Process induced stress for woven fabric thick section composite structures

A semi-numerical model was developed to simulate processing induced stress for woven fabric composite material structures. The approach consists three main parts. The first part was the simulation of resin chemical kinetic cu re behavior and micromechanics for cure dependent resin and glass fiber. Th e second was the analytical extension of TEXCAD woven fabric micromechanics model (Naik RA. TEXCAD-Textile Composite Analysis for Design. NASA report 4639, December 1994) to cure dependent textile unit cell model. The last wa s the introducing of the effective unit cell properties to finite element s tructure modeling. Cure dependent material response includes thermoset resi n hardening and volumetric shrinkage during cure. The approach was incremen tally employed whereby the model predicts the composite fabric unit cell ef fective modulus, processing-induced strains and stresses (thermal expansion and chemical shrinkage) during cure. Case studies were presented which ill ustrate the effective modulus and processing stress/strain development duri ng cure for a plain weave S2-glass/vinyl-ester composite laminate. An under standing of the complex relationships between cure, modulus and processing- induced stress/strain development represents a significant step towards opt imizing processing strategies for thick-section woven fabric composite stru ctures. (C) 2000 Elsevier Science Ltd. All rights reserved.