Learning Forum

[StudenteAnsys]

Hello everyone, I'm trying to simulate a bending plate using shell181 elements but I get an unacceptable percentual error in the results and I can't figure out why.

Lenghts are in mm.

The geometry of my plate is 100x50x1 (bxhxt).

Bending moment: 100Nmm.

Settings for the shell element

In this picture all the constrains are shown

 

 

I got from the simulation these results

 

But I expected a stress of 12MPa.

What am I missing?

[peteroznewman]

If you exclude the elements along the fixed support edge, the stress is very close to 12 MPa, which a hand calculation of Mc/I shows is the correct answer. The simple Mc/I equation applies to beam elements that have only a single node that is fixed.

Shell elements have a row of nodes along the fixed edge. The material has a Poisson’s Ratio. The value of Poisson’s ratio is the negative of the ratio of transverse strain to axial strain. Because the nodes are fixed in the transverse direction, the transverse strain causes an additional stress to the bending stress you calculated. Try changing Poisson’s Ratio to 0 and you should get a more uniform stress result. Alternatively, you could modify the support so that the nodes along that edge are free to move along that line, except for a single node that is fixed.

[StudenteAnsys]

Thank you very much for your help.