Non-linear creep modelling of single-fibre model composites

This paper describes a method for determining the stress/strain fields in a single-fibre model composite subjected to creep loading conditions. The method is based upon Eshelbyʹs thought experiment and the integration of interfacial tractions. The non-linear viscoelastic behaviour is modelled through an incremental stress/strain formulation based on the Schapery model. Comparisons have been made between the predictions from the model, a non-linear finite-element model, and experimental fibre strains measured by micro-Raman spectroscopy and good qualitative agreement is observed. The nature of the interfacial tractions controls the form of the interfacial shear stress which govern the shape of the longitudinal fibre stress profile. As a consequence the rates at which the strain is building up in the fibre are different when comparing calculations and experiments. However, the characteristics of the experiments are reflected in the theoretical predictions. Generally, it is seen that the initial residual stress in the fibre is restricting the level of the fibre strain during subsequent creep loading and can be beneficial in delaying tensile fibre fractures.