A numerical investigation on the quasi-static and dynamic response characteristics of steel lazy wave cable

Description

Complex-configuration marine cables use buoyancy sections and seabed contact to redistribute weight, buoyancy and hydrodynamic loads, but the relationship between the static configuration and dynamic response of steel lazy wave cable remains insufficiently understood. This study develops a sequential static-dynamic numerical model for a steel lazy wave cable. The static equilibrium configuration is solved under self-weight, buoyancy, current loading and seabed constraints, and the effects of current velocity, touchdown position and buoyancy-section length on configuration and effective tension are examined. The obtained configuration is then used as the initial state for time-domain analysis with Morison-type loading, a wake oscillator model and prescribed top-end heave motion. The results show that current increases the overall effective-tension level and changes the global configuration. A tension-transition region forms near s/L = 0.5, while the maximum-tension region occurs near s/L = 0.615. Touchdown position and buoyancy-section length further alter the suspended length, buoyancy-section position and local tension transition. Dynamic simulations indicate spatially selective cross-flow vortex-induced vibration (VIV). The tension-transition and maximum-tension regions show multi-frequency participation and high-frequency energy concentration. Under different current velocities, the root-mean-square (RMS) displacement peak and dominant mode do not vary monotonically with current speed, but depend on vortex-shedding frequency, local effective tension and modal matching. Large-amplitude top-end heave amplifies RMS displacement over s/L = 0.1-0.55 and broadens low- to intermediate-frequency spectral peaks. These findings indicate that dynamically sensitive regions can be identified from static tension and configuration characteristics, providing support for key-region selection and VIV safety assessment of steel lazy wave cable.

Institutions

• Shanghai Jiao Tong University

  Shanghai, Shanghai

Categories

Funders

• National Natural Science Foundation of China

  Beijing

  Grant ID: 52371283
• National Natural Science Foundation of China

  Beijing

  Grant ID: 52501343
• Science and Technology Commission of Shanghai Municipality

  Shanghai Municipal People's Government

  Shanghai

  Grant ID: 24YF2721600

Licence