Crushing of carbon-fiber reinforced thermoplastic energy absorbers under axial impact: numerical modelling and experimental tests

Abstract

[Abstract] Thermoplastic composite materials are increasingly considered for aerospace applications due to their recyclability and ease of processing compared to traditional thermoset composites. However, a thorough understanding of their dynamic behavior is essential to fully exploit these benefits in structures subjected to impact loads. This study presents a numerical and experimental investigation aimed at assessing the impact behavior, energy absorption characteristics, and failure modes of thermoplastic composite energy absorbers subjected to axial impact loads. The energy absorbers consist of thin-walled cylinders manufactured from woven polyphenylene sulfide carbon composite. Finite element analyses are conducted to predict the structural response of the tubes under impact loading conditions. To validate the numerical predictions, two specimens are fabricated and subjected to impact tests. The experimental results reveal a progressive failure mode characterized by brittle fracture and delamination of the composite fabric. Comparative analyses between numerical predictions and experimental results demonstrate good agreement regarding structural behavior. Specific energy absorption values of up to 45 kJ/kg are achieved by the thermoplastic composite energy absorbers, indicative of their satisfactory crashworthiness performance under impact loading conditions. In addition, the results are compared with four quasi-static tests conducted in a previous study to investigate the influence of strain rate. Compared to quasi-static conditions, the composite tubes tested under dynamic conditions exhibit an average force about 60% lower. This suggest that the energy absorption capabilities of the material are dependent on the strain rate.