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Crack Kinking Out of an Interface - realization in a software
Dear Collegues,
I'm looking for solving of a problem of crack kinking out of an interface. According paper of Mr. Hutchinson (paragraf 3.3 Crack Kinking Out of an Interface) "the energy release rates for interface advance versus kinking, and on the relative toughnesses of the interface and the adjoining materials". So, we have a crack propagating along an interface (for this propably Cohesive Zone Model is suitable) . An I need to be able to calculate kinking of crack from interface (this for my mind could be solved using VCCT for isotropic material where a crack is kinking).
Has anybody experience with solving this problem using commercial or open source software? May be can somebody give me ideas how to implement it using FEM code like ansys or abaqus or any other tools? Thanks a lot in advance for comments. Anna
Hi Anna: Maybe you'll
Hi Anna:
Maybe you'll find something in this:
Abstract:
An interfacial fracture mechanics analysis of a thin film structure subjected to thermal stresses is carried out. Of primary importance is substrate cracking phenomenon which is frequently observed in systems that contain brittle interfaces, the films being under tensile stresses. An interfacial delamination that advances into the substrate typically propagates parallel to the interface at a certain depth. Ultimately the portion that remains above the crack may spall resulting in failure by loss of structural integrity. Fracture mechanics of interfaces is a field still under development with some problems that have not been solved yet. Such a problem is the determination of the angle at which the interface crack kinks into the substrate. The problem of crack kinking in a homogeneous medium has been studied and different theories have been proposed. We considered the crack extension force theory for a homogeneous medium and determined its counterpart in the bimaterial crack configuration. The theory that is developed is then compared with experimental results for a straight interface crack-front under plane strain conditions. We show that our prediction of crack length at which substrate cracking initiates agrees with the experimental observations. The problem is greatly simplified by the assumption of plane strain, unfortunately typical delaminations usually initiate at the corners of the structure. In order to model this a three-dimensional model of the structure that contains a curvilinear crack-front is constructed. The loading at the crack-tip is further complicated by the introduction of the anti-plane deformation modes and the theory of crack propagation used in the plane strain configuration does not apply in this case. In addition, due to the complexity of the problem, very few experimental observations on the three-dimensional problem which can be used to compare new theories with, exist. We propose a simple model based on the plane strain model to predict cracking in curvilinear crack-fronts.
Okyar. A.F., "Delamination and Fracture in Thin Film Systems Under Thermal Loading", Ph.D. Thesis, Illinois Institute of Technology, 2000.