Service life modelling of fibre composites: A unified approach

A model for simulated ageing of glass fibre reinforced composites is presented, based on the micromechanics 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.