A numerical analysis of time dependent stress fields ahead of stationary interface cracks at creep regime—Part I. Interface cracks in bimaterials

Abstract

In this study, the behavior of stationary interface cracks at creep regime in plane-strain condition and pure crack opening dominated mode-I load state is investigated numerically. The bimaterials considered are elastic-creeping with power law and bimaterials having identical elastic properties but creeping at different rates. The results indicate that the amplitude of the crack tip singularity is dominated by the faster creeping sector. Neither the elastic properties (hence the initial elastic stress distribution) nor the creep properties of the slower creeping sector significantly affect the evolution of the C ∗ value for the interface cracks under identical applied loading condition. At steady-state, the angular distribution of the stresses ahead of the interface cracks in the faster creeping sector resembles the HRR stress singularity that occurs ahead of the cracks in homogeneous materials at creep regime. However, the observed C ∗ values for the interface cracks were about half of that seen for the crack in the homogeneous case under identical applied loading; and the occurrence of much larger radial, shear and hydrostatic stress components at significant distances ahead of the interface cracks was observed. On the other hand, the magnitudes of the normal stress component remained relatively the same for both crack types. Based on these observations, the possible growth rate of the interface cracks due to creep damage is also discussed.