平織で強化した軟質プラスチック複合シ-トの音響特性

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The acoustic behaviours…transmission loss…of flexible plastics sheet reinforced with plain woven fabrics, compounded with iron oxide powder have been investigated expermentally. The mechanism of sound transmission was analyzed by the resonance-curve method and the mass law. The calculated value were compared with experiments. 1) For single wall (double wall patched with the same material) of flexible plastics, the relation between the measured transmission loss and the value calculated by the mass law has shown that : (a) when mf (mass per unit area × frequency) <3 ×103Kg/m2·Hz, measured transmission loss is larger than the value calculated by the mass law by several decibels, and (b) when mf>3×103, however, transmission loss is smaller due to an internal friction and viscosity . 2) No coincidence effect has been found in the single wall of flexible plastics sheet. 3) If the mass per unit area is equal, the transmission loss of sandwich structure is better than single wall and double walls. 4) The resonance-curve method and the mass law are useful for evaluating the acoustic behaviours of flexible plastics sheet.
社団法人日本繊維機械学会の論文