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WORKSHOP 5
Spatial Variation of Physical Properties
Aluminum
Steel
45°
Radius 1”
Radius 3”
Radius 4”
MSC.Nastran 120 Exercise Workbook 5-1
Objective:
■ Model the variation of physical properties as a function of spatial coordinates.
5-2 MSC.Nastran 120 Exercise Workbook
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-3
Model Description:Create a model of a tapering annular plate. Due to the model’ssymmetry only a 45° slice of the plate will be modeled. Definespatially varying material and physical properties for the plate.
Figure 5.1
Table 5.1 - Finite Element Properties
Table 5.2 - Material Properties
Analysis Code: MSC.Nastran
Element type: Quad4
Element Global Edge Length: 0.5
Material: Steel Aluminum
Modulus of Elasticity: 30E+06 10E+06
Poisson Ratio: 0.30 0.20
Density: 7.324E-04 2.588E-04
1 3 4Radial Distance, r, inches
Thi
ckne
ss, i
nche
s
0.20
0.10
y
xz
Surface 1Steel
Surface 2Aluminum
1.0” 2.0” 1.0”
45°
5-4 MSC.Nastran 120 Exercise Workbook
Suggested Exercise Steps:
■ Create a new database called circular_plate.db.
■ Create geometry that represents a 45° slice of the circular plate shown in Figure 5.1.
■ Create a finite element mesh using the information listed in Table 5.1.
■ Define a cylindrical coordinate frame whose origin is located at [0,0,0], where the R-, T-, Z-axis are aligned with the X-, Y-, Z-axes respectively of the global coordinate system.
■ Using the cylindrical coordinate frame, define a spatially varying field named thickness_spatial, that represents the model’s thickness. Verify the field by displaying an XY-plot.
■ Define material properties using the material constants shown in Table 5.2.
■ Inspect the constitutive (stiffness) matrices, Cijkl, of each material type.
■ Define element properties assigning the material type and element thickness to the correct region of the model.
■ Verify that the spatial variation of the element thickness has been assigned correctly to the model by rendering a scalar plot of the thickness.
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-5
Exercise Procedure:1. Create a New Database and name it circular_plate.db.
2. Change the Tolerance to Default and the Analysis Code toMSC.Nastran in the New Model Preferences form. Verify that theAnalysis Type is Structural.
NOTE: Whenever possible, toggle off the ❑ Auto Execute option byleft clicking the check box.
3. Create geometry that represents a 45° slice of the circular plateshown in Figure 5.1.
Create the 45 degree slice of the circular plate by creating twoadjacent surfaces that lie in the global xy-plane. The two surfacesmeet along the material boundary. See Figure 5.1 for thedimensions. The model should look similar to Figure 5.2.
File/New...
New Database Name circular_plate
OK
New Model Preference
Tolerance Default
Analysis Code: MSC/NASTRAN
Analysis Type Structural
OK
5-6 MSC.Nastran 120 Exercise Workbook
Figure 5.2
4. Create a finite element mesh.
The mesh should resemble Figure 5.3.
Finite Elements
Action: Create
Object: Mesh
Type: Surface
Global Edge Length 0.5
Element Topology Quad 4
Surface List Surface 1, 2
Apply
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-7
Figure 5.3
5. Create a cylindrical coordinate frame located at [0,0,0] with the R-,T-, Z-axis are aligned with the X-, Y-, Z-axes, respectively, of theglobal coordinate system.
6. Use the cylindrical coordinate frame to define a spatially varyingfield named thickness_spatial, which represents the model’sthickness. Verify the field values using an XY-plot.
Geometry
Action: Create
Object: Coord
Method: 3Point
Type: Cylindrical
Origin [0, 0, 0]
Point on Axis 3 [0, 0, 1]
Point on the Plane 1-3 [1, 0, 0]
Apply
Fields
Action: Create
5-8 MSC.Nastran 120 Exercise Workbook
To describe the thickness across the plate, enter three thickness valuesinto the table as shown in Figure 5.4.
6a. Verify the field using a XY plot.
The plot should appear in a new window resembling Figure 5.5.
Object: Spatial
Method: Tabular Input
Field Name thickness_spatial
Coordinate System Coord 1
Active Independent Variable R
Input Data...
OK
Apply
Fields
Action: Show
Select Field to Show thickness_spatial
Specify Range...
Use Existing Points
OK
Apply
Figure 5.4
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-9
Figure 5.5
5-10 MSC.Nastran 120 Exercise Workbook
7. Close the XY Plot.
Chose Yes when asked about deleting the XY result window.
8. Define material properties.
Define a second material for the model.
XY Plot
Action: Delete
Object: XY Window
Existing XY Windows XY Result Window
Apply
Materials
Action: Create
Object: Isotropic
Method: Manual Input
Material Name steel
Input Properties...
Elastic Modulus 30.0E6
Poisson Ratio 0.3
Density 0.0007324
OK
Apply
Materials
Action: Create
Object: Isotropic
Method: Manual Input
Material Name alum
Input Properties...
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-11
9. Inspect the constitutive (stiffness) matrices, Cijkl, of each material.
To verify the material constants, select Show from the Action optionmenu on the Materials form.
10. Define element properties for the model using fields.
10a. Repeat step 10 to define element properties for Surface 2.
Elastic Modulus 10.0E6
Poisson Ratio 0.2
Density 0.0002588
OK
Apply
Action: Show
Material Name steel
Show Material Stiffness...
Properties
Action: Create
Dimension: 2D
Type: Shell
Property Set Name prop_1
Input Properties...
Material Name m:steel
Thickness f:thickness_spatial
OK
Select Application Region Surface 1
Add
Apply
5-12 MSC.Nastran 120 Exercise Workbook
11. Verify element properties using a scalar plot of the thickness.
It may be necessary to reset the range to span the actual propertyrange.
The Viewport will appear as follows.
Figure 5.6
Properties
Action: Show
Existing Properties Thickness
Display Method Scalar Plot
Group Filter Default_group
Apply
Display/Ranges...
Fit Results
Calculate
Apply
Cancel
WORKSHOP 5 Spatial Variation of Physical Properties
MSC.Nastran 120 Exercise Workbook 5-13
To clear out the scalar plot, clean up the display using the ResetGraphics tool on the Patran menu bar.
Quit MSC.Patran after finishing this exercise.
Reset Graphics
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