Natural vibration characteristics of short-span submarine power cables with bending stiffness and sag

Abstract

Based on a continuum model that governs the dynamics of submarine power cables, analytical solutions of the natural frequencies and modal shapes for free spanning cables are derived. The effects of sag, axial and bending stiffness are all included. The cable sag calculation has considered the effects of bending stiffness on the static profile. The accuracy of the derived solutions is validated by the results from a laboratory experiment. The applicable ranges of these solutions and that of Ricciardi (Ricciardi and Saitta, 2008) [15] are determined. Also, the effects of static profile, boundary conditions and non-dimensional parameters (ξ and λ2) on the cable natural frequencies and modal shapes are discussed. The results show that the static profile and boundary conditions have significant effects on the modal properties for free spanning submarine power cables. It must be noted that, for lower ξ values, the frequencies of the symmetric modes show a non-monotonic dependence on bending stiffness. The single-degree-of-freedom approach is adopted to further analyze the mechanisms of the non-monotonic behavior.