Crashworthiness and Impact Energy Absorption Study Considering the CF/PA Commingled Composite Processing Optimization

Abstract

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.

New Advances in Thermoplastic Commingled Composites: Processing and Molecular Dynamics

“…resulting in a time/temperature graph, considering the time and temperature required to provide the softening range of the thermoplastic matrix without reaching its degrees of temperature onset damage degradation [7]. Thermal degradation must be considered when processing thermoplastic composites.…”

“…Figure 4: DSC thermal cycles of thermoplastic polymer to reveal endothermic and exothermicpeaks associated to melting point and crystallization (adapted from[7]). …”

Experimental investigation of the crush performance of prepreg platelet molding compound tubes

“…22 However, the SEA is not solely dependent upon the material system. Studies have shown that choices regarding processing conditions, [33][34][35][36] test geometry, 28,37,38 and testing parameters also impact the SEA. For instance, circular cross sections absorb more energy than square and rectangular shapes for the same material.…”