Journal
EXPERIMENTAL MECHANICS
Volume 58, Issue 1, Pages 111-123Publisher
SPRINGER
DOI: 10.1007/s11340-017-0335-6
Keywords
Carbon fibers; Polymer-matrix composites; Interfacial strength; Environmental degradation; Cohesive shear traction separation law; Finite element analysis
Categories
Funding
- AFOSR [FA9550-14-1-0227]
- FA9550-14-1-0227 [ECCS-1307997, CMMI-1636306]
Ask authors/readers for more resources
Fiber push-in nanoindentation is conducted on a unidirectional carbon fiber reinforced bismaleimide resin composite (IM7/BMI) after thermal oxidation to determine the interfacial shear strength. A unidirectional IM7/BMI laminated plate is isothermally oxidized under various conditions: in air for 2 months at 195 A degrees C and 245 A degrees C, and immersed in water for 2 years at room temperature to reach a moisture-saturated state. The water-immersed specimens are subsequently placed in a preheated environment at 260 A degrees C to receive sudden heating, or are gradually heated at a rate of approximately 6 A degrees C/min. A flat punch tip of 3 mu m in diameter is used to push the fiber into the matrix while the resulting load-displacement data is recorded. From the load-displacement data, the interfacial shear strength is determined using a shear-lag model, which is verified by finite element method simulations. It is found that thermal oxidation at 245 A degrees C in air leads to a significant reduction in interfacial shear strength of the IM7/BMI unidirectional composite, while thermal oxidation at 195 A degrees C and moisture concentration have a negligible effect on the interfacial shear strength. For moisture-saturated specimens under a slow heating rate, there is no detectable reduction in the interfacial shear strength. In contrast, the moisture-saturated specimens under sudden heating show a significant reduction in interfacial shear strength. Scanning electron micrographs of IM7/BMI composite reveal that both thermal oxidation at 245 A degrees C in air and sudden heating induced microcracks and debonding along the fiber/matrix interface, thereby weakening the interface, which is the origin of failure mechanism.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available