Designing curing conditions in order to analyse the influence of process-induced stresses upon some mechanical properties of carbon / epoxy laminates at constant T\textlessSubscript\textgreaterg\textless/Subscript\textgreater and degree of cure
Résumé
In the aim to study of the effects of process-induced stresses upon some mechanical properties of simple stacking sequence composite laminates, three different cure cycles were designed. This was achieved on the basis of a cure kinetics modelling. A minimum number of curing parameters were modified in order to restrain changes in material physical properties. Those latter were determined from the molecular network of the thermosetting matrix to the fibres volume fraction and thermal expansion of the laminated plates. The level of process-induced stresses generated by the three cure cycles was assessed by measuring the out-of-plane deflection on unsymmetrical laminated strips. Manufactured laminates were submitted to a set of tensile tests in order to determine the changes in their mechanical properties due to the different curing conditions. All the mechanical tests were followed by acoustic emission. This has enabled to distinguish the occurrence of the various damaging processes with respect to curing conditions and therefore process-induced stresses. Lastly, process-induced stresses on a micromechanical level were theoretically determined. This determination has enabled a first analysis of the effects of process-induced stresses upon mechanical properties to be settled.