To design the cure process of thick composite parts: experimental and numerical results

The cure degree must be as uniform as possible during the manufacture of polymer matrix composite components in order to have a product without defects. For thick composite components, this condition is not often respected; in fact, the cure degree trend between the core and the external surface is different causing structural and geometrical/dimensional unconformities. In most cases, these problems can be solved through a redesign of cure process in terms of thermal cycle, in fact that one recommended by furnisher is usually suitable for thin components. The optimization of cure thermal cycle should include several performance criteria for the production system such as the targeted cure degree, the targeted maximum temperature of the part and the duration of the cure cycle, as well as the production system limitations such as the maximum allowable heating rate, the maximum allowable cooling rate and so on. A previous work shows a method to optimize the cure degree of a thick composite component. The present work presents an indirect way to validate the proposed method: some experimental tests have been carried out by implementing the cure cycle identified by this method, the values of temperatures have been recorded by thermocouples and the obtained temperature trend has been compared with that due to numerical approach. Further considerations on the cure degree and the cure rate have been deduced. The experimental results show a good agreement with the numerical ones.