piano soundboard beam deflection
piano soundboard beam deflection
(OP)
I'm trying to find a formula to determine max deflection @ center of a simply supported beam, rectangular section, with 2 point loads located at non-center location.
Jim
Jim





RE: piano soundboard beam deflection
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RE: piano soundboard beam deflection
I would use the Macauley method and here is a link:-
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then go to worked example number 6 on page 13 of 18
desertfox
RE: piano soundboard beam deflection
While the end result is a deflection, the equivalent point load that causes such a deflection has little relevance to the tension applied to the wires.
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RE: piano soundboard beam deflection
However as independent small artisan types we don't have ready access to finite systems or other complex/expensive modeling products. The price point of this work doesn't allow for that kind of consulting for each board, so we come up with trends which are ballparked with # crunching, and back it up with empirical tests and experience. There are definitely trends.
The bridge or bridges are located in discreet positions along the ribs. They transfer string loads at each intersection of bridge and rib. The total load is 700lbs or more down force exerted by the strings on the soundboard.
WHile calling these points "point loads" is not precisely correct, calling them as such does allow me to narrow down the "guess" range, and clean up small discreencies after the board and strings are all put together. Seat of the pants engineering.
So anyway my question remains...I will see if I can deal with the Macauley math.
RE: piano soundboard beam deflection
Any deflection in the soundboard affects the pitch of the strings, and the achievable region of adjustment of the stringe to the desired pitch. It also affects the ability of the strings to hold the pitch with time. The stiffer the soundboard, the less dampening, and the pitch loss over time tends to be in the string itself rather than the deflection of the soundboard.
We have a Kawai studio piano, but Chickerings are good too. Have played on them in the last too.
Mike McCann
MMC Engineering
RE: piano soundboard beam deflection
y=F*A(3*L^2-4*A^2)/(24*E*I)
where
L = beam length
A= distance of each load from ends
F = point load value
E modulus of elasticity
I section modulus (B*D^3/12)rectangular beam
B= beam width
D = beam depth
RE: piano soundboard beam deflection
Mike McCann
MMC Engineering
RE: piano soundboard beam deflection
Is the far end of the frame much stiffer than the end that deflects, or are they roughly similar, or in between?
Cheers
Greg Locock
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RE: piano soundboard beam deflection
http:/
http://www.frederickcollection.org/works.html
the applied tension is in the many tons range.
Additionally, the stiffness of the soundboard structure is provided by separate load-bearing metal ribs, in additional to off-angle wood ribs on the bottom: http:
http://www.absolute-piano.com/structural.htm
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RE: piano soundboard beam deflection
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: piano soundboard beam deflection
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