Hi folks,
I'm trying to design and test a 16mm aluminium hub similar to this product. However, the stress analysis comes back with rather high P1 stresses for 30Nm input torque:
Is P1 stress around the shaft holder supposed to be acceptable or is the product just not designed for 30Nm? If acceptable, how come? I thought 30Nm is meant to be fairly low. I've also attached the part.
Thanks
Sure, a radius or chamfer will no doubt help, but I'm trying to imitate the product which has no radius or chamfer. I presume ball endmills would add to the cost of the part.
Actually the stress concentration aren't on corners but on edges:
About stress concentration on corners, if those can be ignored, then when should we not ignore high stress readings?
Thanks
Ball endmill?
Not turning on a lathe? Most insert has radius.
How about endmill with radius "corner"? Or endmill that use insert.
How much does an extra tool cost compare to a failed part?
Edge is a corner. Whenever two face are not tangent, there is a "corner".
then when should we not ignore high stress readings?
Experience.
like Frederick said, this is going to get turned. In the real world all inner corners have some radius. Every machine tool breaks down and leaves something less than a sharp corner. In any situation where you have a high stress part you should not have sharp corners, inner or outer. For inner corners you should have radii and while radii are better chamfers on the outer edges is generally less expensive.
Sharp corners means cracks.
The high stress is due to a singularity caused by the sharp corner. See if the explanation in this article makes sense.
Put a radius or chamfer there and see if it helps.
Stress concentration on corners.
Sim could amplify the problem because it use mesh which create lots of corners.
Usually we can "ignore" it from experience.
Still the stress will cause fatigue failure.