Analytical and experimental study of the dynamic response of segmented cable systems

Abstract The present paper is a review of experimental and analytical investigations dealing with the dynamic response of vertically hanging segmented cable systems where the upper portion is a stranded steel cable and the lower segment is a nylon rope. Such systems are frequently used in oceanographic applications. A generalized distributed mass model has previously been developed by the authors for a segmented cable made up of two viscoelastic materials including internal damping and linear external damping of the payload and cable. In that model the viscoelastic behavior is simulated by a two-parameter Voigt model and external linear viscous damping is used for the payload and the cable, but an approximate method takes into account non-linear damping effects due to the solid-fluid interaction. In general, good agreement is obtained between that mathematical model and the experimental results. It is also shown that the agreement is better if one approximates the viscoelastic behavior of the nylon rope by a lumped three-parameter system. The behavior of single nylon cables is also studied analytically and experimentally under dynamic conditions in air and in water media. The problem of “snap loading” is also studied and several conclusions of practical interest from a designer's point of view are drawn.