<DOC>
<DOCNO>
724
</DOCNO>
<TITLE>
structural acoustic proof testing .
</TITLE>
<AUTHOR>
schjeldrup,h.c.
</AUTHOR>
<BIBLIO>
air eng. 1959.
</BIBLIO>
<TEXT>
with the introduction of high-powered
propulsion systems, and paralleling their
continued development, an accompanying
increase in acoustical problems has arisen .
  of these acoustical problems, that of
acoustical fatigue failures has become paramount
in the eyes of the structural engineer .  aircraft
designed to normal strength requirements have
been known literally to fall apart under acoustical
loading .  this problem has required much endeavour
to produce a solution, and considerable
structural research, based upon results of siren or
other testing, have proved inadequate .  this
failure to find a satisfactory solution has resulted
in the conviction that the final proof of a design
can be found only in proof testing .  proof testing,
in the acoustic fatigue sense, is the testing of a
design structure in a simulated acoustical environment
for a period of time long enough to assure
equality with design life .
</TEXT>
</DOC>
