WORKSHOP 12
RBE2 vs. RBE3
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
WS12-2

Workshop Objectives

Practice constructing RBE2 and RBE3 in Patran.

Understand the difference between RBE2 and RBE3.
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
WS12-3

Problem Description

A rectangular plate is fixed at its left and right edges. A rigid
body element is in the middle of the plate. Model this two ways
in one database using RBE2 and RBE3 elements.

E = 10 x 106 psi

n =0.33

t = 0.2 in
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
WS12-4

Suggested Exercise Steps
1.
Create a new database and name it rbe2_vs_rbe3.db.
2.
Create four rectangular surfaces.
Mesh the surfaces to create plate elements.
Create two additional nodes.
Create an RBE2 MPC.
Create an RBE3 MPC.
Apply Loads and Boundary Conditions.
Create material properties.
Create physical properties.
Run analysis with MSC.Nastran.
Read the results into MSC.Patran.
Plot the Von Mises stress and displacement.
Create vector marker plots to compare the RBE2 and RBE3 elements.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 1. Create New Database
a
Create a new database called
rbe2_vs_rbe3.db
a. File / New.
b. Enter rbe2_vs_rbe3 as
the file name.
c. Click OK.
d. Choose Default
Tolerance.
e. Select MSC.Nastran as
the Analysis Code.
f. Select Structural as the
Analysis Type.
g. Click OK.
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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e
f
b
c
g
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Step 2. Create Rectangular Surfaces
Create a surface
a. Geometry: Create /
Surface / XYZ.
b. Enter <10 10 0> for
the Vector
Coordinates List.
c. Enter [0 0 0] [0 15 0]
[20 0 0] [20 15 0] for
the Origin
Coordinates List.
d. Click Apply.
a
b
c
d
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 3. Mesh the Surfaces
Create a surface mesh
a. Elements: Create / Mesh
/ Surface.
b. Select the surfaces.
c. Enter 2.5 for the Global
Edge Length.
d. Click Apply.
a
b
c
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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d
Step 4. Create Two Nodes
f
Create two nodes
a. Elements: Create / Node
/ Edit.
b. Enter 1000 for the Node
ID.
c. Enter [15 5 0] for the
Node Location List.
d. Click Apply.
e. Repeat the procedure
with 2000 as the Node
ID and [15 20 0] as the
Node Location.
f. Click on the Node Size
Icon
a
b
c
d
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 5. Create RBE2
Define dependent nodes.
a. Elements: Create / MPC
/ RBE2.
b. Enter 1000 for the MPC
ID.
c. Click on Define Terms.
d. Disable Auto Execute.
e. Select the nodes on the
lower inner edges, as
shown.
f. Select all six degrees of
freedom in the DOFs
list.
g. Click Apply.
a
b
c
d
e
f
g
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 5. Create RBE2
Define independent nodes
a. Select Node 1000 in
the Node List box.
b. Click Apply.
c. Click Cancel.
d. Click Apply in the
Finite Elements form.
d
a
b
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Copyright 2005 MSC.Software Corporation
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Step 6. Create RBE3
Define dependent nodes.
a. Elements: Create /
MPC / RBE3.
b. Enter 2000 for the
MPC ID.
c. Click on Define
Terms.
d. Select Node 2000 in
the Node List box.
e. Select all six degrees
of freedom in the
DOFs list.
f. Click Apply.
a
b
c
d
e
f
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 6. Create RBE3
Define independent nodes
a. Click on Create
Independent.
b. Select the nodes on
the upper inner
edges, as shown.
c. Select UX, UY, and
UZ in the DOFs list.
d. Click Apply.
e. Click Cancel.
a
b
c
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e
Step 6. Create RBE3
Finish creating RBE3
a. Elements: Create /
MPC / RBE3.
b. Click Apply.
a
b
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Step 7. Apply Loads and Boundary Conditions
Create a boundary condition
a. Loads/BCs: Create /
Displacement / Nodal.
b. Enter fixed as the New Set
Name.
c. Click Input Data.
d. Enter <0 0 0> for
Translations and Rotations.
e. Click OK.
a
d
b
c
e
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 7. Apply Loads and Boundary Conditions
Apply the boundary condition
a. Click Select
Application Region.
b. For the Geometry
Filter select
Geometry.
c. Set the Selection
Filter to Curve or
Edge and select an
outer edge, as shown.
d. Click Add.
e. Repeat the procedure
until all four edges
have been added.
f. Click OK.
g. Click Apply.
b
c
d
f
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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g
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Step 7. Apply Loads and Boundary Conditions
Create a load
a. Loads/BCs: Create / Force
/ Nodal.
b. Enter point_load as the
New Set Name.
c. Click Input Data.
d. Enter <100 0 0> for Force.
e. Click OK.
a
d
b
c
e
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 7. Apply Loads and Boundary Conditions
Apply the load
a. Click Select
Application Region.
b. For the Geometry
Filter select FEM.
c. Select Nodes 1000
and 2000.
d. Click Add.
e. Click OK.
f. Click Apply.
b
c
d
e
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Copyright 2005 MSC.Software Corporation
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f
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Step 8. Create Material Properties
a
Create an isotropic material
a. Materials: Create / Isotropic
/ Manual Input.
b. Enter aluminum for the
Material Name.
c. Click Input Properties.
d. Enter 10e6 for the Elastic
Modulus.
e. Enter 0.33 for the Poisson
Ratio.
f. Click OK.
g. Click Apply.
d
e
b
c
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Step 9. Create Physical Properties
a
Create physical properties
a. Properties: Create / 2D /
Shell.
b. Enter plate as the Property
Set Name.
c. Click Input Properties.
d. Click on the Select
Material Icon.
e. Select aluminum as the
material.
f. Enter 0.2 for the Thickness.
g. Click OK.
d
f
b
c
e
g
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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Step 9. Create Physical Properties
Apply the physical properties
a. Click in the Select
Members box.
b. Rectangular pick all
surfaces as shown.
c. Click Add.
d. Click Apply.
b
a
c
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Step 10. Run Linear Static Analysis
a
Analyze the model
a. Analysis: Analyze /
Entire Model / Full
Run.
b. Click Subcases.
c. Choose Default from
Available Subcases.
d. Click Output
Requests.
e. Select Multi Point
Constant Forces.
f. Click OK.
g. Click Apply.
h. Click Cancel.
i. Click Apply.
c
e
d
b
f
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i
Step 11. Read Results into MSC.Patran
Attach the results file
a. Analysis: Access Results /
Attach XDB / Result
Entities.
b. Click Select Results File.
c. Choose the results file
rbe2_vs_rbe3.xdb.
d. Click OK.
e. Click Apply.
a
c
d
b
NAS120, Workshop 12, May 2006
Copyright 2005 MSC.Software Corporation
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e
Step 12. Plot Stress and Displacement
a
Create a quick plot
a. Results: Create / Quick
Plot.
b. Select Stress Tensor as
the Fringe Result.
c. Select Displacements,
Translational as the
Deformation Result.
d. Click Apply.
b
c
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Step 13. Plot Vector Markers
a
b
Create a marker plot
a. Click on Reset Graphics
b. Results: Create / Marker /
Vector.
c. Select MPC Constant
Forces, Translational as
the Vector Result.
d. Select Show As
Resultant.
e. Click Apply.
c
d
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Step 13. Plot Vector Markers
b
a
Create a marker plot
a. Results: Create / Marker /
Vector.
b. Click Reset Graphics.
c. Select MPC Constant
Forces, Translational as
the Vector Result.
d. Select Show As
Component.
e. Select only XX as the
Component.
f. Click Apply.
c
d
e
NAS120, Workshop 12, May 2006
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Step 13. Plot Vector Markers
a
Create a marker plot
a. Results: Create / Marker /
Vector.
b. Select MPC Constant
Forces, Translational as
the Vector Result.
c. Select Show As
Component.
d. Select YY as the
component.
e. Click Apply.
b
c
d
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Copyright 2005 MSC.Software Corporation
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Copyright 2005 MSC.Software Corporation
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