Effect of multiple impacts on GFRP laminates exposed to hydrolytic ageing using acoustic emission monitoring

In this study, pristine, single impacted and double impacted GFRP specimens were subjected to ageing by immersion in seawater at ambient temperature for different periods of time. The dominating failure mode of the aged specimens was found using acoustic emission monitoring. The water absorption capacity and flexural strength of specimen subjected to ageing were assessed to study the trend of variation. A reduction in residual strength was observed between single and double impacted specimens. Stress cycle plots from AE monitoring indicate that the onset of failure occurs sooner as the ageing time progresses. From those of impacted specimens, it can be seen that the onset of failure and damage initiation occurs sooner in double-impacted specimens than in single-impacted counterparts. Parametric peak frequency analysis shows that fiber-matrix debonding was the predominant mode of failure.