Contactless control of suspended loads for offshore installations: Proof of concept using magnetic interaction

Current offshore wind turbine installation and positioning methods require mechanical equipment attached on the lifted components and human intervention. The present paper studies the development of a contactless motion compensation technique by investigating a magnetically controlled pendulum. The technique involves the interaction of a...

A new numerical modelling framework for fixed oscillating water column wave energy conversion device combining BEM and CFD methods: Validation with experiments

The Oscillating Water Column (OWC) wave energy converter has been shown to have high potential, thus rendering extensive development in recent years. In order to further accelerate its development, highly accurate yet computationally efficient tools are necessary particularly when studying the interaction of multiple OWC devices. This paper...

A numerical study on the effect of asymmetry on underwater noise emission in offshore monopile installation

Offshore wind energy holds significant promise as a solution in the energy transition. However, installing offshore pile foundations can generate substantial levels of underwater noise, posing potential risks to marine life. This paper examines the influence of asymmetric impact forces and pile inclination on producing underwater noise and...

Underwater noise from vibratory pile driving with non-linear frictional pile–soil interaction

Vibratory offshore pile driving offers a potential solution for reducing the underwater noise generated during the installation of foundation piles compared to using impact hammers. Existing noise prediction models are specifically tailored to impact pile driving scenarios. This paper introduces a novel methodology for underwater noise...

Motion Control of a Pendulum via Magnetic Interaction

The present study introduces a modified version of PD Control for the<br/>case of a magnetically controlled pendulum. The response was observed in both<br/>experimental and numerical simulations taking into consideration the non-linearity posed by the system. The modified PD controller was compared to the simple counterpart for further concrete...

Experimental and numerical study of a magnetic pendulum

An experiment has been performed on a magnetic pendulum, which interacts with an electromagnet. The free non-linear vibrations of the pendulum-magnet system are studied to identify and analyse the system’s characteristics. Due to the presence of the electromagnet, a modulation of the pendulum’s natural frequency is observed. A mathematical model...

On the existence of a critical speed of a rotating ring under a stationary point load

Method for extracting an equivalent Winkler model of the 3D dynamic soil-structure interaction of large-diameter offshore monopile foundations

The motivation for this work stems from the offshore wind industry, where designers are faced with a discrepancy between the available design methods and the typical dimensions of the offshore wind foundations that call for other design approaches. Throughout the years, much valuable work has been performed in the prediction of long, slender,...

A mixed time-frequency domain method to describe the dynamic behaviour of a discrete medium bounded by a linear continuum

To minimize the calculation time required by numerical models that de- scribe dynamic interactions involving nonlinear behaviour, it is useful to divide the model into two separate domains. One domain close to the interaction point, which consists of a sophisticated model capable of describing nonlinear phenomena, and another domain at a...

Added damping of a wind turbine rotor: Two-dimensional discretization expressing the nonlinear wind-force dependency

In determining wind forces on wind turbine blades, and subsequently on the tower and the foundation, the blade response velocity cannot be neglected. This velocity alters the wind force, which depends on the wind velocity relative to that of the blades This blade response velocity component of the wind force is commonly referred to as added...

Assessing the small-strain soil stiffness for offshore wind turbines based on in situ seismic measurements

In this contribution, in situ seismic measurements are used to derive the small-strain shear modulus of soil as input for two soil-structure interaction (SSI) models to assess the initial soil stiffness for offshore wind turbine foundations. This stiffness has a defining influence on the first natural frequency of offshore wind turbines (OWTs),...

Model-based force identification in experimental ice-structure interaction by means of Kalman filtering

The level-ice forces exerted on a scale model of a compliant bottom founded structure are identified from noncollocated strain and acceleration measurements by means of a joint input-state estimation algorithm. The identification is performed based on two different finite element models: one entirely based on the blueprints of the structure, and...

Aerodynamic damping of nonlinearily wind-excited wind turbine blades

This paper presents the first step of the derivation of an aerodynamic damping matrix that can be adopted for the foundation design of a wind turbine. A single turbine blade is modelled as a discrete mass-spring system, representing the flap and edge wise motions. Nonlinear wind forcing is applied, which couples the degrees of freedom. The...

Estimation of the vibration decrement of an offshore wind turbine support structure caused by its interaction with soil