A study on dynamic response of cable-seabed interaction

Abstract

A numerical method is developed to investigate the dynamic response of cable-seabed interaction in this paper. The motion of cable is described by the Lumped Parameter Method, while the seabed, unlike the prevailing simplified model of elastic foundation, is modeled as an irregular continuous rigid surface with rebound and friction existing, and the forces exerted by the seabed consist of normal counterforce and isotropic tangential Coulomb friction resistance. To describe the detailed dynamic response, two coefficients are introduced by analogy with the theory of rigid body collision with friction. The cable-seabed kinematic and dynamic contact conditions are formulated subsequently, and are used to incorporate the seabed effect into the cable dynamics to produce a set of ordinary differential governing equations. In this paper, we employ 4th order Runge-Kutta method to solve these equations. Several simulation cases are presented to illustrate the seabed effect. The results show that friction and impact have a prominent influence on the statics and dynamics of the cable.

Numerical modelling of seabed impact effects on chain and small diameter mooring cables

“…Wang et al [10] used the lumped mass approach to model a mooring line in conjunction with a seabed model based on rigid body collision analysis. It was noted by the authors that, upon line impact with the seabed, there were fluctuations in the fairlead tension which they attributed to the spatially discrete nature of the line structural model.…”

Evaluation and mitigation of modelling errors in numerical simulations of mooring line and seabed contact

“…However, previous studies have suggested that the spring mattress model is prone to discretisation errors associated with line contact with the seabed, particularly spurious tension fluctuations as noted by Refs. [112,113]. The dependence of these models on force coefficients which are difficult to define and calibrate for various seabed and case-specific environmental excitation conditions is an area where further work is required.…”

“…Wang et al [113] used the lumped mass approach to model a mooring line in conjunction with a seabed model based on rigid body collision analysis. It was noted by the authors that, upon line impact with the seabed, there were fluctuations in the fairlead tension which they attributed to the spatially discrete nature of the line structural model.…”