ex 4 beam plate meshing
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meshTRANSCRIPT
2-1
Exercise 4 – Beam/Plate Meshing
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-2
Exercise 4 -
Beam/Plate Meshing
In this example we will read in simplified wireframe geometry of the
following assembly
The top plate will be modeled with plate elements, and the underlying
support beams will be modeled with beam elements.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-3
1. Import the geometry from a DXF file
a) Select the File, Import, Geometry command
b) Import GEOMMESH.DXF, located in the Training Files subdirectory of
the Femap Training folder on your desktop.
c) This geometry will be meshed with elements, whose properties and
materials we will now define.
Exercise 4 -
Beam/Plate Meshing
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-4
Exercise 4 -
Beam/Plate Meshing
2. Create the Material
a) Select the Model, Material command
or right-click on the Materials object
in the Model Info window and select
New.
b) In the Define Material – ISOTROPIC
dialog box, press Load.
c) Select the material, 7050-T651 Al
Plate .25 - .5 in the Select from
Library dialog box. Press OK to load
the material attributes into the
Define Material – ISOTROPIC
dialog box.
d) Press OK to create the material.
e) Press Cancel or use the esc key to
exit the command.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-5
Exercise 4 -
Beam/Plate Meshing
3. Create the Plate Property
a) To create the plate property,
right-click the Properties
object in the Model Info
window and select New.
b) In the Define Property – enter
the Title
c) Select the material previously
created in the Material field.
d) Enter Thickness of 0.1.
e) Press OK to continue (Don’t
exit the command by pressing
Cancel the esc key).
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-6
Exercise 4 -
Beam/Plate Meshing
4. Create the Beam property
a) To change to a beam property,
press the Elem/Property Type
button, and change the
Elem/Property Type to Beam. OK
b) Instead of entering the beam
properties, press Shape button to
enter the cross-section data
directly
c) Select I-Beam or Wide Flange (W)
for the shape. Set H = 2.0, Width,
Top = 1.0, W Bot =1.0, Thick, Top
= 0.1, Thick, Bot = 0.1, Thickness
= 0.1.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-7
Exercise 4 -
Beam/Plate Meshing
5. Continue to create Beam property
a) In addition to the cross-section
definition, be sure to change the
Orientation Direction to Up, this will
be useful in our example to align
the cross-section with respect to
the rest of the model.
b) Press OK when finished, and
Femap will return to the standard
Beam input with appropriate values
filled in.
c) Be sure to fill in a title, it will make
selecting properties later more
intuitive.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-8
Exercise 4 -
Beam/Plate Meshing
6. Create Boundary Surfaces that will be
meshed with plates
a) Select the Geometry, Boundary Surface, From
Curves then six curves (curves 1-6) that make
up the left boundary in any order. Press OK to
create the boundary surface
b) Create another Boundary Surface using the
four curves (curves 2 and 7-9) in the right cell
7. Convert Boundary Surfaces to Parasolid
surfaces
a) Select Geometry, Surface, Convert command
b) Select all surfaces and press OK.
c) When prompted to “OK to delete original
surfaces?”, press OK.
d) Note how the two surfaces now appear in the
Model Info window as sheet solids.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-9
Exercise 4 -
Beam/Plate Meshing
About Mesh Sizing
The default mesh spacing in a new Femap model is 1.0. By using the
tools available under the Mesh, Mesh Control command set, you can
customize the mesh spacing almost infinitely.
The figures below show meshes performed on boundary surfaces with
different mesh sizes specified for the various curves.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-10
Exercise 4 -
Beam/Plate Meshing
8. Visualize the mesh size
a) To visualize the mesh spacing, select View
Options (F6) command,
b) Under the Labels, Entities and Color category,
select the Curve – Mesh Size option, and the
Show As option to Symbols (all curves) to turn on
the Mesh Size indicators on curves. Also, check
the Draw Entity option on.
c) Press OK to display the Mesh Size indicators.
d) If you cannot see the mesh size indicators, try
increasing the symbol size by choosing Tools and
View Style as the category, selecting Symbols
from the Options list, then selecting a larger
symbol size from the Symbol Size list.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-11
Exercise 4 -
Beam/Plate Meshing
9. Turn off display of the surfaces
a) Using either Visibility icon on View toolbar or the Ctrl-Q hotkey
b) Press the Geometry Off button, then check the Curves option on.
c) Press Done to update the display.
10. Adjust the mesh size on the arc
a) Select Mesh, Mesh, Control Size Along Curve then select the arc, OK
b) Change the Number of Elements to 8, OK
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-12
Exercise 4 -
Beam/Plate Meshing
11. Model constraints
We will add boundary conditions to the geometry of the model before
meshing. Femap will automatically expand the boundary conditions out to
the nodes when exporting the analysis model to your solver.
a) To fix the edges of this model, select the Model, Constraint, On Curve
command, fill Title in the box as shown, and press OK to continue.
b) Select the five curves indicated.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-13
Exercise 4 -
Beam/Plate Meshing
12.Complete constraining the model
a) Choose Fixed under Standard
Types to fix the model at all nodes
on the curves that were selected.
By associating the constraints with
the geometry, the model can be
re-meshed without having to
redefine the constraints.
Note: Advanced Types allows you to
create constrains based upon any
or all six degrees of freedom on
an existing coordinate system, or
by specifying the constraint type
based on a surface or
cylinder/hole.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-14
Exercise 4 -
Beam/Plate Meshing
13.Apply a 100 lb/inch load to the model
a) Select Model, Load, On Curve command and start with a new load set,
entering the Title 100 lb Load.
b) Select the arc, and press OK.
c) In the Create Loads on Curves dialog box, set the load type as Force Per
Length and set the value to FZ = 100.
d) Press OK to create the load.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-15
Exercise 4 -
Beam/Plate Meshing
14. Mesh the surfaces
a) Select the Mesh, Geometry, Surface command. Since we are going to
mesh all the surfaces in this model (the two boundary surfaces), use the
Select All button and then press OK.
b) Change the Property reference to the plate property we created, by
selecting it in the Property drop down menu. Use the default values for
Mesher and Mapped Meshing, press OK to mesh
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-16
Exercise 4 -
Beam/Plate Meshing
15.Add the support beams
a) Select Mesh, Geometry, Curve then four curves as indicated
b) Select the property of the I-Beam. Press OK to continue.
c) Femap will now ask for a vector to orient the Y-Axis of the beam
elements, align the beam Y-Axis with the Global Z-Axis (base: 0,0,0
tip: 0,0,1).
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-17
Exercise 4 -
Beam/Plate Meshing
16.Modify the beam offsets (offset the Neutral Axis and Shear Center).
a) Select the Modify, Update Elements, Line Element Offsets command.
b) Select Method as Type, and scroll to Type 5. L Beam. Select All, then press
OK to continue.
c) Now check the options for Update End A and Set End B=End A and OK
d) This will open the Vector Locate dialog box.
Note: You can also
graphically select one
of the beams to
specify the type.
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran
17.Continue to modify the beam offsets
a) Press on Methods, and change the vector location method to Global Axis.
b) Set the Direction to Negative Z Axis and the Length to 1.05.
c) Press OK to modify the Beam offsets.
17.Clean up the display by removing unnecessary entities
a) Press Ctrl+Q to bring up Visibility dialog box
b) Select Geometry Off, and then toggle off the Nodes. Press Done.
18.Rotate the model
a) Select View, Rotate, Model command from the menu (Ctrl+R) or F8,
choose a Dimetric View.
2-18
Exercise 4 -
Beam/Plate Meshing
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-19
Exercise 4 -
Beam/Plate Meshing
Change the visualization of the elements to
display the beam shape(s)
a) Select the View Options (F6) command.
b) Set Category to Labels, Entities and Color.
c) Set Options to Element –
Orientation/Shape, and Element Shape to
3..Show Cross Section, Press OK
d) Or go to View Style icon and select
Thickness/Cross Section
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-20
Exercise 4 -
Beam/Plate Meshing
Run final checks on the model
When you mesh different portions of a model at different times, there are
invariable, coincident nodes, sections of your model that overlap.
a) Select Tools, Check, Coincident Nodes. Select All of the nodes
b) Toggle on Merge Coincident Entities and List Coincident Entities
c) Press OK to merge the nodes
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-21
Exercise 4 -
Beam/Plate Meshing
20.The model is ready to analyze, using NEiNastran solver follow the
below steps
a) Select the Model, Analysis command or right-click on the Analyses
object in the Model Info window and select Manage to open the
Analysis Set Manager dialog box.
b) Press on New to create a new analysis set.
c) Give it a title, set the Solver to NEiNastran, the Analysis Type to
1..Linear Statics, and press OK to accept the default analysis options.
d) Press on Analyze to start the analysis, save the Nastran input (.NAS)
and press F5 in NEiNastran Editor
e) Press Continue for any Information and Warning Messages and close
Editor
© UGS Corp. 2006. All rights reserved.Femap with NX Nastran 2-22
Exercise 4 -
Beam/Plate Meshing
21.Display the deformed model, displacement and stress results using
View, Select
22.Using the View, Select, turn off stresses and deformation and display
the Free Body display using the Freebody Display option in the Select
Postprocessing Data dialog box