Residual stress development during laminate processing

A one-dimensional finite difference model has been developed to simulate the progression of material properties during the processing of metal-clad, multi-layered, fiber mat reinforced, thermoset resins. Using a micro-mechanical model, the simulation is capable of predicting the dimensional movement during processing as well as the through-thickness residual stress distribution within thin laminates that will lead to warpage or curling. It has been found that the dominant factor that leads to warpage in asymmetric laminates is the difference in the coefficient of thermal expansion, CTE, of the individual plies. Thus, by selecting appropriate combinations of the degree of cure and resin content of the thermoset in the plies, it is possible to reduce the dimensional movement.