THE INFLUENCE OF THE VARIATION OF THE COEFFICIENT OF THERMAL-EXPANSION WITH TEMPERATURE ON THE MICROCRACKING BEHAVIOR OF K3B IM7 AND X5260/G40-800 COMPOSITES/

The effects of the coefficients of thermal expansion (CTE) of K3B/IM7 and X5260/G40-800 cross-ply laminates on matrix cracking are investiga ted. The composite CTEs are measured in the temperature range -50 degr ees C to 175 degrees C. Based on this measured CTE as a function of te mperature, the thermal residual stresses and energy release rates at t he crack tip are calculated using the finite element method and compar ed to those results computed under the assumption of a constant CTE va lue. The residual stresses in the laminates will have the potential to reduce the mechanical properties of the composites. This paper clarif ies the thermal energy release rate change in a temperature range and predicts the critical applied matrix cracking load of the laminates. ( C) 1998 Published by Elsevier Science Limited. All rights reserved.