Tensile cracks in creeping solids
This paper aims to determine which loading parameter determines the stress and strain fields near a crack tip, and thereby the growth of the crack, under creep conditions. The stress intensity factor K/sub I/, the path-independent integral C*, and the net section stress sigma/sub net/ have been proposed in the literature. The answer is based on the time-dependent stress analysis of a stationary crack in Mode I tension. The material behavior is modeled as elastic-nonlinear viscous, where the nonlinear term describes power law creep. At the time t = 0, load is applied to the cracked specimen, and in the first instant the stress distribution is elastic. Subsequently, creep deformation relaxes the initial stress concentration at the crack tip, and creep strains develop rapidly near the crack tip. These processes may be analytically described by self-similar solutions for short times t. An important result of the analysis is that small-scale yielding may be defined. In creep problems, this means that elastic strains dominate almost everywhere except in a small creep zone which grows around the crack tip. If crack growth ensues while the creep zone is still small compared with the crack length and the specimen size, the stress intensity factor governs crack growth behavior. If however, the calculated creep zone becomes larger than the specimen size, the stresses become finally time-independent and the elastic strain rates can be neglected. In this limiting case, the stress field is the same as in the fully-plastic limit of power law hardening plasticity that has been treated in the literature. The loading parameter that determines the near tip fields uniquely is then the path-independent integral C*.
- Research Organization:
- Brown Univ., Providence, RI
- DOE Contract Number:
- AC02-80ER10556
- OSTI ID:
- 5740056
- Report Number(s):
- ASTM-STP-700; CONF-7905104-
- Journal Information:
- Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States), Journal Name: Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States); ISSN ASTTA
- Country of Publication:
- United States
- Language:
- English
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