Hi all
Similar to my other post, I'm trying to simulate a hoop pulling down on a hook with a 50N force.
This is what I've tried to emulate that a hoop sits on those top surfaces.
However, it appears that stress concentrates at the edge of a fillet The magnitude of the stress is up to 200MPa, which exceeds the yield strength of 159MPa.
Any idea to why might that be the case? There should be more material in the fillet, so shouldn't it be a stronger area instead?
Thank you
John
Hi Janko,
Yes, I'm using a curvature-based mesh with max. 0.3mm. The hook has a diameter of 1.5mm.
Perhaps the geometry will need to be changed. Do you know why stress is concentrated at the edge of the fillet? I've tried adding a gusset on the bottom, but that doesn't seem to help. Usually what kind of geometry change is needed to overcome stress concentration?
Thanks
John
The absolute size of the mesh is ofcourse not relevant, it is about the relative size. Stress convergence is critical if you check the maximum stress.
The stress is concentrated in the middle of the loaded area, because these mesh elements capture most energy from compression. The elements on the side of the loaded area also capture energy, but the energy there is partly transferred to the elements outside of the loaded area.
Look at it ass a glas of water that is heated. The inside will warm up quicker than the outside where energy can be dissipated.
Janko Stellaard
Cadmes BV
The Netherlands
I see. I've now added mesh control (0.1mm) to the critical area and this is the result I get.
It seems like the stress is concentrated at the ends of the curve for some reason. I'm hoping to have the part die-cast in aluminium, so there aren't many options for another material. Is a change to geometry the only solution?
Thanks
John
John,
Please have a look again at my first post in this topic. If point 2 and 3 are not possible, you should consider the first one.
And did you make the mesh at the stress peak smaller (and smaller, and smaller) untill the stress values become constant?
Janko Stellaard
Cadmes BV
The Netherlands
hello , what you want to show in this modelisation
explain clearly you idea .
you just want to study stress concentration or you want to design
explain clearly please
Hi John,
Did you refine the mesh in the critical area untill you got a constant stress value?
If yes, you can conclude that your model will yield. Solutions for that:
Janko Stellaard
Cadmes BV
The Netherlands