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in our design there are diaphragm tapped with magnet below that we have cantilevers. we need a input as vibration to diaphragm for that we don't know wat kind of physics that need to apply. so we need a suggestion wat kind of physics can we select for that.

1 Reply Last Post 17 mar 2011, 02:52 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 17 mar 2011, 02:52 GMT-4
HI

if you have a "structure" or some material moving/flexing under load you need the Solid in v4 or one of the SMD/structural in 3.5

If you want to display the magnetic fields of the magnet you need ACDC MF

Then how do you drive the vibration ? an external force OK that is taken care of in the Solid module, if its a coil with current acting via the magnet, then the MF should take care of that part

Do not forget to decide if you can work in 2D, 2D-axi or 3D (2D is easier to begin with)

if ypu have a sinus vibration at a given frequency (or a frequency bandwidth) its the Frequency domain solver to use which does a harmonic development of the physics


But first start simple, one physics at the time, model the SOLID apart, load it with forces or pressures, check its behavior in stationary, then in frequency seep mode

then model the magnet apart with only MF, get the magnetic fields, if you have a coil get the current going as wanted and measure the force on the magnet

Then couple both, probably you will need another physics such as ALE to couple the large displacements of the membrane which is not trivial to start with, sometimes its simple as (almost) as good to only use the spatial frame of the SOLID mode (must be turned on in v3.5 and its called the reference frame if I remember right, pls check, on by default in v4)

--
Good luck
Ivar
HI if you have a "structure" or some material moving/flexing under load you need the Solid in v4 or one of the SMD/structural in 3.5 If you want to display the magnetic fields of the magnet you need ACDC MF Then how do you drive the vibration ? an external force OK that is taken care of in the Solid module, if its a coil with current acting via the magnet, then the MF should take care of that part Do not forget to decide if you can work in 2D, 2D-axi or 3D (2D is easier to begin with) if ypu have a sinus vibration at a given frequency (or a frequency bandwidth) its the Frequency domain solver to use which does a harmonic development of the physics But first start simple, one physics at the time, model the SOLID apart, load it with forces or pressures, check its behavior in stationary, then in frequency seep mode then model the magnet apart with only MF, get the magnetic fields, if you have a coil get the current going as wanted and measure the force on the magnet Then couple both, probably you will need another physics such as ALE to couple the large displacements of the membrane which is not trivial to start with, sometimes its simple as (almost) as good to only use the spatial frame of the SOLID mode (must be turned on in v3.5 and its called the reference frame if I remember right, pls check, on by default in v4) -- Good luck Ivar

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