Flexural Investigation of Woven Composites with Sea Water Exposure

Abstract

Naval structures tend to be exposed to hazardous environments and extreme temperatures. Composite materials have encompassed a large percentage in the manufacturing process of the same, appealing to a new focus in naval material research. In this paper, the adverse effects of sea water and arctic temperatures on carbon fiber composite laminates were studied in the form of moisture uptake, flexural moduli impact, strength impact, and structural damage. Moreover, an effort was made to calculate diffusion coefficients accounting for anisotropy within the composite laminate. Diffusivities were 6.25E-6 􀯠􀯠 􀯦 for in-plane Dx=Dy, 1.44E-6 􀯠􀯠 􀯦 for transverse Dz, and an effective coefficient D of 1.81E-6 􀯠􀯠 􀯦 . Flexural testing showed a strong decline in material strength with a 19.45% reduction, while the flexural moduli displayed a fluctuating behavior in the form of linear equation y = -0.0011x3 + 0.0579x2 - 0.7933x + 42.289 throughout the experiments. Scanning electron microscopy was implemented for comparison between the microstructure of dry and wet composite samples; images showed a smoother, saturated surface for the wet samples compared to the rougher, dented surface of the dry samples.