Sound  insulation  walling  with  vibration  absorption.  Part  2
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 Sound  insulation  walling  with  vibration  absorption.  Part  2

The magnitude of the velocity of elastic waves are strongly influenced by the shear strains in the intermediate layer.
   Analysis of expression of the amplitude fluctuations Wmn panel indicates that its values ​​are different for the individual frequency ranges. Based on the analysis it can be said that the degree of transmission of sound is greatest at high frequencies, reduced - in the middle and lower - for a low.
   The magnitude of the radiated acoustic power is defined as the product of the vibrational velocity panels and sound pressure sound waves passed over the area in the ax. As a result, we obtain an expression for the area of ​​complete spatial resonances.
   For the midrange, where the predominant contribution to make incomplete spatial resonances, we obtain the dependence.
   In accordance with the above assumption of a rigid connection continuously distributed vibrodempfiruyuschego layer, the magnitude of the velocity of propagation of elastic waves can be determined from the differential equation of sandwich panels.
   It is noteworthy that if we take C2 = C3, which is possible under the condition h1 = h2 < Analysis of the equation (4) shows that the full frequency band can be split into three areas.
   1. At low frequencies, where C1 < and the last terms of the equation, we have that CuC3 panel
   varies as a flexural wave plate with an areal density of m `and the cylindrical rigid N.
   2. At high frequencies, when C1 < will mainly be determined by the flexural vibrations of the skins, the loaded weight of the middle layer.
  
   To be continued.

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