impedance for 99

[Ron Nossaman]

>Ron,
>I might be able to save you some time.
>
>BUT...
>
>I've been doing FEA stuff for the past 6 or so years, and to be honest, the
>first two or so years didn't contribute much to the improvement in disk
>drive design.  Even with the experience I have now, I would guess it would
>be a few months of serious modeling  and lab work to be to a point where I
>would direct design decisions.  Since this is not a funded project, no
>promises.
>
>All that said, work (or play) is now underway.  My first cut was a few
>months ago with just a string and the end constraint differences.  Next I
>will add a flat soundboard with non-homogeneous material properties to study
>the first order coupling of string to board.  Then add crown and, followed
>by ........
>
>Just remember, NO PROMISES!
>
>doug
>


Doug,
It's interesting to me that your approach to this is from the other end of
the problem than mine. While you are starting with the details of string
termination and building up, I was factoring most of that kind of detail
out, assuming the modifying effects would be similar across the compass. I
was thinking I'd build a (very) coarse model to see if I could get a
correlation between what the strings produced, and what the soundboard
assembly would accept, and refine it as necessary. I figured that even a
pretty crude set of curves should show maximum divergence at the points
where we can hear the problems in the piano being modeled. From what I've
seen, tried, and heard, there seems to be a fairly wide range of
acceptability in mismatch here. Just defining the approximate center of the
road as a graphable reality check while in the throes of the diagnostic
and/or design muse, would be a big comfort to me. Ah well, I suppose that's
the difference between professional engineers, and basement tinkerers. I
suspect that the availability of tools has just a bit to do with the
different approaches too, eh? The fact that I don't even have a basement,
and have been accused of thinking left handed for most of my life couldn't
possibly be a factor.

Any rash promises or predictions of positive results not entertained until
further notice. I have some rough idea what you're up against.  

>PS  Did you ever get the impression that I don't like the word impedance
>when discussing mechanical structures  :~)

No, really? I didn't get that impression at all. =^*^=
                                                   ~ 

 Ron