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Environmental effects on graphite-epoxy fatigue properties
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Sumsion, H. T. |
| Copyright Year | 1976 |
| Description | Effects of torsional and flexural fatigue on the long-time Integrity of advanced graphite-epoxy structural composites have been investigated. Torsional fatigue tests were run at stress ratios of R = 0 (zero to maximum, repeated) and R = -1 (zero mean stress) on unidirectional, angleply, and woven graphite fiber materials in air and water at room temperature and at 74 C. Flexural fatigue tests (four-point bending) with R = -1 were run in air and water at room temperature, and with R = 0 in air. Results show that, in torsional cycling, both water environment and higher test temperature contribute to significant degradation of torsional stiffness. The degradation of stiffness from torsional stress cycling was observed to be much greater with R = -1 than with simple R = 0 cycling. The effect of environment also is greater in the fully reversed cycling. Flexural fatigue results on +/- 30 deg material show a large fatigue effect, with fatigue limits of less than 50% and 30% of the static failure strength for specimens tested under stress ratios of R = 0 and R = -1, respectively. Compliance measurements indicate that the final failures are preceded by damage initiation and accumulation, which begins at about 1% of the specimen life. |
| File Size | 653834 |
| Page Count | 12 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19980211610 |
| Archival Resource Key | ark:/13960/t90912913 |
| Language | English |
| Publisher Date | 1976-03-01 |
| Access Restriction | Open |
| Subject Keyword | Inorganic And Physical Chemistry Cycles Torsional Stress Environmental Tests Water Temperature Stress Ratio Degradation Fatigue Tests Composite Materials Bending Fatigue Environment Effects Graphite-epoxy Composites Stiffness Composite Structures Room Temperature Crack Initiation Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
