WORKSHOP PROBLEM 1d

Spring Element with Nonlinear

Analysis Parameters
(Restart a Multi-Step Analysis)

Objectives:
Demonstrate the use of the restart feature on the previous
analysis by introducing an intermediate load case and
using the data obtained from the first part of the previous
analysis.

MSC/NASTRAN 103 Exercise Workbook

1d-1

1d-2

MSC/NASTRAN 103 Exercise Workbook

Spring Element w/ Nonlin Params

WORKSHOP 1d

Model Description:
For the structure below:
Y

CROD
A = 0.01 in2
E = 1.E7 psi
L = 10.0 in

K = 1.E3 lb/in
P = 29.E3 lbs
X
CELAS1

Add Case Control commands and Bulk Data Entries to:

1.

Add a new subcase before the third subcase and restart

the analysis from a 20x103 lbs load in the new subcase
with 8 increments. Restarting a job with increased
increments is a common practice when dealing with
convergence problems.

MSC/NASTRAN 103 Exercise Workbook

1d-3

Suggested Exercise Steps:

Modify the existing MSC/NASTRAN input file by adding
the subcase and appropriate restart analysis control
parameters and saving it as prob1d.dat.
Request the data stored in prob1c analysis run to be used in
the current analysis (ASSIGN, RESTART).
Designate the appropriate restart parameters (LOOPID,
SUBID).
Add a new subcase before the third subcase with the
appropriate nonlinear analysis parameters (SUBCASE,
NLPARM).
Delete all entries in the existing Bulk Data section, and add
the new NLPARM entry.
Generate an input file and submit it to the MSC/NASTRAN
solver for nonlinear static analysis.
Review the results.

1d-4

MSC/NASTRAN 103 Exercise Workbook

WORKSHOP 1d

Spring Element w/ Nonlin Params

Input File from Workshop 1c for Modification:

prob1c.dat
ASSIGN OUTPUT2 = prob1c.op2 , UNIT=12
ID NAS103, WORKSHOP 1C SOLUTION
TIME 10
SOL 106 $ NONLIN
CEND
TITLE=SIMPLE ROD SPRING - COLD ANALYSIS AND RESTART WORKSHOP
SUBTITLE=GEOMETRIC NONLINEAR
ECHO=BOTH
DISP=ALL
OLOAD=ALL
FORCE=ALL$
SPCF=ALL
$ APPLY X LOAD
$
SUBCASE 10 $ LOAD=16.E03
LABEL=APPLY LOAD P IN X DIRECTION = 16E+03
LOAD=1
NLPARM=10
SUBCASE 20 $ LOAD=24.E03
LABEL=APPLY LOAD P IN X DIRECTION = 24E+03
LOAD=2
NLPARM=20
SUBCASE 30 $ LOAD=29.E03
LABEL=APPLY LOAD P IN X DIRECTION = 29E+03
LOAD=3
NLPARM=30
OUTPUT(PLOT)
SET 1 ALL
MAXI DEFO 5.
AXES Z, X, Y
VIEW 0., 0., 0.
FIND SCALE ORIGIN 1 SET 1
PLOT STATIC 0 MAXIMUM DEFORMATION 5. SET 1
BEGIN BULK
PARAM, POST, -1
PARAM, PATVER, 3.0
GRID, 1, 0, 0.0, 0.0, 0.0, , 23456
GRID, 3, 0, 0.0, 10.0, 0.0, , 123456
CROD, 3, 3, 3, 1
MSC/NASTRAN 103 Exercise Workbook

1d-5

CELAS1, 2, 2, 1, 1, 0
PROD, 3, 3, .01
PELAS, 2, 1.0E3
MAT1, 3, 1.0E7
FORCE, 1, 1, 0, 1.6E4, 1.0
FORCE, 2, 1, 0, 2.4E4, 1.0
FORCE, 3, 1, 0, 2.9E4, 1.0
PARAM, LGDISP,1
NLPARM, 10, 4, , SEMI, , , , YES, +
+, , , , , 0, 0, , , +
+, 0
NLPARM, 20, 8, , AUTO, , , W, YES
NLPARM, 30, 2
ENDDATA

1d-6

MSC/NASTRAN 103 Exercise Workbook

Spring Element w/ Nonlin Params

WORKSHOP 1d

Exercise Procedure:
1.

Users who are not utilitizing MSC/PATRAN

for generating an input file should go to Step
4, otherwise, proceed to step 2.

2.

Open the existing database called prob1a.db.

File/Open...
Database List:

prob1a

OK
3.

Set up the new subcase and restart parameters through the

analysis form.

Analysis
Action:

Analyze

Object:

Restart

Method:

Analysis Deck

Select an Initial Job

prob1c

Restart Job Name

prob1d

Subcase Create ...

Subcase Name

case_2a

Available Load Cases

case_2

Subcase Parameters...
Number of Increments

Matrix Update Method:

Automatic

OK
Output Requests ...
Form Type:

Advanced

Output Requests:

STRESS(SORT1...

Delete
MSC/NASTRAN 103 Exercise Workbook

1d-7

Select Result Type

Element Forces

Create
Intermediate Output Option:

Yes

OK
Apply
Cancel
Subcase Select...
Double click on the Unselect All radio button to clear all the
selected subcases.
Next, select the following subcases in this order:.
Subcases for Solution Sequence:

case_1
case_2
case_2a
case_3

OK
Restart Parameters...
Start from Version Number =

Start from Increment

Number (LOOPID) =

Start from Subcase

Number (SUBID+1) =

3
Save Old Restart Data

OK
Apply
Another input file called prob1d.bdf will be generated.
MSC/PATRAN users should now proceed to Step 5.

1d-8

MSC/NASTRAN 103 Exercise Workbook

Spring Element w/ Nonlin Params

WORKSHOP 1d

Generating an input file for MSC/NASTRAN Users:

4.

MSC/NASTRAN users can generate an input file using

the the input file from the previous exercise (prob1c.dat).
The result should be similar to the output below
(prob1d.dat):

ASSIGN OUTPUT2 = prob1d.op2 , UNIT=12

ASSIGN MASTER = prob1c.MASTER
RESTART VERSION=1,KEEP
ID NAS103, WORKSHOP 1D SOLUTION
TIME 10
SOL 106 $ NONLIN
CEND
TITLE=SIMPLE ROD SPRING - COLD ANALYSIS AND RESTART WORKSHOP
SUBTITLE=GEOMETRIC NONLINEAR
ECHO=BOTH
PARAM,LOOPID,8
PARAM,SUBID,3
DISP=ALL
OLOAD=ALL
FORCE=ALL$
SPCF=ALL
$ APPLY X LOAD
$
SUBCASE 10 $ LOAD=16.E03
LABEL=APPLY LOAD P IN X DIRECTION = 16E+03
LOAD=1
NLPARM=10
SUBCASE 20 $ LOAD=24.E03
LABEL=APPLY LOAD P IN X DIRECTION = 24E+03
LOAD=2
NLPARM=20
SUBCASE 21
LOAD=2
NLPARM=21
SUBCASE 30 $ LOAD=29.E03
LABEL=APPLY LOAD P IN X DIRECTION = 29E+03
LOAD=3
NLPARM=30
OUTPUT(PLOT)
SET 1 ALL
MAXI DEFO 5.
MSC/NASTRAN 103 Exercise Workbook

1d-9

AXES Z, X, Y
VIEW 0., 0., 0.
FIND SCALE ORIGIN 1 SET 1
PLOT STATIC 0 MAXIMUM DEFORMATION 5. SET 1
BEGIN BULK
NLPARM, 21, 8, , AUTO, , , , YES
ENDDATA

1d-10 MSC/NASTRAN 103 Exercise Workbook

Spring Element w/ Nonlin Params

WORKSHOP 1d

Submit the input file for analysis:

5.

Submit the input file to MSC/NASTRAN for analysis.

5a.

To submit the MSC/PATRAN .bdf file, find an available

UNIX shell window. At the command prompt enter
nastran prob1d.bdf scr=yes. Monitor the analysis
using the UNIX ps command.

5b.

To submit the MSC/NASTRAN .dat file, find an

available UNIX shell window and at the command
prompt enter nastran prob1d.dat scr=yes. Monitor the
analysis using the UNIX ps command.

6.

When the analysis is completed, edit the prob1d.f06 file

and search for the word FATAL. If no matches exist,
search for the word WARNING. Determine whether
existing WARNING messages indicate modeling errors.

6a.

While still editing prob1d.f06, search for the word:

D I S P L A C E (spaces are necessary).

What is the x-displacement of the guided end at the end of
the restart?
T1 =

MSC/NASTRAN 103 Exercise Workbook 1d-11

Comparison of Results:
7.

Compare the results obtained in the .f06 file with the

results on the following page:

1d-12 MSC/NASTRAN 103 Exercise Workbook

SUBCASE 1
LOAD STEP =

1.00000E+00

POINT ID.
1
2
SUBCASE 2
LOAD STEP =

TYPE
G
G

T1
6.300765E+00
0.0

T2
0.0
0.0

T3
0.0
0.0

R1
0.0
0.0

TYPE
G
G

T1
7.062655E+00
0.0

T2
0.0
0.0

T3
0.0
0.0

MSC/NASTRAN 103 Exercise Workbook 1d-13

SUBCASE 4
LOAD STEP =

R1

R2
0.0
0.0

R3
0.0
0.0

3.00000E+00

TYPE
G
G

T1
7.751178E+00
0.0

T2
0.0
0.0

T3
0.0
0.0

V E C T O R
R1

0.0
0.0

R2
0.0
0.0

R3
0.0
0.0

4.00000E+00
D I S P L A C E M E N T

POINT ID.
1
2

V E C T O R

0.0
0.0

D I S P L A C E M E N T
POINT ID.
1
2

R3
0.0
0.0

TYPE
G
G

T1
8.540173E+00
0.0

T2
0.0
0.0

T3
0.0
0.0

V E C T O R
R1

0.0
0.0

R2
0.0
0.0

R3
0.0
0.0

Spring Element w/ Nonlin Params

SUBCASE 3
LOAD STEP =

R2
0.0
0.0

1.50000E+00
D I S P L A C E M E N T

POINT ID.
1
2

V E C T O R

WORKSHOP 1d

D I S P L A C E M E N T

8.

This ends the exercise for MSC/NASTRAN

users. MSC/PATRAN users should proceed to
the next step.

9.

Open a new database to import the results.

First, close the present database.

File/Close
Next, create a new database titled prob1d.db
File/New...
New Database Name:

prob1d

OK
In the New Model Preference form set the following:
Tolerance:

Default

Analysis Code:

MSC/NASTRAN

Analysis Type:

Structural

OK
10.

Proceed with the Reverse Translation process, that is,

importing the prob1d.op2 results file into MSC/
PATRAN. To do this, return to the Analysis form and
proceed as follows:

Analysis
Action:

Read Output2

Object:

Both

Method:

Translate

Select Results File...

Selected Results File:
OK
Apply

1d-14 MSC/NASTRAN 103 Exercise Workbook

prob1d.op2

Spring Element w/ Nonlin Params

WORKSHOP 1d

11.

When the translation is complete bring up the Results form.

Now we will generate the fringe plot of the model.

Results
Action:

Create

Object:

Fringe

Now click on the Select Results icon.

Select Results

Select Result Case(s)

(Seqentially select the result

cases.)

Select Fringe Result

Displacements, Translational

Quantity:

Magnitude

Next click on the Target Entities icon.

Target Entities

Target Entity:

Current Viewport

Click on the Display Attributes icon.

Display Attributes

Style:

Discrete/Smooth

Display:

Free Edges

For better visual quality of the fringe plot, change the width of
the line.
Width:

(Select the third line from top.)

MSC/NASTRAN 103 Exercise Workbook 1d-15

Now click on the Plot Options icon.

Plot Options

Coordinate Transformation:

None

Scale Factor

1.0

Apply
The final fringe plot displaying the physical deformation of the model
can be created as follows:
Results
Action:

Create

Object:

Deformation

Now click on the Select Results icon.

Select Results

Select Result Case(s)

(Seqentially select the result

cases.)

Select Fringe Result

Displacements, Translational

Show As:

Resultant

Click on the Display Attributes icon.

Display Attributes
In order to see the deformation results accurately, set the display
scale factor to actual deformation (=1).
Line Width:

(Select the third line from top.)

True Scale
Scale Factor

1.0

Show Undeformed
Line Width:
1d-16 MSC/NASTRAN 103 Exercise Workbook

(Select the third line from top.)

WORKSHOP 1d

Spring Element w/ Nonlin Params

Now click on the Plot Options icon

Plot Options

Coordinate Transformation:

None

Scale Factor

1.0

Apply

As you look at each result case, you will notice that the change in
deflection lessens as more of the loading force is axially
distributed. This is the benefit of running a nonlinear geometric
analysis, which accounts for large displacements that change the
distribution of the force along the beam.
Quit MSC/PATRAN when you have completed this exercise.

MSC/NASTRAN 103 Exercise Workbook 1d-17

MSC/PATRAN .bdf file: prob1d.bdf

$ NASTRAN input file created by the MSC MSC/NASTRAN input file
$ translator ( MSC/PATRAN Version 7.5 ) on January 16, 1998 at
$ 11:51:40.
ASSIGN OUTPUT2 = prob1d.op2, UNIT = 12
$ Direct Text Input for File Management Section
ASSIGN MASTER=prob1c.MASTER
RESTART VERSION=1,KEEP
$ Nonlinear Static Analysis, Database
SOL 106
TIME 600
$ Direct Text Input for Executive Control
CEND
SEALL = ALL
SUPER = ALL
TITLE = MSC/NASTRAN job created on 16-Jan-98 at 11:51:35
PARAM,LOOPID,8
PARAM,SUBID,3
ECHO = NONE
MAXLINES = 999999999
$ Direct Text Input for Global Case Control Data
SUBCASE 1
$ Subcase name : case_1
SUBTITLE=case_1
NLPARM = 1
SPC = 2
LOAD = 2
DISPLACEMENT(SORT1,REAL)=ALL
SPCFORCES(SORT1,REAL)=ALL
FORCE(SORT1,REAL,BILIN)=ALL
$ Direct Text Input for this Subcase
SUBCASE 2
$ Subcase name : case_2
SUBTITLE=case_2
NLPARM = 2
SPC = 2
LOAD = 4
DISPLACEMENT(SORT1,REAL)=ALL
SPCFORCES(SORT1,REAL)=ALL
FORCE(SORT1,REAL,BILIN)=ALL
$ Direct Text Input for this Subcase
SUBCASE 3
$ Subcase name : case_2a
SUBTITLE=case_2
NLPARM = 3
1d-18 MSC/NASTRAN 103 Exercise Workbook

WORKSHOP 1d

Spring Element w/ Nonlin Params

SPC = 2
LOAD = 6
DISPLACEMENT(SORT1,REAL)=ALL
SPCFORCES(SORT1,REAL)=ALL
FORCE(SORT1,REAL,BILIN)=ALL
$ Direct Text Input for this Subcase
SUBCASE 4
$ Subcase name : case_3
SUBTITLE=case_3
NLPARM = 4
SPC = 2
LOAD = 8
DISPLACEMENT(SORT1,REAL)=ALL
SPCFORCES(SORT1,REAL)=ALL
FORCE(SORT1,REAL,BILIN)=ALL
$ Direct Text Input for this Subcase
BEGIN BULK
/,1,999999
PARAM POST -1
PARAM PATVER 3.
PARAM AUTOSPC NO
PARAM COUPMASS -1
PARAM K6ROT 100.
PARAM WTMASS 1.
PARAM LGDISP 1
PARAM,NOCOMPS,-1
PARAM PRTMAXIM YES
NLPARM 1
4
SEMI 5
25
PW
+
A
.001 1.-7
NLPARM 2
8
AUTO 5
25
W
+
B
1.-7
NLPARM 3
8
AUTO 5
25
PW
+
C
.001 1.-7
NLPARM 4
5
AUTO 5
25
PW
+
D
.001 1.-7
$ Direct Text Input for Bulk Data
$ Elements and Element Properties for region : prop_1
PROD 1
1
.01
CROD 1
1
1
2
$ Elements and Element Properties for region : prop_2
PELAS 2
1000.
CELAS1 2
2
1
1
$ Referenced Material Records

YES

YES

YES

NO

MSC/NASTRAN 103 Exercise Workbook 1d-19

$ Material Record : mat_1

$ Description of Material : Date: 19-Jun-97
Time: 15:12:40
MAT1 1
1.+7
$ Nodes of the Entire Model
GRID 1
0.
0.
0.
GRID 2
0.
10. 0.
$ Loads for Load Case : case_1
SPCADD 2
10
12
LOAD 2
1.
1.
1
$ Loads for Load Case : case_2
LOAD 4
1.
1.
5
$ Loads for Load Case : case_2
LOAD 6
1.
1.
5
$ Loads for Load Case : case_3
LOAD 8
1.
1.
7
$ Displacement Constraints of Load Set : constraint_1
SPC1 10
123456 2
$ Displacement Constraints of Load Set : constraint_2
SPC1 12
23456 1
$ Nodal Forces of Load Set : load_3
FORCE 7
1
0
29000. 1.
0.
0.
$ Nodal Forces of Load Set : load_1
FORCE 1
1
0
16000. 1.
0.
0.
$ Nodal Forces of Load Set : load_2
FORCE 5
1
0
24000. 1.
0.
0.
$ Referenced Coordinate Frames
ENDDATA 6b9c8805

1d-20 MSC/NASTRAN 103 Exercise Workbook