Influence of Seawater Ageing on Fracture of Carbon Fiber Reinforced Epoxy Composites for Ocean Engineering

Abstract

Carbon fiber reinforced composite materials are finding new applications in highly loaded marine structures such as tidal turbine blades and marine propellers. Such applications require long-term damage resistance while being subjected to continuous seawater immersion. However, few data exist on which to base material selection and design. This paper provides a set of results from interlaminar fracture tests on specimens before and after seawater ageing. The focus is on delamination as this is the main failure mechanism for laminated composites under out-of-plane loading. Results show that there are two contributions to changes in fracture toughness during an accelerated wet ageing program: effects due to water and effects due to physical ageing. These are identified and it is shown that this composite retains over 70% of its initial fracture properties even for the worst case examined.

Effect of Seawater Ageing on Fracture Toughness of Stitched Glass Fiber/Epoxy Laminates for Marine Applications

“…Composite materials have a wide range of applications in various manufacturing industries such as marine, aerospace and automotive, due to their high toughness chemical resistance and light weight [1][2][3][4][5]. Boat hulls, sonar domes, marine building, the waterfront barriers, the offshore structures, propellers and hatch covers are some of the marine applications of composites [6][7][8]. The exposure of composite materials to seawater for prolonged periods affects the materials' strength and interphase region [9].…”

“…E José-Trujillo et al [18] noted delamination, fibers de-bonding and resin crumbling in the composite due to seawater ageing. Similarly, a detailed overview of the effect of mechanical properties of various type of composite materials, such as carbon fiber-reinforced epoxies and polyetheretherketone (PEEK) composites, was presented by Guen-Geffroy et al [6]. However, there is limited literature on the use of composite material in the marine application in general and the effect of water absorption on delamination in particular, especially for short-term immersion.…”

“…Different experimental methods, i.e., Mode I, Mode II and end-loaded split (ELS), are established in the literature to measure fracture toughness in composite laminates [6]. The Mode I test method was considered as simplest of all and was used extensively by most researchers [12,13,26,27].…”

Influence of Embedded Gap and Overlap Fiber Placement Defects on Interlaminar Properties of High Performance Composites

“…This is a powerful method to enable the interaction of local singularities with a propagating crack to be characterized, and fracture mechanics values are being increasingly integrated in design in order to evaluate damage tolerance. A recent paper describes these tests [ 25 ].…”

“…This is a powerful method to enable the interaction of local singularities with a propagating crack to be characterized, and fracture mechanics values are being increasingly integrated in design in order to evaluate damage tolerance. A recent paper describes these tests [25]. This paper will examine the influence of singularities deliberately introduced at the mid plane of [90/0 7 /90] S laminates on the out-of-plane fracture properties of the same carbon/epoxy composites as those previously studied under in-plane loading [17,18].…”