Vibration Measurements of a Cylindrical Shell in Air and Water

An experimental system is described for vibration measurements on a 21-in. diam cylindrical shell. The measurements were conducted in both air and water at water depths up to 50 ft. The shell was excited by a pure-tone constant force over the audible frequency range. Data are presented to compare the shell vibration levels in air and in water. No appreciable change in vibration level is shown with submergence depth. The vibration levels of various points on the shell and the mechanical impedance of the driven point is also presented. Radiated sound pressure measurements are compared to vibration levels on the shell. The inherent difficulties with this type of experiment are discussed.