Stretch Forming Studies on Thermoplastic Composite

Thermoplastic composites have the potential to reduce the weight of automobiles significantly. The use of thermoplastic composites is currently not widespread in automotive applications due to the lack of understanding of mass production of these materials. Currently stamp forming is used for mass production in the automotive industry. To date, many composite forming studies have centred around the draw forming of fabrics, with little consultation of the extensive body of knowledge on sheet metal forming. In this work, stretch forming behaviour of a pre-consolidated self-reinforced polypropylene composite (Curv) was carried out to elucidate the forming behaviour. This was accomplished by stamp forming blanks of varying geometry in a customised press that utilised a lock ring to enforce stretch forming conditions. The experimental results were used to generate a Forming Limit Diagram (FLD) for Curv at room temperature. It was determined that Curv exhibits a considerably different forming behaviour to metals, and it was observed that there was a shift of the FLD into the positive minor strain region, suggesting that Curv can sustain larger minor strains for a given major strain than the metals used in comparison. Accordingly, Curv exhibits superior formability to Aluminium, facilitating the manufacture of more complex and intricate parts.