Abstract: Large-tow carbon fiber reinforced plastics (CFRP) hold significant promise for various applications, attributed to their exceptional cost-effectiveness and exceptional performance. This study delves into the impact of hygrothermal environments on the tensile and compressive capabilities of plain-woven large-tow CFRP, accompanied by an in-depth analysis of its damage patterns and failure mechanisms. Utilizing 48K plain-woven large-tow carbon fiber prepregs, two types of laminates, namely [0]₄ and [45/0/-45/90]_S, were crafted. These laminates were subjected to tensile and compressive tests after being exposed to room-temperature dry and elevated temperature wet conditions for 14 days. The findings reveal a substantial decline in the compressive properties of large-tow CFRP following hygrothermal treatment. Scanning electron microscopy (SEM) was utilized to scrutinize the fracture morphologies. A dual-perspective analysis, encompassing both macroscopic and microscopic viewpoints, was conducted to elucidate the failure modes and mechanisms of the material. It was observed that the degradation of the resin matrix after hygrothermal treatment weakened both the fiber-matrix interface and the orthogonal woven interface, ultimately altering the failure modes of large-tow CFRP and compromising its mechanical properties.

Key words: hygrothermal, large tow CFRP, mechanical properties, failure mechanism, composites