ws4-1 workshop 4 stadium truss nas120, workshop 4, november 2003

WS4-1

WORKSHOP 4

Stadium Truss

NAS120, Workshop 4, November 2003

WS4-2NAS120, Workshop 4, November 2003


Problem Description Three truss designs are presented on the following pages. Select

one design and analyze it. The truss is made from steel with E = 30 x 106 psi and = 0.3. The cross-sectional area is A = 4.516 in2. The torsional constant is 37.398 in4. A 500-lb point load is applied at (60,168,0). The truss is bolted down at the Y=0 boundary. Model the truss with rod elements.


Workshop Objectives Build the truss model and analyze it. Determine the maximum

displacement and stresses. Is your design better than the arched-roof truss design presented in the Case Study?

Visualize the load path in the truss by plotting the rod element axial stresses. Follow the load from the load application point to the fixed base. Do the stresses make sense to you?

Become familiar with the .f06 file


Configuration #1

Problem Information


Configuration #2


Configuration #3


Suggested Exercise Steps1. Select a truss configuration to model2. Create a new database3. Create nodes and elements4. Create Material Properties 5. Create Physical Properties6. Apply Loads and Boundary Conditions7. Run the finite element analysis using MSC.Nastran8. Read the results into MSC.Patran9. Plot displacements and stresses10. Examine the .f06 file


Step 1. Choose a Truss Configuration

Configuration #1


Step 2. Create New Database

Create a new database called stadium_truss.db.

a. File / New.b. Enter stadium_truss 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

d

e

f

gb c


Step 3. Create Nodes and Elements

Create the first node.a. Elements: Create / Node

/ Edit.b. Enter [420 0 0] for the

Node Location List.c. Click Apply.d. Click the Node size icon.

d d

a

b

c



Finish creating all 11 nodes.



Create an element between the first two nodes.

a. Elements: Create / Element / Edit.

b. Set the Shape to Bar, Topology to Bar 2, and Pattern to Standard.

c. Screen click on Node 1 and Node 2. An element is automatically created because Auto Execute is checked.

b

c

a

Node 1 Node 2


Finish creating all19 elements.



Step 4. Create Material Properties

Create an isotropic materiala. Materials: Create /

Isotropic / Manual Input.b. Under Material Name

input Steel.c. Click Input Properties,

then enter 30e6 for the elastic modulus and 0.3 for the Poisson Ratio.

d. Click OK.e. Click Apply.

a

e

b

d

c

d


Step 5. Create Physical Properties

Create physical properties for the rod elements

a. Properties: Create / 1 D / Rod.

b. Under Property Set Name input Circular_Rod.

c. Click Input Properties.d. Click on the Select Material

Icon e. Select steel for the material. f. Enter 4.516 for the Area.g. Enter 37.398 for the

Torsional Constant.h. Click OK.

a

b

c

df

e

g

h



Select application regiona. Click in the Select

Members Box.b. Select the Beam

element filter.c. Use the cursor to

drag across all elements

d. Click Add.e. Click Apply.

a

b

c

d

e


Step 6. Apply Loads and Boundary Conditions

Create the boundary conditiona. Loads/BCs: Create /

Displacement / Nodal.b. For the set name, input

Fixed.c. Click Input Data.d. Enter <0 0 0> for

Translations and <0 0 0> for Rotations.

e. Click OK.

a

b

c

d

e



Apply the boundary conditiona. Click Select

Application Region.b. For the Geometry

Filter, select FEM.c. For the application

region, select the base of the truss.

d. Click Add.e. Click OK.

a

b

c

d

e


Finish creating the boundary condition

a. Click Apply.


a



Create another boundary condition to constrain DOFs not connected to any element

a. Loads/BCs: Create / Displacement / Nodal.

b. For the set name, input Unused_DOF.

c. Click Input Data.d. Enter < , ,0> for

Translations and < , ,0> for Rotations.

e. Click OK.

a

b

c

d

e



Apply the displacementsa. Click Select



region, select the rest of the truss.

d. Click Add.e. Click OK.f. Click Apply.

a

c

d

e

f

b


Create a load named forcea. Loads/BCs: Create / Force /

Nodal.b. For the New Set Name,

enter Force.c. Click Input Data.d. Enter a force of <0 –500 0>.e. Click OK.


a

b

c

d

e



Apply the load forcea. Click Select



region, select the node at the tip of the truss as shown.


a

b

c

d

e


Finish creating the loada. Click Apply.


a


Step 7. Nastran Analysis

Analyze the modela. Analysis: Analyze / Entire

Model / Full Run.b. Click Solution Type c. Choose Linear Static.d. Click OK.e. Click Apply.

b

a

e

c

d


Step 8. Read Results File into Patran

Attach the results filea. Analysis: Access Results

/ Attach XDB / Result Entities.

b. Click Select Results File.

c. Choose the results file stadium_truss.xdb.


e

a

b

c

d


Step 9. Plot Displacements and Stresses

Create a quick plota. Results: Create / Quick

Plot.b. Select Stress Tensor

and X Component as the Fringe Result.

c. Select Displacements, Translational as the deformation result.

d. Click Apply. e. Record the maximum

displacement and maximum and minimum stress.

Max displacement = ______

Max X Stress = ______

Min X Stress = ______

a

b

c

d



a

b

d

e

f

Create a fringe plota. Results: Create / Fringe.b. Select Stress Tensor as

the Fringe Result.c. Select X Component as

the Fringe Result Quantity.

d. Click on the Plot Options Icon.

e. Set the Averaging Definition Domain to None.

f. Click Apply.

c



View the un-averaged resultsa. Note the change in

maximum stress.

Un-averaged Max Stress =

____________________

Un-averaged Min Stress =

____________________


Step 10. Examine the .f06 File

Examine the .f06 filea. Open the directory in

which your database is saved.

b. Find the file titled stadium_truss.f06 .

c. Open this file with any text editor.

d. Verify that the displacement and stress results agree with the graphical results shown in Patran.



Configuration #2







Analysis Type.

g. Click OK.

a

d

e

f

gb c





Node Location List.c. Click Apply.d. Click the Node Size icon.

d d

a

b

c







b

c

a

Node 1 Node 2


Finish creating all15 elements.







then enter 30e6 for the elastic modulus and 0.3 for the Poisson Ratio.


a

e

b

d

c

d






c. Click Input Properties. d. Click on the Select

Material icon. e. Select steel for the

material. f. Enter 4.516 for the

Area.g. Enter 37.398 for the


a

b

df

e

g

c

h








a

b

c

d

e







e. Click OK.

a

b

c

d

e








a

b

c

d

e



a. Click Apply.


a








e. Click OK.

a

b

c

d

e








a

c

d

ef

b






a

b

c

d

e






region, select the node below the tip of the truss as shown.


a

b

c

d

e




a





b

a

e

c

d








e

a

b

c

d












a

b

c

d



a

b

d

e

f






f. Click Apply.

c




maximum stress.


____________________


____________________



Configuration #3







Analysis Type.

g. Click OK.

a

d

e

f

gb c





Node Location List.c. Click Apply.d. Click the Node Size icon.

d d

a

b

c







b

c

a

Node 1 Node 2


Finish creating all 34 elements.







then enter 30e6 for the Elastic Modulus and 0.3 for the Poisson Ratio.


a

e

b

d

c

d


df

e

g





c. Click Input Properties.d. Click on the Select Material

Icon. e. Select steel for the material. f. Enter 4.516 for the Area.g. Enter 37.398 for the


a

b

c

h








a

b

c

d

e







e. Click OK.

a

b

c

d

e








a

b

c

d

e



a. Click Apply.


a








e. Click OK.

a

b

c

d

e








a

c

d

e

f

b






a

b

c

d

e






region, select the node at the tip of the truss as shown.


a

b

c

d

e




a





b

a

e

c

d








e

a

b

c

d












a

b

c

d








f. Click Apply.

a

b

d

e

f

c




maximum stress.


____________________


____________________

ws4-1 workshop 4 stadium truss nas120, workshop 4, november 2003

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