| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Ceramic Matrix Composites
|
| Presentation Title |
Subcritical Crack Growth during Static Fatigue of Hi-Nicalon-S SiC Fiber |
| Author(s) |
Randall S. Hay, Marina Ruggles-Wrenn |
| On-Site Speaker (Planned) |
Randall S. Hay |
| Abstract Scope |
Three subcritical crack growth (SCG) laws were used to model sequential filament failure and ultimately tow failure during static fatigue of Hi-NicalonTM-S SiC fiber tows in air and steam. Model parameters were updated to fit tow failure times and steady-state strain rates for brittle creep previously measured at 700 to 1100°C to new data at 500 and 600°C under initial applied stresses up to 1350 MPa. The stress increase on intact filaments as others fractured and as filaments oxidized, and the increase in stress intensity geometric factors as crack size increased were incorporated in the models. The stress dependence of SCG rates and activation energies are determined. The fits to data for different models and model validity are discussed. The change in filament strength distributions after SCG are determined, possible effects of residual stress are calculated, and SCG mechanisms are discussed. |