WS6-1 WORKSHOP 6 BRIDGE TRUSS NAS120, Workshop 6, November 2003.
WORKSHOP 6 BRIDGE TRUSS - FSB Online · BRIDGE TRUSS. WS6-2 NAS120 ... zLearn to view the different...
Transcript of WORKSHOP 6 BRIDGE TRUSS - FSB Online · BRIDGE TRUSS. WS6-2 NAS120 ... zLearn to view the different...
WORKSHOP 6
BRIDGE TRUSS
WS6-2NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
WS6-3NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Workshop ObjectivesLearn to mesh line geometry to generate CBAR elements
Become familiar with setting up the CBAR orientation vector and section properties
Learn to set up multiple load cases
Learn to view the different CBAR stress components in Patran
WS6-4NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Problem DescriptionThe preliminary design of a steel truss bridge has just been finished. You are asked to evaluate the structural integrity ofthis bridge.The truss is made from steel with E = 30 x 106 psi and n = 0.3The truss members are I-beams with H = 18 in, W = 12 in, Tf = 0.5 in, and Tw = 0.5 in The bridge needs to be able to support a 23,000 lb truck traveling over it. The truck weight is supported by two planar trusses. Model one planar truss with half the truck weight applied to it.One end of the truss is pinned while the other end is free to slide horizontally.
WS6-5NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
11,500 lb
(Subcase 1)
x
y
11,500 lb
(Subcase 2)
WS6-6NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Suggested Exercise Steps1. Create a new database. 2. Create a geometry model of the truss using the table on the previous
page. 3. Use Mesh Seeds to define the mesh density.4. Create a finite element mesh. 5. Define material properties. 6. Create Physical Properties using the beam library. 7. Create boundary conditions.8. Create loads.9. Set up load cases.10. Run the finite element analysis using MSC.Nastran.11. Review the Nastran input file.12. Plot displacements and stresses.13. Review the .f06 file.
WS6-7NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
b c
d
e
f
g
Step 1. Create New Database
Create a new database called bridge_truss.db
a. File / New.b. Enter bridge_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
WS6-8NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 2. Create Geometry
Create the first pointa. Geometry: Create / Point /
XYZ.b. Enter [0 0 0] for the Point
Coordinate List.c. Click Apply.d. Turn Point size on.
a
b
c
d
WS6-9NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 2. Create Geometry
Finish creating all 12 points.
WS6-10NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 2. Create Geometry
Create curves to represent the truss members
a. Geometry: Create / Curve / Point.
b. Screen pick the bottom left point as shown.
c. Screen pick the top left point. A curve is automatically created because Auto Execute is checked.
a
b
c
WS6-11NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 2. Create Geometry
Finish creating all 21 curves.
WS6-12NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 3. Create Mesh Seeds
Create a uniform mesh seeda. Preferences/Picking… Set
rectangular/polygon picking to Enclose Centroid.
b. Elements: Create / Mesh Seed / Uniform.
c. Enter 6 for the Number of Elements.
d. Click in the Curve List box.e. Rectangular pick the
bottom of the truss.
b
c
d
e
a
WS6-13NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 3. Create Mesh Seeds
Create another mesh seeda. Elements: Create / Mesh
Seed / Uniform.b. Enter 2 for the Number of
Elements.c. Click in the Curve List
box. d. Rectangular pick the rest
of the truss, as shown.
a
b
c
d
WS6-14NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 4. Create Mesh
Create a finite element mesha. Elements: Create / Mesh /
Curve.b. Set Topology to Bar2.c. Click in the Curve List box.d. Rectangular pick all of the
curves as shown.e. Click Apply.
a
b
c
d
e
WS6-15NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 4. Create Mesh
Equivalence the modela. Elements: Equivalence /
All / Tolerance Cube.b. Click Apply.
a
b
WS6-16NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 5. Create Material Properties
Create an isotropic materiala. Materials: Create / Isotropic
/ Manual Input.b. Enter steel as the Material
Name.c. Click Input Properties.d. Enter 30e6 for the elastic
modulus and 0.3 for the Poisson Ratio.
e. Click OK. f. Click Apply.
d
e
a
b
c
f
WS6-17NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 6. Create Physical Properties
Create element propertiesa. Properties: Create / 1D /
Beam.b. Enter i_beam as the
Property Set Name.c. Click Input Properties.d. Click on the Select
Material Icon.e. Select steel as the
material.f. Click on the Beam Library
button.
a
b
fc
d
e
WS6-18NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 6. Create Physical Properties
Define the beam section a. Enter i_section for the
New Section Name.b. Enter the appropriate
values to define the beam’s dimensions .
c. Click Calculate/Displayto view the beam section and its section properties.
d. After verifying that the section is correct, Click OK.
a
b
c
d
WS6-19NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 6. Create Physical Properties
Define the bar orientation a. Enter <1 2 0> for the
Bar Orientation.b. Click OK.
Note:Any vector in the XY plane that is not parallel to any truss member would work as well.
a
b
WS6-20NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 6. Create Physical Properties
Select application regiona. Click in the Select
Members box.b. Rectangular pick the
entire truss as shown.c. Click Add.d. Click Apply.
b
a
c
d
WS6-21NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 6. Create Physical Properties
Verify the beam sectiona. Display: Load/BC
/ Element Props.b. Set Beam Display
to 3D:FullSpan.c. Click Apply.d. Shade the model.e. Rotate the model
and zoom in to verify that the I-beams are oriented correctly.
f. Return to the front view.
g. Set Beam Display back to 1D:Line.
h. Click Apply.
a
d
e
f
b g
c h
WS6-22NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
d
e
Step 7. Create Boundary Conditions
Create a boundary conditiona. Loads/BCs: Create /
Displacement / Nodal.b. Enter left_side as the New
Set Name.c. Click Input Data.d. Enter <0 0 0> for
Translations and <0,0, > for Rotations.
e. Click OK.
a
b
c
WS6-23NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 7. Create Boundary Conditions
Apply the boundary conditiona. Reset graphics.b. Click Select
Application Region.c. Select the bottom left
point as the application region.
d. Click Add.e. Click OK. f. Click Apply.
be
f
c d
a
WS6-24NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 7. Create Boundary Conditions
Create another boundary condition
a. Loads/BCs: Create / Displacement / Nodal.
b. Enter right_side as the New Set Name.
c. Click Input Data.d. Enter < ,0,0> for
Translations and <0,0, > for Rotations.
e. Click OK.
d
e
a
b
c
WS6-25NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 7. Create Boundary Conditions
Apply the boundary conditiona. Click Select
Application Region.b. Select the bottom
right point as the application region.
c. Click Add.d. Click OK. e. Click Apply.
b c
da
e
WS6-26NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 8. Create Loads
Create the mid span loada. Loads/BCs: Create / Force /
Nodal.b. Enter mid_span_load as
the New Set Name.c. Click Input Data.d. Enter <0 –11500 0> for the
Force.e. Click OK.
d
ec
b
a
WS6-27NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Apply the mid span loada. Click Select Application
Region.b. Set the geometry filter to
FEM.c. For the application region
select the node in the middle of the span to the right of the center, as shown.
d. Click Add.e. Click OK.f. Click Apply.
Step 8. Create Loads
a
cd
e
f
b
WS6-28NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 8. Create Loads
Create the truss joint loada. Loads/BCs: Create / Force /
Nodal.b. Enter truss_joint_load as
the New Set Name.c. Click Input Data.d. Enter <0 –11500 0> for the
Force.e. Click OK.
d
e
a
b
c
WS6-29NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 8. Create Loads
Apply the loada. Click Select Application
Region.b. Set the geometry filter to
Geometry.c. For the application
region select the point at the center of the bridge, as shown.
d. Click Add.e. Click OK.f. Click Apply.
b
c d
e
f
a
WS6-30NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 9. Set Up Load Cases
Create a load casea. Load Cases: Create.b. Enter mid_span as the
Load Case Name.c. Click Input Data…d. Click on Displ_left_side,
Displ_right_side, andForce_mid_span_load to add them to the Load Case.
e. Click OK.f. Click Apply.
d
e
a
b
c
f
WS6-31NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 9. Set Up Load Cases
Create another load casea. Load Cases: Create.b. Enter truss_joint as the
Load Case Name.c. Click Input Data…d. Click on Displ_left_side,
Displ_right_side, andForce_truss_joint_load to add them to the Load Case.
e. Click OK.f. Click Apply.
d
e
a
b
c
f
WS6-32NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 10. Run Linear Static Analysis
Choose the analysis typea. Analysis: Analyze / Entire
Model / Full Run.b. Click Solution Type.c. Choose Linear Static.d. Click OK.
d
c
a
b
WS6-33NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 10. Run Linear Static Analysis
Analyze the modela. Analysis: Analyze / Entire
Model / Full Run.b. Click Subcase Select.c. Click Unselect All.d. Click on mid_span and
truss_joint to add them to the Subcases Selected list.
e. Click OK.f. Click Apply. c
d
e
a
b
f
WS6-34NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 11. Review the Nastran Input File
Review the Nastran input file.a. Open the file
bridge_truss.bdfb. Review the two subcases.
WS6-35NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Attach the results filea. Analysis: Access Results /
Attach XDB / Result Entities.
b. Click Select Results File.c. Choose the results file
bridge_truss.xdb.d. Click OK. e. Click Apply.
a
b
c
e
d
WS6-36NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create a deformation plot for the mid span result case
a. Results: Create / Deformation.
b. Select the Mid Span Result Case.
c. Select Displacements, Translational as the Deformation Result.
d. Check Animate.e. Click Apply.f. Click Stop Animation
and Refresh Results Tools.
Max Deformation =
____________
a
c
d
e
b
WS6-37NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create a Fringe Plot of X Component Axial Stress
a. Results: Create / Fringe.
b. Select the Mid Span Result Case.
c. Select Bar Stresses, Axial as the Fringe Result.
d. Select X Componentas the Fringe Result Quantity.
e. Click on the Plot Options icon.
f. Set the Averaging Definition Domain to None.
g. Click Apply.
b
c
d
a
e
f
g
WS6-38NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
View the resultsa. Record the maximum
and minimum X component axial stress.
Max X Axial Stress =
_________________
Min X Axial Stress =
__________________
WS6-39NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create Fringe Plots of maximum and minimum combined bar stresses
a. Results: Create / Fringe.b. Click on Select Results
icon.c. Select the Mid Span
Result Case.d. Select Bar Stresses,
Maximum Combined as the Fringe Result.
e. Click Apply.f. Record the Maximum
combined stress. Max Stress= _______
g. Repeat the procedure with Bar Stresses, Minimum Combined as the Fringe Result and record the Minimum Stress. Min Stress = _______
a
b
c
d
e
WS6-40NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create a deformation plot for the truss joint result case
a. Reset graphicsb. Results: Create /
Deformation.c. Select the Truss Joint
Result Case.d. Select Displacements,
Translational as the Deformation Result.
e. Check Animate.f. Click Apply.g. Click Stop Animation
and Refresh Results Tools.
Max Deformation =
____________
b
d
a
c
f
e
WS6-41NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create a Fringe Plot of X Component Axial Stress
a. Results: Create / Fringe.b. Select the Truss Joint
Result Case.c. Select Bar Stresses,
Axial as the Fringe Result.
d. Select X Component as the Fringe Result Quantity.
e. Click on the Plot Options icon.
f. Set the Averaging Definition Domain to None.
g. Click Apply.
b
c
d
a
e
f
g
WS6-42NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
View the resultsa. Record the maximum
and minimum X component axial stress.
Max X Axial Stress =
_________________
Min X Axial Stress =
__________________
WS6-43NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 12. Plot Displacements and Stresses
Create Fringe Plots of maximum and minimum combined bar stresses
a. Results: Create / Fringe.
b. Click on Select Results icon.
c. Select the Truss Joint Result Case.
d. Select Bar Stresses, Maximum Combined as the Fringe Result.
e. Click Apply.f. Record the Maximum
combined stress. Max Stress= _______
g. Repeat the procedure with Bar Stresses, Minimum Combined as the Fringe Result and record the Minimum Stress.Min Stress = _______
a
b
c
d
e
WS6-44NAS120, Workshop 6, May 2006Copyright© 2005 MSC.Software Corporation
Step 13. Examine the .f06 File
Examine the .f06 file
a. Open the directory in which your database is saved.
b. Find the file titled bridge_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.