case3_1

the

only

nt side

where

nel, the

uring a

dash

om the

Case 3 : Buckling Analysis of Front Side Member

ABSTRACT: The buckling analysis of the front side panel is performed to verify aspects of

deformation during a frontal crash. The analysis model is generated from the early design data

(typcially the shapes of the cross section) when there is no detailed design information about the fro

panel of the vehicle. The buckling analysis is also done during the early stages of design, in a period

the structural changes are possible. The front side panel is to be connected to the fender inner pa

dash panel, and the lower dash member of the car body. Since the role of the fender inner panel d

frontal impact is insignificant, the analysis is done by constraining only the locations connected to the

panel and lower dash member. The load is applied at the connections to the fender. The results fr

analysis are used to decide whether reinforment should be added.

Solution Type : Sol 105 Buckling Analysis

< Model Geometry >

206

or each

n

g.

The fir st step : Modeling

File | New... New Data Base Name : case3

There are five neutral files prepared for each component. Before reading these files, create group f

component.

Group | Create New Group to Name : inner

-Apply- Elements to be created from now on will be included i

the current group, inner.

Read a model to be meshed. File | Import...

Find the directory including neutral files and select ‘inner’ file.

Neutral Options...

Select entities required in the first imported file.

Select nodes and elements only.

Ok

- Apply-

Click OK about a message being displayed when importin

207

Display | Finite Elements...

Shrink factor : 0.07

Group | Create... New Group Name : inner_ref

Make Current

Unpost All Other Groups

-Apply-

File | Import... inner_ref.out Click

-Apply-

It is not necessary to define Neutral Option again.

Group | Create... New Group Name : outer

Make Current


-Apply-

208

File | Import... out_pan.out.1 Click

-Apply-

Group | Create... New Group Name : extend

Make Current


-Apply-

File | Import... add_outer.out.1 Click

-Apply-

Connect each component by RBE2.

209

e

.

Connect the inner panel and the inner reinforcement.

Group | Post... inner

inner_ref

Post onlt two groups.

Define a current Group to the inner group.

Set nodes in the inner group to be

independent nodes, and creat

RBE2 (nodes inside circles).

Finite Elements

Determine the dependent node and the independent node

210

e

y

s

Auto Switch is on.

Select one dependent node to on

independent node, and create RBE2.

If clicking nodes of the inner_ref

component, then it becomes an

independent node.

Fix all DOF via dragging mouse.

Select independent nodes b

referring to the previous picture,

and click apply under Define

Terms....

Select nodes from left to right.

Define nodes in the inner group a

independent nodes.

Node Label (depen. Indepen.)

(8 259) (9 260) (10 261)

(11 262) (12 263)

Create five RBE2 according to

node label.

211

(175 337) (176 338) (180 293)

(179 326) (186 294) (225 295)

(230 329 ) (223 303) (47 324)

(101 449) (99 448) (33 400)

212

(34 401) (35 402) (36 403)

(195 346) (193 349) (192 374)

(133 381) (132 387)

(127 390) (119 395)

213

s

Connect the inner component and the outer component.

Group | Post... Post the inner and the outer only.

The current group is the inner group.

Create | MPC | RBE2 Define Terms...

Connect the flange line between components.

Connect nodes of theflange line

crossly.

Define nodes in the inner group a

independent nodes by referring to

the location of circles.

(726 265) (718 266) (724 267)

(716 268) (722 275) (714 325)

214

.

215

(888 705) ( 890 450) (874 501)

Keep connecting the flange line

(876 497) (873 399)

(1118 502) (508 848)

(509 940) (942 484)

(513 943) (946 578) (947 930)

Connect the lower-end flange

line.

216

o

s

Create | MPC | RBE2

MPC ID

From 46

Define Terms

Keep defining nodes in the inner

group as independent nodes.

(759 363) (756 361) (762 365)

(755 352)

MPC 21 to MPC 24 are created by

the edit adding dependent nodes t

MPC created already.

Modify | MPC

MPC ID

Click the list box and select MPC

21.

Click Modify Terms....

Turn on Modify.

Click column 195 listed up in

Dependent Terms.

Change Select Menu to + and

select Node 809, and then 809 i

listed behind 195.

Do apply twice, and then it is modified.

Again click MPC ID box, and then select MPC 22 on the graphic screen.

Click Modify Terms.... Add nodes listed below to each MPC.

MPC 22 ( Dependent Node : 812 )

MPC 23 (Dependent Node : 814 )


MPC22

MPC21

MPC23

MPC24

217

e

e

g-

o-

Because RBE2 inside the four large

circle has the same location as th

location where they are connected

with the inner_ref component, use

Modify adapted previously without

creating new one.




Modify | MPC MPC ID Select RBE2 to be modified.

Modify Terms...

Modify

After clicking Dependent Node box, add nodes of th

outer component in Node List Box.

This is to define dependent node as two without chan

ing independent nodes (nodes of the inner comp

nent).

-Apply-

Connect the inner component and the extend component.

MPC25

MPC26

MPC27

218

d

.

Group | Post... Post the inner and the extend groups only.

A current group is the inner.

Create | MPC | RBE2

Define Terms...

Define nodes in the inner compo-

nent as independent nodes an

create RBE2.

(Circles in the picture)

(1081 474) (1078 529)

(1083 559) (1080 531)

Only dependent nodes are posted

(1024 524) (1021 520)

(1026 526) (1023 522)

(1019 528) (1012 535)

219

s). But,

BE2

d

Connect the outer and the extend.

Group | Post... Post the inner, outer, and extend groups.

A current group is the extend.

Create RBE2, selecting dependent and independent node one to one (based on the location of circle

use Modify like the previous way at the junction of three groups, inner, outer, and extend, where R

points are duplicated (modify only the RBE2 of point 1).

For this portion, create RBE2 in

zigzags, and connect the outer an

the extend.

1

220

Create | MPC | RBE2

Define Terms..

(1086 866) MPC52 (add 1082)

(1089 868) (1095 832)

(1091 923) (1094 924)

(1060 902) (1062 908)

(1064 904) (1066 910)

Post only the outer and extend

groups to select nodes easily.

Group | Post...

Post the outer and the extend group.

A current group is the extend group.

(1139 1371) (1138 1369)

(1140 1365) (1132 1131,1363)

Two dependent nodes are used.

(1130 1359) (1129 1357)

(1128 1355)

(1130 1359) (1129 1357)

(1128 1355)

221

(1126 1353) (1127 1337)

(1145 1331) (1098 1271)

(1143 1340) (1097 1255)

( 1142 1346) (1137 1350)

(1136 1377) (1134 1375)

(1133 1373)

222

s nec-

s

).

If the connection between components is done without omitting, then edit the properties and thicknes

essary for analyzing.

First of all, create the material table to apply thickness.

Materials

Define the name of a material.

Click and edit Youngs Modulus (20700) and Poisson

Ratio (0.3).

-Apply-

Edit the thickness of each component. Post only the group whose thickness is 1.2 (inner and inner_ref

Group | Post... Select the inner and the inner_ref.

A current group is the inner.

Properties

Create | 2D | Shell Property Set Name : thick_1.2

Input Properties..

Material Name : steel

Thickness : 1.2

Ok

Select Members

223

-

n

After changing Select Menu to 2D

Shell, select elements on the

screen.

If element list is registered in

Application Region, then do

apply.

Post only the group whose thickness is 1.4 (outer, extend). A current group is the outer.

Create | 2D | Shell Property Set Name : thick_1.4

Input Properties..

Material Name : steel

Thickness : 1.4

Ok

Select Members

After changing Select Menu to 2D Shell, select ele

ments on the screen.

If element list is registered in Application Region, the

do apply.

224

Create boundary conditions.

Loads / BCs

Define from elements of the inner group. Post the inner group only.

Create | Displacement | Nodal New Set Names : all_fixed

Input Data...

Translations < T1 T2 T3 >

< 0 0 0 >

Rotations < R1 R2 R3 >

< 0 0 0 >

Ok

Select Application Regions

FEM

Select Nodes

Select all nodes on the end of the frame model.

Add

Ok

-Apply-

Post the outer and extend groups only and define the outer as a current group.

225

t

, define

.

Modify | Displacement | Nodal

Select all_fixed.

Click Modify Application

Region….

Set Select Menu to =, and selec

the end nodes only.

Add

-Apply-

Edit the loads.

Create a center point at the very front cross-section and define that as the independent node. And then

nodes around the cross-section as dependent nodes and connect the very front nodes by RBE2.

Group | Post... Post the inner and the outer only.

A current group is the outer.

Creating a Center Point

Geometry

Create | Point | Interpolate Option : Point

Number of Point : 1

Uniform

Auto Execute

Point 1 Coordinates List

Node 252

Point 1 Coordinates List

Node 758

Newly created point 1.

Make turn point into node.

Finite Elements

Create | Node | XYZ

Select Point 1 and make node.

And then, node 1378 is generated

226

Finite Elements

Create | MPC | RBE2

Define Terms...

Dependent Node

Node 773 733:758:5 428 429

344:341:-1 282 276 437

438 252:264:6 720

Independent Node

Node 1378

Create RBE2.

Apply load to this center node.

227

◆Loads / BCs

Create | Force | Nodal New Set Name : Force

Input Data.... ==> Click.

Force < F1 F2 F3 > : < 100.,0.,0. >

Analysis Coordinate Frame : Coord 0

OK

Select Application Region.... ==> Click

Geometry Filter

◆ FEM

Application Region

Select Nodes :

Add | OK | Apply

Verify whether load is applied correctly.

Node 1378

228

e

The second step : Solution

1. Creating the MSC/NASTRAN input file

◆Analysis | Analyze | Entire Model | Analysis Deck

Jobname : case 3

Solution Type ===> Click

Solution Type :◆ BUCKLING

OK

Apply ===> Input file named case3.bdf is created in th

current directory.

Verify the input file using editor.

> vi case3.bdf

< The summary of the contents of case3.bdf file >

SOL 105

CEND

ECHO = NONE

SUBCASE 1

SPC = 2

LOAD = 2

DISPLACEMENT(SORT1,REAL)=ALL

SUBCASE 2

SPC = 2

METHOD = 1

VECTOR(SORT1,REAL)=ALL

BEGIN BULK

229

PARAM POST -1

EIGRL 1 1

$ Direct Text Input for Bulk Data

$ Elements and Element Properties for region : thick_1.2

PSHELL 2 1 1.2 1 1

CQUAD4 1 2 1 2 8 7

CQUAD4 2 2 2 3 9 8

CQUAD4 3 2 3 4 10 9

CQUAD4 4 2 4 5 11 10

CQUAD4 5 2 5 6 12 11

CQUAD4 6 2 7 8 14 13

CQUAD4 7 2 8 9 15 14

CQUAD4 8 2 9 10 16 15

CQUAD4 9 2 10 11 17 16

CQUAD4 10 2 11 12 18 17

.

.

.

CQUAD4 967 4 953 1143 1144 1098

CQUAD4 968 4 1098 1144 1145 951

CQUAD4 969 4 949 1127 1145 951

CQUAD4 970 4 954 1142 1137 956

CQUAD4 971 4 961 1128 1126 959

CQUAD4 972 4 976 1135 1139 970

MAT1 1 20700. .3 7.95E-10

$ Multipoint Constraints of the Entire Model

RBE2 1100 259 123456 8

RBE2 1101 260 123456 9

RBE2 1102 261 123456 10

.

.

.

RBE2 1183 1346 123456 1142

RBE2 1184 1350 123456 1137

RBE2 1185 1377 123456 1136

RBE2 1186 1375 123456 1134

RBE2 1187 1373 123456 1133

RBE2 1188 1378 123456 252 258 264 276 282 + A

230

+ A 341 342 343 344 428 429 437 438 + B

+ B 720 733 738 743 748 753 758 773

$ Nodes of the Entire Model

GRID 1 -535. 441.399 309.

GRID 2 -500. 441.399 309.

GRID 3 -465. 441.399 309.

GRID 4 -430. 441.399 309.

GRID 5 -395. 441.399 309.

GRID 6 -360. 441.399 309.

GRID 7 -535. 468.200 310.737

GRID 8 -500. 468.200 310.737

GRID 9 -465. 468.200 310.737

GRID 10 -430. 468.200 310.737

.

.

.

.

GRID 1371 87.0110 451.5 146.

GRID 1373 86.9819 435.776 124.091

GRID 1375 87.0017 412.969 92.3450

GRID 1377 90.7357 394.344 66.8584

GRID 1378 -540.900 470.700 219.649

$ Loads for Load Case : Default

SPCADD 2 1

LOAD 2 1. 1. 1

$ Displacement Constraints of Load Set : all_fixed

SPC1 1 123456 562 563 564 565 566 567 + C

+ C 579 584 592

SPC1 1 123456 608 THRU 630

SPC1 1 123456 898 899 900 901 917 918 + D

+ D 919 920 935 937 1039 1040 1041 1043 + E

+ E 1048 1049 1050 1051 1054 1055 1056 1059 + F

+ F 1071 1072

$ Nodal Forces of Load Set : force

FORCE 1 1378 0 100. 1. 0. 0.

ENDDATA

231

After checking the input file, execute MSC/NASTRAN.

❑ nast69 case3.bdf

If running the job is done, then check the result files.

First of all, check whether there are fatal errors and verify whether the value of epsilon is less than 10-6.

>vi case3.f06

< The summary of the contents of case3.f06 file >

..

0 N A S T R A N E X E C U T I V E C O N T R O L D E C K E C H O

SOL 105

CEND

0

0 C A S E C O N T R O L D E C K E C H O

CARD

COUNT

1 ECHO = NONE

2 SUBCASE 1

3 SPC = 2

4 LOAD = 2

5 DISPLACEMENT(SORT1,REAL)=ALL

6 SUBCASE 2

7 SPC = 2

8 METHOD = 1

9 VECTOR(SORT1,REAL)=ALL

10 BEGIN BULK

INPUT BULK DATA CARD COUNT = 2379

TOTAL COUNT= 2272

OLOAD RESULTANT

T1 T2 T3 R1 R2 R3

0 1 1.0000000E+02 0.0000000E+00 0.0000000E+00 0.0000000E+00 2.1964900E+04 -4.7070000E+04

...

0*** USER INFORMATION MESSAGE 5293 FOR DATA BLOCK KLL

232

S
LOAD SEQ. NO. EPSILON EXTERNAL WORK EPSILONS LARGER THAN .001 ARE FLAGGED WITH ASTERISK
1 2.9074562E-13 2.3728092E+00

SUBCASE 1

.

.

.

D I S P L A C E M E N T V E C T O R

POINT ID. TYPE T1 T2 T3 R1 R2 R3

1 G 3.235775E-03 2.235421E-01 -1.816825E-01 -1.152107E-04 -3.644177E-04 -4.386741E-04

2 G 3.238796E-03 2.080157E-01 -1.695592E-01 -7.757525E-05 -3.215211E-04 -4.496954E-04

3 G 3.253969E-03 1.924683E-01 -1.574537E-01 -1.138076E-04 -3.673213E-04 -4.401017E-04

4 G 3.303498E-03 1.769516E-01 -1.454092E-01 -1.001949E-04 -3.195727E-04 -4.485227E-04

5 G 3.378572E-03 1.615387E-01 -1.334580E-01 -1.118659E-04 -3.769469E-04 -4.343758E-04

6 G 3.470389E-03 1.463215E-01 -1.216843E-01 -1.666119E-04 -2.771154E-04 -4.302906E-04

7 G 1.452225E-02 2.237154E-01 -1.843373E-01 -8.291727E-05 -3.877734E-04 .0

8 G 1.451239E-02 2.081915E-01 -1.721896E-01 -1.170768E-04 -3.346481E-04 -3.579081E-04

.

.

.

TABLE OF SHIFTS: (REIGL)

SHIFT # SHIFT VALUE FREQUENCY, CYCLES # EIGENVALUES BELOW # NEW EIGENVALUES FOUND

1. -2.3553771E-01 -7.7241436E-02 0 0

2. 5.8078220E+01 1.2129049E+00 1 1

3. -1.9761407E+02 -2.2373250E+00 2 2

SUBCASE 2

E I G E N V A L U E A N A L Y S I S S U M M A R Y (REIGL MODULE)

BLOCK SIZE USED ...................... 2

NUMBER OF DECOMPOSITIONS ............. 3

NUMBER OF ROOTS FOUND ................ 1

233

NUMBER OF SOLVES REQUIRED ............ 28

SUBCASE 2

R E A L E I G E N V A L U E S

MODE EXTRACTION EIGENVALUE RADIANS CYCLES GENERALIZED GENERALIZED

NO. ORDER MASS STIFFNESS

1 1 5.190937E+01 7.204816E+00 1.146682E+00 7.798079E-01 4.047934E+01

.

.

SUBCASE 2

EIGENVALUE = 5.363318E+01

R E A L E I G E N V E C T O R N O . 1

POINT ID. TYPE T1 T2 T3 R1 R2 R3

1 G -8.566538E-03 1.921882E-01 1.249841E-02 -1.855682E-05 2.163814E-05 -3.388280E-04

2 G -8.567329E-03 1.802863E-01 1.191208E-02 -2.687820E-05 9.734243E-06 -3.393966E-04

3 G -8.571602E-03 1.683882E-01 1.132989E-02 -1.592053E-05 2.422794E-05 -3.410026E-04

4 G -8.584733E-03 1.564814E-01 1.076477E-02 -2.291050E-05 4.678557E-06 -3.389617E-04

5 G -8.606226E-03 1.445532E-01 1.022823E-02 -1.672048E-05 3.139912E-05 -3.420617E-04

6 G -8.642131E-03 1.325594E-01 9.759452E-03 -6.581736E-06 -1.307769E-05 -3.458741E-04

7 G 5.766959E-04 1.922327E-01 1.181289E-02 -3.036291E-05 -2.821347E-07 .0

8 G 5.784986E-04 1.803324E-01 1.118401E-02 -2.522108E-05 2.027580E-05 -4.640249E-04

9 G 5.763102E-04 1.684324E-01 1.066793E-02 -3.241406E-05 2.485410E-05 -4.643961E-04

10 G 5.741392E-04 1.565349E-01 9.993046E-03 -3.336949E-05 2.754011E-05 -4.567042E-04

*** USER INFORMATION MESSAGE 4110 (OUTPX2)END-OF-DATA SIMULATION ON FORTRAN UNIT 12

(MAXIMUM SIZE OF FORTRAN RECORDS WRITTEN = 1 WORDS.)

(NUMBER OF FORTRAN RECORDS WRITTEN = 1 RECORDS.)

(TOTAL DATA WRITTEN FOR EOF MARKER = 1 WORDS.)

SUBCASE 2

* * * * D B D I C T P R I N T * * * * SUBDMAP = PRTSUM , DMAP STATEMENT NO. 13

234

N

* * * * A N A L Y S I S S U M M A R Y T A B L E * * * *

SEID PEID PROJ VERS APRCH SEMG SEMR SEKR SELG SELR MODES DYNRED SOLLIN PVALID SOLNL LOOPID DESIG

CYCLE SENSITIVITY

--------------------------------------------------------------------------------------------------------------------------

0 0 1 1 ' ' T T T T T T F T 0 F -1 0 F

SEID = SUPERELEMENT ID.

PEID = PRIMARY SUPERELEMENT ID OF IMAGE SUPERELEMENT.

PROJ = PROJECT ID NUMBER.

VERS = VERSION ID.

APRCH = BLANK FOR STRUCTURAL ANALYSIS. HEAT FOR HEAT TRANSFER ANALYSIS.

SEMG = STIFFNESS AND MASS MATRIX GENERATION STEP.

SEMR = MASS MATRIX REDUCTION STEP (INCLUDES EIGENVALUE SOLUTION FOR MODES).

SEKR = STIFFNESS MATRIX REDUCTION STEP.

SELG = LOAD MATRIX GENERATION STEP.

SELR = LOAD MATRIX REDUCTION STEP.

MODES = T (TRUE) IF NORMAL MODES OR BUCKLING MODES CALCULATED.

DYNRED = T (TRUE) MEANS GENERALIZED DYNAMIC AND/OR COMPONENT MODE REDUCTION PERFORMED.

SOLLIN = T (TRUE) IF LINEAR SOLUTION EXISTS IN DATABASE.

PVALID = P-DISTRIBUTION ID OF P-VALUE FOR P-ELEMENTS

LOOPID = THE LAST LOOPID VALUE USED IN THE NONLINEAR ANALYSIS. USEFUL FOR RESTARTS.

SOLNL = T (TRUE) IF NONLINEAR SOLUTION EXISTS IN DATABASE.

DESIGN CYCLE = THE LAST DESIGN CYCLE (ONLY VALID IN OPTIMIZATION).

SENSITIVITY = SENSITIVITY MATRIX GENERATION FLAG.

1 * * * END OF JOB * * *

******************************************************************************************************************

The load used in the static analysis is 100.0 N, and the first eigenvalue in case3.f06 file is 5.190937E+01.

Therefore, the buckling load is;

Pcr = λ * P(external forces)

= 5.190937E+01 * 100. = 5190.937 N

235

ase 1.

n

The third step : Post-processing

If the verification of the text results is done, then read case3.op2 in PATRAN

υAnalysis

Read Output2 | Resulties | Translate Select Result File... ===> Click

Select Result File : case3.op2 ===> Click

OK

Apply

Display the deformed shapes.

υResults | Basic

For the buckling analysis, the results are divided into two based on two Subcase.

The result of Subcase 1 is equal to the result of the static structural analysis, and

the result of Subcase 2 represents the result of the normal mode analysis performed based on Subc

Display the deformed shapes of the static results first.

Select Result Cases

1.1- Default,Static Subcase

Select Fringe Result

1.1-Displacement,Translational

Result Quantity : Magnitude

Select Deformation Result

1. 1_Displacement,Translational

Apply

Before processing, include elements only into a current group.

Group | Create

New Group Name : all_fem

Selection Entity : Add All FEM

-Apply-

Exclude MPC.

Group | Modify

Target Group to Modify : all_fem

Select MPC 1:89 to Member List.

If they are listed up in Member List to Add/Remove box, the

click Remove.

Original Model is the following.

236

The deformed shape of the static result

Display the buckling modes of the buckling analysis results.

237

Select Result Cases

1. 2-Load Case 2,Mode 1

Select Fringe Result

2.1-Eigenvectors, Translational

Result Quantity : Magnitude

Select Deformation Result

2.1-Eigenvectors, Translational

Apply

238

239

Documents

case3_1