Week 1 Stress Concentration on a Plate with hole

Objective :

Design the model for the following 2 cases and determine and compare maximum deformation and stress developed for 2 cases.

Case 1 : 300x120x30 mm plate with a hole of diameter 60 mm at the center.

Case 2 : 300x120x30 mm plate with a hole of diameter 60 mm at the center and 2 holes of diameter 30mm ,at 90 mm offset from the center on each side.

Boundary condition: Fixed at left end and 500 N on the right end.

Material : Structural steel

Element size : 5 mm

Mesh type : Tetrahedral

MODEL & SIMULATION RESULT :

case 1 : 300x120x30 mm plate with a hole of diameter 60 mm at the center.

Fig: Plate with a Hole.

Fig: Plate with boundary condition

Fig: Plate Meshed

No of elements: 41430

No of nodes : 63732

Fig: Total Displacement contour

Max displacement was observed to be 0.00027492 mm.

Fig: Von mises stress contour

Max Stress is found to be 0.60047 MPa.

Case 2:

300x120x30 mm plate with a hole of diameter 60 mm at the center and 2 holes of diameter 30mm ,at 90 mm offset from the center on each side.

Fig: Plate with 3 holes

Fig: Plate with boundary condition

Fig: Plate meshed

No of elements : 7025

No of nodes : 13030

Fig: Total deformation contour

Max deformation is found to be 0.000297 mm

Fig: Von-mises stress contour

Max stress observed to be 0.5828 MPa.

RESULT AND CONCLUSION:

	CASE 1	CASE 2
Total Deforemation in mm	0.00027492	0.000297
Equivalent Von-mises stress in MPa	0.60047	0.5828

1. From Table it shows that in case 1 deformation is less than case 2 but the difference is negligable(0.00002208 mm).

2. Stress developed in case 2 is less than the case 1.

3. From analysis point of view case 2 is better.

Though the deformation in case 2 is more , the difference is negligable. But the stress developed in the case 2 is much less than the case 1 with reduced weight. so analysis point of view case 2 is prefered.

3. From Manufacturing stand point,:

Creating 3 holes involves more cost and time compared to 1 hole as it involvees tool change .But creating 3 holes on given plate can reduce the weight (approx 340 gms).

So if cost and time is important then case 1 is better and if weight is the criteria case 2 is prefered.