equivalent workshop
TRANSCRIPT
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7/28/2019 Equivalent Workshop
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WS-1
WORKSHOP
Define Equivalent Section PlateProperties
NAS121, Workshop , May 6, 2002
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7/28/2019 Equivalent Workshop
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WS-2NAS121, Workshop , May 6, 2002
Problem Description
A 20 in. x 20 in. sandwich plate is
loaded with 15 psi pressure and is
simply supported around the
edges.
The facesheets are 0.05 in. thick
aluminum and the core is 0.5 in.
thick.
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7/28/2019 Equivalent Workshop
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WS-3NAS121, Workshop , May 6, 2002
Hand calculations
a. The T field on the PSHELL is set to the sum of the facesheet thicknesses
T=(2*Tf)=0.10 .
b. The 12/T**3 field on the PSHELL is set to the ratio of the actual sandwich moment
of inertia to the moment of inertia calculated from T on the PSHELL. In this case
the core moment of inertia is ignored:
c. An approximation for the effective shear thickness is TS/T=(5/6)*(Tc+2Tf)/T= 5.0
0.91
12
0.10
12
0.050.05/20.50/20.052
12
T
12
TfTf/2Tc/2Tf2
*3*12/T3
32
3
32
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7/28/2019 Equivalent Workshop
4/16
WS-4NAS121, Workshop , May 6, 2002
Suggested Exercise Steps1. Create a geometry model.
2. Use mesh seeds to define the mesh density.
3. Create a finite element mesh.
4. Apply boundary conditions to the model.
5. Apply loads to the model.
6. Define aluminum material properties.
7. Define equivalent section properties.
8. Submit the model to MSC.Nastran for analysis.
9. Attach xdb Results File.
10. Display stresses using MSC.Patran.
11. Display deformations using MSC.Patran.
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7/28/2019 Equivalent Workshop
5/16
WS-5NAS121, Workshop , May 6, 2002
CREATE NEW DATABASE
Create a new database called
equivalent1.db:
a. In File select New
b. Enter equivalent1 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
b c
d
e
f
g
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7/28/2019 Equivalent Workshop
6/16
WS-6NAS121, Workshop , May 6, 2002
Step 1. Create a geometry model
In Geometry create the first
curve.
a. Select Create / Surface /
Vertex
b. On the Surface Vertex n
Lists enter[0 0 0], [20 0 0],[20 20 0], [0 20 0]
c. Click Apply
a
b
c
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7/28/2019 Equivalent Workshop
7/16WS-7NAS121, Workshop , May 6, 2002
Step 2. Use mesh seeds to define the mesh density
In Elements, create mesh seeds.
a. Select Create / Mesh Seed /
Uniform
b. At Number enter10
c. Click on the bottom edgeof the
plate to create a mesh seedd. Then click on the right edge
a
c
d b
S C f
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7/28/2019 Equivalent Workshop
8/16WS-8NAS121, Workshop , May 6, 2002
Step 3. Create a finite element mesh
In the Elements menu create
surface mesh based on the
mesh seeds.
a. Select Create / Mesh /
Surface
b. Select Quad as the
Elem Shape
c. Click on surface 1
d. Click Apply
a
b
c
d
St 4 A l b d diti t th d l
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9/16WS-9NAS121, Workshop , May 6, 2002
Step 4. Apply boundary conditions to the model
a
b
c
e
f
h
g
In Loads/BCs
a. Select Create /
Displacement /
Nodal
b. For New Set Name
enter constraints
c. In Input Data, enter
for
Translations, then
OK
d. Click on Select
Application Region
e. On the top menu
click on the Curve or
Edge icon
f. Shift click on the fouredges all around the
surface
g. Click Add and OK
h. Click Apply
f
f
f
d
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7/28/2019 Equivalent Workshop
10/16WS-10NAS121, Workshop , May 6, 2002
Step 5. Apply loads to the model
a. On the top menuclick ResetGraphics
b. Select Create /Pressure /Element Uniform
c. Enter pressurefor New Set Name
d. At Target ElementType select 2D
e. In Input Data,Enter15 for TopSurface Pressure,then OK
f. Click on SelectApplicationRegion
g. In the top menuclick on theSurface or Faceicon
h. click on Surface 1
i. Click Add then OK
j. Click Apply
b
c
e
h
j
i
a
g
d
f
St 6 D fi l i t i l ti
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11/16WS-11NAS121, Workshop , May 6, 2002
Step 6. Define aluminum material properties
Go to Material menu
a. Select Create / Isotropic /
Manual Input
b. For Material Name enter
aluminum
c. Click Input Properties, enter
10e6 .3
d. Click OK
e. Click Apply
a
b
c
d
e
St 7 D fi i l t ti ti
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7/28/2019 Equivalent Workshop
12/16WS-12NAS121, Workshop , May 6, 2002
Step 7. Define equivalent section properties
Go to Properties:
a. Select Create / 2D / Shell
b. Enter Equivalent at
Property Set Name
c. At Options select
Equivalent Section
d. In Input Properties click on
Aluminum for Membrane,Bending, and Shear
Materials
e. Enter 0.1 for thickness,
f. 91 for Bending Stiffness
g. 5 for Thickness Ratio
h. .3 and -.3 for Fiber Dist. 1
and 2
i. Click OK
j. Click Application Region
select box and click on
Surface 1 then Add
k. Click Apply
a
b
d
e
f
i
h
c
g
k
j
St 8 S b it th d l t MSC N t f l i
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7/28/2019 Equivalent Workshop
13/16WS-13NAS121, Workshop , May 6, 2002
Step 8. Submit the model to MSC.Nastran for analysis
Go to Analysis:
a. Select Analyze / Entire Model / Full Run
b. Click Apply
a
b
Step 9 Attach xdb Results File
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7/28/2019 Equivalent Workshop
14/16WS-14NAS121, Workshop , May 6, 2002
Step 9. Attach xdb Results File
Go to Analysis:a. Select Attach XDB
/ Result Entities /
Local
b. Click Select
Results File
c. Use the Select File
tool to find your xdb
file in your local
Patran directory and
click it, in this case,
equivalent1.xdb
d. Click OK
e. Click Apply
a
b
c
d
e
Step 10 Display stresses using MSC Patran
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7/28/2019 Equivalent Workshop
15/16WS-15NAS121, Workshop , May 6, 2002
Step 10. Display stresses using MSC.Patran
To display the Von
Mises stress at stress
recovery position Z2:
go to the Results
menu:
a. First turn off the
geometry in
Plot/Erase
Geometry
Erase
b. Select Create /
Quick Plot
c. Click Stress
Tensor
d. Click
DisplacementsTranslational
e. Click Apply
b
c
d
e
a
Step 1 Display deformations using MSC Patran
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7/28/2019 Equivalent Workshop
16/16WS-16NAS121 Workshop May 6 2002
Step 1. Display deformations using MSC.Patran
To display the models
deformations:
go to the Results menu:
a. In the top menu, click on
Reset Graphics
b. Select Create /
Deformation
c. Click Displacements,
Translational
d. Click Apply
c
d
b
The bending deflection should be 91 times less than a plate made with 0.1 in.
aluminum.
The equivalent section can also be modeled as a composite material for more complex
facesheets or more accurate results.
a