Creep crack growth

BE-74E3 Creep crack growth in carbon- manganese steel at 300 420 Mr. R. Maskel BABCOCK ENERGY Ltd... 

SMT-2070 Development of creep crack growth testing and data analyses procedures for Dr. Bilal Dogan GKSS... 

Creep Crack Growth and Creep-Fatigue Crack Growth... 

J. Landes and J. Begley, A Fracture Mechanics Approach to Creep Crack Growth, in Mechanics of Crack Growth, ASTM Technical Publication 590, The American Society for Testing and Materials, Philadelphia, PA, 1976, pp. 128-148. 

J. L. Bassani, D. E. Hawk, and A. Saxena, Evaluation of the C, Parameter for Characterizing Creep Crack Growth Rate in the Transient Regime, in... 

Creep Crack Growth Models in Monolithic Solids... 

Fig. 10.4 Curve showing the predicted creep crack growth rate versus stress intensity factor based on the model of Hui and Riedel.40...

Equation (18) is very similar to the result of Eqn. (17) which was derived for crack growth under elastic field control. From the result of Fig. 10.4, it is clear that Kmin represents the threshold stress-intensity factor for creep crack growth. Kmin is proportional to eceVFc so that an increase in ec and lc leads to an increase in the threshold stress-intensity factor. The creep crack growth rate, on the other hand, is decreased in the asymptotic limit by an increase in lc and ec, as would be expected. 

Modeling of Creep Crack Growth in Ceramic Composites... 

Creep Crack Growth with Fiber Bridging Through a Viscous Fiber-Matrix Interface... 

The second case in this category of creep crack growth with a cohesive zone associated with viscous interfaces is the work of Nair and Gwo.32,53 Nair and Gwo32 considered intermittent crack growth whereas continuous crack growth was considered in the latter study. The principal assumption in these studies was that the stress field in the creep zone follows the ffR-field or RR-field (see Section 10.2) with applied K replaced by Keff. This is only a first approximation, because, as mentioned earlier, these crack tip fields were originally derived for traction-free crack surfaces. 

Fig. 10.11 Curves showing the creep crack growth rate as a function of crack length for different values of the interface viscosity, /. Also shown in the figure is the case wherein fiber bridging is absent. See text for discussion.

In structural ceramic composites, the principal effect considered was one of crack-face closure tractions, or cohesive forces, brought about, for instance, by bridging fibers. A rigorous evaluation of the crack tip fields where the crack faces are not traction free has not yet been attempted. However, an approximate approach for the small-scale creep case is to assume that the crack tip fields are not functionally altered by crack-face tractions, with the effect of the traction being only to introduce a zone of crack tip shielding. This allows for the development of preliminary models for creep crack growth which is inclusive of the role of crack bridging. These preliminary models predict that,... 

A. Saxena, Creep Crack Growth under Non-Steady-State Conditions, in Fracture Mechanics Seventeenth Volume, eds. J. H. Underwood, R. Chait, C. W. Smith, D. P. Wilhem, W. A. Andrews, and J. C. Newman, ASTM STP 905, American Society for Testing and Materials, Philadelphia, PA,... 

A. Saxena, Mechanics and Mechanisms of Creep Crack Growth, in Fracture Mechanics Microstructure and Micromechanisms, eds. S. V. Nair, J. K. Tien, R. C. Bates, and O. Buck, ASM Materials Science Seminar, ASM International, OH, 1987, pp. 283-334. 

W. Blumenthal and A. G. Evans, High-Temperature Failure of Polycrystalline Alumina II, Creep Crack Growth and Blunting, J. Am. Ceram. Soc., 67[11], 751-758 (1984). 

J. L. Bassani, D. E. Hawk, and A. Saxena, Evaluation of the C, Parameter for Characterizing Creep Crack Growth Rate in the Transient Regime, in Nonlinear Fracture Mechanics Volume I—Time Dependent Fracture, eds. A. Saxena, J. D. Landes, and J. L. Bassani, ASTM STP 995, American Society for Testing and Materials, Philadelphia, PA, 1988, pp. 7-26. 

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