Structural Analysis and Comparison of Results Between Plates With Different Number of Holes

Challenge- Static Structural Analysis on Plate with Hole Geometry

Objective:

To perform structural analysis on plates with similar material, dimensions, and boundary conditions, but with a different number of holes and thereby analyze the stress concentration and deformation in both cases.

Steps Involved:

Case1:

• Design Plate A with a single hole.
• Meshing
• Simulate the results

Case 2:

• Design Plate B with three holes
• Meshing
• Simulate the results

• Compare the simulation results in both cases.

Case 1

Step 1: Designing a plate with a single hole (Using ANSYS SpaceClaim)

Plate dimensions

Length: 300mm

Breadth: 120mm

Thickness: 30mm

Hole Dia: 60mm (at the center of the plate)

The material used for analysis is Structural Steel. The selected material has the following properties:

Density 7.850 kg/mm^3

Isotropic Secant Coefficient of Thermal Expansion 1.2E -05 C^-1

Isotropic Thermal Conductivity 0.0605 W/mm degC

Tensile Yield strength 250 MPa

Isotropic Resistivity 0.00017 ohm mm

The 2D geometry is created and then extruded to obtain the following 3D geometry.

Step 2: Meshing and applying boundary conditions

Once the mechanical model is loaded on ANSYS Workbench, meshing is done. I have selected 7mm elements with patching method as Tetrahedrons, to get the best possible efficiency and work within the computational limitations of the academic version of ANSYS.

From the above mesh metric, it is clear that most of the elements are of high quality, i.e, from 0.7 to 1. It is thereby understood that the mesh is of acceptable quality. The mesh looks as follows;

Now, the boundary conditions are applied, where one end is fixed and a tensile load of 500N is applied on the free end.

Step 3: The analysis and simulation are run and the results are obtained.

Case 2

Step 1: Design the plate with 3 holes.

The plate dimensions are similar to that of case 1. The only difference being the two smaller holes of 30mm Dia located at a distance of 90mm on either sides of the hole at the center.

Step 2: Meshing and applying boundary conditions

Tetrahedron patch conforming is adopted and I have used elements of 7mm size, similar to the ones used in case 1.

It is observed that most of the obtained elements range from 0.7 to 1 and are of high quality. The mesh looks as follows;

The boundary conditions are now applied. As in case 1, one end is fixed and the free end is subjected to a tensile load of 500N.

Step 3: The simulation is run and results are obtained.

Comparing the Results

The obtained results are as follows:

Total Deformation

	Minimum (mm)	Maximum (mm)	Average (mm)
Case 1	0	2.748E-004	1.376E-004
Case 2	0	1.577E-004	0.7708E-004

The simulation of total deformation in both cases looks like this;

Case 1: https://youtu.be/injG1IfdIKQ

Case 2: https://youtu.be/tKjPIvwuIzk

This is how a comparison of total deformation in both cases look like:

Equivalent Stresses

	Minimum (MPa)	Maximum (MPa)	Average (MPa)
Case 1	1.344E-002	0.59401	0.15853
Case 2	0.16451E-002	0.3011	0.08804

The simulation of equivalent stress in both cases look like this;

Case 1: https://youtu.be/8mdGooTKOLY

Case 2: https://youtu.be/ZppDxVeegJo

A comparison of stresses in both cases look like this;

Conclusion

The geometries in both cases share similar dimensions with the only difference being the number of holes. I have used similar sized meshing elements in both cases and simulated the results.

Where total deformation is concerned, there is a small difference between the two cases. The maximum deformation varies by 1.17mm and average deformation by 0.6mm, with case 2 demonstrating higher values.

It is noted that the stress concentration is lower in case 2 when compared to case 1. The difference in maximum values is 0.293mm and in average values is 0.07mm.

My Observation

From the Ansys point of view, I would use the design given in Case 2. It is clearly evident that the presence of additional holes facilitates a more uniform stress distribution in the material when compared to the plate with a single hole. The maximum stress acting on the material is also lower in Case 2.

From the manufacturing point of view, I would choose the design from Case 1. The case 2 design would require additional machining work. Since there is no alarming difference in total deformation and stress concentration values in both cases, my intention would be to reduce the manufacturing work involved.