Effects of Thermo-Mechanical Properties of Composites on Viscosity, Temperature and Degree of Cure in Thick Thermosetting Composite Laminates during Curing Process

Abstract

In the present study, the effects of thermo-mechanical properties of composites on viscosity, temperature and degree of cure in thick laminated composites have been investigated. Thermal properties such as the density, specific heat and thermal conductivity are taken to be both temperature and degree of cure dependent. The internal heat generation term is expressed as a function of the cure rate. A non-linear transient heat transfer finite element model is employed to simulate the curing process. Hercules AS4/3501-6 graphite/epoxy composites are considered. The results show that temperature and degree of cure calculations are significantly influenced by the values of thermal conductivities when thickness of laminates increase. The present study indicates that it is necessary to appropriately measure thermal properties in order to accurately predict temperature, viscosity, and degree of cure in thick composites. The effects of fiber volume fraction ratios and bagging materials are also studied. Increasing fiber volume fraction ratios decreases the maximum temperature at the center of laminates. It is also seen that the difference of viscosity values between inside and outside of the laminate increases remarkably as the thickness increases.