Flexural Fatigue Life of Woven Carbon/Vinyl Ester Composites under Sea Water Saturation

TL;DR

This study investigates how sea water saturation affects the fatigue life of woven carbon/vinyl ester composites, revealing significant reductions at higher strains and proposing a non-linear predictive model for their low cycle fatigue life.

Contribution

It introduces a non-linear model to predict fatigue life of composites in dry and sea water saturated conditions, considering damage modes and strain effects.

Findings

Sea water saturation significantly reduces fatigue life at high strains.

Damage modes during fatigue are identified and characterized.

A non-linear model accurately predicts low cycle fatigue life.

Abstract

The adverse effects of sea water environment on the fatigue life of woven carbon fiber/vinyl ester composites are established at room temperature in view of long-term survivability of offshore structures. It is observed that the influence of sea water saturation on the fatigue life is more pronounced when the maximum cyclic displacement approaches maximum quasi-static deflection, that is, the reduction in the number of cycles to failure are comparable between dry and sea water saturated samples at lower strain ranges (~37% at 0.46% strain), but are drastically different at higher strain ranges (~90% at 0.62% strain). Key damage modes that manifest during the fatigue loading is also identified, and a non-linear model is established for predicting low cycle fatigue life of these composites in dry and sea water saturated conditions.