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PML in structural mechanics
Posted Nov 26, 2010, 10:13 a.m. EST 3 Replies
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Is there a way to make a PML in structural mechanics that will match all wavelengths, like the PML in acoustics?
3 Replies Last Post Dec 13, 2010, 4:28 p.m. EST
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Posted:
1 decade ago
Hi
No I do not know about that, but you could try to add some damping on your fixed parts with a boundary force
-k*u -damp*MyLambda
for eigenmodes set MyLambda variable to "lambda" of COMSOL, for frequency sweep try a
myLambda = -i*2*pi*freq
and repeat for v, w ...
however it will make your structure move in all directions
--
Good luck
Ivar
No I do not know about that, but you could try to add some damping on your fixed parts with a boundary force
-k*u -damp*MyLambda
for eigenmodes set MyLambda variable to "lambda" of COMSOL, for frequency sweep try a
myLambda = -i*2*pi*freq
and repeat for v, w ...
however it will make your structure move in all directions
--
Good luck
Ivar
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Posted:
1 decade ago
Hi
Could you please elaborate a bit? I don't understand how I should implement this boundary force...
Is this a boundary force?
Could you please elaborate a bit? I don't understand how I should implement this boundary force...
Is this a boundary force?
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Posted:
1 decade ago
Hi
first of all I have noticed that there are some PML BC's that appear time to time in the structural (v4) (depends on solver mode and on options installed), but I haven really looked into these as I'm not doing accoustic and have not seen any need to try PML's in structural so far.
What I was also saying is that you have the COMSOL implemented damping parameters (that you migh tune in at a given frequency) but you can also defne a "user" boundary load of the type -w*k[N/m] for a spring load along Z, as well as for an eigenfrequency solver a boundary load of load -w*damping[kg/s]*lambda for a damper (that by adapting the "damping" variable might be critical damping a motion at a given frequency). But dependingon your model I'm not sure its that easy to use these somewhat crudes methods. for a frequency sweep lambda is not defined, but you have "freq", and lambda = -i*2*pi*freq (if I have got that right, pls check carefully ;)
--
Good luck
Ivar
first of all I have noticed that there are some PML BC's that appear time to time in the structural (v4) (depends on solver mode and on options installed), but I haven really looked into these as I'm not doing accoustic and have not seen any need to try PML's in structural so far.
What I was also saying is that you have the COMSOL implemented damping parameters (that you migh tune in at a given frequency) but you can also defne a "user" boundary load of the type -w*k[N/m] for a spring load along Z, as well as for an eigenfrequency solver a boundary load of load -w*damping[kg/s]*lambda for a damper (that by adapting the "damping" variable might be critical damping a motion at a given frequency). But dependingon your model I'm not sure its that easy to use these somewhat crudes methods. for a frequency sweep lambda is not defined, but you have "freq", and lambda = -i*2*pi*freq (if I have got that right, pls check carefully ;)
--
Good luck
Ivar