Study of Grouted Connections in Offshore Monopile Structures

2019 ◽  
Author(s):  
Efstathios E. Theotokoglou ◽  
Georgia Papaefthimiou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress State ◽  
Wind Turbine ◽  
Static Loading ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
The Finite Element Method ◽  
Analysis Problem ◽  
Mesh Density

Abstract In this paper the grouted connection (GC) of an offshore wind turbine is studied. The study is performed numerically by the finite element method (FEM). Initially, a description of the connection, its geometrical variations and its materials are presented. Moreover, analytical types about the deformation of the connection are presented. Subsequently, the analysis of the three dimensioned problem is performed numerically and the procedure as well as the parameters used, are given step by step. The case of the contact analysis problem is also studied. Practical issues such as mesh density and materials interaction are confronted. Finally, the stress state (SS) will be given in the analysis results, in order to specify the behavior of the connection under static loading.

Analysis of Octagonal Pile Supporting Offshore Wind Turbines Under Wave Loads

2014 ◽  
Author(s):  
Serena Lim ◽  
Longbin Tao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Computational Cost ◽  
Offshore Wind ◽  
Computational Time ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Element Method

Offshore wind energy development has gained considerable momentum around the world as wind is stronger and steadier offshore compared to land. This has led to a significant increase in production in recent years, especially offshore wind turbine embedded in shallow waters, such as the recent large scale offshore wind farms in the Northern Europe region. Being at the offshore waters, the wind turbines are subjected to harsh environment. The pile supporting the wind turbine must be reliable and able to withstand such sea condition. It is an important part of the design to study the structural behaviour of the piles under the wave loads. Due to the significant capital cost associated with the fabrication of the large circular cylinders, a new recommended innovative design to overcome such problem is to substitute the circular cylinder with a vertical monopile of octagonal cross-sectional shape. This paper describes the development of an efficient numerical model for structural analysis of wave interaction with octagonal pile using a modified semi analytical Scaled Boundary Finite Element Method (SBFEM). In contrast to the existing solutions obtained using the traditional methods such as the Finite Element Method (FEM) which typically suffer from high computational cost and the Boundary Element Method (BEM) which faces limitation from fundamental equations and problems with singularities. The most prominent advantage that SBFEM has over the FEM is in terms of the number of elements used for calculation and hence a reduction in computational time. When compared with BEM, the SBFEM does not suffer from computational stability problems.

Smoothed particle hydrodynamics versus finite element method for blast impact

2013 ◽  
Vol 61 (1) ◽  
pp. 111-121 ◽  
Author(s):  
T. Jankowiak ◽  
T. Łodygowski
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Smoothed Particle Hydrodynamics ◽  
Concrete Slab ◽  
The Finite Element Method ◽  
Particle Hydrodynamics ◽  
Mesh Density ◽  
Smoothed Particle ◽  
Element Method

Abstract The paper considers the failure study of concrete structures loaded by the pressure wave due to detonation of an explosive material. In the paper two numerical methods are used and their efficiency and accuracy are compared. There are the Smoothed Particle Hydrodynamics (SPH) and the Finite Element Method (FEM). The numerical examples take into account the dynamic behaviour of concrete slab or a structure composed of two concrete slabs subjected to the blast impact coming from one side. The influence of reinforcement in the slab (1, 2 or 3 layers) is also presented and compared with a pure concrete one. The influence of mesh density for FEM and the influence of important parameters in SPH like a smoothing length or a particle distance on the quality of the results are discussed in the paper

scholarly journals Finite Element Modelling and In Situ Modal Testing of an Offshore Wind Turbine

2018 ◽  
Vol 6 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Erfan Asnaashari ◽  
Andy Morris ◽  
Ian Andrew ◽  
Wolfgang Hahn ◽  
Jyoti K. Sinha
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Finite Element Modelling ◽  
Modal Testing ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Element Modelling

scholarly journals Support condition monitoring of offshore wind turbines using model updating techniques

2019 ◽  
Vol 19 (4) ◽  
pp. 1017-1031 ◽  
Author(s):  
Ying Xu ◽  
George Nikitas ◽  
Tong Zhang ◽  
Qinghua Han ◽  
Marios Chryssanthopoulos ◽  
...  
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Model Updating ◽  
Element Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Support Condition ◽  
Offshore Wind Turbines ◽  
Wind Turbine System

The offshore wind turbines are dynamically sensitive, whose fundamental frequency can be very close to the forcing frequencies activated by the environmental and turbine loads. Minor changes of support conditions may lead to the shift of natural frequencies, and this could be disastrous if resonance happens. To monitor the support conditions and thus to enhance the safety of offshore wind turbines, a model updating method is developed in this study. A hybrid sensing system was fabricated and set up in the laboratory to investigate the long-term dynamic behaviour of the offshore wind turbine system with monopile foundation in sandy deposits. A finite element model was constructed to simulate structural behaviours of the offshore wind turbine system. Distributed nonlinear springs and a roller boundary condition are used to model the soil–structure interaction properties. The finite element model and the test results were used to analyse the variation of the support condition of the monopile, through an finite element model updating process using estimation of distribution algorithms. The results show that the fundamental frequency of the test model increases after a period under cyclic loading, which is attributed to the compaction of the surrounding sand instead of local damage of the structure. The hybrid sensing system is reliable to detect both the acceleration and strain responses of the offshore wind turbine model and can be potentially applied to the remote monitoring of real offshore wind turbines. The estimation of distribution algorithm–based model updating technique is demonstrated to be successful for the support condition monitoring of the offshore wind turbine system, which is potentially useful for other model updating and condition monitoring applications.

scholarly journals Study on the Effect of Different Delamination Defects on Buckling Behavior of Spar Cap in Wind Turbine Blade

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jianwei Li ◽  
Jinghua Wang ◽  
Leian Zhang ◽  
Xuemei Huang ◽  
Yongfeng Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Reference Value ◽  
Element Model ◽  
Theory And Practice ◽  
The Finite Element Method ◽  
Buckling Behavior ◽  
Element Method

Delamination is detrimental to the composite materials, and it may occur in the manufacturing process of the unidirectional laminate of the spar cap in wind turbine blades. This paper studies the effect of different delamination defects on the strength of the unidirectional laminate. The finite element model of laminate with different delamination areas and delamination heights is established using solid elements. The eigenvalues of laminates have different parameters calculated based on the finite element method. The final coupon test is used to verify the conclusions of simulation results. The finite element method presented in this study shows excellent capabilities to predict the buckling behavior of the laminate. The buckling eigenvalue of tested laminate is negatively correlated with the delamination area and positively correlated with the delamination height under the edgewise load. The S11, which is too high at the boundary of the delamination region, plays a significant role in buckling failure. It has a particular reference value for testing the laminate of blade both in theory and practice.

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