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.

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. **

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

Well, it looks like converging stress then.

I don't know the dimensions on the part, but you mention d=17 mm for the axel.

48 Ksi (331 MPa) is your maximum stress in the radius.

Stress concentration factor used in hand calculation, can give you a hint.

If I guess that you have r=1 mm and axel d=17 mm then r/d = 0,06

If i then guess that the larger D is about 2,5 x d then the Kt for this case is about 2,2

This means that the bending stress in the axel should be about 22 Ksi (150 MPa).

Now, since you use the continous plot instead of the discrete it's hard to say if this is right since 20 to 30 Ksi = green blurr.

But if you have all dimensions, you could verify your results with hand calculation of a cantilever beam in bending.

Here is a link with several stress concentration cases: http://www.mae.ncsu.edu/eischen/courses/mae316/docs/Appendix_C.pdf