Effect of cyclic loading on the creep performance of silicon nitride
- Oak Ridge National Lab., TN (United States). High Temperature Materials Lab.
- National Central Univ., Chung-Li (Taiwan, Province of China). Dept. of Mechanical Engineering
Tension-tension cyclic fatigue tests (triangular waveform, {sigma}{sub max} = 100 MPa, R = 0.1) were conducted on hot isostatically pressed (HIPed) silicon nitride at frequencies spanning several orders of magnitude (5.6 {times} 10{sup {minus}6} to 0.1 Hz or 10{sup {minus}3} MPa/s to 18 MPa/s) at 1,370 C in air. The amount of cyclic creep strain was found to be a function of the frequency or stressing rate with greater strains to failure observed as the frequency or stressing rate decreased. The total strain was viewed as the sum of elastic, anelastic (or transient recoverable), and plastic (viscous or non-recoverable) strain contributions, after the empirical Pao and Marin model. The plastic strain was found to be the dominant component of the total creep and was unsatisfactorily represented by the Pao and Marin model. To circumvent this, a time exponent was introduced in the plastic strain term in the Pao and Marin model. This modification resulted in good correlation between model and experiment at the slower frequencies examined but over-predicted the cyclic creep strain at the faster frequencies. The utility of using the modified Pao and Marin model to predict cyclic creep response from static creep and strain relaxation tests is described.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 52850
- Report Number(s):
- CONF-950629-6; ON: DE95010289; TRN: AHC29515%%121
- Resource Relation:
- Conference: 40. International gas turbine and aeroengine congress and exposition, Houston, TX (United States), 5-8 Jun 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
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