workshop 13a

WORKSHOP 13a

MSC.Nastran 105 Exercise Workbook 13a-1

Load Analysis of a Beam

(using a point force and moment)

Objectives:■ Construct a 1d representation of a beam.

■ Account for induced moments from an off-center compressive load applied on the tip.

■ Prepare an MSC.Nastran input file for a linear static analysis.

■ Review analysis results.

■ Recover element forces.

X

Y

Z

100 lbs

13a-2 MSC.Nastran 105 Exercise Workbook


WORKSHOP 13a Load Analysis of a Beam

Model Description: Part A (Beam w/ force and moment)

Figure 13a-1 is a finite element representation of the beamshown on the exercise title page. The material properties for themodel are specified in Table 13a.1. The beam cross section di-mensions are specified in Table 13a.2.

Since the applied load does not act on the center of the beamcross-section, a bending moment will be induced. One way toaccount for this effect is to use 3D solid elements to model thebeam. However, because the geometry is well suited for a beammodel, this is not a desirable solution. Another possibility is todecompose the load into an equivalent load at the centroid of thebeam x-section and add apply a moment to the model. Figure13a.2 illustrates the loads and boundary conditions for the mod-el.

Figure 13a.1 - Grid Coordinates and Element Connectivities

Figure 13a.2 - Loads and Boundary Conditions

X

Y

Z

1 2 3 4 5 61 2 3 4 5

[0, 0, 0] [10, 0, 0] [20, 0, 0] [30, 0, 0] [40, 0, 0] [50, 0, 0]

1

2

3

4

5

1

2

3

4

5

123456

100.0

200.06

X

Y

Z


Table 13a.1 - Material Properties

Table 13a.2 - Element Properties

Hand Calculation:Applied Moments

Elastic Modulus = 10E6 lb/in2

Poisson’s Ratio = 0.3

Beam Dimensions

H 4.0 in.

W1 2.0 in.

W2 2.0 in.

t 0.1 in.

t1 0.15 in.

t2 0.15 in.

M3 r f×=

2 in( ) 100 lb( )×=

200 in lb⋅( )=



Suggested Exercise Steps:

■ Open a new database.

■ Generate a finite element representation of the beam structure by meshing the curve with desired global edge length.

■ Define material (MAT1) and element (PBAR) properties.

■ Apply fixed boundary constraints (SPC), a point force (FORCE), and a moment (MOMENT).

■ Prepare the model for a linear static analysis (SOL 101 and PARAMs).

■ Generate an input file and submit it to the MSC.Nastran solver.

■ Post-process results.

■ Review the results.


Exercise Procedure:1. Users who are not utilizing MSC.Patran for generating an input file

should go to Step 14 otherwise, proceed to Step 2.

1. Create a new database called lesson13a.db

In the New Model Preferences form set the following:

1. Activate the entity labels by selecting the Show Labels button on the toolbar.

1. Also, activate the Node Size button.

1. Create the parent geometry.

File/New

New Database Name lesson13a

OK

Tolerance ◆ Default

Analysis code: MSC/NASTRAN

OK

◆ Geometry

Action: Create

Object: Curve

Method: XYZ

Vector Coordinates List: <50, 0, 0 >

Origin Coordinates List: [0, 0, 0]

Apply

Show Labels

Node Size



1. Mesh the parent geometry.

Figure 13a.3 - Nodal and Element Locations

2. Next, define a material using the specified modulus of elasticity andPoisson’s ratio.

◆ Finite Elements

Action: Create

Object: Mesh

Type: Curve

Global Edge Length: 10

Element Topology: Bar2

Curve List: Curve 1

Apply

◆ Materials

Action: Create

Object: Isotropic

Method: Manual Input

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Y

Z

1 2 3 4 5 61 2 3 4 5


In the Current Constitutive Models data box, the line Linear Elastic- [,,,,] - [Active] appear. Click on Cancel to close the form.

3. Define element properties for the analysis model.

Click the beam library icon:

Material Name: mat_1

Input Properties...

Constitutive Model: Linear Elastic

Elastic Modulus = 10e6

Poisson Ratio = 0.3

Apply

Cancel

◆ Properties

Action: Create

Dimension: 1 D

Type: Beam

Property Set Name: beam

Option(s): General Section

Input Properties...

Material Name m:mat_1

Bar Orientation < 0, 1, 0 >

■ Associate Beam Section

Action: Create



4. Verify element connectivities. To make this step easier, use the ele-ment shrink option.

5. Create constraints and apply them to the analysis model.

Type: Standard Shape

New Section Name: beam_section

H 4.0

W1 2.0

W2 2.0

t 0.1

t1 0.15

t2 0.15

Calculate/Display

Close

OK

OK

Select Members: Elm 1:5

Add

Apply

Display/Finite Elements...

FEM Shrink: 0.15

Apply

◆ Loads/BCs

Action: Create

Object: Displacement

Type: Nodal


Figure 13a.4 - Displacement Constraints

New Set Name: fixed

Input Data...

Translations < T1 T2 T3 > <0, 0, 0>

Rotations < R1 R2 R3 > <0, 0, 0>

OK

Select Application Region...

Geometry Filter: ◆ FEM

Select Nodes: Node 1

Add

OK

Apply

1 2 3 4 5 61 2 3 4 5 123456 6

X

Y

Z



6. The beam element are modeled at the neutral axis of the actual 3-Dbeam. Since the axial load is offset from the neutral axis, there is aninduced bending moment at the end of the beam. This bendingmoment is applied with the axial force below (See Hang Calcula-tion).

To verify both the moment and the force, change the view toIsoview_1 by selecting this icon:

◆ Loads/BCs

Action: Create

Object: Force

Method: Nodal

New Set Name: load

Input Data...

Force < F1 F2 F3 > < -100, 0, 0 >

Moment < M1 M2 M3 > < 0, 0, 200 >

OK

Select Application Region...

Geometry Filter: ◆ FEM

Select Nodes: Node 6

Add

OK

Apply

Iso 1 View


Figure 13a.5 - The resultant forces will be displayed as follows:

7. Next observe the beam in 3D to visualize where the force andmoment are being applied.

Display/Loads/BC/Elem. Props...

Beam Display 3D: Full-Span + Offsets

Apply

Cancel

X

Y

Z

1

2

3

4

5

6

1

2

3

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5

123456

100.0

200.0



Figure 13a.6 - 3D representation of the beam

8. Generate an input file for analysis.

Click on the Analysis radio button on the Top Menu Bar andcomplete the entries as shown here.

A MSC.Nastran input file called lesson13a.bdf will be generated.This process of translating the model into an input file is called theForward Translation. The Forward Translation is complete when theHeartbeat turns green. MSC.Patran Users should proceed to step 15.

◆ Analysis

Action: Analyze

Object: Entire Model

Method: Analysis Deck

Job Name: lesson13a

Apply

X

Y

Z

1

2

3

4

5

6

1

2

3

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123456

100.0

200.06


Generating an input file for MSC.Nastran Users:

9. MSC.Nastran users can generate an input file using thedata from 13a-3. The result should be similar to the outputbelow (lesson13a.dat):

ID SEMINAR, lesson13aSOL 101TIME 600CENDTITLE = MSC.Nastran jobECHO = NONEMAXLINES = 999999999SUBCASE 1$ Subcase name : Default SUBTITLE=Default SPC = 2 LOAD = 2 DISPLACEMENT(SORT1,REAL)=ALL SPCFORCES(SORT1,REAL)=ALL STRESS(SORT1,REAL,VONMISES,BILIN)=ALLBEGIN BULKPARAM POST -1PARAM PATVER 3.PARAM AUTOSPC YESPARAM INREL 0PARAM ALTRED NOPARAM COUPMASS -1PARAM K6ROT 0.PARAM WTMASS 1.PARAM,NOCOMPS,-1PARAM PRTMAXIM YES$ Elements and Element Properties for region : beamPBAR 1 1 .97 2.64660 .200308 .005783 + A+ A 2. 1. -2. 1. -2. -1. 2. -1. + B+ B .381443 .618557 0.CBAR 1 1 1 2 0. 1. 0.CBAR 2 1 2 3 0. 1. 0.CBAR 3 1 3 4 0. 1. 0.CBAR 4 1 4 5 0. 1. 0.CBAR 5 1 5 6 0. 1. 0.$ Material Record : mat_1MAT1 1 1.+7 .3$ Nodes of the Entire ModelGRID 1 0. 0. 0.GRID 2 10. 0. 0.GRID 3 20. 0. 0.GRID 4 30. 0. 0.GRID 5 40. 0. 0.GRID 6 50. 0. 0.



$ Loads for Load Case : DefaultSPCADD 2 1LOAD 2 1. 1. 1 1. 3$ Displacement Constraints of Load Set : fixedSPC1 1 123456 1$ Nodal Forces of Load Set : loadFORCE 1 6 0 100. -1. 0. 0.$ Nodal Forces of Load Set : loadMOMENT 3 6 0 200. 0. 0. 1.$ Referenced Coordinate FramesENDDATA


SUBMITTING THE INPUT FILE FOR MSC.Nastran and MSC.Patran USERS:

10. Submit the input file to MSC.Nastran for analysis.

10a. To submit the MSC.Patran .bdf file, find an available UNIXshell window. At the command prompt enter nastranlesson13a.bdf scr=yes. Monitor the run using the UNIX pscommand.

10b. To submit the MSC.Nastran .dat file, find an available UNIXshell window and at the command prompt enter nastranlesson13a scr=yes. Monitor the run using the UNIX pscommand.

11. When the run is completed, edit the lesson13a.f06 file and search forthe word FATAL. If no matches exist, search for the word WARN-ING. Determine whether existing WARNING messages indicatemodeling errors.

11a. While still editing lesson13a.f06, search for the word:

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

MSC

.Nastran 105 E

xercise Workbook

13a-17

WO

RK

SH

OP

13a L

oad Analysis of a B

eam

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 0.0 0.0 0.0 0.0 0.0 0.0 2 G -1.030928E-04 3.778421E-04 0.0 0.0 0.0 7.556842E-05 3 G -2.061856E-04 1.511368E-03 0.0 0.0 0.0 1.511368E-04 4 G -3.092783E-04 3.400579E-03 0.0 0.0 0.0 2.267052E-04 5 G -4.123711E-04 6.045473E-03 0.0 0.0 0.0 3.022737E-04 6 G -5.154639E-04 9.446052E-03 0.0 0.0 0.0 3.778421E-04


Comparison of Results:

12. Compare the results obtained in the .f06 file with the results on theprevious page:

Also compare the results in the .f06 file with the following handcalculations applicable to node #6.

Deflection from the axial load:

Deflection from the bending moment:

Rotation at the end:

∆T1P L⋅A E⋅----------- 100 50⋅

0.97 106×10( )⋅

--------------------------------------== ∆T1 5.15E 4 in⋅–=

∆T2M L

2⋅2 I E⋅ ⋅----------------- 200 50

2⋅

2 2.65( ) 106×10( )⋅ ⋅

--------------------------------------------------== ∆T2 9.43E 3 in⋅–=

∆R3M L⋅E I⋅------------ 200 50⋅

106×10( ) 2.65( )⋅

------------------------------------------== ∆R3 3.77E 4 rad⋅–=



13.MSC.Nastran Users have finished this exercise. MSC.Patran Users should proceed to the next step.

14. Proceed with the Reverse Translation process, that is, importing the lesson13a.xdb results file into MSC.Patran. To do this, return to the Analysis form and proceed as follows:

You may reset the graphics if you click on this icon:

15. When the translation is complete and the Heartbeat turns green,bring up the Results form.

Find the deformation in the X-direction.

◆ Analysis

Action: Attach XDB

Object: Result Entities

Method: Translate

Select Results File...

Selected Results File lesson13a XDB

Ok

Apply

◆ Results

Action: Create

Object: Deformation

Select Result Case(s) Default, Static Subcase

Select Deformation Result Displacements, Translational

Show As: Component

■ XX ❑ YY ❑ ZZ

Apply

Reset Graphics


Figure 13a.7 - The Display Should Appear as Below:

Note: Compare the results to what was found in the .f06 file on page13a-17.

15a. Find the deformation in the Y-direction.

◆ Results

Action: Create

Object: Deformation



Show As: Component

❏ XX ■ YY ❑ ZZ

Apply




Note: Compare the results to what was found in the .f06 file on page 13a-17.

15b. Find the resultant deformation.

◆ Results

Action: Create

Object: Deformation



Show As: Resultant

Apply



Note: Compare the results to what was found in the .f06 file on page 13a-17.

The resultant is simply:

Continue to lesson 13b after completing this exercise.

∆T12 ∆T2

2+∆ =

Resultant

5.15–04–×10( )2

9.4303–×10( )

2+=

9.4403–×10=

workshop 13a

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