ASA 127th Meeting M.I.T. 1994 June 6-10

2pSA10. An experimental apparatus for measuring underwater acoustic scattering from structurally complex finite cylinders.

George S. McCall, II

Peter H. Rogers

School of Mech. Eng., Georgia Inst. of Technol., Atlanta, GA 30332-0405

Theoretical predictions of the scattering from submerged circular cylinders benefit from the simplicities inherent in the assumption of infinite length. Consequently, experimental verification of these predictions typically involves cylinders with high length to diameter ratios in order to approximate this assumption. However, there are obvious advantages in dealing with shorter targets. This paper describes an experimental apparatus for measuring the scattering from circular cylinders with length to diameter ratios of one. By minimizing the scattering from the endcaps and minimizing the extent to which the endcaps restrict the motion of the shell, the cylinder can be made to have scattering characteristics (in the plane perpendicular to its axis) similar to that of an infinitely long cylinder. Because larger diameters can be accommodated, a wide range of structural details can be more easily studied. Experimental results are presented for this shells, thin shells with ring supports, and ring supported thin shells with compliant outer layers. The experimental data are compared with numerical results from two- and three-dimensional computer models. [Work supported by ONR.]