Soundboard stiffening

[David Love]

Well, you're the engineer, but if it takes 100lbs to compress the
soundboard 1", doesn't it take considerably more than that to compress it
the next inch?  Doesn't that suggest a stiffening of the board as it's
compressed?

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Phillip Ford <fordpiano@earthlink.net>
> To: Pianotech <pianotech@ptg.org>
> Date: 2/1/2004 11:15:28 PM
> Subject: RE: Soundboard stiffening
>
> >At the risk of oversimplification, isn't a crowned soundboard just a big
> >spring, the more you compress it, the more rigid it becomes?
> >
> >David Love
> >davidlovepianos@earthlink.net
> >
>
> David,
>
> This is the point that I was trying to make.  I believe that the 
> soundboard is essentially just a big spring.  A spring doesn't get 
> more rigid or stiff the more you compress it.  Within its working 
> range it has a constant spring rate or stiffness.  If a spring's 
> spring rate is 100 lb/in. then it takes 100 lbs to deflect it the 
> first inch.  It takes 100 additional lbs to deflect it another inch. 
> It doesn't matter if you start from a zero deflection point or an 
> initial 1 inch deflection point - the spring rate (or stiffness) is 
> still 100 lbs/in.  It's not getting stiffer because you're putting 
> load on it or deflecting it.  True, it takes twice as much load to 
> get twice as much deflection, but that is still a constant stiffness. 
> I would expect a soundboard to work the same way.  If the board is 
> actually getting stiffer as a result of applied load then it's not 
> acting like a spring or a beam, and I would like to understand what 
> mechanism is causing that to happen.
>
> Phil Ford
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