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1989
Conference Proceeding
Titel
Recent advances in modelling creep crack growth
Abstract
At the time of the previous International Conference on Fracture, the C integral had long been recognized as a promising load parameter for correlating crack growth rates in creep-ductile materials. The measured crack growth rates as a function of C integral and of the temperature could be understood on the basis of micromechanical models. The distinction between C -controlled and K sub I-controlled creep crack growth had been clarified and first attempts had been made to describe creep crack growth in the transient regime between elastic behaviour and steady-state creep. This paper describes the progress in describing transient crack growth including the effect of primary creep. The effect of crack-tip geometry changes by blunting and by crack growth on the crack-tip fields and on the validity of C is analyzed by idealizing the growing-crack geometry by a sharp notch and using recent solutions for the notch-tip fields. A few new three-dimensional calculations of C are cited and import ant theoretical points are emphasized regardingj the three-dimensional fields at crack tips. Finally, creep crack growth is described by continuum-damage models for which similarity solutions can be obtained. Crack growth under small-scale creep conditions turns out to be difficult to understand. Slightly different models yield very different crack growth rates. (IWM)