Pile-Soil Interaction Under Cyclic Loadings for Offshore Wind Monopiles

2014 ◽  
Author(s):  
Yunsup Shin ◽  
Morten Saue ◽  
Thomas Langford ◽  
Hans Petter ◽  
Kyunghwan Cho ◽  
...  
Keyword(s):  
Constitutive Models ◽  
Friction Angle ◽  
Cyclic Stress ◽  
Fe Analysis ◽  
Offshore Wind ◽  
Soil Profiles ◽  
Element Analysis ◽  
Lateral Resistance ◽  
The Finite Element Analysis ◽  
Clay Layers

Offshore wind structures are subjected to cyclic loadings from wind, wave and current which must be accounted for when designing foundations. The effects of cyclic loadings can govern the dimension of the foundations. However, less standard and calculation procedure for designing foundations under cyclic loadings is generally accepted in practical design. A parametric study at the generic clay profiles were carried out by using the conventional beam column approach and the finite element analysis. In addition, a monopile foundation at the layered soil profiles in Korean West Sea were designed taking into cyclic loading effect account. Both design results show that the bending moments and shear forces along the pile by using beam column approach are larger than the results from the FE analysis. The FE analysis gives less pile displacement and rotation than the beam column approach. The reason for these differences can be partially explained by the soil reactions in the upper soil profiles. For the clay layers the lateral soil resistance is generally higher in the FE analyses compared to the cyclic p-y curves. However the lateral resistance in the silt sand layers is greater by using the standard cyclic p-y curves with a drained friction angle than using the constitutive models applying cyclic properties. Based on the results, a practical approach of monopile design for the specific offshore location can be recommended by calibrating and simplifying cyclic p-y curves from the results of FE analyses taking into account the cyclic stress-stain response of the soil.

Analysis of Working Condition and Load Direction for Tripod Substructure of Offshore Wind Turbine

2013 ◽  
Vol 454 ◽  
pp. 27-33
Author(s):  
Bin Wang ◽  
Ying Li ◽  
Na Lv ◽  
Bin Bin Zhu ◽  
Wei Li
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Working Condition ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Load Direction ◽  
Element Analysis ◽  
Static And Dynamic Analysis ◽  
The Finite Element Analysis ◽  
Control Load

The control working condition and the control load direction of the typical Tripod substructure for the offshore wind turbine are studied by the finite element analysis software SACS. The results show that the different control criterions are corresponding to the different control working conditions for the Tripod substructure of the offshore wind turbine, and the control load directions vary with the structure form and the marine environments. Therefore, the static and dynamic analysis of the offshore wind turbine substructure in the single or limited load directions cant reflect the static and dynamic characteristic of the structure sufficiently. The multidirectional static and dynamic analysis of the offshore wind turbine structure has to be carried out.

J Resistance Curve Estimation of Inhomogeneous CT Specimen

2002 ◽  
Author(s):  
Kiminobu Hojo ◽  
Kazutoshi Ohoto ◽  
Itaru Muroya
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Stress Condition ◽  
Estimation Method ◽  
Fe Analysis ◽  
Fracture Toughness Test ◽  
Plane Stress Condition ◽  
Element Analysis ◽  
Curve Estimation ◽  
The Finite Element Analysis

In order to obtain the fracture toughness curve of inhomogeneous CT specimens, a simplified J-R curve estimation method has been proposed. To verify the applicability of this method, the fracture toughness test and the finite element analysis has been conducted. In overmatching case (mismatch ratio M = 2.2), the conventional ASTM standard’s J-R curve exceeded the J-R curve from the FE analysis in the plane strain condition by over 20%. On the other hand, the simplified J-R curve was located between J-R curves from the FE analyses in plane strain and plane stress condition. In undermatching case (M = 0.5), experimental J-R curves with and without the inhomogeneity effect were almost same and the conventional standard is applicable.

scholarly journals DRUCKER-PRAGER MODELS FOR DYNAMIC ANALYSIS OF GRANULAR METAMATERIALS IN EARTHQUAKE ENGINEERING

2021 ◽  
Vol 4 (2) ◽  
pp. 5-11
Author(s):  
A.A. Al' Shemali A.A.
Keyword(s):  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Seismic Waves ◽  
Friction Angle ◽  
Fe Model ◽  
Element Analysis ◽  
Seismic Shear ◽  
The Finite Element Analysis ◽  
Modern Methods ◽  
Slab Foundation

Problem of developing methods for protecting buildings and structures from the vibrations transmitted to them from the soil under the action of seismic effects is extremely important to date. One of these modern methods is seismic pads. The purpose of this work was to study the effectiveness of adding a pad of granu-lar metamaterials under the foundation of the building to decrease influence of seismic shear waves. The Finite Element Analysis of Mohr-Coulomb models was used to achieve this goal. The FE model consists of a ten-story superstructure rested on the slab foundation, under which there is a layer of granular metamateri-als. The values of five variables that affect the mechanical properties of these metamaterials were analyzed (density – cohesion – internal friction angle – Young's modulus – Poisson's ratio) for two different pad thicknesses. The dynamic analysis performed using the software package Abaqus/CAE showed the effec-tiveness of the granular metamaterials in their ability to significantly reduce magnitudes of displacements, velocities and accelerations in the building compared to the same values in the absence of these metamateri-als. The analysis also revealed that among the studied variables, the cohesion is the parameter most influenc-ing the effectiveness of metamaterials in their ability to dissipate seismic waves, while no significant effect was observed for the other parameters

Constitutive Models for AZ31 Magnesium Alloys

2008 ◽  
Vol 367 ◽  
pp. 87-94 ◽  
Author(s):  
Carlo Bruni ◽  
Lorenzo Donati ◽  
Mohamad El Mehtedi ◽  
M. Simoncini
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Models ◽  
Extrusion Process ◽  
Flow Behaviour ◽  
Az31 Magnesium Alloy ◽  
Strain Rates ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Different Temperatures ◽  
Power Law Equation

The present investigation aims at studying and modelling the flow behaviour of the AZ31 magnesium alloy by means of torsion tests performed in extended ranges of temperature and strain rates. Two types of rheological models were considered. The former is based on the power law equation, whilst the latter is based on the Sellars and Tegart approach. The effectiveness of the two constitutive models in describing the flow behaviour of the AZ31 magnesium alloy under investigation was evaluated. It was observed that both the equations are able to predict the flow behaviour of the material at different temperatures and strain rates. In particular, the former is very effective in predicting the hardening stage of the flow curve, whilst the latter allows to fit the softening stage. The models were used for the finite element analysis of a complex extrusion process and the results, in terms of the load-stroke curves, compared to each other.

The Study on Rubber’s Constitutive Model about Parameters Identification and the Effect of Fitting Error

2012 ◽  
Vol 503-504 ◽  
pp. 1094-1099
Author(s):  
Wen Tao Wang ◽  
Wen Bin Shang Guan
Keyword(s):  
Biaxial Tension ◽  
Constitutive Models ◽  
Least Square Method ◽  
Least Square ◽  
Test Material ◽  
Model Parameters ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Hyper Elastic ◽  
Fitting Accuracy

Fitting accuracy of hyper-elastic constitutive models of rubber and parameter identification of the models play important roles in the finite element analysis of rubber components. In this paper, to obtain stress-strain characteristics, uniaxial and planar as well as biaxial tension of a standard rubber sample are measured. Model parameters of three kinds of classic constitutive models are identified using least square method. Then, the fitting accuracy among different models is compared. The comparison shows that the fitting accuracy is getting higher when the test material strain is increased. Also, it can be concluded that Mooney-Rivlin model and Van der Waals model as well as third-order Ogden model have relatively stable fitting accuracy.

A Study on Jumping Characteristics in Synchronous Belt Drives: Experimental Results and FE Analysis at Driven Pulley Jumping

2003 ◽  
Author(s):  
Tomio Koyama ◽  
Weiming Zhang ◽  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Load Distribution ◽  
Fe Analysis ◽  
Experimental Results ◽  
Experimental Result ◽  
Element Analysis ◽  
Belt Drives ◽  
The Finite Element Analysis

The jumping characteristics at the driven pulley of L type synchronous belt drives are experimentally and analytically discussed. The number of the driving and the driven pulley teeth is the same and the wrapping angle of the belt on both pulleys is π radian. In this paper, the meshing state of belts on both of the driving and driven pulleys just before jumping is analyzed using the Finite Element analysis. Standardized L type synchronous belts and pulleys are used for analysis and experiments of the meshing states between belt and pulley, load distribution stress analysis and jumping torque. A 337L075 trapezoidal tooth profile synchronous belt and a 36L075 synchronous pulley are used in the analysis and the experiments. The wrapping angle of belt on both the driving and the driven pulley is equal to π radian. “ABAQUS/Standard” is used for the simulation and analysis of the belt. The simulation of the FE analysis of the wrapping angle of the belt on the driven pulley is almost the same with the experimental result. FE analysis of the load distribution just before jumping on the driven pulley agrees well with the experimental results.

scholarly journals Consistent numerical implementation of hypoelastic constitutive models

2020 ◽  
Vol 71 (5) ◽  
Author(s):  
Mehrdad Palizi ◽  
Salvatore Federico ◽  
Samer Adeeb
Keyword(s):  
Constitutive Models ◽  
Elasticity Tensor ◽  
Element Analysis ◽  
Kirchhoff Stress ◽  
User Subroutine ◽  
Jaumann Rate ◽  
The Finite Element Analysis ◽  
Kirchhoff Stress Tensor ◽  
Objective Stress Rate ◽  
Objective Stress

Abstract In hypoelastic constitutive models, an objective stress rate is related to the rate of deformation through an elasticity tensor. The Truesdell, Jaumann, and Green–Naghdi rates of the Cauchy and Kirchhoff stress tensors are examples of the objective stress rates. The finite element analysis software ABAQUS uses a co-rotational frame which is based on the Jaumann rate for solid elements and on the Green–Naghdi rate for shell and membrane elements. The user subroutine UMAT is the platform to implement a general constitutive model into ABAQUS, but, in order to update the Jacobian matrix in UMAT, the model must be expressed in terms of the Jaumann rate of the Kirchhoff stress tensor. This study aims to formulate and implement various hypoelastic constitutive models into the ABAQUS UMAT subroutine. The developed UMAT subroutine codes are validated using available solutions, and the consequence of using wrong Jacobian matrices is elucidated. The UMAT subroutine codes are provided in the “Electronic Supplementary Material” repository for the user’s consideration.

scholarly journals Study of the Harmonic Analysis and Energy Transmission Mechanism of the Frequency Conversion Transformer

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 519
Author(s):  
Zhonghuan Su ◽  
Longfu Luo ◽  
Jun Liu ◽  
Zhongxiang Li ◽  
Hu Luo ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Frequency Conversion ◽  
Frequency Converter ◽  
Three Dimensional ◽  
Offshore Wind ◽  
Element Analysis ◽  
Offshore Wind Power ◽  
Transmission Distance ◽  
Harmonic Content ◽  
The Finite Element Analysis

Since the transmission distance of submarine cable transmission is inversely proportional to the input frequency, to solve the problem of large losses in the transmission process of offshore wind power, this paper proposes a three-frequency transformer which enables the output of 50 Hz at the input of 50/3 Hz excitation. In this paper, the magnetic flux of a three-dimensional wound core transformer is analytically modeled, the existing condition of magnetic flux harmonics of a three-dimensional wound core transformer is analyzed, the distribution of harmonic content in magnetic flux is obtained, and the principle of realizing frequency conversion is expounded. Secondly, the finite element analysis of the frequency converter is carried out. Finally, a prototype of a frequency transformer is made and tested to verify the correctness of the proposed scheme.

Design, fabrication, and testing of an active camber rotor blade tip

2021 ◽  
pp. 1045389X2110639
Author(s):  
Etana Ferede ◽  
Farhan Gandhi
Keyword(s):  
Fe Analysis ◽  
Blade Design ◽  
Element Analysis ◽  
Aerodynamic Loads ◽  
Actuation Mechanism ◽  
Aerodynamic Loading ◽  
The Finite Element Analysis ◽  
Blade Tip ◽  
Mechanical Actuation ◽  
Good Agreement

This paper presents a morphing blade design for wind turbine application with flexibility in chord-wise bending while providing sufficient stiffness to carry the aerodynamic loads. The NACA64 profile is selected for the camber morphing blade demonstrator. A corrugation concept is chosen because it is relatively easy to manufacture and provides sufficient stiffness to resist deformation due to the aerodynamic loads (through the provision of effective stringers) while providing the required flexibility for chord-wise bending. A mechanical actuation mechanism is employed to achieve the desired morphing angle and increase the stiffness of the morphing airfoil section to resist aerodynamic loading. The design of a morphing blade demonstrator is presented together with the manufacturing process. Finally, an experimental study is conducted where the morphing angle is measured for increasing actuation load and compared with FE analysis showing good agreement between the experimental results and results from the finite element analysis in addition to achieving the desired morphing angle.

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