scholarly journals A numerical finite element study on connections of SFRC offshore wind towers with prestressed CFRP reinforcement and steel connectors

2020 ◽  
Vol 5 ◽  
pp. 101-113
Author(s):  
Chandan Gowda ◽  
Fabio P. Figueiredo ◽  
Joaquim A. O. Barros ◽  
António Ventura-Gouveia
Keyword(s):  
Finite Element ◽  
Friction Angle ◽  
Offshore Wind ◽  
Advanced Materials ◽  
Limit States ◽  
Steel Fibre Reinforced Concrete ◽  
Shear Friction ◽  
Nonlinear Features ◽  
Parametric Analyses ◽  
Material Nonlinear

The growing need for sustainable production of electricity highlights the importance and the necessity of having higher number and more effective offshore wind towers. The rapid growth of offshore wind towers is estimated to produce 4% of electricity demands in Europe by the end of 2020. The research described in this paper is part of a project dedicated for the development of innovative structural system using advanced materials for lightweight and durable offshore towers. Specifically, it discusses the nonlinear finite element modelling of the connection between representative prefabricated rings of offshore wind tower made by steel fibre reinforced concrete (SFRC), and prestressed by a hybrid system of carbon fibre reinforced polymers (CFRP) bars and steel strands. This connection is assured by post-tension high steel strength cables and concrete-concrete shear friction width an idealized geometric configuration of the faces in contact. The model takes into account the loads from the rotor, wind and water currents, by considering the critical loading conditions for the safety verifications of serviceability and ultimate limit states. The material nonlinear analyses are carried out with FEMIX V4.0 software, considering a 3D constitutive model capable of simulating the relevant nonlinear features of the SFRC, and interface finite elements for modelling the shear friction of the concrete-concrete surfaces in contact. The parametric analyses involve the influence on the relevant results of the SFRC fracture parameters, pre-stress level of the reinforcements, shape of interlock mechanism, friction angle and interface cohesion.

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

Finite Element Analysis of Drilling Frame on Down-the-Hole Drill Based on Mechanical Mechanics and Mechanical Properties

2014 ◽  
Vol 908 ◽  
pp. 282-286
Author(s):  
Wan Rong Wu ◽  
Lin Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Working Condition ◽  
Slenderness Ratio ◽  
Stress And Strain ◽  
Limit States ◽  
Element Analysis ◽  
Practical Engineering ◽  
Structure Strength ◽  
Strength And Stiffness

Drilling frame on TD165CH Down-The-Hole Drill that has large slenderness ratio and be longer than 10m is one component of Down-The-Hole drill which is mainly subjected to load.In the process of drilling, drilling frame is not only subjected to loads which are like tensile, compression and torsion and so on, and be under the influence of impacting and vibration of impactor,the situation of force is complicated.By analysing of working condition of Down-The-Hole drill,there get all kinds of limit states of typical working conditions, and then using Ansys doing finite element analysis, there get distribution of the stress and strain of drilling frame and the result of modal analysis to check whether drilling frame meets the requirements of strength and stiffness or not,and whether it is possible to resonate with the impactor or not.By analysis,Structure strength and stiffness of drilling Frame on TD165CH Down-The-Hole drill meet the requirements of practical engineering, and drilling Frame does not resonate with the impactor.

A Comparative Study on the Plastic Formulations of Ship Shell Plating Under Patch Loading

2008 ◽  
Author(s):  
Lin Hong ◽  
Jo̸rgen Amdahl
Keyword(s):  
Finite Element ◽  
Comparative Study ◽  
Permanent Deformation ◽  
Nonlinear Finite Element ◽  
Limited Area ◽  
Resource Exploitation ◽  
Limit States ◽  
Patch Load ◽  
Ice Loads ◽  
Patch Loading

The purpose of the present study is to further develop the response formulation of ship shell plating under general patch loading, considering the effect of finite, permanent deformation. A comparative study is conducted between various formulations for the load-carrying capacity of laterally patch loaded plates with the aid of nonlinear finite element method. The increasing public interest of transportation and resource exploitation in Arctic area gives rise to advances in ice strengthening of ship structures. As a result, the subject of ship shell plating under ice loads has been extensively studied. Similar to ice loads, wave slamming loads, wheel loads of vehicles and accidental loads, e.g. collision and grounding, are all likely to take place over a limited area of the plate, and can be termed as ‘patch loading’. Consequently, the resistance of ship shell plating under ‘patch loading’ is of significant interest. In this study, a recently developed plastic formulation for patch loaded plates is further extended for general patch loading condition, i.e. patch load with limited extension in both length and height direction. After a brief review of the development of the response and design formulations for plates under uniform lateral load and patch load, comparative studies are made in cases of limited and finite permanent deformation with the aid of nonlinear finite element methods. By allowing a certain level of permanent deformation, significant weight savings can be achieved. Some main findings will be concluded from the comparative study. The present formulation may be used as a versatile tool for predicting the resistance of plates under various types of patch loads, notably when finite, permanent deformations are accepted, e.g. in the Accidental (Abnormal) Limit States design.

scholarly journals Sensitivity Analysis of Influencing Factors of Building Slope Stability Based on Orthogonal Design and Finite Element Calculation

2018 ◽  
Vol 53 ◽  
pp. 03076
Author(s):  
RUAN Jin-kui ◽  
ZHU Wei-wei
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Design Method ◽  
Orthogonal Design ◽  
Slope Angle ◽  
Friction Angle ◽  
Range Analysis ◽  
Factors Affecting ◽  
Orthogonal Test Design ◽  
The Stability

In order to study the sensitivity of factors affecting the homogeneous building slope stability, the orthogonal test design method and shear strength reduction finite element method were used. The stability safety factor of the slope was used as the analysis index, and the range analysis of results of 18 cases were carried out. The results show that the order of sensitivity of slope stability factors is: internal friction angle, slope height, cohesion, slope angle, bulk density, elastic modulus, Poisson's ratio. The analysis results have reference significance for the design and construction of building slope projects.

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 Increasing Damping of Thin-Walled Structures Using Additively Manufactured Vibration Eliminators

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2125 ◽  
Author(s):  
Paweł Dunaj ◽  
Stefan Berczyński ◽  
Karol Miądlicki ◽  
Izabela Irska ◽  
Beata Niesterowicz
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Steel Beam ◽  
Finite Element Models ◽  
Fem Model ◽  
Thin Walled Structures ◽  
Resonance Frequencies ◽  
Thin Walled ◽  
Parametric Analyses

The paper presents a new way to conduct passive elimination of vibrations consisting of covering elements of structures with low dynamic stiffness with polylactide (PLA). The PLA cover was created in 3D printing technology. The PLA cover was connected with the structure by means of a press connection. Appropriate arrangement of the PLA cover allows us to significantly increase the dissipation properties of the structure. The paper presents parametric analyses of the influence of the thickness of the cover and its distribution on the increase of the dissipation properties of the structure. Both analyses were carried out using finite element models (FEM). The effectiveness of the proposed method of increasing damping and the accuracy of the developed FEM models was verified by experimental studies. As a result, it has been proven that the developed FEM model of a free-free steel beam covered with polylactide enables the mapping of resonance frequencies at a level not exceeding 0.6% of relative error. Therefore, on its basis, it is possible to determine the parameters of the PLA cover. Comparing a free-free steel beam without cover with its PLA-covered counterpart, a reduction in the amplitude levels of the receptance function was achieved by up to 90%. The solution was validated for a steel frame for which a 37% decrease in the amplitude of the receptance function was obtained.

scholarly journals Numerical Analysis of the Deformation Performance of Monopile under Wave and Current Load

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6431
Author(s):  
Libo Chen ◽  
Xiaoyan Yang ◽  
Lichen Li ◽  
Wenbing Wu ◽  
M. Hesham El Naggar ◽  
...  
Keyword(s):  
Finite Element ◽  
Deformation Mechanism ◽  
Large Diameter ◽  
Offshore Wind ◽  
Stokes Wave ◽  
Reverse Direction ◽  
Design Parameters ◽  
Embedment Depth ◽  
Current Load ◽  
Maximum Displacement

The research on the deformation mechanism of monopile foundation supporting offshore wind turbines is significant to optimize the design of a monopile foundation under wave and current load. In this paper, a three-dimensional wave-pile-soil coupling finite element model is proposed to investigate the deformation mechanism of monopile undercurrent and fifth-order Stokes wave. Different from the conventional assumption that there is no slip at the pile-soil interface, Frictional contact is set to simulate the relative movement between monopile and soil. Numerical results indicate that under extreme environmental conditions, the monopile foundation sways within a certain range and the maximum displacement in the loading direction is 1.3 times the displacement in the reverse direction. A further investigation has been made for a large-diameter pipe pile with various design parameters. The finite element analyses reveal that the most efficient way to reduce the deflection of the pile head is by increasing the embedment depth of the monopile. When the embedment depth is limited, increasing the pile diameter is a more effective way to strengthen the foundation than increasing the wall thickness.

Nonlinear Finite Element Analysis for Thermoplastic Pipes

1998 ◽  
Vol 1624 (1) ◽  
pp. 225-230 ◽  
Author(s):  
Chuntao Zhang ◽  
Ian D. Moore
Keyword(s):  
Finite Element ◽  
Geometrical Nonlinearity ◽  
Constitutive Models ◽  
Material Behavior ◽  
Pipe Material ◽  
Limit States ◽  
Element Analysis ◽  
Finite Element Program ◽  
Highly Nonlinear ◽  
Nonlinear Constitutive Models

Thermoplastic pipes are being used increasingly for water supply lines, storm sewers, and leachate collection systems in landfills. To facilitate limit states design for buried polymer pipes, nonlinear constitutive models have recently been developed to characterize the highly nonlinear and time-dependent material behavior of high-density polyethylene (HDPE). These models have been implemented in a finite element program to permit structural analysis for buried HDPE pipes and to provide information regarding performance limits of the structures. Predictions of HDPE pipe response under parallel plate loading and hoop compression in a soil cell are reported and compared with pipe response measured in laboratory tests. Effects on the structural performance of pipe material nonlinearity, geometrical nonlinearity, and backfill soil properties were investigated. Good correlations were found between the finite element predictions and the experimental measurements. The models can be used to predict pipe response under many different load histories (not just relaxation or creep). Work is ongoing to develop nonlinear constitutive models for polyvinylchloride and polypropylene to extend the predictive capability of the finite element model to these materials.

Prediction of Friction Coefficients During Scratch Based on an Integrated Finite Element and Artificial Neural Network Method

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Haibo Xie ◽  
Zhanjiang Wang ◽  
Na Qin ◽  
Wenhao Du ◽  
Linmao Qian
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Finite Element ◽  
Friction Coefficient ◽  
Process Parameters ◽  
Neural Network Method ◽  
Network Method ◽  
Shear Friction ◽  
Artificial Neural Network Method ◽  
Artificial Neural

Abstract An integrated finite element and artificial neural network method is used to analyze the impact of scratch process parameters on some variables related to elastoplastic deformation of titanium alloy. The elastoplastic constitutive parameters applied for scratch simulations are obtained from the nanoindentation experiments and finite element analysis. The validity of the finite element model of scratch is confirmed by comparing the friction forces from simulations to those from experiments. The input parameters of the artificial neural network are three scratch process parameters: tip normal force, tip radius, and shear friction coefficient. The outputs are four variables related to material deformation measured during scratch: scratch depth, elastic recovery height, plowing height, and plowing friction coefficient. The network is trained with pairs of input and output datasets generated by scratch simulations. The prediction results of the neural network are in agreement with the finite element results. The model provides assistance for the prediction and analysis of complex relationships between scratch process parameters and variables related to material deformation, and between the plowing friction coefficient and the relevant parameters. The results show the independence of scratch depth and the shear friction coefficient, and the positive relationships between the shear friction coefficient and plowing friction coefficient.

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