Soundboard stiffening

[Richard Brekne]

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Delwin D Fandrich wrote:

>>I don't know how gradual or abrupt the transition was. I wasn't testing for that. These were just observations made along the way. Personally, I have no
>>trouble at all understanding why the transition region was incremental.
>>
>>Del
>>  
>>
>     Great !.. then it should be no problem explaining this to the rest
>     of us.
>
>      
>
> I have already done so.
>  
> Del

Probably me just getting hung up in how whats been said is said 
again.... regardless somehow I've gotten crossed up here and I'd 
appreciate getting whatever misunderstandings I have cleared up... The 
following may help clarify my quandry... You said....

"On reflection I suspect this was because the initial load support came
entirely from compression within the soundboard panel while the ribs (though
lightly crowned they were also moderately bent as in a compression-crowned
soundboard system) were actually working to straighten the panel. Once the
ribs reached their neutral configuration they began helping the compressed
panel in supporting the load rather than fighting it, hence increasing the
spring rate of the system."


But this seems like you are saying the increase in the spring rate does 
not occur until the ribs have become flat, which is not consistant with 
the incremental increase in stiffness you cited in the paragraph exactly 
preceeding...where you say

    As best as I can recall the amount of deflection was greater per
    incrementat the beginning of the loading. With each increase in
    weight the board went flatter, but not by as much as with the
    previous increment. The biggest change in the amount of deflection
    came at the beginning. Toward the end it was pretty difficult to
    measure accurately.

So...if you please... straight me out on this... Thanks

RicB



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