Blade Life: A Comparison by Cumulative Damage Theories

1999 ◽  
Vol 123 (4) ◽  
pp. 886-892 ◽  
Author(s):  
J. S. Rao ◽  
A. Pathak ◽  
A. Chawla
Keyword(s):  
Modal Analysis ◽  
Turbine Blade ◽  
Flow Path ◽  
Cumulative Damage ◽  
Practical Application ◽  
Dynamic Stresses ◽  
Linear And Nonlinear ◽  
Comparison Of The Results

A turbine blade is modeled as a rotating pretwisted beam and subjected to aerodynamic excitation from the flow path interference. The resonant stresses are determined using a modal analysis. With the help of steady steam bending and centrifugal stresses and the dynamic stresses, life estimates are made using the linear and nonlinear cumulative damage theories and a comparison of the results is presented. Based on these results, recommendations are made on the usefulness of different theories for practical application.

scholarly journals Blade Life — A Comparison by Cumulative Damage Theories

1999 ◽  
Author(s):  
J. S. Rao ◽  
A. Pathak ◽  
A. Chawla
Keyword(s):  
Modal Analysis ◽  
Turbine Blade ◽  
Flow Path ◽  
Cumulative Damage ◽  
Practical Application ◽  
Dynamic Stresses ◽  
Linear And Nonlinear ◽  
Comparison Of The Results

A turbine blade is modeled as a rotating pretwisted beam and subjected to aerodynamic excitation from the flow path interference. The resonant stresses are determined using a modal analysis. With the help of steady steam bending and centrifugal stresses and the dynamic stresses, life estimates are made using the linear and nonlinear cumulative damage theories and a comparison of the results is presented. Based on these results, recommendations are made on the usefulness of different theories for practical application.

scholarly journals Modal analysis of an iced offshore composite wind turbine blade

2021 ◽  
pp. 0309524X2110116
Author(s):  
Oumnia Lagdani ◽  
Mostapha Tarfaoui ◽  
Mourad Nachtane ◽  
Mourad Trihi ◽  
Houda Laaouidi
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Wind Turbine Blade ◽  
Resonance Phenomenon ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Numerical Work ◽  
Composite Blades

In the far north, low temperatures and atmospheric icing are a major danger for the safe operation of wind turbines. It can cause several problems in fatigue loads, the balance of the rotor and aerodynamics. With the aim of improving the rigidity of the wind turbine blade, composite materials are currently being used. A numerical work aims to evaluate the effect of ice on composite blades and to determine the most adequate material under icing conditions. Different ice thicknesses are considered in the lower part of the blade. In this paper, modal analysis is performed to obtain the natural frequencies and corresponding mode shapes of the structure. This analysis is elaborated using the finite element method (FEM) computer program through ABAQUS software. The results have laid that the natural frequencies of the blade varied according to the material and thickness of ice and that there is no resonance phenomenon.

scholarly journals THE HUMAN RACHIS: CAN IT BE CONSIDERED A SHOCK ABSORBER (THAT WAS PRODUCED BY EXAPTATION) RATHER THAN A COLUMN?

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
M. Tanga ◽  
F. Ghelli ◽  
G. Gelati
Keyword(s):  
Modal Analysis ◽  
Shock Absorber ◽  
Elastic System ◽  
Axial Direction ◽  
Continuous Line ◽  
Dynamic Stresses ◽  
Mechanical Feature ◽  
Physiological Conditions ◽  
Typical Function ◽  
Eigenvectors And Eigenvalues

Our paper is focused on two fundamental points: the first one is a terminological proposal and the second one is a question. Obviously these two things are strictly related one another. The terminological proposal is aimed to name “vertebral shock absorber” the human rachis (globally considered, when it is in physiological conditions) in its most typical function: to sustain static/dynamic stresses, that moreover are directed according to its axial direction, obviously when this coincides with gravitational line. This aspects can be studied by modal analysis and by the model of Eigenvectors and Eigenvalues. According to our opinion, the mechanical feature must be considered as prevalent if compared with the structural one. Following it human rachis is usually named “column”. This mechanic sustain is distributed on three lines that are summarily parallel and are linked one another (by isthmuses and vertebral arches to build an horizontal ring) so they can be considered a unique compact viscous-elastic system. Each one of these three vertical sub-structure is built as a stacking of metameric elements (modules) along a continuous line.

Experimental Identification Approach of Dynamic Parameters of Precise Horizontal Machining Centre Based on Component-System

2011 ◽  
Vol 467-469 ◽  
pp. 1686-1690
Author(s):  
Zhi Feng Liu ◽  
Zhong Hua Chu ◽  
Qiang Cheng ◽  
Guang Bo Liu ◽  
Dong Sheng Xuan
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Modal Testing ◽  
Element Calculation ◽  
Element Simulation ◽  
Modes Of Vibration ◽  
Identification Approach ◽  
Comparison Of The Results ◽  
Machine Structure

This paper integrates experiment modal analysis and the analytical modal analysis to study on the vibration phenomena occurring occasionally at the different components of a precise horizontal machining centre. The paper is focused on extracting the mode shape of the major components of the machine in order to ensure resonance phenomena as a cause of vibration. At first the main natural frequencies with the corresponding modes of vibration of the machine structure are obtained by the experiment modal analysis. Then the dynamic behavior of the machine components is simulated using a finite element simulation model. The comparison of the results based on finite element calculation with their experimental counterparts shows the reasonableness. The model is evaluated and corrected with experimental results by modal testing of the machine components.

Asymptotic modal analysis for dynamic stresses of a plate

1987 ◽  
Vol 81 (5) ◽  
pp. 1267-1272
Author(s):  
Yuji Kubota ◽  
Earl H. Dowell
Keyword(s):  
Modal Analysis ◽  
Dynamic Stresses

Modal Analysis of Turbine Blades by Means of Distributed Optical Fiber Sensors

2020 ◽  
Author(s):  
Paolo Pennacchi ◽  
Gabriele Cazzulani ◽  
Alejandro Silva
Keyword(s):  
Optical Fiber ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Optical Fiber Sensors ◽  
Operating Conditions ◽  
Fiber Sensors ◽  
Steam Turbine Blade ◽  
3D Printed ◽  
Distributed Optical Fiber

Abstract This paper investigates the possibility of identifying and monitoring the modal shapes of a turbine blade by means of continuous optical fiber sensors based on Optical Backscatter Reflectometry (OBR). The advantage of this approach would be the possibility of embedding the sensors in future carbon fiber blades, in order to make this modal analysis approach available also for the blade operating conditions, since no modifications in the blade fluid-structure interaction occur. The paper describes the proposed method and provides some experimental results obtained on a 3D printed model of an existing steam turbine blade.

Modal Analysis of a Wind Turbine Blade Using a Computational Method

2021 ◽  
pp. 23-34
Author(s):  
M.J. Pawar ◽  
Amar Patnaik ◽  
Vikas Kukshal ◽  
Ashiwani Kumar ◽  
Vikash Gautam
Keyword(s):  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Computational Method

scholarly journals Modal Analysis of Vertical Wind Turbine Blade

2018 ◽  
Vol 217 ◽  
pp. 01003 ◽  
Author(s):  
Lee Zhou Yi ◽  
Choe-Yung Teoh
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Wind Turbine Blade ◽  
Flow Induced Vibration ◽  
Low Wind Speed ◽  
Teak Wood ◽  
Blade Failure ◽  
Wind Induced Vibration

Wind turbines cannot simply be installed in Malaysia due to low wind speed condition. the project has analyzed the existing wind turbine blade (Aeolos-V 1k) design based on modal properties using computational approach (ANSYS Workbench) and redesign it. the modal analysis is simulated to observe natural frequency and corresponding mode shaped of the system under free vibration. the flow induced vibration can cause blade failure due to resonance or fatigue. Fluid Structural Interaction (FSI) ANSYS is used to the determined the interaction between the wind flow and the blade. Harmonic Response ANSYS is used to analyze the frequency response of the blade under wind induced vibration. After modification, the first mode has increased from 91.42 Hz to 102.12, since it is more than 50.92 Hz (Turbine maximum operating frequency), resonance would not occur during operating condition. the Aeolos-V’s blade has been modified by using. teak wood material and. redesign the blade for weight. reduction and aim for lower blade cost. the weight of modified blade has reduced 72.8 % after using teak wood and the efficiency of the wind turbine also increased. Modified design has been tested under Malaysia maximum wind speed of 9.44 m/s, the yield stress of teak wood (10.3 MPa) is higher than the maximum stress (4.2 MPa) obtained under force vibration which gives safety factor of 2.4. Hence, modified blade is reliable, efficient and more economic for Malaysia.

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