Multiscale Process Modeling of a Carbon Fiber/Epoxy Composite for Predicting Residual Stress and Strength

During the manufacturing of composite structures, cure shrinkage of the thermoset matrix and differential thermal contraction mismatch between the matrix and fiber reinforcement cause the formation of residual stresses, which can result in a loss in structural durability. New multiscale computational process modeling is essential for linking material chemistry, processing parameters, residual stress evolution, and optimizing mechanical performance. This study establishes a new multiscale process modeling method to accurately predict residual stresses in a unidirectional carbon fiber/epoxy composite using molecular dynamics and finite element analysis simulation techniques. The results of this work demonstrate that process-induced residual stresses have a significant impact on the composite strength in transverse tension, out-of-plane shear, and in-plane shear, with a maximum reduction in strength of 35%. Moving forward, this method can be used as a design and optimization tool for future composite structures for specific engineering applications and can provide processing parameters that can maximize desirable composite properties and/or minimize composite manufacturing energy and cost.