Residual Cure Stress Buildup in Thermosetting Composite: Modeling and Experimental Validation

Abstract

The evolution of resin properties was measured using differential scanning calorimetry for cure rate characterization, digital image correlation for measuring coefficients of chemical shrinkage and thermal expansion and dynamic mechanical analysis for storage modulus. These experiments provided necessary information for deriving homogenized composite properties during the cure cycle, which were implemented into a thermo-mechanical constitutive model of the composite using finite elements. To observe residual stress development in the thermosetting composite, a bi-lamina strip configuration that consisted of [0/904] laminate stacking sequence was used. The proposed experimental procedure allowed separating the contribution of the chemical and thermal shrinkage to the constrained deformation inside of the composite. Modeling of bi-lamina strip during the cure cycle predicted the evolution of the deflection profiles of the sample during cure, which agreed closely with the experimentally observed deflection profiles.