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A procedure for evaluation the crack propagation taking into account the material plastic behaviour

Rossetti, Andrea and Zerres, Patrick and Vormwald, Michael (2012):
A procedure for evaluation the crack propagation taking into account the material plastic behaviour.
In: The 4th Int. Conf. on "Crack Paths" (CP 2012), [Conference or Workshop Item]

Abstract

Fatigue crack growth is one of the main causes for failure in structures under predominantly cyclic loading. A current challenge in numerical simulation of fatigue crack propagation is to evaluate the crack propagation taking into account the cyclic plasticity effects. For example, the autofrettage of intersecting holes generates extremely high compressive residual stress fields following large plastic deformation. These stresses, in combination with the plastic deformations, decelerate the fatigue crack growth at the hole intersection notch. In this work a method is presented which allows the simulation of fatigue crack propagation based on finite element analysis by taking into account the elastic-plastic material behaviour. Particular attention should be paid to these effects because, especially in the area of short cracks and high loads, the crack growth is significantly influenced by plasticity effects. The procedure here presented is numerically implemented in a programming system based on the commercial finite element software ABAQUS. Within this procedure, the calculation of the crack growth life is done by integrating a crack propagation law, which is based on the effective range of the crack tip parameter, as the stress intensity factor or the Jintegral. At this point, a new model with the new crack shape is created and meshed, whereas the status variables, such as the components of the back stress tensor and the plastic strains, are transferred from the old mesh to the new one. The latter numerical technique, like the conventional node release algorithms, is capable to preserve the history of plastic deformation for structures with increasing crack length. However, the proposed procedure differs from the nodal release technique because it allows the crack front to develop freely in a non-predetermined way.

Item Type: Conference or Workshop Item
Erschienen: 2012
Creators: Rossetti, Andrea and Zerres, Patrick and Vormwald, Michael
Title: A procedure for evaluation the crack propagation taking into account the material plastic behaviour
Language: English
Abstract:

Fatigue crack growth is one of the main causes for failure in structures under predominantly cyclic loading. A current challenge in numerical simulation of fatigue crack propagation is to evaluate the crack propagation taking into account the cyclic plasticity effects. For example, the autofrettage of intersecting holes generates extremely high compressive residual stress fields following large plastic deformation. These stresses, in combination with the plastic deformations, decelerate the fatigue crack growth at the hole intersection notch. In this work a method is presented which allows the simulation of fatigue crack propagation based on finite element analysis by taking into account the elastic-plastic material behaviour. Particular attention should be paid to these effects because, especially in the area of short cracks and high loads, the crack growth is significantly influenced by plasticity effects. The procedure here presented is numerically implemented in a programming system based on the commercial finite element software ABAQUS. Within this procedure, the calculation of the crack growth life is done by integrating a crack propagation law, which is based on the effective range of the crack tip parameter, as the stress intensity factor or the Jintegral. At this point, a new model with the new crack shape is created and meshed, whereas the status variables, such as the components of the back stress tensor and the plastic strains, are transferred from the old mesh to the new one. The latter numerical technique, like the conventional node release algorithms, is capable to preserve the history of plastic deformation for structures with increasing crack length. However, the proposed procedure differs from the nodal release technique because it allows the crack front to develop freely in a non-predetermined way.

Title of Book: The 4th Int. Conf. on "Crack Paths" (CP 2012)
Volume: ISBN 9788895940441
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics > Fachgebiet Werkstoffmechanik
13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics
13 Department of Civil and Environmental Engineering Sciences
Date Deposited: 30 Jan 2015 13:20
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