Structural #6: Analysis 
        of a 3D solid object
        
         
        
        Introduction: 
        In this 
        example you will learn to use the Solid element in ANSYS. Also you will 
        learn some basic 3D modeling.
        
        Physical Problem: See 
        figure.
        
        Problem Description:
        
        
         
        
          |  | 
          We will model the 
          object using solid Tetrahedral 10 node element.  | 
          |  | 
          Material: 
          Assume the structure is made of steel with modulus of elasticity E=200
          GPa.
           | 
          |  | 
          Boundary conditions: 
          The object is fixed around the inner surface of the hole.  | 
          |  | 
          Loading: 
          The object is loaded uniformly (1000 N/cm2) 
          along 
          the top surface of the extended beam.  | 
          |  | 
          Objective:
          
           
            |  | 
            To plot deformed 
            shape.  |  |  | 
            To determine the 
            principal stress and the von Mises 
            stress. (Use the stress plots to determine these. Do not print the 
            stress list)  |  |  | 
            What is the 
            maximum load the object can take. Clearly 
            mention the yield stress that you have assumed for steel. Also 
            assume factor of safety of 1.25.  |  | 
          |  | 
          You are required to 
          hand in print outs for the above.  | 
          |  | 
          Figure:  | 
        
        
                      
        
            
        
        STARTING ANSYS:
        
        
         
        
          |  | 
          Click on ANSYS 
          6.1 in the programs menu.  | 
          |  | 
          Select 
          Interactive.  | 
          |  | 
          The following menu 
          that comes up. Enter the working directory. All your files will be 
          stored in this directory. Also enter 64 for Total Workspace and
          32 for Database.  | 
          |  | 
          Click on Run.
           | 
        
        
         
        
               
        
 
        
        MODELING THE STRUCTURE:
        
         
        
          |  | 
          Go to the ANSYS 
          Utility Menu.  | 
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          Click 
          
          
          Workplane>WP 
          Settings.
           | 
          |  | 
          The following 
          window comes up:  | 
        
        
         
        
        
        
         
        
          |  | 
          Check the Cartesian 
          and Grid Only buttons.  | 
          |  | 
          Enter the values 
          shown in the figure above.  | 
        
        
         
        
          |  | 
          We will model the 
          object as four seperate volumes and then 
          add them up.  | 
          |  | 
          Go to the ANSYS 
          Main Menu 
          
          Preprocessor>Modeling>Create>Volumes>Blocks>By 
          2 corners & Z.
           | 
          |  | 
          Select the two 
          corners and enter the depth in the "depth " 
          field so as to create the first rectangular part of the figure. The 
          isometric view looks like the figure below.  | 
        
        
         
        
        
        
         
        
          |  | 
          Now create two 
          cylinders representing the holes. Use the 
          
          Preprocessor>Modeling>Create>Volumes>Cylinder>Solid 
          Cylinder, 
          and select the center and the radius and the depth of the cylinder.
           | 
          |  | 
          Now subtract these 
          two cylinders from the main rectangular block. Use the 
          
          Preprocessor>Modeling >Operate>Booleans>Subtract>Volumes 
          menu. Select the base area first (the rectangular block). Then select 
          the volumes to be subtracted (the two cylinders). Click OK. The 
          isometric view of the figure looks like the figure below.  | 
        
        
         
        
        
        
         
        
          |  | 
          Now we will create 
          the extended portion of the object.  | 
          |  | 
          Go to 
          
          Utility Menu>WorkPlane>Offset
          Workplane by Increments. 
          The following window will come up.  | 
        
        
         
        
        
                              
        
         
        
          |  | 
          Now offset the
          workplane in the +Z direction by an amount 
          equal to the thickness of the previous rectangular block we made. This 
          thickness is 0.01 m which is 4 times of the snap (0.0025). So we set 
          the 'snaps' to 4 and click on the +Z once. The
          workplane looks like this from the left 
          side view.  | 
        
        
         
        
        
        
         
        
        Now 
        create the first extended rectangular block. The figure will look like 
        the one below in isometric view.
        
         
        
        
        
         
        
          |  | 
          Now offset the
          workplane further along the +Z axis by an 
          amount equal to the length of the extended block (0.06 meter).
           | 
          |  | 
          So the
          workplane looks like this from the left 
          side view.  | 
        
        
         
        
        
        
         
        
          |  | 
          Now create another 
          block (block 3) by  | 
          |  | 
          
          Preprocessor>Modeling>Create>Volumes>Blocks>By 
          2 corners & Z.
           | 
          |  | 
          We make this block 
          separately so that we can create the required fillet easily.
           | 
        
        
         
        
        
        
          |  | 
          Now create the 
          block 4.  | 
        
        
         
        
        
                    
        
         
        
          |  | 
          Now glue parts 
          together. Go to 
          
          Preprocessor>Modeling>Operate>Booleans>Glue>Volumes.
           | 
          |  | 
          In the window that 
          comes up click Pick All and click OK.  | 
          |  | 
          Now we will create 
          the fillet. Go to 
          
          Preprocessor>Modeling>Create>Lines>Line 
          FilletSelect two lines on the "L" shape to create Fillet in between. Do this 
          for both top and bottom sides. See the Figure below:
 | 
        
        
         
        
        
        
         
        
          |  | 
          Now create two 
          lines. Go to 
          
          Preprocessor>Modeling>Create>Lines>Lines>Straight 
          Line.Pick keypoints to create lines as shown in 
          the figure below:
 | 
        
        
         
        
        
        
         
        
          |  | 
          Now, create areas 
          to close the fillet.Go to 
          
          Preprocessor>Modeling>Create>Areas>Arbitrary>By 
          Lines
 Create 3 areas of the fillet (Top, Bottom and Front) as shown in 
          Figure below
 | 
        
        
         
        
        
        
         
        
          |  | 
          Two more areas are 
          needed to define the fillet volume.Go to 
          
          Operate>Booleans>Divide>Area by Line.
 Select the inner area of the "L" shape click OK.
 | 
        
        
         
        
        
        
         
        
          |  | 
          Then select the 
          line as shown to divide the area into two pieces and click OK
           | 
        
        
         
        
        
        
         
        
          |  | 
          Repeat the dividing 
          areas steps for the other inner area of the "L" shape
           | 
          |  | 
          Now create the 
          volume within the fillet by 
          
          Preprocessor>Modeling>Create>Volumes>Arbitrary>By 
          Areas. 
          Select the areas which enclose the fillet volume and click OK. The 
          final model will look as follows.  | 
        
        
        
                   
        
        
          |  | 
          Now go to 
          
          Preprocessor>Modeling>Operate>Booleans>Add>Volumes. 
          Click on Pick All. So now we have added all the volumes into a 
          single volume.  | 
        
        
         
        
        MATERIAL PROPERTIES:
        
         
        
          |  | 
          Go to the ANSYS 
          Main Menu  | 
          |  | 
          Click 
          
          Preprocessor>Material Properties>Material Models.  
          In the window that comes up, select 
          
          Structural>Linear>Elastic>Isotropic.
           | 
        
        
         
        
        
        
         
        
          |  | 
          Material model 1 is 
          automatically selected. The following window comes up  | 
        
        
         
        
        
        
         
        
          |  | 
          Fill in 2e11 
          for the Young's modulus and 0.3 for minor Poisson's Ratio. 
          Click OK.  | 
          |  | 
          Now the material 1 
          has the properties defined in the above table. We will use this 
          material for the structure.  | 
        
        
         
        
        ELEMENT PROPERTIES:
        
         
        
          |  | 
          SELECTING ELEMENT 
          TYPE:  | 
          |  | 
          Click 
          
          Preprocessor>Element Type>Add/Edit/Delete... 
          In the 'Element Types' window that opens click on Add... The following 
          window opens:  | 
        
        
         
        
        
        
         
        
          |  | 
          Type 1 in 
          the Element type reference number.  | 
          |  | 
          Click on 
          Structural Solid and select Tet 
          10node 92. Click OK. Close the 'Element types' window.  | 
        
        
         
        
        MESHING:
        
         
        
          |  | 
          Go to 
          
          Preprocessor>Meshing>Size Controls>Manual Size>Lines>Picked 
          Lines. Pick 
          all the lines on the outer boundary of the figure and click OK.
           | 
          |  | 
          In the menu that 
          comes up type 0.005 in the field for 'Element edge length'.
           | 
        
        
         
        
        
        
         
        
          |  | 
          Click on OK.
           | 
          |  | 
          Now go to 
          
          Preprocessor>Meshing>Mesh>Volumes>Free.
           | 
          |  | 
          Click Pick All 
          in the "Mesh Areas" dialog box. The meshed model looks like this.
           | 
        
        
         
        
        
        
         
        
          |  | 
          Now the object is 
          divided into Solid Tetrahedral elements.  | 
        
        
         
        
        BOUNDARY CONDITIONS AND 
        CONSTRAINTS:
        
         
        
          |  | 
          APPLYING BOUNDARY 
          CONDITIONS  | 
          |  | 
          The object is fixed 
          around the inner faces of the holes.  | 
          |  | 
          Go to Main Menu
          
          
          Preprocessor>Loads>Define Loads>Apply>Structural>Displacement>On 
          Areas.
           | 
          |  | 
          Select the areas on 
          the inner surface of the holes and click OK. The following window 
          comes up.  | 
        
        
         
        
        
        
         
        
          |  | 
          Select All DOF and 
          click OK. The holes will look like the following after zooming in.
           | 
        
        
         
        
        
        
         
        
          |  | 
          APPLYING FORCES
           | 
          |  | 
          Go to the Main Menu
           | 
          |  | 
          
          Click on 
          
          Preprocessor>Loads>Define Loads>Apply>Structural>Pressure>On 
          Area.
           | 
          |  | 
          Select the top 
          surface of the cantilever like arm.  | 
          |  | 
          Click on OK in the 
          'Apply PRES on areas' window. The following window will appear:
           | 
        
        
         
        
        
        
         
        
          |  | 
          Enter the value of 
          the pressure as shown above.  | 
          |  | 
          Click OK.
           | 
        
        
         
        
          |  | 
          The model should 
          look like the one below.  | 
        
        
         
        
        
        
         
        
          |  | 
          Now the Modeling of 
          the problem is done.  | 
        
        
         
        
        SOLUTION:
        
         
        
          |  | 
          Go to ANSYS 
          
          Main Menu>Solution>Analysis Type>New Analysis.
           | 
          |  | 
          Select Static 
          and click on OK.  | 
          |  | 
          Go to 
          
          Solution>Solve>Current LS.
           | 
          |  | 
          Wait for ANSYS to 
          solve the problem.  | 
          |  | 
          Click on OK and 
          close the 'Information' window.  | 
        
        
         
        
        POST-PROCESSING:
        
         
        
        You can 
        also plot the displacements and stress.
        
        Go to
        
        
        General Postprocessing>Plot Results>Deformed 
        Shape. 
        The following window comes up:
        
         
        
        
        
         
        
        Select
        Def+undef edge and click OK. 
        The output will be like the figure below
        
         
        
        
        
         
        
        
        
         
        
         
        
        Select 
        a stress (say von Mises) to be 
        plotted and click OK.  The output will be like this.
        
         
        
         
        
        
        
         
        
        