Download or read book Feasibility of Vibration based Damage Detection for Pinned Turbine Blades written by Leon Brits and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine blades are subjected to various damage mechanisms with fatigue as the primary contributor. During operation, damage accumulates in the form of crack initiation and propagation. This may lead to catastrophic failure, which is cause for concern in terms of availability and safety of the turbine. To optimize the maintenance schedule and to provide operational exibility of the turbine, the state of health of the blades is monitored. This is usually accomplished through non-destructive testing (NDT) during outages. Conventional NDT techniques for in-situ inspection of turbine blade and disk assemblies is di cult and often ine ective, due to limited access to areas of concern, as well as the complex geometries of blade roots. O -site inspection can be costly if the blades are still assembled in the turbine disk since the process of removing and reinstalling these blades is critical and labour-intensive, increasing the turbine downtime and overall costs. These problems could potentially be overcome by employing inspection techniques that o er the prospect of assessing obstructed areas through monitoring the global dynamic characteristics of the structure, which provide relatively easily interpretable data. With global inspection methods, a degree of measurement sensitivity is forfeited but the potential to detect more severe damage, without prior knowledge of the precise damage area location, exists. In this dissertation, the feasibility of a vibration-based structural damage identi cation technique that could be usable in support of conventional NDT to detect cracks in pinned turbine blades during o -line in-situ inspection, is evaluated. The investigation was limited to considering uninstalled single blades only, and thus o -site inspection of this component is regarded above the turbine disk assembly. This is clearly a simpli ed case and does not address the critical case from a practical perspective of having a large number of blades mounted onto a disk with pins, which is really the circumstance under which the technique could become useful. This study must thus be considered as a rst step towards addressing the real practical problem. In this simpli ed problem, the following questions are answered: Is it possible to detect damage in an unconstrained and isolated blade using vibration response, and if so, can di erent damage scenarios be identi ed? The proposed vibration-based damage detection method entails a multi-class support vector machine classi cation procedure in which the natural frequencies are employed as the discriminatory feature for damage detection and identi cation of di erent single-location damage scenarios. The natural frequencies were acquired from accurate experimental modal analysis of freely supported individual pinned turbine blades through impact testing. To con rm and predict the expected behaviour of the blades, a healthy numerical model was built and validated whereafter defects and damage were introduced. This includes geometrical variability at the root, observed in the procured blades, and the anticipated worstcase single-location damage at the most probable locations near or on the root, obtained from literature and discussions with experts in the industry. Arti cial damage, i.e. a uniform 1mm notch, was introduced in the root at the upper pinhole on the leading edge pressure side; and just above the root at the aerofoil base on the trailing- and the leading edge. To establish the discriminative quality of the modal property natural frequency, it was necessary to determine its sensitivity to geometrical variability and damage. It was also required to establish the damage-speci c behaviour or damage trend in the experimental data of i Executive Summary Feasibility of Vibration-based Damage Detection for Pinned Turbine Blades these damage scenarios to conclude their distinctiveness. This analysis was extended to outlining the feature quality by exploring the separability of class clusters for the healthy and damage scenario(s). The feasibility of the proposed method is assessed using experimental data through simple hypothesis testing regarding the detection and identi cation of both geometrical variability in healthy blades, and damage. It was found that healthy blades are very similar, as geometrical variability cannot be detected. This is because the distributions of natural frequencies fall within a range about a mean value in an ambiguous cluster. In contrast to this, the damage scenarios were found to be distinct, and thus discernible from the healthy blades. These classes formed discrete clusters, each with a similar distribution than the healthy blades. The conclusion of the feasibility study serves as proof of concept.

Download or read book Vibration based Condition Monitoring of a Turbomachinery Bladed System written by Anees ur Rehman and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Static and rotating blades in turbine engines are susceptible to vibration-induced failure because of the high dynamic operating loads. Excitation can be broadband or linked to the rotation speed. The accurate functioning of the complete turbomachinery system depends on the structural integrity of individual blades as any propagating damage, in the form of a fatigue crack, intimidates the functioning of the entire system. Because of this, there is growing interest in the early detection of damage in blades. Damage detection in mistuned turbomachinery bladed systems is addressed in this research utilising a statistical approach to vibration-based damage detection. Initially, a modal characteristics-based damage identification technique is developed by obtaining damage indices based on the differences in the Modal Assurance Criterion (MAC) that give a measure of the change in the mode shapes. These damage indices are then correlated to the depth/location of the damage and also to the level/pattern of the mistuning present. The possibility of characterising cracks from their nonlinear response is investigated by detecting and classifying nonlinearity arising from a breathing crack interface. Nonlinearity detection is achieved by obtaining the amplitude dependent Frequency Response Functions (FRFs) and classification is accomplished by obtaining their Hilbert transform (HT). The breathing crack nonlinear behaviour is numerically validated by drawing a comparison between experimental and numerical results. The Coulomb friction-induced damping at the crack interface is quantified by obtaining relationships between crack depth/coefficient of friction and damping levels/friction stress/crack face pressures. Based on the conclusions from the breathing crack nonlinear behaviour investigations, damage detection in the mistuned bladed disc is addressed utilising outlier analysis. The effect of noise on the damage detection is studied by obtaining the maximum, mean and minimum damage detectability levels for varying noise. Both, the frequency and time domain data from the bladed disc are considered for damage detection. For the frequency domain, FRFs for varying mistuning levels in the bladed disc are obtained and damage detection is addressed when the FRF peak of the crack mode cannot be distinguished from the cluster of mistuning modes. In the time domain, the effectiveness of the developed damage detection procedure is examined for reduced data sets from the blade tips (blade tip timing).

Download or read book Turbine Engine Rotor Blade Damage Detection Through the Analysis of Vibration of Stationary Components written by Jon Rylan Cox and published by . This book was released on 2016 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotor blade fault detection and health monitoring systems are crucial for gas turbine engine testing and evaluation. The most commonly used techniques involve monitoring blades directly using strain gages, or drilling optical access holes in the engine casing for non-contact probes to monitor blade deflection and vibration. In this work, less intrusive, indirect techniques for rotor blade fault detection are developed, based on the hypotheses that the vibratory response of stationary components excited by the rotor blade dynamic pressure pulse can be used to detect the presence, location, and severity of rotor blade damage and changes in rotor blade natural frequency. The vibratory responses of a stator probe and the fan casing are processed using two novel techniques and a modified version of an existing technique. The two novel techniques are vibratory peak arrival analysis, used to detect damage causing blade offset, and vibratory peak statistical analysis, used to detect damage causing increased non-integral vibration amplitude. The third technique, spectral sideband tracking analysis, uses an exact solution to a previously published indeterminate technique used to detect damage causing changes in blade natural frequency. Ultimately, the vibratory peak arrival analysis technique was successful in detecting the presence, location, and severity of an offset rotor blade using data from the stator probe. The vibratory peak statistical analysis technique results were less clear, most likely due to the presence of rotor imbalance and lack of blade non-integral vibration. The spectral sideband tracking technique can, in theory, detect changes in rotor blade natural frequency. However, in practice, the required spectral peaks do not rise above the noise present in the casing accelerometer data spectrum, again most likely due to the lack of rotor blade non-integral vibration. The major contributions to the state-of-the- art of rotor blade health monitoring include: 1) a successful method (vibratory peak arrival analysis) of determining the presence, location, and severity of damage causing blade offset using the vibratory response of a stationary component (stator probe), and 2) a solution to a previously published indeterminate equation to calculate rotor blade rotating natural frequency using the casing vibratory response.

Download or read book Turbomachine Blade Vibration written by J. S. Rao and published by New Age International. This book was released on 1991 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue Failures Of Blades Is One Of The Most Vexing Problems Of Turbomachine Manufacturers, Ever Since The Steam Turbine Became The Main Stay For Power Generating Equipment And Gas Turbines Are Increasingly Used In The Air Transport. The Problem Is Very Complex, Involving The Excitation Due To Aerodynamic Stage Interaction; Damping Due To Material Deformation, Friction At Slip Surfaces And Aerodynamic Damping; Vibration Of An Asymmetric Aerofoil Tapered Along Its Length And Mounted On A Rotating Disc At A Stagger Angle. The Problem Is Also Governed By Heat Transfer Analysis And Thermal Stresses.His Book Deals With A Basic Understanding Of Free Vibratory Behaviour Of Turbine Blades- Free Standing, Packetted, And Bladed-Discs. The Analysis Is Based On Continuous And Discrete Models Using Energy Principles And Finite Element Techniques. A Clear Understanding Of The Interference Phenomenon In A Thin Cambered Airfoil Stage In Subsonic Flow Is Presented To Determine The Nonsteady Excitation Forces Acting On The Blades. A Comprehensive Treatment On The Blade Damping Phenomenon That Occurs In Turbines Is Given. The Nonlinear Damping Models Account For Material Damping And Friction Damping As A Function Of Rotational Speed For Each Mode. Resonant Response Calculation Procedures For The Steadily Running As Well As Accelerating Blades Are Given.Cumulative Damage Calculations Are Then Outlined For Fatigue Life Estimation Of Turbomachine Blades. The Book Also Deals With Heat Transfer Analysis And Thermal Stress Calculations Which Help In A Comprehensive Understanding Of The Blade Problems.

Download or read book Turbine Blade Life Estimation written by J. S. Rao and published by Alpha Science Int'l Ltd.. This book was released on 2000 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: The blade life estimation is a multifaceted technology, involving free and forced vibration forces, that lead to the determination of steady and dynamic stresses at different critical speeds during the startup and shutdown procedures, as well as in the operational speed range. Propagation and unstable fracture are described with practical examples to estimate blade life.

Download or read book An Investigation Into Vibration Based Techniques for Wind Turbine Blades Condition Monitoring written by Abdelnasser Abouzid Abouhnik and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Vibration Based Method written by Krissanapong Wongsawarng and published by LAP Lambert Academic Publishing. This book was released on 2012-02 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to highly competitive global markets, the breakdown of gas turbine is the single biggest operating parameters in terms of production loss, repair cost, and safety. Blade failure is regarded as one of the most critical problems on gas turbine and always causes critical failure. Consequently, the early faults detection of blade damage becomes more attractive to many developers to improve the inspection technique and minimize such critical downtimes. The research presented in this dissertation is based on theoretical modelling used to develop vibration based techniques to distinguish combined faults of crack and support looseness in a cantilever beam, representing a turbine blade. There are three vibration based methods studied in this work, which comprise of modal analysis, response analysis, and spectrum analysis. All of them are simulated by the Finite Element (FE) modelling and analysis incorporating with simplified crack model, which gives good accuracy at few low frequency modes, to validate each method through similar algorithms. The study on a cantilever beam model in each method consists of four conditions; no fault, root looseness fault, crack fault, and combined faults.

Download or read book Vibration based Damage Detection Using Machine Learning Techniques with Application to Offshore Wind Turbines written by Y. Zhang and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vibration based Damage Detection Using High speed Camera written by Chao Wan and published by . This book was released on 2019 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Damage Detection in a Wind Turbine Blade Using Modal Analysis written by Erik George Gross and published by . This book was released on 1999 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural Damage Identification in Wind Turbine Blades Using Piezoelectric Active Sensing with Ultrasonic Validation written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper gives a brief overview of a new project at LANL in structural damage identification for wind turbines. This project makes use of modeling capabilities and sensing technology to understand realistic blade loading on large turbine blades, with the goal of developing the technology needed to automatically detect early damage. Several structural health monitoring (SHM) techniques using piezoelectric active materials are being investigated for the development of wireless, low power sensors that interrogate sections of the wind turbine blade using Lamb wave propagation data, frequency response functions (FRFs), and time-series analysis methods. The modeling and sensor research will be compared with extensive experimental testing, including wind tunnel experiments, load and fatigue tests, and ultrasonic scans - on small- to mid-scale turbine blades. Furthermore, this study will investigate the effect of local damage on the global response of the blade by monitoring low-frequency response changes.

Download or read book Vibration based Damage Detection Using Mode Shape Curvature an Experimental Verification written by Khoon Hong Tong and published by . This book was released on 2011 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling Behaviour of Damaged Turbine Blades for Engine Health Diagnostics and Prognostics written by Jason Van Dyke and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vibration Based Damage Detection in Ceramics and Glass written by Ruth Anne Rule and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1048 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Vibration Analysis for Civil Structures written by Joel P. Conte and published by Springer. This book was released on 2017-10-11 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edited volume presents selected contributions from the International Conference on Experimental Vibration Analysis of Civil Engineering Structures held in San Diego, California in 2017 (EVACES2017). The event brought together engineers, scientists, researchers, and practitioners, providing a forum for discussing and disseminating the latest developments and achievements in all major aspects of dynamic testing for civil engineering structures, including instrumentation, sources of excitation, data analysis, system identification, monitoring and condition assessment, in-situ and laboratory experiments, codes and standards, and vibration mitigation.

Download or read book Structural Health Monitoring Damage Detection Systems for Aerospace written by Markus G. R. Sause and published by Springer Nature. This book was released on 2021 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book presents established methods of structural health monitoring (SHM) and discusses their technological merit in the current aerospace environment. While the aerospace industry aims for weight reduction to improve fuel efficiency, reduce environmental impact, and to decrease maintenance time and operating costs, aircraft structures are often designed and built heavier than required in order to accommodate unpredictable failure. A way to overcome this approach is the use of SHM systems to detect the presence of defects. This book covers all major contemporary aerospace-relevant SHM methods, from the basics of each method to the various defect types that SHM is required to detect to discussion of signal processing developments alongside considerations of aerospace safety requirements. It will be of interest to professionals in industry and academic researchers alike, as well as engineering students. This article/publication is based upon work from COST Action CA18203 (ODIN - http://odin-cost.com/), supported by COST (European Cooperation in Science and Technology). COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation.