Crashworthiness and Impact Energy Absorption Study Considering the CF/PA Commingled Composite Processing Optimization
The processing of the thermoplastic composites can cause matrix thermo-oxidative degradation. Understanding the level of thermo-oxidative degradation, as well as the thresholds of temperature and processing time, allows the manufacture of high performance composites with higher crashworthiness. This study evaluated the matrix thermo-oxidative degradation by Friedman's isoconversional kinetic model to a carbon fiber/polyamide (CF/PA) commingled fabric. In addition, the CF/PA commingled composite was manufactured by consolidation under pressure at 240°C, 250°C, 260°C, 270°C and 280°C to observe the influence of the matrix thermo-oxidative degradation on its energy absorption capacity. Impact test and compression after impact (CAI) determined the energy absorbed by the CF/PA commingled composite at different processing temperatures. The results demonstrated that the matrix thermo-oxidative degradation affected the energy absorption capacity of the CF/PA composite when the processing temperature exceeded 260°C, which is in accordance with the prediction of the degradation study. Therefore, the optimal processing cycle occurs at 260°C for 20min. When it processed in temperatures above 260°C, the CF/PA commingled composite reduces in 0.14J/°C the energy absorption ability due to the matrix degradation in high temperatures, leading to a considerable reduction on crashworthiness and its performance.