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

5-14 MSC.Nastran 120 Exercise Workbook