Durability Analysis of Polymer Matrix Composites: 1978–2003 — Results and Needs

Polymer matrix composites exhibit some local and global time dependent behaviour due to the viscoelastic nature of the matrix in interaction with the elastic nature of the reinforcement. As usual this viscoelastic behaviour is also influenced by the environmental conditions: especially temperature changes and moisture uptake and diffusion. Internal transformations in the polymer matrix, known as physical and/or chemical ageing have also to be taken into account. For reliable applications of polymer matrix composites in structural components it is necessary to have a prediction of the stiffness and strength evolutions function of time, environmental changes and a complex loading history. The analysis of the stress-strain relations allows us to obtain the stiffness evolution. For the strength evolution we can use a limit criterion with time and environmental dependent characteristics, but it is also possible to predict damage initiation and development related to the loading history. After an overview of different methods we introduce a nonlinear viscoelastic-viscoplastic model for stiffness prediction under quasi static loading conditions with corrections for interactions between different loading modes. Finally we will discuss the prediction of the strength evolution and we suggest a follow-up of the damage development by a full field optical method able to observe the heterogeneisation and localisation of the strain field. Predictions of stiffness and strength evolutions give us the basis of a complete durability analysis for those polymer matrix composite based structural components.