Modelling of environmentally induced damage in polymer matrix composites

摘要

An investigation has been performed into the behavior of composite laminates exposed to severe environmental conditions. Given material properties, laminate geometry and specified cyclical thermal and moisture environments, a model predicts absorbed moisture, chemical degradation, and stresses in the laminate as functions of position and time. A simplified solution allows very efficient calculations for large numbers of complex thermal and moisture cycles. Cases relevant to the proposed High Speed Civil Transport show two types of moisture absorption behavior: rapid fluctuation of levels near the surface, and gradual settling to an easily computed equilibrium value in the interior. Chemical degradation is (based on preliminary, parametric calculations) shown to be a concern for surface plies. Stress levels due to these effects will enhance damage in surface plies. Stress effects do not fully account for observed moisture induced damage, suggesting material property changes or enhanced cracking mechanisms.