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structure borne simulation / transfer function

Matthias Becker
Hi all,

I'm still new in the field of FEM simulation and dealing with Comsol Multiphysics. First, my problem: I am searching for the transfer function of structure-borne in various materials. This, I do an impact hammer test impact and measure the input and output signals (vibrations perpendicular to the surface). In the simulation, I would now like to simulate an impact of the hammer and the expansion of the structure born sound. The vibration perpendiculars to the surface at some point are also to be simulated. Based on the impact energy and the vibration at the excitation point and the measured vibration at the remote point, I would like to determine the transfer function.
How do I choose a suitable approach in Comsol?
How do I simulate an impact? Can I just choose a mass element with a predefined speed?
How can I output the vibration perpendicular to the surface?

The geometry I have already created.

For tips and ideas, I would be very grateful!

Matthias Becker

1 Reply Last Post 15/10/2012, 05:51 GMT-04:00
Posted: 5 years ago 15/10/2012, 05:51 GMT-04:00
Hi

that is a delicate issue, as you need to define up to which frequency you want to study the effects. Impact is in theory an instantaneous effect, butwith FEM you need to make it continuous, even if "short". I use oftena gaussian impulse, but this also defines a filter function on the modes you excite. >Therefore, I then use time modal developmnents with a limited number of modes, this is becoming more and more usefriendly in the latest versions, but I expect still a few uppgrades, such that one can more easily extract a transfer function / state space matrix of a REDUCED model with if possible non contiguous modes selected by the user, based on i.e. modal mass values

--
Good luck
Ivar
Hi that is a delicate issue, as you need to define up to which frequency you want to study the effects. Impact is in theory an instantaneous effect, butwith FEM you need to make it continuous, even if "short". I use oftena gaussian impulse, but this also defines a filter function on the modes you excite. >Therefore, I then use time modal developmnents with a limited number of modes, this is becoming more and more usefriendly in the latest versions, but I expect still a few uppgrades, such that one can more easily extract a transfer function / state space matrix of a REDUCED model with if possible non contiguous modes selected by the user, based on i.e. modal mass values -- Good luck Ivar

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