Discrete Element Analysis of Ice-Induced Vibrations of Offshore Wind Turbines in Level Ice

Abstract

Self-excited vibrations of offshore structures interacting with sea ice, characterized by low frequency and high amplitudes, pose significant hazards to offshore wind turbines (OWTs) in cold seas. This study employs the discrete element method (DEM) with a parallel bonding model to investigate the interaction between sea ice and OWTs. Two bond-failure models are compared, with the results showing that the model considering stiffness softening and fracture energy provides better alignment with field data in the Bohai Sea. The DEM is employed to analyze the ice-induced vibration of OWTs under varying ice velocities, revealing that brittle failure of sea ice occurs at higher ice speeds, leading to random structure vibration. At slower ice speeds, both brittle and ductile sea ice failure modes result in self-excited vibrations. This suggests a strong connection between self-excited vibration and the brittle-ductile failure of sea ice, influenced by the relative speeds between ice and the structure. This study employs the DEM to elucidate the mechanism of self-excited vibrations in OWTs from the perspective of brittle-ductile sea ice failure. The results show that the DEM model accurately describes the brittle-ductile transition in sea ice failure, and that the structural motion aligns well with field measurements.

Effect of magnetic needle magnetic particle grinding process on the performance of metal aluminum plates

“…Because of the intricate and irregular motion of magnetic needles in the MN-MAF process within the polishing drum, this study utilizes the Particle Selections functionality in the EDEM software to trace specific motion trajectories and velocity distribution of magnetic needles during the machining process [22,23]. Taking Region III as the research object, the mechanical parameters of the magnetic needles such as contact force, velocity, and pressure between magnetic needles and the workpiece are extracted from the simulation in EDEM software, which are used to be the parameters for predicting residual stress in next step [24].…”

Numerical Simulation of Extreme Ice Loads on Complex Pile Legs of Offshore Substation Structures

“…The interaction between the ice particles uses an elastic-viscous contact model based on the Mohr-Coulomb theory [33], and a parallel bonding model is used when combining spherical ice particles into smooth ice. Two adjacent sea ice elements are considered bonded together through the parallel bonding model, with an elastic bonding disc set between the bonded particle units, as illustrated in Figure 2 [11]. Such a model can transmit both forces and moments, capable of withstanding certain tension and compressive forces, and they break upon collision with structures under the influence of ocean currents, thereby allowing for the study of sea ice failure modes [34,35].…”

“…Sea ice is composed of spherical elements of uniform mass and size, arra regular pattern, with the three non-contacting sides fixed using linear spring bo Because of the effect of ice particle size, to maintain the same density of ice partic different contact areas, the height of each layer of ice particles is kept consisten teraction between the ice particles uses an elastic-viscous contact model base Mohr-Coulomb theory [33], and a parallel bonding model is used when combini ical ice particles into smooth ice. Two adjacent sea ice elements are considere together through the parallel bonding model, with an elastic bonding disc set be bonded particle units, as illustrated in Figure 2 [11]. Such a model can transmit b and moments, capable of withstanding certain tension and compressive forces, break upon collision with structures under the influence of ocean currents, there ing for the study of sea ice failure modes [34,35].…”

“…Ji et al [10] studied the interaction between sea ice and offshore engineering structures based on the discrete element method, observed the sea ice failure process, and calculated the ice vibration response of the structure to provide data support for its fatigue life assessment. Long et al [11] utilized the discrete element method to simulate the interaction between sea ice and offshore wind turbines, investigating the sea ice failure mode and structural vibrations at different ice velocities, as well as revealing the correlation between self-excited vibrations and the ductile-brittle transition of sea ice.…”

Analysis of the Impact Resistance Characteristics of a Power Propulsion Shaft System Containing a High-Elasticity Coupling

“…By establishing a water-lubricated bearing model that combines the wave impact function, Reynolds equation, and Euler equation, they analyzed the impact of wave impact magnitude, direction, and entry time on the starting performance of the bearing. Long et al [14] employed the discrete element method to study the interaction between sea ice and offshore wind turbines, analyzing factors of brittle and ductile failure, and confirmed a strong correlation between self-excited vibration and the brittle-ductile failure of sea ice. Huang et al [15] investigated the response characteristics of the outer hull of a ship's double-layer panel after being penetrated by an energetic metal jet and subjected to a secondary near-field explosion, using the Coupled Eulerian-Lagrangian method for numerical calculations and validated the analysis through experimental verification.…”