Design criteria of thermoplastic composite parts using the thermoforming process.

摘要

The application of thermoplastic composite, TPC, materials has made a steady advance since the 1980's with most applications in the automotive and aerospace industries. The advantages afforded by these laminations include the combination of property specific materials such as low weight-high strength and modulus, high impact and abrasion resistance, high chemical resistance and have the advantages of being recyclable, with economical cycle times, and process in an environmentally friendly clean, dry process when compared to comparable thermosets. In this research, a commercially available woven material, with commingled thermoplastic polypropylene and E-glass fibers, was formed as layered composites with various polymer sheets as surface plies, and fused by the thermoforming process.;To evaluate the specimens produced and the variation in structural integrity between them, investigations were made into compatibility of materials for cohesion and adhesion. Various test methods and standards were reviewed and the T-peel test was selected to quantify the quality of the bonds.;To predict forming behavior both analytical and numerical methods were investigated. Classical mathematical analysis based on geometry, mass balance, and material properties at process temperatures were used to develop a simple program to predict cavity forming percentage and thickness. Forming percentage, results varied from physical specimens by less than five percent. Thickness, on the other hand, proved less predictable. To generate improved predictions numerical simulations were used. Two commercially available finite element analysis programs were reviewed in terms of performance and accuracy. The benefits of a full three dimensional simulation was clearly apparent, showing thin areas, stress concentrations, webbing and folds. As with numerical methods, thickness results proved less reliable. Advantages and shortcomings were highlighted, as well as suggestions for improvements.