scholarly journals NUMERICAL METHODS FOR THE SIMULATION OF DEFORMATIONS AND STRESSES IN TURBINE BLADE FIR-TREE CONNECTIONS

2019 ◽  
Vol 17 (1) ◽  
pp. 1 ◽  
Author(s):  
Justus Benad
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Numerical Methods ◽  
Turbine Blade ◽  
Complex Geometry ◽  
Great Success ◽  
Numerical Techniques ◽  
Application Range ◽  
Method Of Dimensionality Reduction ◽  
Computationally Expensive

In this work, different numerical methods for simulating deformations and stresses in turbine blade fir-tree connections are examined. The main focus is on the Method of Dimensionality Reduction (MDR) and the Boundary Element Method (BEM). Generally, the fir-tree connections require a computationally expensive finite element setup. Their complex geometry exceeds the limitations of the faster numerical techniques which are used with great success within the framework of the half-space approximation. Ways of extending the application range of the MDR and the BEM to the particular problem of highly undulating surfaces of the fir-tree connection are shown and discussed.

scholarly journals The implementation of the boundary element method to the Helmholtz equation of acoustics

2021 ◽  
pp. 13-19
Author(s):  
Sergey Sivak ◽  
Mihail Royak ◽  
Ilya Stupakov ◽  
Aleksandr Aleksashin ◽  
Ekaterina Voznjuk
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Element Method ◽  
Numerical Methods ◽  
Helmholtz Equation ◽  
Boundary Value Problems ◽  
Boundary Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Element Method

Introduction: To solve the Helmholtz equation is important for the branches of engineering that require the simulation of wave phenomenon. Numerical methods allow effectiveness’ enhancing of the related computations. Methods: To find a numerical solution of the Helmholtz equation one may apply the boundary element method. Only the surface mesh constructed for the boundary of the three-dimensional domain of interest must be supplied to make the computations possible. This method’s trait makes it possible toconduct numerical experiments in the regions which are external in relation to some Euclidian three-dimensional subdomain bounded in the three-dimensional space. The later also provides the opportunity of not using additional geometric techniques to consider the infinitely distant boundary. However, it’s only possible to use the boundary element methods either for the homogeneous domains or for the domains composed out of adjacent homogeneous subdomains. Results: The implementation of the boundary elementmethod was committed in the program complex named Quasar. The discrepancy between the analytic solution approximation and the numerical results computed through the boundary element method for internal and external boundary value problems was analyzed. The results computed via the finite element method for the model boundary value problems are also provided for the purpose of the comparative analysis done between these two approaches. Practical relevance: The method gives an opportunityto solve the Helmholtz equation in an unbounded region which is a significant advantage over the numerical methods requiring the volume discretization of computational domains in general and over the finite element method in particular. Discussion: It is planned to make a coupling of the two methods for the purpose of providing the opportunity to conduct the computations in the complex regions with unbounded homogeneous subdomain and subdomains with substantial inhomogeneity inside.

Deformation Analysis of Fixturing for Workpiece with Complex Geometry

2005 ◽  
Vol 291-292 ◽  
pp. 631-636 ◽  
Author(s):  
Yan Wang ◽  
Xun Chen ◽  
Nabil Gindy
Keyword(s):  
Finite Element ◽  
Turbine Blade ◽  
Complex Geometry ◽  
Early Stage ◽  
Fe Analysis ◽  
Accurate Prediction ◽  
Deformation Analysis ◽  
Design Problems ◽  
Surface Error

Finite element (FE) analysis is very useful in the early stage of a fixture development in order to reduce or eliminate design problems. Accurate prediction of fixture-workpiece deformation requires an appropriate representation of the contact relationship between fixture elements and workpieces. The paper addresses the special features of the deformation analysis between complicatedly shaped components and fixture elements. The effectiveness and the scope of applicability of commonly used methods are analysed. The verified FE analysis is used to predict surface error arising from deformations, and to evaluate the deformation distributions from fixture elements and workpiece. Based on the FE analysis, the tolerance can be allocated to the fixture elements and the workpiece. The development of a turbine blade fixture is provided as case study.

scholarly journals Numerical behavior of singular two-point boundary value problems in a comparative way

2017 ◽  
Vol 7 (3) ◽  
pp. 288-292
Author(s):  
Selmahan Selim ◽  
Gözde Elver ◽  
Murat Sari
Keyword(s):  
Finite Element ◽  
Numerical Methods ◽  
Boundary Value Problems ◽  
Finite Element Methods ◽  
Model Equation ◽  
Boundary Value ◽  
Point Boundary ◽  
Numerical Techniques ◽  
Physical Processes ◽  
Advantages And Disadvantages

This article concentrates on discovering numerical behavior of the singular two-point boundary value problems through various numerical techniques. This is carried out in a comparative way by mainly using differential quadrature and finite element methods. Also a discussion has been done by means of advantages and disadvantages of the numerical methods of interest.To properly understand the behavior of the physical processes represented by the model equation, the calculated solutions have been discussed in detail. 

Structural Design and Finite Element Analysis of Composite Wind Turbine Blade

2012 ◽  
Vol 525-526 ◽  
pp. 225-228 ◽  
Author(s):  
Shi Fan Zhu ◽  
Ibrohim Rustamov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Structural Reliability ◽  
Complex Geometry ◽  
Wind Turbine Blade ◽  
Blade Design ◽  
Horizontal Axis Wind Turbine ◽  
Element Method

This paper presents structural studies of a medium scale composite wind turbine blade construction made of epoxy glass fiber for a 750kW rated power stall regulated horizontal axis wind turbine system. The complex geometry of the blade with a skin-spar foam sandwich structure was generated by utilizing commercial code ANSYS finite element package. Dimensions of twist, chord and thickness were developed by computer program. NREL S-series airfoils with different chord thickness are used along current blade cross-sections. The current design method uses blade element momentum (BEM) theory to complete satisfactory blade design and can be carried out using a spreadsheet, lift and drag curves for the chosen aerofoil. According to composite laminate theory and finite element method, optimal blade design was obtained. The focus is on the structural static strength of wind turbine blades loaded in flap-wise direction and methods for optimizing the blade cross-section to improve structural reliability. Moreover, the natural frequencies and modal shapes of the rotor blade were calculated for defining dynamic characteristics. Structural analysis was performed by using the finite element method in order to evaluate and confirm the blade to be sound and stable under various load conditions.

A Coupled Finite Element–Wave Based Approach for the Steady-State Dynamic Analysis of Acoustic Systems

2003 ◽  
Vol 11 (02) ◽  
pp. 285-303 ◽  
Author(s):  
B. van Hal ◽  
W. Desmet ◽  
D. Vandepitte ◽  
P. Sas
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Degrees Of Freedom ◽  
Complex Geometry ◽  
Low Frequency ◽  
Response Analysis ◽  
Frequency Range ◽  
Application Range ◽  
State Dynamic ◽  
High Convergence Rate

The finite element method (FEM) is widely accepted for the steady-state dynamic response analysis of acoustic systems. It exhibits almost no restrictions with respect to the geometrical features of these systems. However, it is limited to the low-frequency range due to the rapidly growing model size for increasing frequencies. An alternative method is the wave based method (WBM), which is based on the indirect Trefftz approach. It exhibits better convergence properties than the FEM and therefore allows accurate predictions at higher frequencies. However, the applicability is limited, since the high computational efficiency only appears for systems of moderate geometrical complexity. In order to benefit from the advantageous features of both methods, i.e. the wide application range of the FEM and the high convergence rate of the WBM, the coupling between both methods is proposed. Only the parts of the problem domain with a complex geometry are modeled using the FEM, while the remaining parts are described with a wave based model. The resulting hybrid model contains less degrees of freedom, which allows a further model refinement. The proposed coupled approach has the potential to cover the mid-frequency range, where it is still difficult to obtain satisfactory prediction results with currently existing deterministic techniques.

Mesh Coarsening for the Finite and the Boundary Element Method in Acoustics

2003 ◽  
Vol 11 (03) ◽  
pp. 351-361
Author(s):  
Dietmar Giljohann
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Element Method ◽  
Numerical Methods ◽  
Computer Graphics ◽  
Boundary Element ◽  
The Finite Element Method ◽  
Mesh Decimation ◽  
Mesh Coarsening ◽  
Element Method

The process of mesh coarsening describes the reduction and simplification of a highly detailed mesh in such a way that the original geometry is best possible preserved. The earliest coarsening algorithms were developed for real time visualizations in the upcoming field of computer graphics and later on adopted for some element topologies of the finite element method (FEM). An algorithm is presented in this article which applies the mesh decimation process to the requirements of both the FEM and the Boundary Element Method (BEM) in acoustics. The capabilities of the algorithm in order to significantly reduce the CPU times for both numerical methods are shown.

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

Numerical implementation of finite-element method of control volume using irregular mesh

2010 ◽  
Vol 7 ◽  
pp. 98-108
Author(s):  
Yu.A. Gafarova
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Delaunay Triangulation ◽  
Complex Geometry ◽  
Control Volume ◽  
Test Case ◽  
The Finite Element Method ◽  
Irregular Mesh ◽  
Discrete Analogues ◽  
Element Method

To solve problems with complex geometry it is considered the possibility of application of irregular mesh and the use of various numerical methods using them. Discrete analogues of the Beltrami-Mitchell equations are obtained by the control volume method using the rectangular grid and the finite element method of control volume using the Delaunay triangulation. The efficiency of using the Delaunay triangulation, Voronoi diagrams and the finite element method of control volume in a test case is demonstrated.

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