Crack-Path Analysis for Brittle and Non-Brittle Cracks: A Cell Method Approach

Abstract

Defining the crack path in brittle and non- brittle crack is not easy, due to several unknowns. If the direction of crack propagation can be computed by means of one of the existing criteria, it is not known whether this direction will remain constant during crack propagation. A crack initiation leads to an enhanced stress field at crack tip. During propagation, the en- hanced tip stress field propagates into the solid, locally interacting with the pre-existing stress field. This inter- action can lead to modifications of the propagation di- rection, depending on the domain and crack geometry. Moreover, trajectory deviation affects the length of crack propagation. Thus, the length of crack propagation too depends on the domain and crack geometry. Finally, the local interaction between stress fields of opposite signs can return a modified condition of crack arrest. Crack stability analysis cannot be performed without consider- ing this interaction. The problem of defining trajectory deviation,propagationlengthand crack stabilizationisof particular interest in brittlecracks, since these cracks de- velopstaticallyfrom themoment ofcrack initiationforth. It will be shown here how a numerical code for use with the CM returns an accurate crack path for brittleand non- brittle cracks. In both cases, the stress analysis has been performed on the plane of Mohr for each step of the car- rying process. At crack propagation, an automatic tool of nodal relaxation with remeshing is used to update the domain geometry. keyword: Cell Method, automatic remeshing, crack stability,failure mechanism analysis.