Contour Integrals For Creep Crack Growth Analysis

Abstract

Of the parameters which characterise conditions at the crack tip, those which can be accurately calculated are contour integrals around the tip. For a viscous material an integral C* is most appropriate. For solids which creep, other integrals, which are valid in the non-steady state case, have more physical significance, may be more readily determined from stress analysis results, and for steady state secondary creep tend to a value very close to that of C*. To find out which integral provides the best correlation for ½CrMoV Steel several such integrals are computed for compact tension specimens of this material, under both load and displacement controlled loading using data on crack growth at 838K.