PART 2.4 Compare predictions from BIGBOSOR4 with those from PANDA2 that are listed in PART 1.19, CHAPTER 14 (LOCAL buckling) Compare with the eigenvalue from CHAPTER 14 of the PANDA2
file, cylstif.OPM, for the perfect shell:
BUCKLING LOAD FACTORS FROM BOSOR4-TYPE DISCRETIZED MODEL...
(skin-stringer discretized module of local buckling)
AXIAL BUCKLING KNOCKDOWN FOR KNOCKDOWN FOR BUCKLING HALF- LOAD FACTOR TRANSVERSE SHEAR IN-PLANE SHEAR LOAD FACTOR WAVES BEFORE KNOCKDOWN DEFORMATION LOADING AND/OR AFTER KNOCKDOWN ANISOTROPY
M EIGOLD KSTAR KNOCK EIGOLD*KSTAR*KNOCK 1 1.21563E+00 9.83375E-01 1.00000E+00 1.19542E+00 ---
PART 2.5 Execute the BIGBOSOR4 processor called "bosorplot" in order to get a plot of the critical LOCAL buckling mode Get a plot of the buckling mode:
bush-> bosorplot
Please enter the BIGBOSOR4 case name: cylstif
Do you want to use Xgraph or create a PostScript file? (Choose X or P) p One, maybe Two moments please...
Text file(s) have been created containing plot data. The names of the files explain to a greater or lesser extent what the data represent.
Some plot files contain data for more than one plot.
1) cylstif..R,Z_EIGENMODE_1--N_1 2) cylstif..R,Z_EIGENMODE_2--N_1 3) cylstif..R,Z_EIGENMODE_3--N_1 4) cylstif..R,Z_RingLocation CR) to QUIT
Please choose the number of the file you wish to plot: 1
Plotting: Undeformed & Deformed Axial Station as a function of Radius The PostScript file, metafile.ps, has been created.
Please choose one of the three options below:
1) Rename the PostScript file. This is useful if
you don't have access to a PostScript printer on your machine, but you wish to save to a file so you can later transfer it to a different machine for printing.
Example: mv metafile.ps plot1.ps
2) Enter an "lpr" command. This is useful if your default printer is not PostScript, but there is a PostScript printer available on your system.
Example: lpr -PApplelaser metafile.ps
3) Press the return key. This executes the command:
lpr metafile.ps
This assumes that your default printer is a PostScript printer.
Enter your command> <enter>
Printing PostScript plot on the default printer...
Text file(s) have been created containing plot data. The names of the files explain to a greater or lesser extent what the data represent.
Some plot files contain data for more than one plot.
1) cylstif..R,Z_EIGENMODE_1--N_1 2) cylstif..R,Z_EIGENMODE_2--N_1 3) cylstif..R,Z_EIGENMODE_3--N_1 4) cylstif..R,Z_RingLocation CR) to QUIT
Please choose the number of the file you wish to plot: <enter>
--- end of obtaining the plot file, metafile.ps ---
bush-> cp metafile.ps plot1.ps bush-> gv plot1.ps
("gv" means "ghost view": you will see the buckling mode on your screen. Take a "screen shot" of this buckling mode and store it in the file, 3.cylstif.localbuck.panel.png)
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PART 2.6 Execute the PANDA2 processor called "PANEL" and the BIGBOSOR4 processors, bigbosorall and bosorplot, in order to obtain a plot of the critical GENERAL buckling mode and load factor (eigenvalue)
Next, get a plot from BIGBOSOR4 of buckling of the entire shell from a BIGBOSOR4 model generated via the PANDA2 processor called PANEL. In this BOSOR4 model the T-rings
are smeared out and the T-stringers are modeled as flexible shell segments. 180 degrees of the cylindrical shell are included
in the model. The axial length of the model is 300 inches.
The prismatic shell BIGBOSOR4 model is used.
bush-> panel
Please enter PANDA2 case name: cylstif
The correct input for the PANEL processor follows:
---- input, cylstif.PAN, for PANEL for general buckling model --- --- to be analyzed with BIGBOSOR4 --- n $ Do you want a tutorial session and tutorial output?
314.1600 $ Panel length in the plane of the screen, L2
0 $ Enter control (0 or 1) for stringers at panel edges 2 $ Enter control (1=sym; 2=s.s.) for boundary condition -1 $ Enter ILOCAL=0 or 1 or -1 or -2 (Type (H)elp), ILOCAL
1 $ Number of halfwaves in the axial direction [see H(elp)],NWAVE 3 $ How many eigenvalues (get at least 3) do you want?
--- end of cylstif.PAN file for general buckling model ---
The valid input file for BIGBOSOR4, cylstif.ALL, now exists:
-rw-r--r-- 1 bush bush 167939 Feb 22 11:45 cylstif.ALL This is a long file and is not listed here to save space.
Next, we must run BIGBOSOR4. We copy the file, cylstif.ALL, to another working directory and execute BIGBOSOR4 there.
cd (to new working directory)
cp ../(old working directory)/cylstif.ALL . bush-> bigbosor4log
bush-> bigbosorall
Enter case name: cylstif
B (background), F (foreground), or Q (NQS - network queue system): f Running BIGBOSOR4: bigbosorall, case: cylstif
Executing bigbosorall
Normal termination: bigbosorall Job finished.
Inspect the output file cylstif.OUT
Menu: bosorplot, resetup, cleanup, getsegs, modify, input, help4
Inspect the cylstif.OUT file. Search for the string,
"EIGENVALUE(", including the trailing parenthesis.
You will find the following list output there:
--- from the cylstif.OUT file --- BUCKLING LOADS FOLLOW
AXIAL HALF WAVE NUMBER, N = 1 EIGENVALUES =
2.88019E+00 3.62711E+00 4.75444E+00 **** CRITICAL EIGENVALUE AND WAVENUMBER ****
EIGCRT= 2.8802E+00; NO. OF AXIAL HALF WAVES, NWVCRT= 1 ****************************************************
***** EIGENVALUES AND MODE SHAPES *****
EIGENVALUE(AXIAL HALF WAVES)
=======================================
2.8802E+00( 1)
=======================================
---end of "from the cylstif.OUT file" ---
Compare with the prediction from CHAPTER 26 of PART 1.19:
general buckling: smeared stiffeners, C11= 1.0238E+07, radius, R= 1.0000E+02 (lines skipped to save space)
EIGMNC= 2.72E+00 2.72E+00 3.79E+00 6.72E+00 1.00E+17 2.72E+00 1.00E+17 SLOPEX= 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 MWAVEX= 1 1 2 4 0 1 1 NWAVEX= 3 3 3 5 0 3 0 (lines skipped to save space)
Buckling load factor before t.s.d.= 2.7174E+00 After t.s.d.= 2.4489E+00 (lines skipped to save space)
Number of circumferential halfwaves in buckling pattern= 3.0000E+00 Buckling load factor BEFORE knockdown for smeared stringers= 2.4489E+00 Buckling load factor AFTER knockdown for smeared stringers= 2.2966E+00 General buckling load factor before and after knockdown:
EIGGEN(before modification by 5 factors below) = 2.2966E+00 Knockdown factor from modal imperfection(s) = 1.0000E+00 Knockdown factor for smearing rings on cyl. shell = 9.0000E-01 Knockup factor to avoid twice accounting for t.s.d.= 1.0000E+00 1st modifying factor, FKNMOD=1 or 1/(EIG9X*FMDKD9) = 1.0000E+00 2nd modifying factor, EIGMR9=1 or EIGGNX/EIGGEN = 1.0000E+00
After knockdn,EIGGEN*FKNOCK(9)*(RNGKNK/SHRFCT)*FKNMOD*EIGMR9= 2.0669E+00 ---
Get a plot of the general buckling mode:
bush-> bosorplot
Please enter the BIGBOSOR4 case name: cylstif
Do you want to use Xgraph or create a PostScript file? (Choose X or P) p etc., etc. (as above)
--- end of obtaining the plot file, metafile.ps ---
bush-> cp metafile.ps plot2.ps bush-> gv plot2.ps
("gv" means "ghost view": you will see the buckling mode on your screen. Take a "screen shot" of this buckling mode and store it in the file, 4.cylstif.genrlbuck.panel.png)
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PART 2.7 Execute the PANDA2 processor called "PANEL2" and the BIGBOSOR4 processors, bigbosorall and bosorplot, in order to obtain plots of the critical RING SIDESWAY and INTER-RING buckling modes and load factors (eigenvalues) from BIGBOSOR4
Next, get plots from BIGBOSOR4 of buckling of the entire shell from a BIGBOSOR4 model generated via the PANDA2
processor called PANEL2. In this BOSOR4 model the T-stringers are smeared out and the T-rings are modeled as flexible shell segments. The shell is modeled as a cylindrical shell, not as a prismatic shell as is the case when the PANDA2 processor called PANEL is used.