STRESS ANALYSIS OF A PLATE WITH HOLES
OBJECTIVE: To analyze the stress concentration of a plate with modifications using Finite Element Analysis in ANSYS.
CASE 1: The plate has one hole and the stress concentration is simulated.
Geometry Details:
Length=300mm
Height=120mm
Thickness=30mm
Circular Hole at the center:
Diameter=60mm
Steps involved:
1.Designing the model.
2. Meshing of the model
3.Applying forces.
4.Analysing the stresses acting.
MODEL:
MATERIAL:
The material used in this case is structural steel.
MESHING:
A mesh size of 5 mm is used in this case to get the possible efficiency and work within the limitations of computational domain of ANSYS ACADEMIC VERSION.
BOUNDARY CONDITIONS:
The plate is given fixed support on one end and a tensile load of 1000N is given on the other end.
RESULTS:
TOTAL DEFORMATION:
EQUIVALENT STRESS:
CASE 2:
In this case the plate has three holes.
Geometry details:
Plate dimensions:
Length=300mm
Height=120mm
Thickness=30mm
Circular Hole at the center:
Diameter=60mm
smaller holes 90mm away from the center:
Diameter=30mm
MODEL:
The material used in this case is structural steel.
MESHING:
A mesh size of 5 mm is used in this case to get the possible efficiency and work within the limitations of computational domain of ANSYS ACADEMIC VERSION.
BOUNDARY CONDITIONS:
The plate is given fixed support on one end and a tensile load of 1000N is given on the other end.
RESULTS:
TOTAL DEFORMATION:
EQUIVALENT STRESS:
CONCLUSION:
It is seen that the stress concentration in 2nd case is less than 1st case.This is because the stress lines are similar to fluid flow lines. If the cross-section changes steeply theen 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 sttreamlined 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 (1.16 MPa) is pretty lower than that of case 1 (1.22MPa).
1.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 cconcentration would result in more material since the factor of safety in that case would also be higher.
2. Consering 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.