Week 1 Stress Concentration on a Plate with hole

Objective: To design the plate 1 of (300*120*30) dimension with single middle hole of diameter 60mm and with plate 2 of same dimension with 2 holes as shown in below figure and performing the analysis according to the given conditions

Procedure:

Case (i)

• First, we need to assign a material data so to create that in the tool box > analysis systems > static structural > engineering data > structural steel and after creating the material, geometry as been created using the rectangle and circle option as shown in the below image.

• For meshing we need to finalise the mesh size and shape, so by iteration method the 4 mm element size is finalised because mesh is acceptable only when most of the elements are lie within the quality range of 0.7 to 0.9 and tetrahedron shape ia used as shown in below image.

• For boundary condition, fixed support is applied on one side of the plate and tensile load of 500N is applied on the other side.

Case (ii)

• In this case, the plate with similar dimension is modified with 2 holes of 30 mm diameter and 90mm away from the centre on either side of the big hole are added as shown in the below image.

• Structural steel material is used.
• For meshing tetrahedron and mesh size of 4 mm is finalised after by doing iteration method.

• For boundary condition, fixed support is applied on one side of the plate and tensile load of 500N is applied on the other side.

Results :

Total deformation

	Case(i)	Case(ii)
Min deformation (mm)	0	0
Max deformation (mm)	2.74e-4	2.971e-4
Avg deformation (mm)	1.38e-4	1.474e-4

Von mises stress

	Case(i)	Case(ii)
Min equivalent stress (MPa)	1.228e-2	1.548e-3
Max equivalent stress (MPa)	0.607	0.5819
Avg equivalent stress (MPa)	0.170	0.169

Discussion:

• Comparing the deformation and maximum stress.

Comparing the deformation from the values got from the analysis, case 1 as less deformed than case 2 due to reduction in area of the case 2 and the stiffness also reduces.

Comparing the maximum stress the case 1 as more compared to case 2 because in case 1 the stress concentration will be at only single middle hole but in the case 2 the stress will spread at all 3 holes so it reduces the concentration on only single hole.

• From an analysis point of view, which of the design is best ?

Design 2 is best, because the stress concentration is more in the single large hole as it is there in case 1, so it is more susceptible to failure compared to case 2, as in the case 2 the stress concentration is little less due to the 2 other holes on the side so it is better design and longer life compared to case 1.

• From a manufacturing point of view, which of the design is best ?

Design 1 is better, because the case 2 involves to drill 2 extra holes so it takes more time to manufacture compare to case 1