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Analysis of stressed plate with/without hole in ANSYS:
Using General User Interface (GUI) and command codes
(May 27, 2011)
In this training, you will learn how to use the basic GUI and command codes of
ANSYS 11.0 to model a structural problem. The procedure on how to model a
certain structural problem will be presented (i.e. preprocessor solution
general postproc).
The purpose of this analysis is to model a rectangular plate with/without a
hole. The plate is made of isotropic material having elastic modulus of 200000
MPa and Poisson's Ratio of 0.3. The length and width of the plate are 400 mm and
200 mm respectively. The diameter of the hole in the middle of the plate will be
changed or removed to compare the changes of in the magnitude of stresses. The
boundary condition of the left end is fixed and the right end is displaced by 1 mm.
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ANSYS 11.0 Environment
Preprocessing: Defining the Problem
1. Give the current analysis a TitleUtility Menu > File > Change Title
Enter: Biomech Laboratory TrainingAlternatively, you can use the command code instead of GUI
/title, Biomech Laboratory Training
2. Create Geometrya. Create the main rectangular shape
Create the main rectangular area using GUI
Preprocessor > Modeling > Create > Areas > Rectangle > By 2Corners
Utility Menu
Main Menu
Status Bar/Input Window
Work Plane (WP)
View Icons
Command Code Input Line
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Fill in the window as shown above. This will create a rectangle wherethe bottom left corner has the coordinates (0, 0, 0) and the top right
corner has the coordinates (400, 200, 0).
The command line code for the above command isBLC4,0,0,400,200
b. Create the circlePreprocessor > Modeling > Create > Areas > Circle > Solid Circle
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Fill in the window as shown above. This will create a circle where thecenter has the coordinates (200, 100, 0); the center of the rectangle,
and the radius of the circle is 50 mm.
Alternatively, the command line code for the above command isCYL4,200,100,50
c. Subtraction Now we want to subtract the circle from the rectangle. Prior to this
operation, your image should show the following:
Modeling > Operate > Booleans > Subtract > Areas
At this point a 'Subtract Areas' window will pop up and the ANSYSInput window will display the following message: [ASBA] Pick or enter
base areas from which to subtract (as shown below) Therefore, select the base area (the rectangle) by clicking on it.
NOTE: The selected area will turn pink once it is selected.
Ensure that the entire rectangular area is selected (otherwise click'Next') and then click 'OK'.
Click 'OK' on the 'Subtract Areas' window.
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Now you will be prompted to select the areas to be subtracted, selectthe circle by clicking on it and then click 'OK'.
You should now have the following model:
Alternatively, the command line code for the above step isASBA,1,2
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3. Define the Type of ElementIt is now necessary to define the type of element to use for our problem:
Preprocessor Menu > Element Type > Add/Edit/Delete
Add the following type of element: Solid (under the Structural heading) andthe 8node 82 element, as shown in the figure below.
For this example, we need a plane stress element with thickness, therefore
Click on the 'Options...' button. Click and hold the K3 button, and select'Plane strs w/thk', as shown below.
Alternatively, the command line code for the above step is
ET,1,PLANE82
followed byKEYOPT,1,3,3
4. Define Geometric PropertiesPreprocessor menu > Real Constants > Add/Edit/Delete
Enter a thickness of 20 as shown in the figure below. This defines a platethickness of 20mm.
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Alternatively, the command line code for the above step isR,1,20
5. Element Material PropertiesPreprocessor > Material Props > Material models > Structural > Linear > Elastic
> Isotropic
We are going to give the properties of Steel. Enter the following whenprompted:
EX 200000 (elastic modulus)
PRXY 0.3 (Poissons Ratio)
Alternatively, the command line code for the above step is
MP,EX,1,200000
followed byMP,PRXY,1,0.3
Mesh SizePreprocessor > Meshing > Size Cntrls > Manual Size > Areas > All Areas
Alternatively, the command line code for the above step isAESIZE,ALL,5,
MeshNow the frame can be meshed.
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In the 'Preprocessor' menu select Meshing > Mesh > Areas > Free and selectthe area when prompted
Alternatively, the command line code for the above step isAMESH,ALL
You should now have the following:
Save Your Job
Utility Menu > File > Save as...
Solution: Assigning Loads and Solving
You have now defined your model. It is now time to apply the load(s) and constraint(s) and
solve the resulting system of equations.
1. Define Analysis Type Ensure that a Static Analysis will be performed (Solution > Analysis Type >
New Analysis).
Alternatively, the command line code for the above step isANTYPE,0
2. Apply Constraints As indicated previously, the left end of the plate should be fixed.
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Solution > Define Loads > Apply > Structural > Displacement > On Lines
Select the left end of the plate and click on 'Apply' in the 'Apply U,ROT onLines' window.
Fill in the window as shown below.
This location is fixed which means that all DOF's are constrained. Therefore,select 'All DOF' by clicking on it and enter '0' in the Value field as shown
above.
NOTE: You will see some blue triangles in the graphics window indicating the
displacement constraints.
Alternatively, the command line code for the above step isDL,4,,ALL,0
3. Apply LoadsSolution > Define Loads > Apply > Structural > Displacement > On Lines
When the window appears, select the line along the right hand edge of theplate and click 'OK'
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Alternatively, the command line code for the above step isDL,4,,UX,1
4. Solving the SystemSolution > Solve > Current LS
Alternatively, the command line code for the above step isSOLVE
Postprocessing: Viewing the Results
1. DeformationGeneral Postproc > Plot Results > Deformed Shape > Def + undeformd
(to view both the deformed and the undeformed object)
Observe the locations of deflection.
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2. DeflectionGeneral Postproc > Plot Results > Nodal Solution... Then select DOF solution,
USUM in the window.
3. StressesGeneral Postproc > Plot Results > Nodal Solution... select Stress, von Mises inthe window. OR General Postproc > List Results. Select Stress, Principals SPRIN
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Other Tasks:
1. Analyze a plate without hole and obtain the stress at the same region.2. Reduce the hole radius (i.e. 50 mm 10 mm 5 mm). Obtain the stress
at the same region and compare it with the plate without hole.
Summary of Command Line Codes
! The exclamation mark is used to cancel a command in ANSYS
/title, Biomech Laboratory Training
/PREP7 !Enter preprocessor
BLC4,0,0,400,200 !Create rectangle, bottom left corner coordinate, width, height
CYL4,200,100,50!Create circle, center coordinate, radius
ASBA,1,2 !Substract area 2 from area 1
ET,1,PLANE82 !Use element type (plane 42)
KEYOPT,1,3,3 !This is the changed option to give the plate a thickness
R,1,20 !Real Constant, Material 1, Plate Thickness
MP,EX,1,200000 !Material Properties, Young's Modulus, Material 1, 200000
MP,PRXY,1,0.3 !Material Properties, Major Poisson's Ratio, Material 1,
AESIZE,ALL,5 !Element sizes, all of the lines, 5 mm
AMESH,ALL !Mesh the lines
FINISH !Exit preprocessor
/SOLU !Enter solution
ANTYPE,0 !The type of analysis (static)
DL,4, ,ALL,0 !Apply a displacement to Line 4 to all DOF
DL,2, ,UX,1 !Apply a displacement to Line 2 (5mm)
SOLVE !Solve the problem
FINISH !Exit solution
Change radius Put ! if
no hole
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