Strain-Gage Vibration Measurements on a Submarine-Towed Antenna Cable

As part of the developmental work on a submarine-towed ELF loop antenna, the mechanics of cable vibration have been studied analytically and cable vibration measurements with accelerometets and strain-gages have been carried out from surfaces vessels and from a submarine. The results are that both cable longitudinal strain and cable curvature, over the frequency range of 20 to 200 Hz, are excited by the fluctuating forces on the surface of the cable arising from the cable's own turbulent boundary layer. Neither vibration of the tow point nor the submarine wake are significant sources of mechanical energy. Generalized force spectra are derived from the measured vibration spectra. These then allow the levels of both types of vibration to be calculated for an arbitrary cable towed at an arbitrary speed. See also report dated 30 Mar 1972, AD744825.