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, was fitted to extant data in the literature for both polymer- and cement-matrix composites. Correlation coefficients of >0.95 were obtained in all cases. Derived parameters suggest that for a diffusion-based approach is most useful. Applied strain apparently alters the fundamental ageing process. The activation energy for the ageing process ranged from 41 to 118 kJ/mol; there is some evidence that 90–100 kJ/mol is probably the true value, correlating with studies on aqueous glass degradation. Bulk water ingress into the samples was fundamentally not correlated with the strength loss process. A more advanced analysis of OH− ion transport in glass fibre composites is required to clarify the mechanism. Half-lives of ∼20 and ∼80 years were predicted for cement- and polymer-matrix composites, respectively, at service lives of 20 °C.