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Numerical treatment of creep crack growth

: Hollstein, T.; Kienzler, R.
: Fraunhofer-Institut für Werkstoffmechanik -IWM-, Freiburg/Brsg.

Freiburg/Brsg., 1990
Wissenschaftlicher Bericht - Fraunhofer-Institut für Werkstoffmechanik, W 9/90
Fraunhofer IWM ()
C*-integral; creep; creep crack growth; finite element analysis; fracture mechanic; high-temperature component

To accomplish the safety analysis and to predict the lifetime of high-temperature components with flaws, several concepts have been proposed to correlate creepcrack initiation and growth with fracture mechanics parameters. The concepts of stress-intensity factor K, reference stress o sub ref, line integral C *, and others will be discussed. Among them, the C *-integral concept seems to have the widest range of applicability, if large creep zones develop and steady state creep conditions can be assumed. The numerical evaluation of C * by the virtual crack extension method is described. The methods are demonstrated by two- and three-dimensional finite element simulations including creep crack growth. As for ductile fracture experiments, plane stress and plane strain simulations are bounds to the three-dimensional simulations which agree well with corresponding experiments.