| 摘要 |
<p>The invention relates to a metal shell assembly for a vehicle that is of revolution about a longitudinal axis comprising stiffeners with a periodic distribution having a period and comprising a plurality of resonant annular acousto-mechanical elementary structures indexed according to an index and arranged respectively in a plurality of positions along the longitudinal axis and having respectively a plurality of resonant frequencies, a metal internal layer having internal acoustic impedance and a radial internal thickness, an intermediate layer having an intermediate acoustic impedance and a radial intermediate thickness, an external layer made up of a portion of the shell of a length substantially equal to said period and centred on said longitudinal position. In addition, at least one of the resonant frequencies of an elementary structure is contained within a determined frequency band containing frequencies of acoustic waves dependent on the periodic distribution of the stiffeners, and at least one of the radial thicknesses can be varied according to the index so that the resonant frequencies associated with the radial thicknesses are also variable.</p> |
