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Thread Subject:
simmechanics: ground excited model

Subject: simmechanics: ground excited model

From: pietro

Date: 12 Mar, 2013 16:35:07

Message: 1 of 2

Hi all,

I'm just trying to develop a ground excited model of single degree of freedom model. The excitation is in terms of displacement. Here you can see the model.

http://imageshack.us/f/820/modelqg.png/

I get a huge spike of the body acceleration in the beginning of the simulation. The problem arises from the double integration of the displacement, i.e. the sine wave block. Infact after the first derivative a discontinuity of the first derived signal, as you can see in this plot:

http://img829.imageshack.us/img829/3527/signals.png

the purple signal is the one of the sine wave block output and the yellow one is of the first derivative block output. As you can see there is the discontinuity. How could I fix this problem?

Thanks

cheers

Pietro

Subject: simmechanics: ground excited model

From: pietro

Date: 18 Mar, 2013 08:16:15

Message: 2 of 2

"pietro " <bracardi82@email.it> wrote in message <khnlfr$1no$1@newscl01ah.mathworks.com>...
> Hi all,
>
> I'm just trying to develop a ground excited model of single degree of freedom model. The excitation is in terms of displacement. Here you can see the model.
>
> http://imageshack.us/f/820/modelqg.png/
>
> I get a huge spike of the body acceleration in the beginning of the simulation. The problem arises from the double integration of the displacement, i.e. the sine wave block. Infact after the first derivative a discontinuity of the first derived signal, as you can see in this plot:
>
> http://img829.imageshack.us/img829/3527/signals.png
>
> the purple signal is the one of the sine wave block output and the yellow one is of the first derivative block output. As you can see there is the discontinuity. How could I fix this problem?
>
> Thanks
>
> cheers
>
> Pietro

Any help is appreciated

Thanks

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