Hygrothermal effects on ballistic behavior of toughened CFRP laminates

Abstract

High-speed impact resistance is a critical consideration in the design and assessment of composites for aerospace applications during their service life, especially in the context of hygrothermal aging. This study, combining experiment and numerical simulation, investigates hygrothermal effects on the high-speed impact performance of a toughened T700/EH301 carbon/epoxy composite material. Three distinct hygrothermal conditions, namely Unaged, Aged, and Redried, are investigated. Experimental results reveal an apparent improvement in ballistic limit after hygrothermal aging (170.2 m/s, a notable increase of 11.2%), still maintaining an excellent performance even after redrying (158.5 m/s, an increase of 3.2%). Inspired by the micrographic analysis, a high-fidelity finite element model, referred to as HFEDCM (High Fidelity Explicit Discrete Crack Model), has been developed. This model not only explains the positive effects of hygrothermal aging on high-speed impact performance but also accurately captures the macroscopic damage morphology of composite laminates. It has been quantitatively and qualitatively demonstrated that the enhancement of the fracture toughness of the “fiber bundle” plays a critical role in improving the high-speed impact resistance of composites under hygrothermal aging.