STRESS-TIME-TEMPERATURE-HUMIDITY EFFECTS ON DELAMINATION OF GRAPHITE EPOXY LAMINATES

The effect of sustained load and hygrothermal environments on Mode I delamination behavior of T300/934 unidirectional graphite/epoxy laminates has been studied. Several double cantilever beam specimens were subjected to constant load in presence of various hygrothermal conditions either for short duration (a few minutes to a few hours) or for long duration (several months). The pre-loaded specimens were then tested to determine delamination behavior. It is indicated that the crack growth does not occur as a result of exposure to load and environment. On the contrary, an increase in fracture toughness around the crack tip is observed for pre-loaded specimens and the increase is seen to depend on exposure duration and environment.