Experimental and numerical study of CFRP laminates after seawater immersion

Abstract

In this paper, the residual strength of carbon fiber reinforced polymer composites (CFRP) for marine applications has been studied. The seawater absorption tests, regular tensile tests, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis of CFRP exposed to seawater at 25 °C, 40 °C and 60 °C respectively were conducted. A hydro-mechanical coupling progressive damage model has also been established to predict the mechanical behavior and damage evolution, considering both hydrothermal- and mechanical load-induced damage. The experimental results show that the seawater immersion significantly affects the transverse mechanical properties, while having little effect on the in-plane shear and longitudinal properties. The microstructural comparative analysis indicates that the accelerated moisture absorption, induced by high immersion temperature, increases salt deposition and weakens the adhesion between fiber and matrix. The finite element analysis (FEA) results shows good fidelity, with relative errors not exceeding ±10 % in predicting residual strength. Seawater immersion significantly accelerates matrix tensile damage, increasing its area, but has minimal effect on fiber tensile damage. This model can assist engineers in predicting the durability of composite load-bearing structures in marine environment.