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High Stress Concentration of a fillet

Question asked by Nilanga Gamage on Apr 3, 2013
Latest reply on Apr 8, 2013 by Nilanga Gamage

Hello Everyone,

 

I have done the FEA for a loading fixture and found high stress concentration at some areas as shown below. (Shaft Diameter is 17mm)

 

Material - 304

Yield Strength - 31.5 Ksi

Load - 250 Lbf (1112N)

 

Max Von Mises Stress is 47.6 Ksi and it's larger than the yield strength of the material.

sdfsdfd.JPG

I also used the following mesh control for this

 

Mesh Type - Curved Based Mesh, Max element size: 4mm, Min element size: 0.8mm

 

0.1mm mesh control at the fillet as shown below.

Mesh Control.JPGsdfsdfs.JPG

For the mesh control of 0.1mm and 0.5mm, results are almost the same. When I see through Iso Clipping, I could find that it's only the outer surface of the small fillet where the stress is greater than 30 Ksi as shown in the above figure.

 

I know I can eliminate this by adding a lager fillet but I doubt whether this is really happening in the real world. I am already using a machined part with this configuration. I have also applied loads little larger than 250Lbf to the part cannot see any cracks or permanent deformation of the .

 

I need to know whether FEA shows approximately real values or this is a stress singularity that can be ignored. Pls advice me.

 

Thanks,

Nilanga

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