Modal analysis

[Richard Brekne]

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Hi folks.

This subject has been up from time to time with varying opinions about
its worth, and questions about whether or not factories use it, and
why.  I like to try and ask people directly if I can, and I got this
back from one of the fellows at the research department at Petrof.
Thought you might like to hear what he had to say.



     "Dear Richard
     We are using EMA for piano design. Most of all we are
     observing modal shapes
     of soundboard with / without bridge in free conditions. We
     have also
     laboratory brass frame for fixed piano soundboard conditions
     (can be seen in
     our web bulletin No 01/2000). Ocassionally we make also EMA of
     grand outer
     rim. It can be helpfull for construction changes results
     observing . For
     instance comparing of modal shape amplitude between soundboard
     and rim can
     say something about acoustic efficiency of new prototype.
     We made some works on computer modelling of piano soundboard
     by FEM and
     comparing Fem model modeshape results with real soundboards
     from EMA. Some
     results of my colleague work You can see at proceedings of
     ISMA 1995 France,
     Dourdan -
     Alois Raffaj: Vibrations of piano soundboards, pg 373."

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html


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