S. Schedin et al., TRANSIENT ACOUSTIC NEAR-FIELD IN AIR GENERATED BY IMPACTED PLATES, The Journal of the Acoustical Society of America, 99(2), 1996, pp. 700-705
The transient acoustic near field in air from impacted cantilever plat
es of two different geometrical shapes and materials is studied using
two-reference-beam double-pulsed holographic interferometry. The acous
tic waves, observed in two directions simultaneously, are generated by
traveling flexural waves in the plates and by the impact process itse
lf. A subsequent phase-stepping procedure is used for quantitative eva
luation of the registered two-dimensional projections of the acoustic
fields. An interesting observation is the acoustic radiation at the fr
ee end of the plate, where sound waves propagate into the air in obliq
ue directions from the plate. At the region right above the free end n
o acoustic waves are observed. Supersonic flexural waves in the plates
generate trace-matched acoustic waves in the surrounding air. Calcula
tions of the corresponding two-dimensional transient acoustic fields a
re performed. Those are based on an analytical solution of the Kirchho
ff plate equation. Calculated results reproduce the character of the o
bserved transient acoustic waves quite well. (C) 1996 Acoustical Socie
ty of America.