Deformation in the modalanalysis

[s073714]

Hi

I have made a modal analysis of a structure. The modal deformations shapes are illustrated on the Pdf file.  The deformations only moves in one direction and then back to initial rest position. I would assume that oscillation would move in both directions relative to the initial position of the structure.

How can I make an animation, which illustrates that, the deformations from the oscillations moves in both directions?

Best regards

Birgitte

[jad.dellel]

Hi,

You should change the mode selected to see the modal deformation in the other direction, generally:

mode 1 illustrates translation of the structure / X

mode 2 illustrates translation of the structure /Y

mode 3 ..... rotation ... /Z

...

[jad.dellel]

How can I make an animation, which illustrates that, the deformations from the oscillations moves in both directions?

Select modes-> switch ON modes + All + accept and run your animation as usual.

[s073714]

Hi Again

Thank you very much for the answer. I have now made an animation of the combined 3 first modes. I have attached a screen shot of the combined deformation (see attached file).

-           Is it supposed to look like that, where the individual bar elements devide from the rest of the structure?

-          Also I thought that it would be possible to illustrate first total downwards movement, and after that total upwards movement, so the structure would oscillate up and down.  In the combined modal-case, all elements move in different direction at the same time.

-          Just to clarify is the next 3 modes (mode 4-6) illustrating the second combined oscillation-shape… and so on?

Thank you

Birgitte

[Pawel.Pulak · Accepted solution]

Hi Birgitte,

it seems that there was some misunderstanding when answering this post:

1/ deformations from different modes should not be combined

2/ as for now it is not possible to display in RSA the animation of vibration shape showing it for full vibration period (both positive and negative aplitudes in all points). The animation is showing only one half of the vibration period - opposite directions of harmonic vibrations are not shown. Implementing such functionality in on the wish list for some time

Regards,

[jo2ny]

Somehow close to the subject:

Is is possible, when visualising the deformed shape of a mode, to display the period instead of the frequency?

Thanks,

(I'm using ARSA Pro 2012 )

[Artur.Kosakowski]

No, that is not possible.

[jo2ny]

Thanks. Maybe in a future version?
In our country we commonly use period instead of frequency as the response spectrum has periods on the X-axis and it's quicker to classify the vibration of the first mode (between (Tb;Tc) (Tc;Td), greater than Td. etc.)

[Artur.Kosakowski]

I have made such development request.