Service life modelling of fibre composites: A unified approach

A model for simulated ageing of glass-fibre reinforced composites is presented, based on the micro-mechanics of the primary strength loss process i.e. fibre degradation. The model fitted extant data in the literature for both polymer- and cement-matrix composites well, with correlation coefficients > 0.95 in all cases, and suggests that for most systems, a diffusion-based approach is most useful. There is some evidence that applied strain alters the fundamental ageing process, with a threshold between 30 and 45% of ultimate strain. The activation energy for degradation ranged from 41 to 118 kJ/mol; there is some evidence that a value of 90-100 kJ/mol is probably the true value, correlating well with studies on aqueous glass degradation. However, bulk water ingress into the samples was fundamentally not correlated with the strength loss process and it is suggested that a more advanced analysis OH- ion transport in glass-fibre composites is required. Half-lives of ~20 and ~80 years were predicted for cement- and polymer-matrix composites respectively at service lives of 20°C.

Publication year:2008

Keywords:Durability, GRP, GRC, modelling