A note upon the development of residual curing strains in carbon/epoxy laminates. Study by thermomechanical analysis

This work is directed towards analysing the development of process-induced strains in carbon/epoxy laminates during their curing. To this end, we have developed an original method using a thermomechanical analyser (TMA). This method makes possible the continuous follow-up of any longitudinal displacements. The longitudinal strains of unsymmetrical laminated strips are directly recorded by the thermomechanical analyser probe during their curing. This enables the out-of-plane deflections of unsymmetrical laminate strips to be continuously determined throughout the curing. Beyond this continuous measurement method, several preliminary experiments were carried out to study the changes in mechanical and rheological properties of the material during cure. Furthermore, the chemical shrinkage of the unreinforced polymeric matrix were accurately measured. Combination of the preliminary test results and measurements taken on various laminated strips while they are cured allows us to analyse the development process of residual strains and therefore stresses.