Relevance of meso‐scale modelling of creep crack initiation and growth to component defect assessment

Issue title: International Conference on Complexity and Frontiers in Strength and Fracture (ICS 2001), Sendai, Japan, 24–27 June 2001 Part I

Article type: Research Article

Authors: Nikbin, K.

Affiliations: Department of Mechanical Engineering, Imperial College, London SW7 2BX, UK

Abstract: High temperature components, which are subjected to creep or creep‐fatigue loading, may fail by crack growth, net section rupture or a combination of both processes. Creep crack development in structures can be separated into two regimes of failure consisting of initiation/incubation and a steady cracking behaviour both of which are affected by constraint. The parameter described as C* has been the accepted parameter to correlate the different stages of crack growth. The meso‐scale model developed previously has been used to produce a material independent engineering diagram bounding over the plane stress/strain steady state using the concepts of void growth to predict multiaxial ductility. However this model does not quantify the range of crack initiation and growth due to size and geometry. Therefore a two‐parameter approach may be needed to improve correlation for the cracking behaviour. The development of this parameter is computer intensive in terms of analysis and preliminary results on laboratory geometries are promising. The paper reviews the previously developed modelling ideas and considers the future options with regards to component life assessment.

Keywords: Creep crack growth, fracture mechanics, creep damage, constraint

Journal: Strength, Fracture and Complexity, vol. 1, no. 1, pp. 47-57, 2003