impedance (was negative crown_

[Doug Richards]

So how would YOU measure the mechanical impedance of a structure?  Is it
just the real and imaginary part of a transfer function?  I still don't know
how to measure mechanical impedance...

doug

> -----Original Message-----
> From:	Stephen Birkett [SMTP:birketts@wright.aps.uoguelph.ca]
> Sent:	Tuesday, December 29, 1998 9:02 PM
> To:	pianotech@ptg.org
> Subject:	impedance (was negative crown_
> 
> Del wrote: 
> 
> > Ah, but Doug, the idea of mechanical impedance, or wave impedance, is
> > very important if one is to understand the function of a vibrating body
> > such as the piano soundboard.  It is a function of the square root of
> the
> > inertia times
> >
> To Systems people impedance is a concept that can be applied in all 
> physical domains, including multi-domain systems for which it it 
> especially useful.
> 
> Don't forget that impedance is a complex number - the usual intuitive
> "definition" (above) is the magnitude of that complex number only. The
> time behaviour - lead and lag- comes from the relative size of the real
> and imaginary parts of the impedance. 
> 
> Stpehen
> 
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> email: birketts@wright.aps.uoguelph.ca