ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

5aSA5. Structural intensity in an infinite cylindrical shell driven by normal forces.

Donald J. McDowell, Jr.

Naval Undersea Warfare Ctr., Div. Newport, Detachment New London, Code 423, New London, CT 06320

Courtney B. Burroughs

Penn State Univ., State College, PA 16801

Carlos M. Godoy

Naval Undersea Warfare Ctr., Newport, RI 02841

The structural intensity formulation provided by Williams [J. Acoust. Soc. Am. 89, 1615--1622 (1991)] is used to consider the flow of power along an infinite length, thin cylindrical shell driven by a harmonic force applied in the radial direction. Finite element modeling is used to show that the active component of the time-averaged intensity oscillates with respect to the axial coordinate of the shell at a wave number given by the difference between the bending and longitudinal wave numbers. The reactive component of the intensity also oscillates at this rate and is in phase quadrature with the active component. This suggests that the total power at any point along the shell is constant and power is exchanged between wave types. The stored (reactive) power is shown to be associated with circumferential expansions and contractions of the shell.