Summary for versions 7.2 and 7.1

General

• The maximum allowed model size is increased to 50000 elements and 250000 nodes.
• The maximum number of f.e. runs is increased from 99 to 999.
• A new option is introduced to use displacement based results to calculate crack growth.
• Time dependent or combined time and fatigue crack growth prediction can be carried out. New options are available to enter da/dt data and time dependent load and temperature data for time based analysis.
• Material, crack growth data and threshold data can now be temperature dependent.
• A new scheme is introduced to control the integration step size between f.e. analyses based on the maximum allowable error in G between the last 2 f.e. runs. This scheme allows a more reliable and accurate result to be obtained.
• A fully automated control of the analysis step size can now be achieved by omitting keyword TOLERANCE.
• Load system superposition method 1 is complimented by a method 2 option that can be used when non-linearities are present (e.g. crack face contact).
• Retardation models are available (basic Willenborg and generalised Willenborg).
• A user defined initial crack front can be specified. Zencrack positions a cubic spline through the points and the crack front nodes are positioned along the cubic spline. This allows for a better representation of unusual crack front shapes and can be used as a manual restart capability.
• The starting point in a spectrum file can be specified using the START or COMPLETED options on keyword SPECTRUM.
• Boundary shifting and transfer routines have been made more robust and general e.g. they now cater for curved element edges, rotation of crack-blocks during non-planar growth to minimise element distortion and have checks to prevent crack-blocks becoming too small compared to adjacent elements.
• Transfer of crack-blocks to new element locations is extended to work for multiple cracks in a model.
• The transfer of crack-blocks to new locations is extended to work for non-planar crack growth cases.
• A relaxation algorithm is implemented to reduce element distortion around the crack-blocks when boundary shifting is activated.
• Any node that has been moved from a surface or edge is mapped back onto the surfaces as defined by the original nodes and elements of the uncracked mesh. This improves the way the program operates on meshes with curved outer surfaces.
• Crack face loading is updated on all crack face elements after transfer of crack-blocks to a new location.
• Threshold data input as TYPE=POINTS is interpolated using log-linear or harter-t to be consistent with interpolation methods for tabular growth data.
• The first step at which files are saved and the interval after that at which files are saved can be defined by the user.
• Crack-blocks can be inserted into 8 noded bricks as well as 20 noded bricks.
• All calculations are now in double precision. In version 7.0 only the integration scheme used double precision.
• The number of available user subroutines has been increased.

Abaqus interface

• A "transition element" capability is introduced to improve surface based tying between large crack-blocks and the surrounding mesh.
• Crack face contact applied via *CONTACT is updated on all crack face elements after transfer of crack-blocks to a new location.
• The user can now select crack fronts onto which crack face contact is automatically generated.
• All Abaqus *DLOAD options are processed and updated if necessary in all Abaqus analysis steps.
• Displacements are now extracted from the Abaqus .fil file as well as j-integrals if the *ENERGY RELEASE RATE, RESULTS=FIL-USER option is used.

Ansys interface

• This is a new interface in this release.