| 摘要 |
948,483. Laminates. BOLT BERANEK & NEWMAN Inc. Jan. 1, 1960 [March 23, 1959], No. 123/60. Heading B5N. A structure designed to damp a predetermined band of vibrational-wave frequencies comprises two acoustically dissimilar transmission elements separated by a viscous medium. The two elements are in the form of plates, rods, tubes &c. and have different propagation velocities for waves transmitted in a bending mode. The velocity difference is obtained by using different dimensions, materials or operating temperatures for the two elements. As shown, two steel plates 1, 3 of different thicknesses are separated by a liquid medium 5 e.g. silicone oil. The two plates may have the same thickness and a difference in velocities msy be obtained by notching one of them. The plates may be spaced by foam plastic separators 7. The two plates may be made of translucent or transparent glass and the medium 5 may be light-transmitting. |
