| Autor: |
Luis J. Sanchez, Robert E. Taylor, David T. Rusk, Bruce A. Pregger |
| Rok vydání: |
2020 |
| Předmět: |
|
| Zdroj: |
Journal of the American Helicopter Society. 65:1-7 |
| ISSN: |
2161-6027 |
| DOI: |
10.4050/jahs.65.012008 |
| Popis: |
A program has recently concluded that generated fatigue test data for the influence of a rotorcraft main rotor blade root bending spectrum (Helix) on the crack nucleation mechanisms in 7075-T651 aluminum. High-frequency tests were performed that generated spectrum fatigue failures out to nearly 109 cycles. Fractographic examination showed a distinct change in crack nucleation from slip initiated to inclusion-initiated cracking as the spectrum peak stress level was increased. Spectrum life predictions were made using three different baseline constant-amplitude S-N curves, one using a traditional rotorcraft original equipment manufacturer fitting methodology, one using the high-cycle fatigue (HCF) portion of a strainlife curve, and one that was fitted to S-N data with test lives out to 3×108 cycles. The spectrum life prediction using the S-N curve that properly modeled material behavior in the very high cycle fatigue regime provided a good correlation to the spectrum fatigue test data. Predictions using the other S-N curves were highly conservative. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
