Analysis of warm prestress data
- Knolls Atomic Power Lab., Schenectady, NY (United States)
- Oak Ridge National Lab., TN (United States)
Loading a cracked structure at elevated temperature, or warm prestressing (WPS), enhances its fracture resistance at a lower temperature. Five data sets, comprising 119 unclad pressure vessel steel specimens, were combined to derive correlations for WPS-enhanced fracture toughness (K{sub Ifrac}) in the absence of ductile tearing. New WPS test results for 27 surface-flawed specimens, eight subclad-flawed specimens, and five strain-aged specimens are discussed. K{sub Ifrac} exceeded non-WPS fracture toughness, K{sub Ic}, for all experiments. The WPS data showed that no specimens failed while K was decreasing, and that at least an additional 7% additional reloading from the minimum value of applied K{sub I} took place prior to final fracture. The data included complete and partial unloading after WPS prior to final fracture. Crack tip three-dimensional elastic-plastic finite element (3DEPFE) analysis was performed to support statistical analysis of the data. Regression models were compared with the Chell WPS model. The regression model for partial unloading accurately predicted the behavior of full-scale pressure vessel WPS experiments. All but one of the 174 experiments considered lie above the lower 2{sigma} estimate of the regressions. The experiments all supported Type I WPS, i.e., there was no fracture during cooling until reloading occurred. However, the regression equations apply to the reload and are inapplicable to Type I WPS.
- OSTI ID:
- 544224
- Report Number(s):
- CONF-950618-; TRN: IM9749%%176
- Resource Relation:
- Conference: 27. ASTM symposium on fatigue and fracture mechanics, Williamsburg, VA (United States), 26-29 Jun 1995; Other Information: PBD: 1997; Related Information: Is Part Of Fatigue and fracture mechanics: 27. volume; Piascik, R.S.; Newman, J.C. Jr.; Dowling, N.E. [eds.]; PB: [650] p.; ASTM special technical publication 1296
- Country of Publication:
- United States
- Language:
- English
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