A closure model for predicting crack growth under creep-fatigue loading
- Univ. of Idaho, Moscow, ID (United States). Mechanical Engineering Dept.
A strip-yield model was formulated here to simulate creep-fatigue crack growth and to quantify the influence of hold time on plasticity-induced crack closure during creep-fatigue crack growth. Creep-fatigue experiments have shown that longer creep hold times result in faster crack growth rates in subsequent fatigue cycles. This model advances the idea that a decrease of plasticity-induced crack closure is experienced by the crack during fatigue loading when a longer hold time is applied each creep-fatigue cycle. Consequently, the crack tip experiences an increase in the effective stress intensity factor range causing faster growth rate during the fatigue loading. The weight function method was used to compute stress intensity factors and surface displacements for cracks embedded in a material experiencing elastic, plastic and creep deformations at elevated temperatures. It is shown that the longer the hold time, the larger the creep deformation and crack opening displacements in the near crack-tip region. In turn, this leads to a decrease in the crack-tip opening stress/load and faster crack growth rates during the subsequent fatigue cycle. The model was used to perform simulations of creep-fatigue crack growth at elevated temperatures in a nickel-base superalloy and AISI 316 austenitic steel.
- Research Organization:
- Univ. of Idaho, Moscow, ID (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- Grant/Contract Number:
- NE0008443
- OSTI ID:
- 1502740
- Alternate ID(s):
- OSTI ID: 1547613
- Journal Information:
- International Journal of Fatigue, Vol. 125; ISSN 0142-1123
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Fatigue and creep-fatigue crack growth in alloy 709 at elevated temperatures
|
journal | September 2019 |
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