Navigation: 5. Work Flow >

5.1 Data Entry and Project Setup

Previous Next

 

 

 

These steps are common for all the work flows.

 

There are two ways to start a project:  one is manually input, and the other one is reading ANSYS .rst result file.

 

5.1.1 Manually Input

 

Choose File>New..., or click New button  on tool bar.  The New dialog box is displayed. 

 

 

Check Manually input radio button in New dialog box.

 

The Use stress type group box is for ANSYS result file option; checking any radio button in this group has no effect on manually input project.  If the manually inputted data come from an FEA result, and the user wish to show the stress type and node/element number in the charts and report, check appropriate radio button.  Otherwise just leave them alone.

 

Clicking OK button will bring out the Manual Input dialog box.

 

 

Follow instructions in 4. Input Data Editor to complete data entry.

 

When completed, the main window is displayed.  The chart in the center of the main window displays stress time history entered by the user.

 

Now the Project Setup button  on the toolbar becomes activated.

 

5.1.2 Read ANSYS .rst Result File

 

5.1.2.1 Prepare ANSYS Interface

 

In order to read .rst files, the binlib.dll file must be present in the same folder as FatiguePlus.exe.  If for whatever the reason the binlib.dll is missing in FatiguePlus.exe folder, it is required to manually copy the file.  The binlib.dll file is included in your ANSYS distribution media.   If ANSYS is installed on your computer, the binlib.dll file can be found at

 

\Program Files\ANSYS Inc\vxxx\ANSYS\custom\misc\winx64\binlib.dll

 

where vxxx is the version number of ANSYS.  The following is an example:

 

C:\Program Files\ANSYS Inc\v194\ansys\custom\misc\winx64\binlib.dll

 

Copy binlib.dll file to the folder where FatiguePlus.exe is installed.

 

5.1.2.2 Read .rst File

 

Choose File>New..., or click New button on tool bar.  The New dialog box is displayed.  In the Select data input method group box, choose Read ANSYS .rst result file.  In the Use stress type group box, choose desired stress type.

 

 

Click OK button.  The Open ANSYS .rst file dialog box pops up.  Select .rst file (in the example below, file.rst) and click Open button.

 

 

The program starts to read data from file.rst.  Wait until the progress bar disappears.  

 

 

 

When completed, the main window is displayed.  The chart in the center of the main window displays stress time history for the node/element having the highest stresses.

 

The unit of the stresses and temperatures is read from ANSYS .rst file.

 

Now the Project Setup button  on the toolbar becomes activated.

 

5.1.3 Project Setup

 

Choose Input>Project Setup or click Project Setup button  on the toolbar.  The Project Setup dialog box displays.

 

 

The user can select from the Fatigue model/code drop-down menu the following:

 

1) None - When "None" in Fatigue model/code drop-down menu is selected, the Kandil-Brown-Miller criterion and Fatemi-Socie criterion in Multiaxial fatigue model group box are activated:

 

 

Select either Kandil-Brown-Miller criterion and Fatemi-Socie criterion to proceed.  Check Ignore normal compressive benefit checkbox to ignore beneficial average stress effect due to normal compressive stresses; uncheck it to consider the benefit effect.

 

Note: The availability of the items in the Multiaxial fatigue model group box is context-sensitive.  See 4.3 Stress Method for a decision matrix.  The Matake criterion will be activated where shear stress + normal stress combination or 6-component stresses exist even "None" in Fatigue model/code drop-down menu is NOT selected.

 

2) Basquin -  Fatigue life analysis using Basquin's Equation.  From the Mean stress criterion drop-down menu, select Soderberg, Goodman, Gerber, Morrow, Smith-Watson-Topper, Walker, or None.

If Walker mean stress criterion is selected, enter Walker parameter γ.  Note that typical γvalues are in the range 0.4 to 0.8.  There is a trend of decreasing γ with increasing strength, indicating an increasing sensitivity to mean stress.

 

3) Basquin-Coffin-Manson - Fatigue life analysis using Basquin-Coffin-Manson Relation.  From the Mean stress criterion drop-down menu, select Morrow, Smith-Watson-Topper, Walker, Manson-Halford, or None. If Walker mean stress criterion is selected, enter Walker parameter γ.  Note that typical γvalues are in the range 0.4 to 0.8.  There is a trend of decreasing γ with increasing strength, indicating an increasing sensitivity to mean stress.

 

 

4) EN 12952-3 - Water-tube boilers and auxiliary installations — Part 3: Design and calculation for pressure parts of the boiler.

5) EN 13445-3 - Unfired pressure vessels Part 3: Design.

6) ASME Sec VIII Div 2 - Rules for Construction of Pressure Vessels — Alternative Rules.

7) ASME Sec VIII Div 3 - Rules for Construction of Pressure Vessels — Alternative Rules for Construction of High Pressure Vessels.

8) ASME Sec III Appxs -  Rules for Construction of Nuclear Facility Components — Appendices.

 

The Bin size spin box is used for rainflow cycle counting.  Bin size is the number of bins in stress range histogram and fatigue damage ratio charts.  Changing this value will not affect calculation results; rather, it only changes the presentation of the results.  The default value is 18.  The value range is from 5 to 200. 

 

For manually input method, the Stress Type Labeling group box provides options for labeling the charts if the user choose to show node/element number on the charts, for example, if the stresses were obtained from FEA results, the user wants to identify the node or element number, and weather the stresses were averaged or unaveraged; checking any of the radio buttons has no effect on the analysis results.

 

If the input data were read from ANSYS .rst file, the Stress Type Labeling group box is deactivated, because selection had been made when reading the .rst file.

 

Where component stresses are available, the user can select Loading Type by clicking Proportional or Nonproportional radio buttons.  When von Mises stresses or signed von Mises stresses are used, the Nonproportional request is ignored. The nonproportional fatigue life analysis provides more realistic and rational results when principal stresses change directions with time.  This type of analysis scans critical planes that create highest damage ratios.  For large FEA models, the nonproportional analysis takes significant longer time than proportional analysis.  The user is to take a judgment by inspecting the stress time history chart and decide which loading type to use.

 

Select Report Type by checking Summary, or Report, or Detailed report radio button.  If Summary is selected, the results only show the input summary, cycle counting and damage ratios for the most critical node or element.  If Report is chosen, the standard report format is invoked, which shows not only the contents in Summary, but also the stress time history and critical plane angles where applicable.  The standard report shows results for all nodes or elements where applicable.  Detailed report shows detailed calculations for each stress range in addition to all the contents in standard report.  Depending on the type of analysis selected, sometimes "Report" and "Detailed report" can be identical.

 

The Project Information group box contains Project name, Job No., Created by, Checked by, Approved by, and Date.  There is no limitation on the format of these data.

 

When completed, click OK button to return to the main window.

 

 

 

 

 

 

Copyright © 2022 Fatigue Life LLC