b | 4.2 | |
K | 1.0 x 1015 |
b1 | -0.238 | |
SRI1 | 3728 MPa |
sine wave 1 at 1 Hz with stress range √10,000 x 1.41 x 2= 282 MPa
sine wave 2 at 10 Hz with stress range √2,500 x 1.41 x 2=141 MPa
Mn = 40,000 x 1n + 10,000 x 10n
Mo = 12,500
M1 = 35,000
M2 = 260,000
M4 = 25,010,000
Operation | Comments |
mcoe | Invoke MCOE from the system prompt. |
Create | Select the Create option. |
Input Filename: simple.psd OK/OK | Enter a file name such as simple.psd. Then click the OK button twice to accept it. The file will be created on completion of the exercise in MCOE. |
Sample Rate: 1 | Enter 1 as the sample rate. |
X-axis Label: Frequency | Change the X-axis label to Frequency. |
X-axis Units: Hz | Change the X-axis label to Hz. |
Y-axis Label: RMS Power | Change the Y-axis label to RMS Power. |
Y-axis Units: MPa2/Hz | Change the Y-axis label to MPa2/Hz. |
OK | Press OK. A spreadsheet will appear. |
1 Hz: 10000; 10 Hz: 2500 | Enter 10,000 in the 1 Hz row and 2,500 in the 10 Hz row for the Y value. Enter zero for all other up to say 11 Hz. |
File/OK | Under the File pulldown menu, select OK. This will save the file. |
mqld | Invoke MQLD from the system prompt. The default file to display should be simple.psd. |
Display | Towers | Change the display to plot as towers as opposed to joined. You should see a plot similar to that in the above figure. |
File | Exit | Quit from MQLD. |
Operation | Comments |
mflf | Invoke MFLF from the system prompt. |
Input Filename: simple.psd | Select the file just created and click the OK button twice. |
Bins Required: 128 | Change the bins to 128 and click OK. |
Dataset Name: | Press the List button here and select any dataset. |
Edit Data: Yes | Turn on the Edit Data switch by setting it to Yes and then press the OK button. |
SRI1: 3728 | Change Stress Range Intercept to this value. |
b1: -0.238 | Change the First Slope to this value and then press the OK button twice. The calculation will proceed. Press the End button after the results are displayed. |
Analysis method | Press the Analysis method button from the main menu options. |
All | Select All as the analysis method. Press OK when the next form is presented. The number of bins should still be set to 128. |
Recalculate life | Press the Recalculate button. The results from all analysis types will be presented. |
End | eXit | Quit from MFLF when you are ready. |
Operation | Comments |
ptime | Invoke PTIME from the system prompt. |
Add an Entry: Waveform creation | Select the Waveform creation option. |
Filename: sinewaves | Enter a new filename such as sinewave. A file called sinewaves.dac will be created. |
Description 1 | Enter an descriptions you wish. |
Number of fatigue equivalent units: 0.0166667 | This is the conversion factor for reporting a one second signal in hours. |
Fatigue equivalent units: Hours | Change this to hours and click the OK button. Do not worry about the units of the actual time series. MPa will be assumed even though the load type is set to Force and the units to Newtons. These are really just labels in most cases. |
Sample Rate: 200 | Change the sample rate to 200. |
Frequency: 1 | Change the frequency to 1. |
Amplitude: 282 | Enter 282 for the amplitude of the first sine wave at 1 Hz and press the OK button. |
Summation | Press the Summation button. |
Next Frequency: 10 | Enter 10 as the next frequency. |
Next Amplitude: 141 | Enter 141 for the amplitude at 10 Hz. Press the OK button when done. |
Finish | Press the Finish button to indicate that no more are to be added. |
Plot an entry | Plot the new time history. Select sinewaves as the input. |
File | Exit | eXit | Exit from MQLD and exit from PTIME. |
mslf | Invoke the S-N single shot fatigue analyzer MSLF. |
Jobname: test | Enter a jobname. It can be anything. |
Filename: sinewaves | Enter the newly created time history as the filename. Press OK twice. |
Dataset Name | Again enter any valid S-N dataset name. |
Edit Data: Yes | Again turn on the Edit Data switch. |
SRI1: 3728 | Enter 3728 as the Stress Range Intercept value. |
b1: -0.238 | Enter this value as the first slope. Press the OK button three times. The results will be displayed. |
End | eXit | Quit from MSLF when you are ready. |
<install_dir>/mscfatigue_files/examples
Operation | Comments |
ptime | Invoke PTIME either from the system prompt (or do it from the MSC.Fatigue Loading Info form by clicking on the Database Manager button). |
ASCII convert + load | Select the “ASCII convert + load” option to read in the ASCII response files. |
ASCII Filename | Use the List button to show the available time histories stored as ASCII files. Select 1pk.asc. |
Sample Rate: 50 | Enter 50 as the sample rate. This is important that you enter the proper sample rate. Otherwise the subsequent conversion to a PSD will be erroneous. |
Equally Spaced Data: X-y pairs | Change this entry to X-y pairs. Press OK. |
Description 1 | Enter a description such as “1 Peak Stress Responses.” |
Load Type: Pressure | This is a stress response time history so enter Pressure as the load type. Even though it is not actually a load type, this is the best equivalent. |
Units: MPa | Give SAETRN the new name, SAETRN15, and also new description. Press OK. The time history SAETRN will be duplicated and will be called SAETRN15. |
Fatigue Equivalent Units: Hours | One repeat of the response is equivalent to 1 hour. So enter Hours as the equivalent units. |
OK | Press the OK button to start the conversion. This operation could take some time since it is a very large response history. |
Plot an entry | Select the Plot option and accept the default. |
eXit | Repeat this exercise for 2pk.asc and 3pk.asc if desired. Then exit from PTIME. |
Operation | Comments |
mslf | Invoke MSLF from the system prompt. |
Jobname | Enter a jobname, say “1pk” for the first response history. Since it does not exist you will be prompted to create it. |
Filename | On the next screen that appears, enter 1pk as the file name. This is the binary converted response time history. Accept all defaults on the rest of this input page. |
OK | Accept all defaults on the next page, Model Parameters, also. |
Database Name: RQT501 | On the Material S-N Analysis form enter RQT501 as the S-N curve. Accept all other defaults. |
OK | Accept all defaults of the next page, Geometry. |
OK / End / eXit | Accept all defaults on the next page, Results Setup. At this point the analysis will proceed. Permit overwrite If asked for overwrite permission. The analysis results should give approximately 3600 repeats. You can repeat this for 2pk and 3pk or exit from MSLF. |
Operation | Comments |
masd | Invoke MASD from the system prompt. |
Input Filename | Use the List button to select the file 1pk.dac. Accept all other input on this form by clicking the OK button. |
OK | Accept all defaults on the next input screen, Parameter Input. |
OK | Accept all defaults on the next input screen, Output Parameters, also. |
End | At this point the PSD has been calculated by the program. By pressing the End button the PSD will be plotted. |
File/Exit | Quit from the graphics program, MQLD, and repeat for the other responses, 2pk and 3pk, if desired. |
Operation | Comments |
mflf | Invoke MFLF (frequency life fatigue) from the system prompt. |
Input Filename | Use the List button to select the file 1pk.psd. Accept all other input on this form by clicking the OK button. |
OK | Accept all defaults on the next input screen, Intermediate Rainflow Options. |
Dataset Name: RQT501 | On the Material S-N Analysis form enter RQT501 as the S-N curve. Accept all other defaults. |
OK | Accept all defaults on the next input form, Geometry. |
End | At this point the program proceeds with the calculations. You should see a life of approximately 3800 hours. |
eXit | You can quit from MFLF and then repeat the exercise for 2pk and 3pk, if desired. |
Time Domain | Dirlik | Narrow Band | Tunna | Wirshing | Hancock | Kam & Dover | Steinberg | |
1pk | 3626 | 3815 | 3762 | 4485 | 5771 | 3839 | 3352 | 5765 |
2pk | 1549 | 1360 | 1015 | 15637 | 1695 | 1303 | 1367 | 1648 |
3pk | 1032 | 1027 | 570 | 62440 | 964 | 870 | 1077 | 936 |
Load Case | Narrow Band | Dirlik | Wirshing | Bishop | Chaudhury | Hancock |
y12a | 5.14 | 1.03 | 3.91 | 1.52 | 2.13 | 2.75 |
y19a | 5.15 | 1.00 | 3.92 | 1.54 | 2.14 | 2.77 |
y27a | 14.34 | 1.59 | 10.91 | 1.74 | 5.12 | 5.83 |
y35a | 81.87 | 2.34 | 62.23 | 1.95 | 30.08 | 25.08 |
y12b | 1.91 | 0.77 | 1.46 | 1.13 | 0.98 | 1.25 |
y19b | 1.98 | 0.81 | 1.50 | 1.22 | 1.04 | 1.31 |
y27b | 3.67 | 1.07 | 2.79 | 1.29 | 1.47 | 1.92 |
y35b | 18.34 | 1.48 | 13.95 | 1.84 | 5.68 | 6.10 |
y12c | 1.98 | 0.76 | 1.51 | 0.86 | 0.95 | 1.25 |
y19c | 1.87 | 0.73 | 1.43 | 0.86 | 0.92 | 1.20 |
y27c | 2.03 | 0.74 | 1.54 | 0.72 | 0.87 | 1.14 |
y35c | 3.22 | 0.76 | 2.45 | 0.66 | 1.15 | 1.42 |
y12d | 2.09 | 0.84 | 1.59 | 1.15 | 1.03 | 1.33 |
y19d | 2.03 | 0.83 | 1.54 | 1.17 | 1.02 | 1.31 |
y27d | 2.92 | 1.01 | 2.22 | 1.15 | 1.23 | 1.62 |
y35d | 7.50 | 1.12 | 5.70 | 1.23 | 2.75 | 3.29 |
y12e | 2.80 | 0.99 | 2.13 | 1.27 | 1.50 | 1.95 |
y19e | 3.06 | 1.01 | 2.33 | 1.27 | 1.50 | 1.95 |
y27e | 3.50 | 1.03 | 2.67 | 1.53 | 1.65 | 2.16 |
y35e | 8.81 | 1.11 | 6.71 | 1.99 | 3.31 | 4.15 |
y12f | 3.86 | 0.98 | 2.93 | 1.43 | 1.66 | 2.18 |
y19f | 3.97 | 1.00 | 3.02 | 1.61 | 1.78 | 2.33 |
y27f | 3.96 | 1.01 | 3.01 | 1.57 | 1.76 | 2.31 |
y35f | 5.59 | 0.98 | 4.25 | 1.65 | 2.17 | 2.80 |
Average: | 7.98 | 1.04 | 6.08 | 1.36 | 3.08 | 3.32 |
Operation | Comments |
ptime | Invoke PTIME from the system prompt. |
Waveform Creation | Select the Waveform Creation selection under Add an Entry or if no entries currently exist select if from the main menu. |
Filename: wave | Give it a name. Call it “wave.” Also give it some description. |
Load Type: Pressure | Give it a load type of pressure to signify stress. |
Units: MPa | Give it units of MPa. |
Number of Fatigue Equivalent Units: 5.5556e-3 | Enter 0.005556 as the number of fatigue equivalent units for a single block of the time history that will be created. |
Equivalent Units: Hours | Enter hours as the equivalent units. Twenty seconds of time history will be defined below but we want the life to be reported to us in hours. Press OK when done. |
Sample Rate: 200 | Enter 200 as the sample rate. This will ensure enough points will be made to define a 10 Hz signal with the proper amplitude. |
Total Time of Signal: 20 | Enter 20 seconds as the total time of the signal. |
Frequency: 10 | Enter 10 Hz as the frequency. Press OK and accept all other defaults. |
Summation Next Frequency: 9.9 | Press the Summation toggle. This will allow you to define another sine wave with a different frequency to be added to the one just created. Enter 9.9 Hz, press OK accepting the defaults. |
Summation Next Frequency: 10.1 | Do it again with 10.1 Hz as the next frequency. |
Finish | Press the Finish toggle to end. |
Plot an Entry | You may plot it to see a varying sine wave very similar to a narrow band signal. |
Change an Entry | Now we will scale the load up to some realistic stress level. Since we are using MPa as the stress units and with the material to be used, RQT501, a scale factor of 50 will do the trick. |
Filename | Accept “wave” as the file name and overwrite it. |
New Value = | For the multiplication value enter 50. This is the second entry. Leave the others at zero. Press OK twice to accept the new scale factor. Note the RMS of the signal is about if you plot it again 61.23. |
eXit | Exit from PTIME. |
Operation | Comments |
masd | Invoke MASD from the system prompt. |
Filename | Enter wave as the input file. Press OK four times accepting the default each time. The resulting PSD will be plotted after accepting the result page. Note that the RMS is around 55, very close to the original time signal. |
File/Exit | Exit from MASD. |
Operation | Comments |
mslf | Invoke MSLF from the system prompt. |
Filename: wave | Enter “wave” as the input file. Press OK twice accepting the default each time. |
Dataset Name: RQT501 | Enter RQT501 as the material on this form. Press OK three times and allow overwrite. The result should be calculated. Note that it is a very large number (~2E8 Hours). |
End | Leave MSLF running for now and move on to the next step. |
Operation | Comments |
mflf | Invoke MFLF from the system prompt. |
Filename: wave | Enter “wave” as the input file. Press OK twice accepting the default each time. Ignore any warning message. |
Dataset Name: RQT501 | Enter RQT501 as the material name. Press the OK button accepting the defaults until the analysis runs. Note the life is close to 6 years. |
End | Leave MFLF running for now and move on to the next step. |
Operation | Comments |
mflf or mslf | Both these programs should still be running. |
Loading Environment | Enter the Loading Environment menu. |
Scale Factor | Change the scale factor to 2 and accept all other defaults. |
Recalculate | Press the recalculate button. |
eXit | Leave MSLF/MFLF or repeat this exercise for the table of scale factors in Table 14‑16. |
Scale Factor | Time Domain | Dirlik | Narrow Band |
1 | 1.25E6 | 51,290 | 67,381 |
2 | 20 | 13 | 13 |
2.25 | 5.4 | 3.5 | 3.4 |
2.5 | 1.6 | 1.06 | 1.04 |
2.75 | 2025 Seconds | 1303 Seconds | 1279 Seconds |
3.0 | 762 Seconds | 490 Seconds | 1.7 Seconds |
3.1 | 451 Seconds | 339 Seconds | 1.7 Seconds |
3.2 | 221 Seconds | 237 Seconds | 1.7 Seconds |
Operation | Comments |
ptime | Invoke PTIME from the system prompt or from MSC.Patran. It is assumed that the 1PK, 2PK, and 3PK signals are loaded into PTIME already from the previous exercise. If not, load them now or import the ASCII versions as described earlier. |
Change and entry | Polynomial transform | Select this option from the main menu. |
Database Entry to Transform:1PK | Select 1PK as the signal to modify. |
Target Filename: 1PK_PSI | Enter a new name such as 1PK_PSI. We are going to change the descriptive units to PSI since they are the units of the FE model. |
New Value = 0.15 x <old value> | Enter 0.15 in the second databox to act as a multiplier and scale loading history. Press OK. |
Units: lbs force | Change the units to lbs force. |
Number of fatigue equivalent units: 1.3889 | Change this to 1.3889 which is how many hours are in 5000 seconds, the length of the signal. |
Fatigue equivalent units: Hours | Change this to report the life in hours. Press the OK button. |
eXit | Exit from PTIME. |
Operation | Comments |
patran | Invoke MSC.Patran (or MSC.Fatigue Pre & Post) if you have not already done so. |
File / New... | Open a new database from the File pull -down menu. Call it “vibration.” Set the analysis preference to MSC.Nastran if asked. Ignore any warning messages. |
Analysis | Open the Analysis application (or Import in MSC.Fatigue Pre & Post) from the main form of MSC.Patran. |
Action: Read Output2 Object: Both Method: Translate | Set the Action, Object, and Method accordingly. |
Select Results File... | Select the MSC.Nastran OUTPUT2 file to import for the static analysis. It is called bracket_stat.op2. |
Apply | Press the Apply button to import the model into the database. |
Tools / FATIGUE... (Analysis) | Invoke MSC.Patran’s FATIGUE interface by selecting it from under the Tools pull-down menu (or the Analysis application switch in MSC.Fatigue Pre & Post.) |
General Setup Parameters: | |
Analysis: S-N | Set the analysis type to S-N on the main form. |
Res. Units: PSI | Set the units to PSI. |
Jobname: static | Give the job a name. Use “static.” |
Title: Static Example | Give the job a title. |
Solution Parameters Form: | |
Mean Stress Correction: None | Set the parameter to None. The mean of the random response loading is essential zero, so no mean stress correction is necessary. |
Materials Information Form: | |
Material: MANTEN | Place the cursor in the cell under the word Material and click on the mouse. A listbox will appear. Select the material MANTEN from this listbox. |
Finish: Polished | Select Polished from the option menu that appears. The word polished appears in the Finish cell. The SAE specimen was a polished specimen with no surface treatment. |
Treatment: No Treatment | Select No Treatment from the option menu that appears. |
Region: default_group | Select the default group as the region. This contains the node we created at the beginning of this exercise. The Materials Information form can be closed down now by clicking the OK button. You may wish to create a group with only Node 47 in it to expedite the analysis since this is the critical node which we will be looking at in more detail later. If you do, reference this group here. |
Loading Information Form: | |
Results Transformation: Transform to Basic | Set the transformation to Basic so that proper averaging of the element nodal stress results occurs. |
Load Case ID | Activate this cell to make the widgets at the bottom of the form appear. |
Get/Filter Results | Open this form to get the results. |
Select All Results Cases | The easiest way to get the results is to press this toggle and then press the Apply button. |
Select a Results Load Case: | Select the only Results Case that appears in this list box. |
Select a Stress Tensor: | Select the result that says “Stress Tensor.” |
Fill Cell | Press this button to fill the spreadsheet cell with the Results Case ID. |
Time History: 1PK_PSI | Select 1PK_PSI which we created earlier. |
Load Magnitude: 1.0 | Accept the default here by pressing the RETURN key. |
Job Control Form: | |
Full Analysis | Set the action to Full Analysis and press the Apply button. This could take some time if you analyzer the entire model. |
Monitor | Monitor the job if you wish. |
Operation | Comments |
ptime | Invoke PTIME from the system prompt. |
Add an entry... | creaTe psd from time | Select this option from the main menu. This will invoke a separate module called MASD for auto-spectral density calculations. |
Input Filename: 1PK_PSI | When MASD starts, select 1pk_psi as the input filename. |
OK/OK/OK/End | Press the OK button three times to invoke the action. The time signal has now been converted into a loading input PSD. Press the End button to continue. |
Description 1 | Enter any description here. |
Units: lbs force | Change the units. The rest of the form does not need be modified., so click the OK button. A new entry and file called 1pk_psi.psd exists. |
eXit | Exit from PTIME. |
Operation | Comments |
patran | Invoke MSC.Patran (or MSC.Fatigue Pre & Post) if you have not already done so. |
File / Open... | Open the old database from the File pull -down menu if necessary. |
Analysis | Open the Analysis application (or Import in MSC.Fatigue Pre & Post) from the main form of MSC.Patran. |
Action: Read Output2 Object: Results Entities Method: Translate | Set the Action, Object, and Method accordingly. |
Select Results File... | Select the MSC.Nastran OUTPUT2 file to import for the static analysis. It is called bracket_freq.op2. |
Apply | Press the Apply button to import the model into the database. |
Tools / FATIGUE... (Analysis) | Invoke MSC.Patran’s FATIGUE interface by selecting it from under the Tools pull-down menu (or the Analysis application switch in MSC.Fatigue Pre & Post.) |
General Setup Parameters: | |
Analysis: Vibration | Set the analysis type to Vibration on the main form. |
Res. Units: PSI | Set the units to PSI. |
Jobname: vibration | Give the job a name. Use “vibration.” |
Title: Vibration Example | Give the job a title. |
Solution Parameters Form: | |
Mean Stress Correction: None | Set the parameter to None. |
Materials Information Form: This should be setup identically to the pseudo-static job. | |
Loading Information Form: | |
Results Transformation: Transform to Basic | Set the transformation to Basic so that proper averaging of the element nodal stress results occurs. |
Frequency Resp | Activate this cell to make the widgets at the bottom of the form appear. |
Get/Filter Results... | Open this form from the Loading Information form. Select the only Result Case that appears in this top of this form. It may already be selected for you (LOAD_CASE, 58 subcases). |
Filter Method:Global Variable - Variable:Frequency | Turn this option menu to Global Variable and set the Variable to Frequency. This may already be the default settings. |
Filter/Add/Close | Press the Filter button. This will filter only subcases with frequency step information from the Result Case. Remember there is a static load case in these also. Press the Apply button. This will load an abbreviation of the frequency steps into the listbox on the Loading Information form which will be used in the analysis. Close the form down when done. |
Select a Results Load Case: | Select the only Results Case abbreviation that appears in this list box. |
Select a Stress Tensor: | Select the result that says “Stress Tensor.” |
Fill Cell | Press this button to fill the spreadsheet cell with the Results Case IDs. |
Time History: 1PK_PSI.PSD | Select 1PK_PSI.PSD which we created earlier. |
Job Control Form: | |
Full Analysis | Set the action to Full Analysis and press the Apply button. This could take some time if you analyzer the entire model. |
Monitor | Monitor the job if you wish. |
Operation | Comments |
Results... | Open the Results... form from the main MSC.Fatigue form. |
List Results | Set the Action to List Results and click the Apply button. PFPOST will be invoked. |
OK/OK | Press the OK button twice accepting the defaults. |
Most damaged nodes | Select this option to display a list of the most damaged nodes. Take note of the life at node 47. |
Cancel/Cancel | Press the Cancel button twice. |
Jobname: static | Enter “static” as another jobname to view the results from the quasi-static fatigue analysis. |
OK/OK | Press OK twice. |
Most damaged nodes | Again note the life at node 47. |
Cancel | Close the report down. |
eXit | Exit from PFPOST. |
Job | 1pk | 2pk | 3pk |
static | 295 Hrs. | 136 Hrs. | 97 Hrs. |
vibration (15f) | 450 Hrs. | 150 Hrs. | 111 Hrs. |
vibration (29f) | 261 Hrs. | 99 Hrs. | 76 Hrs. |
vibration (57f) | 234 Hrs. | 94 Hrs. | 71 Hrs. |
vibration (141f) | 229 Hrs. | 90 Hrs. | 68 Hrs. |
vibration (ALLf) | 241 Hrs. | 94 Hrs. | 71 Hrs. |
Scale Factor | Time Domain | Dirlik |
0.5 | 1,290,000 | 518,767 |
0.6 | 78,900 | 57,728 |
0.7 | 13,977 | 10,468 |
0.8 | 3,130 | 2,505 |
0.9 | 906 | 719 |
1.0 | 295 | 236 |
1.1 | 108 | 87 |
1.2 | 43 | 35 |
1.3 | 15 | 15 |
1.4 | 3.1 | 6.8 |
1.5 | 0 | 3.3 |