부산대학교 도서관

The influences of the specimen thickness, the ligament length and the overall size on the JR-curves are numerically investigated for CT specimens. The thickness effect is taken into account with 2D analyses by dividing a plain sided specimen into a plane stress part and a plane strain part. For a given geometry the overall out-of-plane constraint of the specimen is determined by the relative thickness of the plane stress and the plane strain part which can be estimated with the help of a simple tridimensional analysis. It is found that the variation of the out-of-plane constraint with the geometries of the specimens is one of the main reasons for the complicated geometry effects on JR-curves. Different patterns of geometry effects are observed for one material in our numerical analyses. Similar patterns have been reported in experimental studies found in the literature. It is also shown that different classes of material may lead to different patterns of geometry effects.