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Overview

Under Development

The new remeshing capability in Zencrack 9.0-1 was an initial implementation onto which more capability has been added with the latest releases, 9.3-1, 9.4-1 and 9.5-1 having the ability to cater for multiple remeshing cracks, merging of remeshed regions and multiple crack fronts connected to a crack plane.

Work continues to enhance the remeshing capabilities with the interface to Simcenter Nastran being upgraded to included support for remeshing in version 9.5-1.

The multi-crack remeshing capability in 9.3-1 included a limitation that the remeshing regions of the cracks do not touch or overlap. Removing this limitation was the main development activity for version 9.4-1 and a pre-cursor to further generalising the remeshing capability for multiple cracks in subsequent releases. In the now-released version 9.5-1, a new capability is included to allow an initial elliptic geometric definition to cut multiple crack fronts into a model. Two examples are shown below. An example of an enhancement in version 9.4-1, in which two cracks whose remesh regions are initially separate become embedded in a single remesh region after some growth has taken place, is also shown below.

Multiple crack fronts on the same crack plane - Example 1

Example of an initial geometric ellipse cutting one crack plane and two crack fronts into a model to generate an initial 45 degree inclined crack

951_cruciform_inclined_crack_preview

Preview of the initial crack front rings and region to be remeshed with inset showing calculated crack path (shown in Zencrack GUI)

951_cruciform_inclined_crack_abaqus

Mises contour plot of advanced crack positions during fatigue crack growth prediction (shown in Abaqus/CAE)

Cruciform hex medial axis parabolic inclinedr exterior deformed 3dview Rotate zcr 060

Example with two separate crack fronts connected to crack plane (deformed plot, Abaqus/Viewer)

Cruciform hex medial axis parabolic inclinedr feature mises 3dview Rotate zcr 060

Example with two separate crack fronts connected to crack plane (Mises deformed plot, feature edges, Abaqus/Viewer)

Multiple crack fronts on the same crack plane - Example 2

Example of an initial geometric ellipse cutting one crack plane and three crack fronts into a symmetry plane of a model

A85uc02 small3rings 1crack symmetry remeshcrackplane step control preview

Preview of the initial crack front rings and crack front node positions with inset showing calculated crack paths (shown in Zencrack GUI)

A85uc02 small3rings 1crack symmetry remeshcrackplane step control abaqus

Mises contour plot of advanced crack positions during fatigue crack growth prediction with mirroring about the two symmetry planes in the model (shown in Abaqus/CAE)

A85uc02 small3rings 1crack symmetry remeshcrackplane step controlr exterior deformed 3dview Rotate zcr 050

Example with three separate crack fronts connected to a symmetry crack plane (deformed plot, Abaqus/Viewer)

A85uc02 small3rings 1crack symmetry remeshcrackplane step controlr feature mises 3dview Mirror zcr 050

Example with three separate crack fronts connected to a symmetry crack plane with mirroring about the two symmetry planes in the model (Mises deformed plot, feature edges, Abaqus/Viewer)

Remeshing with the Simcenter Nastran interface

Example of post-processing in Simcenter 3D Results Viewer using a step from a Zencrack crack growth run carried out with Simcenter Nastran

Dev remeshing nastran01
Dev remeshing nastran02

Remeshing with improved crack plane triangulation during a growth analysis

Retriangulation of the initial crack plane (i.e. at step 1 of the analysis) is now carried into subsequent steps

Dev remeshing retriangulation no 008 ellipse

Crack plane triangulation at analysis step 8 without the new retriangulation option

Dev remeshing retriangulation yes 008 ellipse

Crack plane triangulation at analysis step 8 with the new retriangulation option

Merging of remesh regions

Example of initially separate remesh regions merging as cracks grow towards one another. This feature is available in release version 9.4-1.

A non-linear Kujawski-Ellyin crack growth law will be implemented as per the publication:

  • Non-linear models for assessing the fatigue crack behaviour under cyclic biaxial loading in a cruciform specimen
    M.Lepore, F.Berto, D.Kujawski
    Theoretical and Applied Fracture Mechanics, Volume 100, 14-26, April 2019, DOI: 10.1016/j.tafmec.2018.12.008.

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