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Hi Shaghayegh,

This is a quite interesting question, which I will convert into an enhancement suggestion.

The point here is that the structural mechanics equations are formulated in the material frame. The influence of the predeformation of the shell goes into problem as a prestress, but the underlying model is still the undeformed geometry.

You can get the plot you want by manually superimposing the predeformation in the Deformation node. You can then use an expression like withsol(‘sol2’,u)+multiplier*u. Set the Scale factor to 1 since you want true scale for the preload deformation. The constant multiplier will probably need to be adjusted for each mode in order to get a good visualization. The mode amplitudes can be made more uniform by setting Scaling of eigenvectors to Max in the Eigenvalue Solver node.

Regards,

Henrik

Hello Henrik,

Thank you very much for your time and reply. I followed your suggestion but I haven't received my desired result yet. It's my first time using withsol command, so I've attached a screenshot of the deformation node and the result which is still in flat mode. I've tried to change the multiplier value but no result.. Could you please check it. Thanks.

Kind regards, Shaghayegh

Hi Shaghayegh,

In principle, your settings look correct, under the assumption that the solution to your preload case actually is sol2. The 'withsol' part of the expression picks up any solution that you point to. So the effect should be the same as when you do an ordinary deformation plot for that loadcase (given that the scale factor 1 is used there too).

To find a proper scale factor for the modal part, you can just check what scale factor you get when using a default mode plot. The scale factor used is shown in the text field when the check box for the scale is not selected.

Regards,
Henrik

Dear Henrik,

Thank you very much, it works now. I had to change sol2 (Eigenfrequency solution) to sol1 (preload case). Now the only thing is that I want to see the shell vibration and deformation in each natural frequency. So, I put 'shell.disp' expression. But as a result, I just see the same bent shell with no vibration in all available frequencies. Colour bar shows the displacement values but I cannot directly see the deformations in the shell. What can I do?

Kind regards,

Shaghayegh

Hi Shaghayegh,

The only thing I could think of is that the multiplier in withsol(‘sol2’,u)+multiplier*u is too small. If you try the expression 0*withsol(‘sol2’,u)+multiplier*u, you should be able to switch the deformation scale on and off and see that the mode is displayed.

Also, check that you have selected the intended Solution / Data set.

Regards,
Henrik