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.
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Y
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100 lbs
13a-2 MSC.Nastran 105 Exercise Workbook
MSC.Nastran 105 Exercise Workbook 13a-3
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
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[0, 0, 0] [10, 0, 0] [20, 0, 0] [30, 0, 0] [40, 0, 0] [50, 0, 0]
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200.06
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13a-4 MSC.Nastran 105 Exercise Workbook
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⋅( )=
MSC.Nastran 105 Exercise Workbook 13a-5
WORKSHOP 13a Load Analysis of a Beam
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.
13a-6 MSC.Nastran 105 Exercise Workbook
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
MSC.Nastran 105 Exercise Workbook 13a-7
WORKSHOP 13a Load Analysis of a Beam
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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13a-8 MSC.Nastran 105 Exercise Workbook
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
MSC.Nastran 105 Exercise Workbook 13a-9
WORKSHOP 13a Load Analysis of a Beam
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
13a-10 MSC.Nastran 105 Exercise Workbook
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
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MSC.Nastran 105 Exercise Workbook 13a-11
WORKSHOP 13a Load Analysis of a Beam
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
13a-12 MSC.Nastran 105 Exercise Workbook
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
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123456
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200.0
MSC.Nastran 105 Exercise Workbook 13a-13
WORKSHOP 13a Load Analysis of a Beam
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
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13a-14 MSC.Nastran 105 Exercise Workbook
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.
MSC.Nastran 105 Exercise Workbook 13a-15
WORKSHOP 13a Load Analysis of a Beam
$ 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
13a-16 MSC.Nastran 105 Exercise Workbook
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
13a-18 MSC.Nastran 105 Exercise Workbook
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⋅–=
MSC.Nastran 105 Exercise Workbook 13a-19
WORKSHOP 13a Load Analysis of a Beam
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
13a-20 MSC.Nastran 105 Exercise Workbook
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
Select Result Case(s) Default, Static Subcase
Select Deformation Result Displacements, Translational
Show As: Component
❏ XX ■ YY ❑ ZZ
Apply
MSC.Nastran 105 Exercise Workbook 13a-21
WORKSHOP 13a Load Analysis of a Beam
Figure 13a.8 - The Display Should Appear as Below:
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
Select Result Case(s) Default, Static Subcase
Select Deformation Result Displacements, Translational
Show As: Resultant
Apply
13a-22 MSC.Nastran 105 Exercise Workbook
Figure 13a.9 - The Display Should Appear as Below:
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=