Propagation of Harmonic Waves in Composite Circular-Cylindrical Rods

摘要

Recent interest in the dynamic behavior of sandwich shells used as components in submarines, aircraft, missiles and, particularly, in solid propellant rocket motors has instigated a number of investigations on the propagation of trains of harmonic waves in rods or shells composed of a circular core of an elastic isotropic material bounded by and bonded to a circular casing of another elastic isotropic material. In this investigation the general frequency equation for harmonic waves having an arbitrary number of circumferential nodes, traveling in composite, traction-free, circular, cylindrical rods is established on the basis of the linear three-dimensional theory of elasticity. Simpler degenerate cases of the frequency equation are reduced and discussed. A numerical evaluation of the frequency equation is presented. The results are obtained by programming an iteration procedure on an IBM 7094 digital computer. The effect of the variation of the physical and geometric parameters of the rod on the frequencies and mode shapes of the first few modes is illustrated and discussed. Moreover, the feasibility of utilizing composite rods as delay media in guided wave ultrasonic delay lines is considered briefly. (Author)