Steady state crack growth in elastic-viscoplastic materials
Journal
International Journal of Fracture
Journal Volume
33
Journal Issue
3
Pages
175-194
Date Issued
1987
Author(s)
Abstract
A recent theory of Hart for the steady state propagation of a mode III crack in a ductile material is extended to modes I and II. When a crack is moving at non-zero velocity v, it is shown that for a broad class of materials the stress state at the crack tip is characterized by a r1/2 singularity and by a local stress intensity factor K. The local K is the sum of the 'apparent' stress intensity factor KA and a plastic contribution KP. The value of KA is calculated from the remote loading and the crack geometry under the assumption of linear elastic response alone. The quantity KP characterizes stress relief of non-elastic flow. Numerical calculations are made to determine K as a function of KA and v for elastic-viscoplastic materials. A dependence of v on KA is obtained by imposing a kinetic law for v as a function of K. The plots of v vs. KA show that below some critical values of KA, steady state conditions cannot be sustained. Corresponding to the threshold value of KA there is a definite value for the velocity. © 1987 Martinus Nijhoff Publishers.
Type
journal article