Evaluation of a concept out-of-autoclave process for manufacturing carbon fibre reinforced polymer automotive parts

To comply with increasingly stringent exhaust-emission- and fuel-consumption-legislation imposed on internal-combustion-engine-powered vehicles; and to realise the widespread deployment of electric vehicles hindered by heavy energy storage systems, lightweight construction achieved through application of fibre reinforced polymers, most notably Carbon Fibre Reinforced Polymer, to the mass-produced automotive architecture has been predicted to increase in the coming years. However, this is difficult to envisage by the time-, labour-, energy- and waste-intensive part-manufacturing processes of present, including autoclave-processing and Out-of-Autoclave processes such as Resin Transfer Moulding. In this paper, an innovative concept Out-of-Autoclave process, based on the Prepreg Compression Moulding process, in which hot forming and curing of reinforced thermoset composite prepreg are integrated in one step, previously demonstrated to offer potential for reduced cycle-time, lead-time and financial cost; and greater environmental sustainability compared to current processes, was evaluated for manufacturing Carbon Fibre Reinforced Polymer automotive parts. Formability, springback, geometric accuracy and mechanical properties of parts were determined by macroscopic observation, scanning electron microscopy, flexural testing, tensile testing and fatigue testing. Springback-free parts exhibiting mechanical properties within approximately 80 % of benchmark autoclave-produced parts were produced. Compressive crash-box testing was then conducted across strain-rates of 0.02, 0.20 and 2.00 s-1, with crushed-length, specific energy-absorption and crush-force-efficiency superior to autoclave-produced parts. The concept process thus demonstrated a significant step towards realising the application of Carbon Fibre Reinforced Polymer to the mass-produced automotive architecture and to an array of applications including tensile and flexural strength-critical safety-cell body-parts, impact-energy-absorptive-critical crumple-zone body-parts and fatigue-critical suspension-parts.