Identification of thermal and rheological properties of an aeronautic epoxy resin-simulation of residual stresses

An extensive material study of an aeronautic epoxy resin from commercial prepregs is reported in this article. The kinetics of the chemical reaction and the heat capacity are characterized by differential scanning calorimetry (DSC). The thermal conductivity, the thermal expansion coefficient, crosslinking heat flux and associated degree of cure, the volumetric shrinkage, the effective chemical shrinkage coefficient have been identified using a specific mold (named PVTα mold). Dynamic mechanical measurements are used to determine the rheological properties. The gel times at different curing temperatures are estimated. The degree of polymerization at the gel point is found to be independent of temperature. Finally, the residual stresses in a composite part are calculated using a finite element simulation and taking into account the evolution of the material properties, the temperature and degree of cure gradients during the curing process.