- Software
- Zencrack
- Technical
- Pre and Post Processing
Input Files
Pre and Post Processing
Input Files
The main Zencrack input file uses a keyword type structure similar in concept to the majority of finite element programs. The input file may consist of comment lines, keyword lines and data lines. The majority of options have default values and only a minimal amount of "essential" data is needed. For example, for analysis of an initial crack:
Example for remeshing method:
*FILES, UNCRACKED=example.inp
*OPTIONS, TYPE=Initial
*CRACK FRONT, NAME=Crack front_1, TYPE=Remesh,
CRACK TYPE=Elliptic, MATERIAL=Steel
8, 4, 12, , , 360
, , ,
1.0, 1.0, ,
0.0, 0.0, 0.0
15.0, 0.0, 0.0
0.0, 15.0, 0.0
*MATERIAL, NAME=Steel
210000, 0.3
*END
Example for crack-block method:
*FILES, UNCRACKED=example.inp
*OPTIONS, TYPE=Initial
*CRACK FRONT, NAME=Crack front_1,
INITIAL=SIZE, MATERIAL=Steel
s01_q103x4 1 5 2 1.0 1.0
*MATERIAL, NAME=Steel
210000, 0.3
*ENDIn the remeshing example, the *CRACK FRONT keyword defines the geometric data for the elliptic starter crack and properties of the required mesh e.g. 8 elements along the crack front, 4 rings and 12 segments around the crack front within the rings. The empty data line indicates that element sizes for the tet mesh region should be calculated automatically. Global coordinates of three points are used to define the ellipse position and orientation.
In the crack-block example the data on the *CRACK FRONT keyword is the only difference compared to the remeshing input. A single crack-block, s01_q103x4, replaces element number 1 in the uncracked mesh. The crack is oriented using corner nodes 5 and 2 on that element. The initial crack size is 1.0 along the crack-block edges where the crack front meets the crack-block boundary.
The material data is provided to allow conversions between stress intensity factors and energy release rate.
Extending the above example for a crack growth analysis requires definition of crack growth data and a load history. For example a to use a Paris law and a constant amplitude load system with stress ratio of 0.1:
Example for remeshing method:
*FILES, UNCRACKED=example.inp
*OPTIONS, TYPE=Fatigue
*CRACK FRONT, NAME=Crack front_1, TYPE=Remesh,
CRACK TYPE=Elliptic, MATERIAL=Steel
8, 4, 12, , , 360
, , ,
1.0, 1.0, ,
0.0, 0.0, 0.0
15.0, 0.0, 0.0
0.0, 15.0, 0.0
*MATERIAL, NAME=Steel
210000, 0.3
*CRACK GROWTH DATA, NAME=Steel, TYPE=Paris
7.75E-13, 3.2
*LOAD SYSTEM, TYPE=Constant amplitude
0.1, 1.0
*END
Example for crack-block method:
*FILES, UNCRACKED=example.inp
*OPTIONS, TYPE=Fatigue
*CRACK FRONT, NAME=Crack front_1,
INITIAL=SIZE, MATERIAL=Steel
s01_q103x4 1 5 2 1.0 1.0
*MATERIAL, NAME=Steel
210000, 0.3
*CRACK GROWTH DATA, NAME=Steel, TYPE=Paris
7.75E-13, 3.2
*LOAD SYSTEM, TYPE=Constant amplitude
0.1, 1.0
*ENDA variety of other keyword options are available to give the user full control of the analysis e.g. to specify tolerances rather than using defaults, or to save finite element results files.
User Subroutines
In addition to the standard options built into Zencrack a number of user subroutines are available to give extended control to the user. These allow, for example, the use of proprietary crack growth models and data. Available subroutines include:
- Crack growth data for fatigue analysis.
- Crack growth data for time dependent analysis.
- Threshold data for fatigue analysis.
- Threshold data for time dependent analysis.
Additional Input Files
Depending upon the analysis type there are a number of additional input files that may be required. These are all ASCII files whose format is provided in the user manual:
- Tabular crack growth data file.
- Cyclic spectrum file defining counted load cycles.
- Load time history file for "simplified" time dependent crack growth.
- Temperature time history file for "simplified" time dependent crack growth.
Technical
Pre and Post Processing
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