Numerical Lab

Problem Description

 An aluminum circular plate with a diameter of 1000 mm is pushed down by a steel piston head, as shown in Fig. 1. The piston head has two sections with diameters 500 mm and 50 mm. The elastic modulus and Poisson's ratio for the aluminum plate are given as Eal = 70 GPa and val = 0.35, respectively, whereas the corresponding properties for steel are Est = 210 GPa and vst = 0.3. The aluminum plate is clamped along the boundary (all degrees of freedom constrained). The goal is to obtain the displacement and stress fields when the piston is pushed down (at the top) by an amount of 2.5 mm. This problem possesses the conditions necessary for axisymmetry to be employed.

[pic 1]

Solution

Step 1:

Adding as element:

• Structural Mass – Solid – Quad 4 node 182

[pic 2]

Figure 2: Adding element.

Step 2:

• Material Model – Structural – Linear – Elastic – Isotropic
• Enter the value for (Material 1)

• Elastic modulus (EX)                 = 7.0e10
• Poisson’s ratio (PRXY)        = 0.35

• New material (Material 2)

• Elastic modulus (EX)                 = 2.1e11
• Poisson’s ratio (PRXY)        = 0.30

[pic 3]

Figure 3: Entering material value (Elastic modulus and Poisson’s ratio).

Step 3:

• Create rectangle areas by dimensions

• X1 = 0, X2 = 0.5, Y1 = 0 and Y2 = 0.0125
• X1 = 0, X2 = 0.25, Y1 = 0 and Y2 = 0.0375
• X1 = 0, X2 = 0.025, Y1 = 0 and Y2 = 0.1375

• Operate – Booieans – Overlap – Areas

• Pick all

• Meshing – Size Cntrls – Manual Size – Global – Size

• Size = 0.005

[pic 4]

Figure 4: Create three rectangles.

[pic 5]

Figure 5: Overlap the rectangles.

[pic 6]

Figure 6: Specify global element size.

Step 4:

• Meshing – Mesh – Areas – Mapped – 3 or 4 sided

• Picked bottom row rectangles

[pic 7]

Figure 7: Create mesh for aluminium plate.

Step 6:

• Change material attribute

• Material 2

• Mesh the rectangle left (steel piston)

[pic 8]

Figure 8: Change the material attribute for material number.

Step 7:

• Plot elements with different color based on their material

[pic 9]

Figure 9: Create mesh for the steel piston.

Step 8:

• Apply displacement constrains (Aluminium plate)

[pic 10]

Figure 10: Apply displacement constraints.