Impact resistance and damage tolerance of resin‐infused thermoplastic noncrimp e‐glass fabric composites under marine environment

Abstract This article presents the effect of seawater aging on the impact response and damage tolerance of resin‐infused thermoplastic fiber‐reinforced composites (FRCs). The thermoplastic composites were immersed in seawater at two different aging conditions (i.e., 35 and 70°C) until their saturation state. The aged and unaged samples were tested under low‐velocity impact (LVI) at three impact energies (30, 60, and 90 J), followed by the compression after impact (CAI) test to evaluate the degradation in the damage tolerance. The LVI test revealed that increasing the moisture content, the peak force and displacement increased up to 28% and 31%, respectively, indicating higher load‐bearing capacity of thermoplastic composites under aged conditions. This increase in peak force and displacement of FRCs is attributed to the plasticization effect in the thermoplastic matrix due to the hygrothermal environment. Furthermore, the unaged samples showed barely visible impact damage at lower impact energy, while under aged conditions, fiber–matrix interface debonding, fiber breakage, and fiber pullout are the prominent failure mechanisms. The CAI response of thermoplastic composites exhibits up to 45% increase in compressive strength with increasing moisture content. This increase in damage tolerance is attributed to matrix plasticization and swelling caused by hygrothermal aging. The superior impact performance and damage tolerance of thermoplastic composites in hygrothermal conditions indicate their suitability for applications requiring higher bearing strength. Highlights Effect of accelerated aging on impact resistance and damage tolerance of FRC. An increase in moisture content leads to an increase in peak force up to 28%. Hygrothermal aging increases the CAI strength by up to 45%. Plasticization and matrix swelling are dominant damage modes in NCF composite.