CREO 2.0 : large stress/strain state where I apply displacements

[ccantarelli]

Good morning,

I have often noticed that, in CREO Simulate (2.0), stress and strains are usually very large on the feature where I apply a displacement even if, in many cases, I would have not expected them. For example, when I impose a displacement on the free tip of a part that could be seen as a cantilever beam, stress and strain are large not just at the root of the part (the constrained one, as expected) but also in correspondence with the surface/line/point to which I have applied the displacement belonging to the free end.

So I would like to ask if there is any known reason for this behaviour.

Thank you very much for the help!

Regards

[danderson]

Please provide a image of your setup for the cantilevered beam you mentioned and a stress fringe plot of the results.

What you are seeing may be due to how you are applying the load. For example if you applied the load or displacement at a single point on the surface this would create a stress riser as the point is infinitely small.

More details might help us point you in the correct direction.

Thanks,

Don Anderson

[ccantarelli]

Hello,

here I report a simple example. I have a sort of appendage fixed on one side and with an imposed displacement of 0.3 mm on the round surface (even of ot is a narrow surface, it is not infinitely small or thin as if it was a point or a line) of the tip. There is also a picture of the Von Mises stress results : as expected, stress is larger at the constrained root, but it reaches the maximum on a very narrow stripe of the tip. 

Thank you for teh attention!

[danderson · Accepted solution]

Looks like a compressive stress concentration related to the material being used from what I can tell.
I made a similar model to what you have in your pictures and ran an analysis on it using nylon 66 with the 0.3mm displacement and achieve similar results. I changed the material to metal and the plots look normal.

The amount of displacement being applied being applied to the material type relative to the size of the structure appears to be what's causing the high stress concentration.

Changing the analysis to a 2 component contact analysis should give you more more accurate results. From what i can see the VM plot looks correct if you are using a soft material like nylon.

Don