FEA cyclical force

[amedina]

For those mechanica enthusiasts, here is a question.

I got an exhaust tube of some weird looking shape. Now I want to do a modal
analysis but I want to do it in such a way that the force imput is coming
from say a surface.

I'm doing this as basic as possible on a small simple model. All I want to
do is select a surface, tell mechanica to apply a force/moment dependent on
time at that surface and then let is compute. I want to see how applying
this force affect everything else. It seems that in a regular modal analysis
this is not possible. I suppose that I need to run a modal analysis first so
that the resonances can be found, but I also want to be very specific as to
where the movement come from and not let just random movement shake the
exhaust pipe.

any help or a PDF/website tutorial would be appreciated.

regards,

Alfonso

This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.

[ptcuser11]

Hello Alfonso,



A modal analysis will contain no forces, because it is a simulation to
simply find resonant frequencies

and mode shapes of a structure. However, a variant of this is a prestressed
modal where in effects

of stress stiffening can be included.



From what you have written it appears you are trying to perform a forced
vibration analysis within

the time domain (i.e. forces as a function of time). You can download my
presentation from

this year's PTC User conference where I demonstrate how with videos to
create a forced vibration

simulation within the frequency domain (i.e. a Mechanica frequency
analysis). Here is the link: