In order to design the most efficient flywheel energy systems using fiber-reinforced polymer composite rotors, design allowables for the rotor material in a realistic environment and under realistic stresses must first be established. As a first step, this investigation characterizes the 0-deg tensile behavior of unidirectional T700 carbon and E-glass reinforced epoxy composites both as received and after conditioning at a pressure of 15 mtorr and a temperature of 20 to 25C. Constant-amplitude tension-tension cyclic fatigue tests were carried out on half the specimens in a similar medium vacuum environment. Weights of specimens were tracked with immeasurable changes noted due to vacuum conditioning for up to 300 days' duration. E-glass/epoxy specimens had a higher quasi-static strength following conditioning, but this difference was not evident on an absolute stress basis in the fatigue tests. At the baseline comparison point of 105 cycles to failure, there was little difference in fatigue strength of as-received and conditioned E-glass/epoxy specimens. In the case of T700/epoxy, little difference between conditionings was noted in quasi-static tests, but as-received specimens had slightly higher fatigue strength at a lifetime of 105 cycles. Microscopic inspection of fracture surfaces following quasi-static and fatigue failures revealed no significant differences due to the type of loading or conditioning.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Polymers and Plastics
- Materials Chemistry