Week 1 Stress Concentration on a Plate with hole

Stress Concentration on a Plate with hole

AIM:

For the given plates with holes perform a static analysis and choose the appropriate plate which suits the application point of view.

Objectives

Find out the maximum deformation and stress developed in the model.

Whenever there is a discontinuity there will be a stress concentration. ( Applicable only within the elastic limits of the material)

So the maximum stress will be the stress concentration factor (K) times the nominal stress through in the body.

`K = (sigma max)/ (sigma nom)`

This factor is directly related to the length of the discontinuity and inversely related to the radius of the flaw ( smaller the hole more will be the stress concentration factor)`

Model setup and steps in Ansys

• Geometry is created using Spaiceclaim Package according to the dimension givens. ( Smaller holes in 2nd plate are of 30 mm diameter and the rest of the geometry is the same for both the plate)

• The material used for this analysis is structural steel and the properties are:

• A Tetramesh is performed on the plates with element size 5.

• Boundary Condition: The plate is fixed at one end and pulled from the other end with a force of 500N axially.

Results and Conclusion:

	Plate with Single Hole	Plate with multiple Holes
Maximum Deformation (mm)	2.7492e-004	2.9727e-004
Maximum Stress (Von Mises) (MPa)	0.57344	0.60569

Regions of maximum stress developed in the model:

• From an analysis point of view, the plate with multiple holes helps in reducing the stress concentration thereby reducing the maximum stress developed in the model. Hence the plate with multiple holes is preferred from the design point of view as it can withstand more loading than other plate ( even though not by much).

• From a manufacturing standpoint, as the maximum stresses and deformation are similar, we can end up saving material by drilling out the excess material for the plate with 3 holes. Another important thing to consider is that drilling additional holes will lead to more time to manufacture the product. Need to find out whether removing material or drilling more holes is going to save cost and time.