Analysis of Forming Parts from Advanced Thermoplastic Composite Sheet Materials

Thermoforming of advanced thermoplastic composite sheets offers several advantages over traditional processing of these materials, such as tape laying However, some important processing issues have to be resolved before this can become a viable economical process. These include fiber placement control, low cycle times for molding and wrinkle-free complex shape forming. Some of the work that has been reported in the literature so far is reviewed. The major processing considerations that have to be dealt with in going from the design to the thermoforming of a part are discussed. In particular, emphasis is placed on the different processing techniques such as matched-metal forming, hydroforming and diaphragm forming (superplastic aluminum and polymeric) and on material forms such as woven fabrics, angle-plied unidirectional tapes and the newly developed ordered staple formable sheet based on aligned discontinuous fibers. The forming of several shapes using these techniques is presented to illustrate the potential of advanced composite thermoforming and possible limitations. Some rules of thumb are also offered to reduce the trial-and-error approach currently faced by persons new to the field.