Stress concentration on a plate with hole
Aim:-
To design a plate with hole assuming two following case setups and boundary conditions and determine the stress concentration on a plate by conducting structural analysis in Ansys workbench
Case 1:-
For case 1 ,static structural analysis is carried out on a plate with single hole.The analysis is carried out on the ansys workbench.The plate is designed in the space claim.
The dimensions of plate are as follows:-
- Length=300mm
- Height=120mm
- Thickness=30mm
- Circular Hole at the center:Diameter=60mm
3D Model:-
Material used:-
Meshing:-
Mesh quality:-
Boundary condition:-
Force :-500N Right side
Constrain fixed face :- Left side
Case 2:-
For case 2 ,static structural analysis is carried out on a plate with three hole.The analysis is carried out on the ansys workbench.The plate is designed in the space claim.
The dimensions of plate are as follows:-
- Length=300mm
- Height=120mm
- Thickness=30mm
- Circular Hole at the center:
- Diameter=60mm
smaller holes 90mm away from the center:Diameter=30mm
3D Model:-
Material used:-
Meshing:-
Mesh Quality:-
Boundary condition:-
Force :-500N Right side
Constrain fixed face :- Left side
Comparison of results:-
deformation:-
case1:-
deformation animation:- youtube link
https://youtu.be/r0oZ_NzLoD0
case2:-
deformation animation:- youtube link
https://youtu.be/-MBzZAD1D4Y
Maximum stress developed:-
Case1:-
Case2:-
Conclusion:-
It is seen that the Plate with one holes is having a deflection of 2.7495e-004mm plate having three holes shows the maximum deflection of 2.9733e-004mm stress concentration.
In 2nd case the stress concentration is less than 1st case.This is because the stress lines are similar to fluid flow lines. If the cross-section changes steeply then it is seen that the fluid flow lines gets concentrated in one area and so is the case with stress concentration. However when the cross-section changes gradually like in the presence of two small holes and a big hole in the middle as given in case 2, the stress also increases gradually in those areas and the stress concentration is not huge.
If considered the case of fluid flow, the smaller holes changes the direction of fluid slowly and hence we get nearly streamlined flows in this case but with the case of a single big hole, the direction of velocity of flow changes abruptly.Hence it is seen that the stress concentration in case 2 (0.58066 MPa) is pretty lower than that of case 1 (0.60439MPa).
From design point of view
I would go with the second case (case2) since the stress concentration is lower, the factor of safety in that case is also lower and we can eventually save a lot of cost by saving materials as high higher stress concentration would result in more material since the factor of safety in that case would also be higher.
From Manufacturing point of view
Considering the fact that I am not at all considering the stress factors, from Manufacturing point of view I would go with case 1 as the material lost in machining purposes is also less. So the material cost gets saved in this case. If weight is the priority in the design , if we want to make the product with less weight and good strength , then I will opt for the plate with three holes.