a cold matrix; and lastly a process-optimization study to help reduce cycle time for preheating/consolidation and molding steps. The result was development of a semiautomated four-step production process that demonstrated the potential of producing structural-composite parts within 60 sec. Process benefits include high levels of design flexibility regarding fiber orientation, allowing engineers to take full advantage of aligned fibers with opportunities to boost performance or reduce mass and thickness. While the part design (based on the incumbent part in stamped steel) was not optimized for composites, the thermoplastic-composite solution offers comparable costs at lower mass than the baseline design.