Energy dissipation rate analysis of a low upper shelf data set

Abstract

Stable and unstable tearing in metals is currently analysed by J integral theory. Test and analysis methods are fully standardised and the validity of the approach has been demonstrated by reference to laboratory and type testing. A central requirement of the J method is that the J R curve remain invariant as size increases (specimen dimension to structure). A set of data from the literature which show the slope of the J R curve decreasing with increasing specimen size are presented. This represents an unsafe trend in terms of predicting structural behaviour from small specimens tests. The observed behaviour is explained successfully with energy dissipation rate theory. At the same time energy dissipation rate theory can also explain the more normally observed behaviour of size invariant J R curves. It is concluded that stable and unstable tearing in metals is best described by the energy dissipation rate approach.