2.1 Zencrack working Process

Firstly, user must supply zencrack with a mesh that must contain 8 or 20 node brick elements in the region where crack is required.

Secondly, user must supply a supplementary data which contain specification of the required location, orientation and size of the initial crack front. For crack growth prediction additional data such as the crack growth law data is required.

Zencrack will generate a mesh with initial mesh. In this mesh, boundary conditions and pressure loads are updated near the crack front. J-integral and/or COD requests are generated for the new mesh.

Then the cracked component mesh is automatically submitted for analysis using f.e coding. This is the last step if the user only wants to evaluate stress intensities or the energy release rate for a given crack size.

                                                       

If user wants a crack growth prediction with a professional version, Zencrack extracts the required information from the analysis output and calculates a new crack front position and the mesh is updated to contain a crack in this new position. 

                                                 

2.2 Crack - Block Approach in Zencrack 
Zencrack uses a ‘crack-block’ approach to introduce crack fronts into a mesh. A crack-block is a mesh of brick elements which models a section of a crack front. Crack-blocks are mapped into an intact mesh replacing standard brick elements (8 or 20 nodes) in the intact mesh. User can use one or more of these crack-blocks to defined size and position of crack.

                                                  

2.3 Load system
Zencrack supply two superposition methods are available to allow combination of different load types into a load spectrum, these two methods are refer to cyclic-static and max-min.
The cyclic-static method assumes that all steps in the finite element analysis are linear elastic and that results from individual steps can be scaled and combined.
The max-min method is intended for us when the superposition of loading is carried out in the finite element load steps. This is most likely to occur when non-linearities are introduced in the finite element analysis such as plasticity or crack face contact.

                                                       

2.4 Boundary shift and relax

Boundary shift can be used when there is no crack growth to enable shifting of element boundaries in a model. this can allow modeling of an otherwise awkward crack size. In addition, crack fronts consisting of only through crack-blocks can be made to transfer from one set of element locations to another as crack grows and this also need relaxing algorithm, this can improve the mesh around the crack-block region.

                                                              

2.5 Pre/Post Processing
There are two tools in zencrack pre processing.
One is utility “TANH”. It can produces tabular crack
Growth data from tanh equation data. The other is utility program “rainflow”, it can help user to cycle counting of uncounted load spectra and the output is spectrum file ready for use by Zencrack.

                                   

                                                                TANH                                           Rainflow                                    

Process can creates a comma delimited (.csv) file from the output data in the .rep file and can be imported into a spread sheet. “3DMESH” is used produce beam element meshes representing crack growth.

                                                

                                       

                                                                       Process                                              3DMESH                             

3.Zencrack benefits

Zencrack can be used to predict 3-D cracks behavior under static loading and their growth under both fatigue and time-dependent loading, by using Zencrack, you can

•  Increase the efficiency and productivity of your 3D fracture mechanics workforce
•  Reduce your pre and post-processing time for 3D finite element crack analysis
•  Analyze problems that cannot be tackled using conventional fracture mechanics methods
•  Use of industry-standard finite element software as part of the overall solution
•  Complex non-planar crack shapes and geometries can be analysed
•  A wide range of complex loading can be applied, including: Residual stress from shot peening, spectrum load files.

4. Customers