Audio Engineering Society
Chicago
Meeting Review, September 27, 2005
|
9/27/05
Meeting Highlights presentation The
Acoustics and Vibrations of the Concert Harp including New Design Developments
with Composite Materials. Author Melinda Carney studied the harp and composite
materials for her master�s thesis, and is currently a faculty member at PhD candidate at
rigorous
analysis of harp physics as well as a live demonstration and recording
session with a classically
trained harpist.
The presentation
started with an analysis of the harp as we know it today, including a brief history, wood
selection, soundboard construction, and soundboard and string vibration and radiation. Since
wood is susceptible to cracking and changes with humidity and is in short supply, research
into alternative soundboard materials has been ongoing. The author described her recent
research, starting with modal and finite element analysis to determine the
wood�s material
properties and determine matching criteria for experimental materials. Carbon
fiber composite
materials were covered next, particularly the relationship between the number
and orientation of
plies and the resulting mechanical properties. Experimental soundboards were constructed, and
the initial results showed that it is possible to get the resonance
frequencies of either the
bending modes or the torsional modes to match, but not both. This observation
led to an additional
criterion, more experimentation, and better results, however, the damping of
the composite
soundboard was only half that of wood. The author showed the finite element analysis results
for the wood and composite boards, and finished with recommendations for further research
including a full composite soundboard. The meeting
concluded with a lively discussion period, followed by the live demonstration
in the college�s
recording studio. |
