WORKSHOP 12

RBE2 vs. RBE3

WS12-2NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

WS12-3NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

Workshop ObjectivesPractice constructing RBE2 and RBE3 in Patran.

Understand the difference between RBE2 and RBE3.

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Problem DescriptionA rectangular plate is fixed at its left and right edges. A rigid body element is in the middle of the plate. Model this two waysin one database using RBE2 and RBE3 elements.E = 10 x 106 psi ν =0.33t = 0.2 in

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Suggested Exercise Steps1. Create a new database and name it rbe2_vs_rbe3.db. 2. Create four rectangular surfaces.3. Mesh the surfaces to create plate elements. 4. Create two additional nodes.5. Create an RBE2 MPC. 6. Create an RBE3 MPC.7. Apply Loads and Boundary Conditions.8. Create material properties. 9. Create physical properties.10. Run analysis with MSC.Nastran.11. Read the results into MSC.Patran.12. Plot the Von Mises stress and displacement. 13. Create vector marker plots to compare the RBE2 and RBE3 elements.

WS12-6NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

b c

d

f

g

Step 1. Create New Database

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.

a

e

WS12-7NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

Step 2. Create Rectangular Surfaces

Create a surfacea. 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. b

d

a

c

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Step 3. Mesh the Surfaces

Create a surface mesha. Elements: Create / Mesh

/ Surface.b. Select the surfaces.c. Enter 2.5 for the Global

Edge Length.d. Click Apply.

a

b

c

d

WS12-9NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

Step 4. Create Two Nodes

Create two nodesa. 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 SizeIcon

a

b

c

d

f

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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 DOFslist.

g. Click Apply.

a

b

c

d

e

f

g

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Step 5. Create RBE2

Define independent nodesa. Select Node 1000 in

the Node List box.b. Click Apply.c. Click Cancel.d. Click Apply in the

Finite Elements form.

a

b c

d

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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

f

e

WS12-13NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation

Step 6. Create RBE3

e

b

d

c

Define independent nodesa. 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

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Step 6. Create RBE3

Finish creating RBE3a. Elements: Create /

MPC / RBE3.b. Click Apply.

a

b

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Step 7. Apply Loads and Boundary Conditions

Create a boundary conditiona. 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.

b

c

d

e

a

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Apply the boundary conditiona. 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.

af

g

d

b

Step 7. Apply Loads and Boundary Conditions

c

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Step 7. Apply Loads and Boundary Conditions

Create a loada. 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.

d

e

b

c

a

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Apply the loada. 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.

e

d

b

Step 7. Apply Loads and Boundary Conditions

c

a

f

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Step 8. Create Material Properties

Create an isotropic materiala. 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

f

e

a

c

b

g

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Step 9. Create Physical Properties

Create physical propertiesa. 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.

f

d

g

e

a

b

c

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Apply the physical propertiesa. Click in the Select

Members box.b. Rectangular pick all

surfaces as shown.c. Click Add.d. Click Apply.

b

Step 9. Create Physical Properties

a

c

d

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Step 10. Run Linear Static Analysis

Analyze the modela. 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.

hgf

e

d

c

a

i

b

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Step 11. Read Results into MSC.Patran

Attach the results filea. 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

b

c

e

d

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Step 12. Plot Stress and Displacement

Create a quick plota. Results: Create / Quick

Plot.b. Select Stress Tensor as

the Fringe Result.c. Select Displacements,

Translational as the Deformation Result.

d. Click Apply.

a

d

c

b

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Step 13. Plot Vector Markers

Create a marker plota. Click on Reset Graphicsb. Results: Create / Marker /

Vector.c. Select MPC Constant

Forces, Translational as the Vector Result.

d. Select Show As Resultant.

e. Click Apply.

a

b

d

e

c

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Step 13. Plot Vector Markers

Create a marker plota. 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.

b

a

d

f

c

e

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Step 13. Plot Vector Markers

Create a marker plota. 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.

a

c

e

b

d

WS12-28NAS120, Workshop 12, May 2006Copyright© 2005 MSC.Software Corporation