scholarly journals Introducing non-rigid body structural dynamics to WEC-Sim

2020 ◽  
Vol 3 (2) ◽  
pp. 55-63
Author(s):  
Joshua Scriven ◽  
P. Laporte-Weywada ◽  
J. Cruz
Keyword(s):  
Dynamic Response ◽  
Rigid Body ◽  
Structural Dynamics ◽  
Time Domain Analysis ◽  
Point Load ◽  
Rigid Body Dynamics ◽  
Offshore Wind ◽  
Structural Deformation ◽  
Structural Dynamic ◽  
The Individual

This paper describes the development of a structural dynamics add-on to WEC-Sim, an open-source code dedicated to the dynamic analysis of Wave Energy Converters (WECs). When calculating the dynamic response of a body, WEC-Sim by default uses a rigid body dynamics approach. Such an approach ignores the potential effects of structural deformation on the WEC, which can in turn affect e.g. the distributed loads across the WEC and / or the individual (point) load sources that depend on the dynamic response of the WEC. Following a similar approach to tools used in the offshore wind industry, a structural dynamic add-on was developed using Code_Aster as the Finite Element (FE) solver to enable coupled hydro-elastic, time-domain analysis. The add-on was developed and tested using an example Oscillating Wave Surge Converter (OWSC) WEC model, currently being developed as part of the H2020 MegaRoller project. In the examples studied, the inclusion of structural dynamics is shown to affect the estimated peak Power Take-Off (PTO) loads, with variations in PTO force of over 10% being observed when structural dynamics are considered in the analysis.

Aeromechanical Analysis of Two-Bladed Downwind Turbine Using a Nacelle Tilt Control

2017 ◽  
Author(s):  
Qiuying Zhao ◽  
Chunhua Sheng ◽  
Yousuf Al-Khalifin ◽  
Abdollah Afjeh
Keyword(s):  
Wind Turbine ◽  
Structural Dynamics ◽  
Control Method ◽  
Offshore Wind ◽  
Structural Deformation ◽  
Offshore Wind Turbine ◽  
System Response ◽  
High Fidelity ◽  
Dynamics Analysis ◽  
Control Concept

The structural dynamics and response of a two-bladed downwind wind turbine using a new nacelle tilt control are numerically investigated based on a coupled Computational Fluid Dynamics and Computational Structural Dynamics analysis. The new wind turbine tilt control method is investigated to regulate the power output under a varying wind speed environment for offshore wind turbines. The high fidelity aerodynamic loads obtained from CFD computations are used as input in a CSD code to perform a structural dynamics analysis in order to predict the system response and structural deformation of the two-bladed downwind turbine. The coupled CFD and CSD analysis provide high fidelity assessments of the aeromechanical performance with increased accuracy to evaluate the new nacelle tilt control concept, which may lead to an alternative wind turbine control strategy with reduced costs for offshore wind turbine operations.

Numerical Modeling of Dynamic Response of Water Tank in Collision

2017 ◽  
Author(s):  
Qiyu Liang ◽  
Ling Zhu ◽  
Shengming Zhang ◽  
Mingsheng Chen
Keyword(s):  
Dynamic Response ◽  
Structural Deformation ◽  
Simplified Model ◽  
Water Tank ◽  
Time Step ◽  
Kinematic Equation ◽  
Energy Principle ◽  
Side Plate ◽  
Structural Dynamic ◽  
Water Motion

A simplified model is developed to analyse the interaction between the liquid motion and structural dynamic response of the side plate of a water tank. A mathematical model is established to simulate a knife-edged indenter impacting the side plate of a partially-filled water tank. The minimum potential energy principle is used to simulate the structural deformation and the kinematic equation is established to describe the two-dimensional ideal-fluid motion in the water tank. Considering the structural displacement as a connection between the water motion and dynamic response of the side plate, there is a displacement-pressure exchange between the water and the side plate for every time step. With increase of time, the water will finally become still and the plate will arrive at its final deformation. The numerical results based on the present simplified model are compared with the results from numerical simulations of an empty tank under the same impact condition, so as to investigate the effect of the water motion on the structural dynamic response of the side plate.

Model Tests on the Long-Term Dynamic Performance of Offshore Wind Turbines Founded on Monopiles in Sand

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Zhen Guo ◽  
Luqing Yu ◽  
Lizhong Wang ◽  
S. Bhattacharya ◽  
G. Nikitas ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wind Turbines ◽  
Model Tests ◽  
Offshore Wind ◽  
Frequency Change ◽  
Test Results ◽  
Scaled Model ◽  
Structural Dynamic ◽  
Offshore Wind Turbines

The dynamic response of the supporting structure is critical for the in-service stability and safety of offshore wind turbines (OWTs). The aim of this paper is to first illustrate the complexity of environmental loads acting on an OWT and reveal the significance of its structural dynamic response for the OWT safety. Second, it is aimed to investigate the long-term performance of the OWT founded on a monopile in dense sand. Therefore, a series of well-scaled model tests have been carried out, in which an innovative balance gear system was proposed and used to apply different types of dynamic loadings on a model OWT. Test results indicated that the natural frequency of the OWT in sand would increase as the number of applied cyclic loading went up, but the increasing rate of the frequency gradually decreases with the strain accumulation of soil around the monopile. This kind of the frequency change of OWT is thought to be dependent on the way how the OWT is cyclically loaded and the shear strain level of soil in the area adjacent to the pile foundation. In this paper, all test results were plotted in a nondimensional manner in order to be scaled up to predict the consequences for prototype OWT in sandy seabed.

On Singularity of Rigid-Body Dynamics Using Quaternion-Based Models

2012 ◽  
Vol 79 (2) ◽  
Author(s):  
Homin Choi ◽  
Bingen Yang
Keyword(s):  
Dynamic Response ◽  
Rigid Body ◽  
Dynamic Modeling ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Rigid Body Dynamics ◽  
The Body ◽  
Applied Torque ◽  
Body Dynamics

It is well known that use of quaternions in dynamic modeling of rigid bodies can avoid the singularity due to Euler rotations. This paper shows that the dynamic response of a rigid body modeled by quaternions may become unbounded when a torque is applied to the body. A theorem is derived, relating the singularity to the axes of the rotation and applied torque, and to the degrees of freedom of the body in rotation. To avoid such singularity, a method of equivalent couples is proposed.

scholarly journals Effects on the Various Aluminum Foam Fenders of a Tripod Offshore Wind Turbine Collision Due to a Ship

2020 ◽  
Vol 54 (1) ◽  
pp. 79-96
Author(s):  
Zhiwei Han ◽  
Xinlei Zhao ◽  
Chun Li ◽  
Qinwei Ding
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Dynamic Response ◽  
Contact Force ◽  
Aluminum Foam ◽  
Offshore Wind ◽  
Von Mises Stress ◽  
Offshore Wind Turbine ◽  
Structural Dynamic ◽  
Von Mises

AbstractThe interest in offshore wind energy is growing all over the world. Increasingly, offshore wind turbines (OWTs) are being installed close to shipping lanes, which puts them at risk of potential collisions with ships during their service period. This article aims to investigate the structural dynamic response of OWTs to a ship collision. Considering the structure size of the fender as well as the nonlinear characteristics of the structural materials, a finite element model of a 5,000-ton ship colliding with a 4-MW tripod OWT has been developed using the explicit finite element code LS-DYNA. By observing the collision energy conversion, contact force, fender performance, Von Mises stress on the tripod, shear stress, and dynamic response of a nacelle in differently sized fender collision scenarios, it was observed that when the thickness of the fender surpasses 1.1 m, it can protect the OWT from a collision more effectively than with no fender case. Otherwise, the local contact force is cushioned by aluminum foam materials, whose contact force leads to a whole movement of the bearing tripod. The tripod with the aforementioned 1.1-m fender generates a contact force, Von Mises stress, and a shear stress, as well as the anticollision characteristics of a fender and the dynamic responses of a nacelle in 15 scenarios. Therefore, the structural design of the fender is essential in the safety of a tripod foundation in a collision. This article will provide a better understanding of the collision characteristics of the fender in the future.

Reliability Assessment of Fatigue Critical Welded Details in Wind Turbine Jacket Support Structures

2013 ◽  
Author(s):  
Kim Branner ◽  
Henrik Stensgaard Toft ◽  
Philipp Haselbach ◽  
Anand Natarajan ◽  
John D. Sørensen
Keyword(s):  
Structural Dynamics ◽  
Probabilistic Approach ◽  
Reliability Assessment ◽  
Offshore Wind ◽  
Support Structures ◽  
Support Structure ◽  
Operational Conditions ◽  
Offshore Wind Turbines ◽  
Stress Cycles ◽  
The Individual

This paper describes a probabilistic approach to reliability assessment of fatigue critical welded details in jacket support structures for offshore wind turbines. The analysis of the jacket response to the operational loads is performed using Finite Element Method (FEM) simulations in SIMULIA Abaqus. Fatigue stress cycles are computed on the jacket members by applying tower top loads from an aeroelastic simulation with superimposed marine loads and in accordance to the IEC-61400-3 guidelines for operational conditions. The combined effect of the hydrodynamic loads and the rotor loads on the jacket structure is analyzed in a de-coupled scheme, but including the structural dynamics of the support structure. The failure prediction of the welded joints, connecting the individual members of the support structure is based on SN-curves and Miners rule according to ISO 19902 and DNV-RP-C203/DNV-OS-J101. Probabilistic SN-curves and a stochastic model for Miners rule is used to estimate the reliability of selected critical welded details in the jacket structure taken into account the uncertainty in the fatigue stresses.

Research on rolling stability of the flexible waverider based on computational fluid dynamics/computational structural dynamics/rigid body dynamics coupling methodology

2021 ◽  
pp. 095441002110596
Author(s):  
Shang Yiming ◽  
Hua Ruhao ◽  
Yuan Xianxu ◽  
Tang Zhigong ◽  
Wang Zhongwei
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Rigid Body ◽  
Elastic Deformation ◽  
Structural Dynamics ◽  
Rigid Body Dynamics ◽  
Rolling Motion ◽  
Body Dynamics ◽  
Computational Structural Dynamics ◽  
Rolling Stability

The shape of hypersonic aircrafts represented by waveriders is becoming more slender and flatter, thereby greatly reducing the structural rigidity. This innovation is applied to satisfy the demand of long-range flight. The rolling stability of the waveriders is poor due to the slender shape. Therefore, the effect of the elastic deformation on the rolling stability cannot be ignored. The effect of the elastic deformation on the stability of rolling and forced pitching/free rolling coupling motions of the waveriders is studied through computational fluid dynamics (CFD)/computational structural dynamics (CSD)/rigid body dynamics (RBD) coupling methodology. Comparison results of numerical simulation indicate that the elastic deformation of the structure increases the local angle of attack, thereby enhancing the static stability of the waveriders. The rolling motion of the waveriders changes from point attractor to periodic attractor when the vibration velocity due to elastic deformation is considered. The rolling oscillation frequency of the flexible model is higher than that of the rigid model. For the forced pitching/free rolling motion, stability theory based on the rigid body hypothesis is unsuitable when the elastic effect is taken into consideration.

Probabilistic analyses of structural dynamic response with modified Kriging-based moving extremum framework

2021 ◽  
Vol 125 ◽  
pp. 105398
Author(s):  
Cheng Lu ◽  
Cheng-Wei Fei ◽  
Yun-Wen Feng ◽  
Yong-Jun Zhao ◽  
Xiao-Wei Dong ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Structural Dynamic
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