Zencrack 9.0-1 pre-release
A pre-release version allowing testing of the new remeshing capability described below is available upon request for Abaqus users on Windows 10. Please use our contact form to send us a request if you are interested.
New remeshing capability in Zencrack
A new remeshing capability provides mesh independent crack insertion into an uncracked mesh. This approach simplifies the creation of 3D models containing cracks by using a purely geometric definition of an initial crack.
An existing uncracked mesh can be used "as-is" with, in most cases, no need to perform special partitioning or meshing of the uncracked geometry. This means that, for example, a single uncracked mesh can be used to develop models of significantly different cracks by simply changing the geometric crack definition.
- initial crack and crack growth
- remeshing for analysis of initial crack only
- remeshing for general non-planar 3D crack growth using the existing load system methodologies in Zencrack for fatigue, time dependent and combined fatigue/time crack growth prediction
- geometric definition of an initial crack
- initial crack location is fully independent of the underlying mesh
- the underlying mesh may contain hex or tet elements
- crack at a symmetry plane, surface breaking or fully embedded
- initial crack shape may be straight or elliptic (either full ellipse or elliptic arc)
- remeshed region split into hex rings and surrounding tets
- rings of hex elements at the crack front with ring mesh density controlled by the user
- tet mesh surrounding the rings
- fully automatic calculation of the extent of the remeshed tet region and mesh density within that region (with manual control if desired)
- support for static, thermal and coupled analyses
- update of displacement boundary conditions, pressure loads, surface definitions, film coefficients and temperatures in the remesh region
- optional application of pressure and/or film coefficients to the crack face
- the above are functional developments, additional features are in progress
The remeshing capability is fully supported in the Zencrack GUI with options to preview various aspects of the initial crack definition, including:
- option to define geometric positional data by picking nodes in the uncracked mesh
- preview of the geometric crack definition
- preview of the hex rings at the crack front
- preview of the remesh region
- preview of the remesh region with the crack inserted
Definition of elliptic crack position plus ring preview
Ring elements and remesh region preview
Remeshed region preview
Completed mesh with elliptic crack
Other developments in Zencrack
- Implementation of crack growth direction from stress intensity factors based on the work of Richard et al.
- Ref: H.A.Richard, M.Fulland, M.Sander, Theoretical crack path prediction, Fatigue Fract Engng Mater Struct 28, 3-12, 2005.
- Extension of the processing available for interaction integrals to allow them to be used to drive a crack growth analysis.
- Support for the Ansys option for specifying the auxiliary field solution when calculating interaction integrals: mixed, plane stress or plane strain.
- Re-working of some of the options on the *ENERGY RELEASE RATE keyword to accommodate some of the above changes and to allow future additions.
- Implementation of a non-linear Kujawski-Ellyin crack growth law.
- Ref: M.Lepore, F.Berto, D.Kujawski, Non-linear models for assessing the fatigue crack behaviour under cyclic biaxial loading in a cruciform specimen, Theoretical and Applied Fracture Mechanics, Volume 100, 14-26, April 2019.
- for crack-block models, creation of an output set of crack-blocks that are "ready to transfer".
Development work in the Zencrack GUI
- New input, preview and display options to support the new remeshing capability for crack insertion into an uncracked mesh (see additional examples below).
- Re-working of the Energy Release Rate screen to accommodate the changes described above.
- Improved performance for large meshes (faster import and manipulation).
- Import and optional display of the material regions defined in a mesh.
- Identification of disconnected mesh regions.
- Labelling of profiles when displaying crack growth profile results.
- Labelling of splines (Input Tab crack front splines and Display Tab splines).
- Ability to add multiple meshes into one viewport.
- Ability to display some types of surface definitions (initially to support remeshing previews).
Examples of remeshing - crack growth
Four examples of crack growth prediction, each carried out in a single automated analysis. Click thumbmails for full size image.
Additional remeshing examples
These examples show some of the remeshing input screens and the options that are available to control the definition of the remesh region.
Placement of crack into a specific region
Preview of crack front nodes; crack in a specifed region
Connecting rod, crack definition and remeshed region
Bracket, crack definition and remeshed region
Disk, crack definition and remeshed region
Disk, larger crack size
Threaded connection, crack definition and
Threaded connection, confirmation of boundary condition updates and contact surface update (in Abaqus/Viewer)