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Статті в журналах з теми "Vibration indicators":
1
Spirin, Anatoly, Dmytro Borysiuk, Oleksandr Tsurkan, and Igor Tverdokhlib. "NFLUENCE OF VIBRATION ON THE ERGONOMIC INDICATORS OF THE PRODUCTION PROCESS." Vibrations in engineering and technology, no. 1 (108) (May 1, 2023): 45–56. http://dx.doi.org/10.37128/2306-8744-2023-1-5.
Анотація:
Features of the impact of industrial vibration, the nature, depth and direction of physiological changes of various body systems depend on the level, frequency composition of vibrations and physiological properties of the human body. Vibration is one of the main causes of occupational diseases. The study of the sources of production vibration, the ways of its propagation, the specifics of the impact on the human body and protection against harmful effects is currently an urgent issue. The analysis of the latest sources shows that the majority of works consider individual elements of a complex system of ergonomic provision of safe working conditions in case of vibrational impact on workers. Therefore, there is a need to deepen the study of this issue, comprehensive consideration of the causes of vibration, its characteristics and specific effects on the worker's body, planning measures and means to minimize the consequences of its negative effects. There are two types of vibration: local, which primarily affects those organs of the human body that are in direct contact with vibrating elements, and general vibration, which causes the body to move in space and affects the entire body. The main parameters of vibration are amplitude and frequency of oscillations, speed and vibration acceleration. The effect of general vibration on the central nervous system leads to a disturbance in the balance between excitation and inhibition. Under the influence of vibration, workers become irritable, get tired quickly, feel drowsy (and sometimes, on the contrary, insomnia), work capacity decreases, the time it takes to complete production tasks increases, and the time of simple and complex reactions increases. The fight against the harmful effects of mechanical vibrations in most cases boils down to compliance with existing norms and rules. Also, a special role is played by means of protecting workers from the harmful effects of vibration. First of all, this is the improvement of the design of vehicles, machines, mechanisms and tools.
2
Ryazancev, V., M. Gerasimov, and Y. Brazhnik. "REDUCTION OF DIFFERENTLY DIRECTIONAL VIBRATIONS TO ASYMMETRICAL BY CHANGING THE RATIO OF VALUES COMPOSING THE DRIVING FORCE." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, no. 5 (May 18, 2021): 87–94. http://dx.doi.org/10.34031/2071-7318-2021-6-5-87-94.
Анотація:
Vibrating machines play a primary role in the implementation of programs in the construction and road construction kit. The improvement of vibration machines allows to significantly increase the speed of construction and road construction work. The main working unit of a vibrating machine is a vibrating device or vibrator. Currently, in the industry, vibration devices are used with circular or directional, along a certain straight line of vibrations. Further improvement of vibrating machines is carried out in the direction of creating vibration devices with asymmetric vibrations. At present, there are practically no vibrating machines with asymmetric vibrations. These machines allow to distinguish between the "working" process phase and the "idle" phase within each oscillation period. Moreover, the value of the driving force in the phase of performing useful work is several times higher than the value of the driving force in the direction of idling. Therefore, much less work is spent on idling. This allows to get rid of massive elements - overloads that extinguish the magnitude of the driving force in the direction of idling. Therefore, the urgency is to develop a method for converting existing machines with directional vibrations into asymmetric ones, with a given coefficient of asymmetry of the driving force. This makes it possible to reduce the specific indicators of the metal consumption of vibrating machines and the energy consumption of the work performed.
3
Bespalov, A. L., and I. G. Svidrak. "Universalization of the elastic system of vibration feeders with vertical electromagnetic vibration drive." Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 24, no. 97 (June 28, 2022): 41–45. http://dx.doi.org/10.32718/nvlvet-f9707.
Анотація:
Vibrating feed bins with electromagnetic drive are widely used in the automation of production processes in mechanical engineering and instrument engineering. They are used for feeding miniature, small, or medium-sized parts to automated production equipment. This equipment is used in automatic lines, automated complexes, or any other flexible automated production facilities. These devices are most widely used for loading parts to assembly positions in automated assembly complexes. In this case, the parts fed to these positions must be located in a certain stable position. Various orientation tools are used for this purpose. They are located directly on the transport trays in the bins of these devices. Therefore, for reliable operation of orientation devices, the movement of parts on the trays should be smooth without sensitive tossing. The designs of vibrating hopper feeders with a hopper connected to a reactive plate by a directional elastic system in the form of a lattice torsion bar are considered. An electromagnetic vibration exciter is placed between the torsion flanges. The disadvantage of such vibration feeders is low productivity in operating modes, especially when there are increased requirements for the smooth movement of transported parts. An increase in the productivity of such feeders is carried out by increasing the amplitude of hopper vibrations in the direction of movement of parts, that is, the horizontal component of vibrations. However, this also leads to an increase in the vertical component, since vibrations are carried out at an angle to the feeder transport tray. When the vertical component of vibrations increases, the transportation of parts switches to the intensive tossing mode. A further increase in the oscillation amplitude leads to a violation of the normal mode of vibrational transport. Modern production involves the modernization of existing structures, as well as the creation of new models of machines with high technical and economic indicators Therefore, the universalization of existing equipment and the development of new machine schemes is an important task for developers and manufacturers of technological equipment, since even a minimal improvement in its technological or operational indicators can lead to a significant economic effect. The paper considers a complex of additional elements used that make it possible to universalize the design of vibrating hopper feeders with electromagnetic drives having a directional elastic system. These changes make it possible to adjust the horizontal component of the device hopper vibrations at a constant vertical one. Additional structural elements are proposed that increase the range of application of such feeders.
4
Kiyko, V. N., N. M. Naumovich, M. V. Davydov, and V. I. Zhuravliov. "Use of Cable Vibration Isolators for Vibration Protection of Quartz Generators." Doklady BGUIR 21, no. 4 (August 29, 2023): 63–70. http://dx.doi.org/10.35596/1729-7648-2023-21-4-63-70.
Анотація:
Vibration isolators with damping properties of steel multiwire cables for vibration protection of quartz oscillators have been studied. Modeling of vibration characteristics of structural elements was carried out using numerical methods. The elastic characteristics and design parameters of the cable for the vibration isolator are calculated. A harmonic analysis was carried out with given values of mass and stiffness under the influence of external vibrations. A sample of a cable vibration isolator has been developed and manufactured. To verify the calculated results obtained, the structure of the test bench is proposed, which allows determining the values of na tural re sonant frequencies. The study of the dependence of vibration acceleration on the frequency of oscillations with a disturbing effect according to the sinusoidal and random laws with a variable frequency in the range of 10–2000 Hz was carried out. Tests of the cable vibration isolator have shown the effectiveness of vibration suppression for frequencies above 120 Hz. In the lower range of random vibrations, various resonances have a significant effect on each other. The experiments confirmed the simulation results and the effectiveness of the solution used: the difference in indicators in determining the resonant frequencies was less than 10 % with a decrease in the vibration level to a given indicator.
5
Dzhabborov, N., A. Dobrinov, and A. Sergeev. "Vibration parameters and indicators of a dynamic tillage tool." IOP Conference Series: Earth and Environmental Science 937, no. 3 (December 1, 2021): 032048. http://dx.doi.org/10.1088/1755-1315/937/3/032048.
Анотація:
Abstract According to domestic and foreign research on the efficiency of active and passive vibrating tillage tools, the created vibration allows reducing the traction resistance of tillage implements compared to conventional tools, while improving the tillage quality. The study aimed to determine several vibration parameters and indicators of a dynamic tillage tool supplied with an energy storing and transmitting device: frequency and amplitude of oscillations, absolute velocity, vibration velocity, acceleration of vibration, a force of inertia, and oscillation energy. The study applied the energy assessment methods of tillage tools with the measuring and information system designed at IEEP – branch of FSAC VIM; analysis and generalisation of experimental data. Vibration variables were determined by the strain-gauge method. The study revealed a significant effect of oscillation frequency and amplitude of the tillage tool, depending on the machine travel speed and characteristics of elastic elements, on its vibration velocity and acceleration, the force of inertia and the energy of oscillations.The total increase in these forces owing to a high-frequency dynamic impact may affect the soil layer considerably as an additional loosening. The accumulated impact energy can provide a decrease in the traction resistance of the tillage tool.
6
Sánchez, Réne-Vinicio, Pablo Lucero, Jean-Carlo Macancela, Higinio Rubio Alonso, Mariela Cerrada, Diego Cabrera, and Cristina Castejón. "Evaluation of Time and Frequency Condition Indicators from Vibration Signals for Crack Detection in Railway Axles." Applied Sciences 10, no. 12 (June 25, 2020): 4367. http://dx.doi.org/10.3390/app10124367.
Анотація:
Railway safety is a matter of importance as a single failure can involve risks associated with economic and human losses. The early fault detection in railway axles and other railway parts represents a broad field of research that is currently under study. In the present work, the problem of the early crack detection in railway axles is addressed through condition-based monitoring, with the evaluation of several condition indicators of vibration signals on time and frequency domains. To achieve this goal, we applied two different approaches: in the first approach, we evaluate only the vibrations signals captured by accelerometers placed along the longitudinal direction and, in the second approach, a data fusion technique at the condition indicator level was conducted, evaluating six accelerometers by merging the indicator conditions according to the sensor placement. In both cases, a total of 54 condition indicators per vibration signal was calculated and selecting the best features by applying the Mean Decrease Accuracy method of Random Forest. Finally, we test the best indicators with a K-Nearest Neighbor classifier. For the data collection, a real bogie test bench has been used to simulate crack faults on the railway axles, and vibration signals from both the left and right sides of the axle were measured. The results not only show the performance of condition indicators in different domains, but also show that the fusion of condition indicators works well together to detect a crack fault in railway axles.
7
Tian, Kunpeng, Jicheng Huang, Bin Zhang, Aimin Ji, and Zhonghua Xu. "Study on the Impact of Cutting Platform Vibration on Stalk Cutting Quality in Industrial Hemp." Agriculture 14, no. 2 (February 18, 2024): 321. http://dx.doi.org/10.3390/agriculture14020321.
Анотація:
In response to the unclear impact of header vibration on cutting performance (stalk cutting quality and cutting energy consumption) during field operations of industrial hemp harvesters, this study utilized a vibration recorder to collect information on header vibration during the operation of industrial hemp harvesters. Through data processing, the dominant range for the resonant frequency and amplitude of the cutting platform is primarily concentrated between 5–45 Hz and 0–35 mm, respectively. Using numerical simulation techniques, a quadratic orthogonal rotation combination experiment was conducted with vibration frequency and amplitude as experimental factors and stalk cutting quality and cutting energy consumption as indicators. Regression equations were established to reveal the relationships between indicators and factors, elucidating the influence of each factor and its interactions on the indicators. Specifically, for the crack length indicator, the amplitude has a highly significant influence on the model, and there is a significant interaction effect between vibration frequency and amplitude on the model. As for the cutting energy consumption indicator, frequency and the interaction between frequency and amplitude significantly affect the model, while amplitude has an extremely significant impact on the model. Through comprehensive fuzzy evaluation, the optimal vibration parameter combination satisfying comprehensive cutting performance indicators was determined as a vibration frequency of 37.86 Hz and an amplitude of 5.34 mm. Furthermore, the reliability of the model has been further validated. This research can provide a reference for improving the field performance of industrial hemp harvesters.
8
Shpachuk, V. P., M. A. Zasiadko, T. O. Suprun, and V. V. Dudko. "Variation coefficient of torsional vibrations of the connection nodes of vibrating machines." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 6 (2021): 85–89. http://dx.doi.org/10.33271/nvngu/2021-6/085.
Анотація:
Purpose. To formalize the dependence of the eigenfrequencies of translational and torsional vibrations of the structural elements of the vibrating machine articulated by the connection node on their design parameters and mechanical characteristics, as well as regulatory requirements for vibration activity, strength and accuracy. To develop a method for selecting the design parameters of the elastic band element of the package, taking into account the specified values of the amplitude and frequency characteristics of the dynamic loads reproduced by the supporting structure and the coefficient of variation of the natural frequencies of translational and torsional vibrations. Methodology. The research is based on fundamental approaches of applied mechanics, machine dynamics and vibration reliability. Findings. The dependences of the eigenfrequencies of torsional vibrations of the body parts of the vibrating machine connected by the connection node on their design parameters and mechanical characteristics are obtained and analyzed. Vibrations around an axis orthogonal to the working direction of the node are considered. A comparative analysis of the natural frequencies of the node in the direction of the transmitted vibration and its circular vibrations from the design parameters and mechanical characteristics of the elastic band elements, their number in the package and the number of packages in the connection node is performed. Originality. It is in the fact that for the first time the dependences describing the natural frequencies of translational and torsional vibrations of the body parts of a vibrating machine, articulated by a package of elastic band elements, are obtained. Also the paradigm for the choice of design parameters and mechanical characteristics of the elastic band element of the package, which is based on the results of a comparative analysis of the eigenfrequencies of vibrations in the working and connected directions through their coefficient of variation is innovative. This made it possible to include the criterion of vibration reproduction accuracy, which is formalized through the coefficient of frequency variation, together with the criteria of strength and rigidity, in the methodology of synthesis of the structural scheme of the vibrating machine. Practical value. The proposed methodological solutions for the calculation and selection of design parameters and mechanical characteristics of tape elastic elements ensure the achievement of vibration activity indicators of articulated parts, as well as the ratio of natural vibration frequencies in the working and related directions at the level of the requirements of normative documents when upgrading existing machines and creating new modern equipment. As a result, the reliability, durability, safety, productivity and load-bearing capacity of machines, equipment and mechanisms of mining engineering, aviation, transport and space technology are increased.
9
Zedgenizov, V. G., and S. Kh Faizov. "Research results of resonant vibration equipment for compaction of concrete mixtures on a physical model." Russian Automobile and Highway Industry Journal 21, no. 3 (June 18, 2024): 366–75. http://dx.doi.org/10.26518/2071-7296-2024-21-3-366-375.
Анотація:
Introduction. The purpose of this article is to confirm the results of research on resonant vibration equipment for compacting concrete mixtures obtained using a mathematical model. The object of research is an oscillatory system of resonant vibration equipment consisting of two masses interconnected by elastic and dissipative elements. In addition, the first mass is connected to a fixed base through elastic and dissipative elements.Materials and methods. The main provisions of the theory of similarity and statistical processing of experimental data are used in the research. The required number of repeated experiments was determined statistically, and the reproducibility of the experiment was verified by the Cochran criterion. Results. The criteria and indicators of similarity of processes occurring in the system of resonant vibration equipment have been developed, formulas for the transition from the parameters of nature to the parameters of the physical model have been proposed. The technical characteristics of the physical model are presented.During the experiment, oscillograms of the movements of the vibrator and the working body which are shifted relative to each other by an angle of π/2 were obtained. At the same time, the amplitude of vibrations of the vibrator significantly exceeds the amplitude of vibrations of the working body.Discussions and conclusions. The presented dependences of the amplitudes obtained on mathematical and physical models qualitatively repeat each other. In the studied frequency range of the driving force, the maximum error is 12%. This confirms the results obtained on the mathematical model of resonant vibration equipment.
10
Bespalov, A. L., I. G. Svidrak, and O. O. Boiko. "Improving the performance of vibration feeders with an electromagnetic vibration drive and a combined vibration system." Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 22, no. 93 (May 13, 2020): 26–30. http://dx.doi.org/10.32718/nvlvet-f9305.
Анотація:
Vibration loading devices are widely used in various branches of mechanical engineering to load piece blanks of automatic machines and automatic lines as well as robotic systems, automated systems and flexible automated production. Vibration devices for transportation and loading of miniature, small and medium-sized products are the most widely used. Modern designs of vibratory feeders, made according to the classical dynamic scheme and having a two-mass oscillating system, do not fully use the energy of the vibratory exciter to perform useful work. In addition, due to the presence of a heavy reactive mass, they have a fairly large weight. When the vibrating feeder is operating, the energy of the vibration exciter is spent on pumping both the hopper, which performs useful work, and the reactive plate, which performs idle vibrations. Thus, part of the energy of the vibration exciter is not used for performing useful work, but is spent idly. To increase the efficiency of the device, increase its performance and reduce its weight and metal consumption, it is necessary to change the design of the vibratory feeder and some of its elements, which affect the redistribution of the oscillation amplitudes of the working (hopper) and reactive mass of the vibratory feeder. Modern production involves the creation of new models of machines with high technical and economic indicators, therefore, improving the efficiency of existing equipment and the development of new schemes of machines is an important task for designers and manufacturers of technological equipment, as the minimum improvement of its technological and operational performance can lead to a tangible economic effect. To solve this problem we developed a new design vibrating hopper feeder, in which the increase of the horizontal component of the oscillation amplitude of the working element (hopper) is not at the expense of increased power of the vibratory exciter, but due to internal redistribution of energy between the elements of the oscillating system that makes better use of the energy of the vibratory exciter to perform useful work, i.e. to increase the coefficient of useful action. In addition, the weight and metal content of the vibrating feeder structure are simultaneously reduced.
Дисертації з теми "Vibration indicators":
1
Ashwear, Nasseradeen. "Vibration Frequencies as Status Indicators for Tensegrity Structures." Licentiate thesis, KTH, Strukturmekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145164.
Анотація:
Applications of vibration structural health monitoring (VHM) techniques are increasing rapidly. This is because of the advances in sensors and instrumentation during the last decades. VHM uses the vibration properties to evaluate many civil structures during the design steps, building steps and service life. The stiffness and frequencies of tensegrity structures are primarily related to the level of pre-stress. The present work investigates the possibilities to use this relation in designing, constructing and evaluating the tensegrity structures. The first part of the present work studies the improvement of current models for resonance frequency simulation of tensegrities by introducing the bending behaviour of all components, and by a one-way coupling between the axial force and the stiffness. From this, both local and global vibration modes are obtained. The resonance frequencies are seen as non-linearly dependent on the pre-stress level in the structure, thereby giving a basis for diagnosis of structural conditions from measured frequencies. The new aspects of tensegrity simulations are shown for simple, plane structures but the basic methods are easily used also for more complex structures. In the second part, the environmental temperature effects on vibration properties of tensegrity structures have been investigated, considering primarily seasonal temperature differences (uniform temperature differences). Changes in dynamic characteristics due to temperature variations were compared with the changes due to decreasing pre-tension in one of the cables. In general, it is shown that the change in structural frequencies made by temperature changes could be equivalent to the change made by damage (slacking). Different combinations of materials used and boundary conditions are also investigated. These are shown to have a significant impact on the pre-stress level and the natural frequencies of the tensegrity structures when the environment temperature is changed.Användandet av vibrationsbaserade hälsokontrollsmetoder (VHM) för strukturer ökar snabbt.Detta har möjliggjorts av utvecklingen inom mätmetoder och mätutrus- tning under de senaste decennierna.Dessa metoder använder sig av de uppmätta eller simulerade vibrationsegenskaperna underdesign-, uppbyggnads- och nyttjandestadierna hos många slag av byggnadsverk. Styvheten och resonansfrekvenserna hos tensegritets-strukturer är i hög grad beroendepå den aktuella förspänningsnivån. Föreliggande arbete undersöker möjlig- heterna attanvända detta beroende i konstruktion, byggande och utvärdering av sådana strukturer. Den första delen av föreliggande arbete studerar förbättringar av de vanligen användamodellerna för simulering av resonansfrekvenser hos tensegritetsstrukturergenom att införa de ingående komponenternas böjningsegenskaper, och genom att i enriktning koppla normalkraften till böjstyvheten. Genom detta kan såväl lokala som globalavibrationsmoder hittas. Resonansfrekvenserna ses därmed som icke-linjärt beroende avförspänningsnivån i strukturen. Detta ger därmed möjligheter att diagnosticera strukturenskondition från uppmätta frekvenser. De nya simuleringsmöjligheternademonstreras för enkla, plana strukturer, men de utvecklade metoderna kan också lättanpassas till mera komplexa fall. Den andra delen av arbetet undersöker hur strukturernas vibrationsegenskaper ärberoende på temperatureffekter i omgivningen. I första hand beaktas säsongsvisa (likformiga)temperaturvariationer. Förändringar i de dynamiska egenskaperna beroende påtemperaturförändringar jämfördes med dem som beror på en minskande förspänning hos någonav de ingående kablarna. I allmänhet gäller att förändringarna i resonansfrekvenser kanvara av samma storleksordning som de som beror på skador (minskad förspänning).Olika kombinationer av material, och olika upplagsförhållanden undersöktes.Dessa egenskaper visades ha en betydande effekt på förspänningsnivån, och därmed ocksåpå resonansfrekvenserna, hos tensegritets-strukturerna som utsätts för temperaturvariationer.
QC 20140514
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Sandoval, Núñez Diego Aníbal. "Diagnosis of low-speed bearings via vibration-based entropy indicators and acoustic emissions." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673495.
Анотація:
Wind energy is one ofthe main renewable energies to replace fossil fuels in the generation of electricityworldwide. To enhance and accelerate its implementation at a large scale, it is vital to reduce the costs associated with maintenance. As com ponent breakages force the turbine to stop for long repair times, the wind industry m ust switch from the old-fashioned preventive or corrective maintenance to condition-based maintenance (also called predictive maintenance). The conditionbased maintenance of pitch bearings is especiallychallenging, as the operating conditions include high mechanical stress and low rotational speed. Since these operating conditions im pact negatively on the results of the standard methods and techniques applied in current condition-based monitoring systems, the condition-based maintenance of pitch bearings is still a challenge.
Therefore, this thes is is focused on the research of novel methods and techniques that obtain reliable information on the state of pitch bearings for condition-based maintenance. lnitially, the acknowledgment ofthe state ofthe art is performed to recognize the methods and signals. This step endorses the decision to analyze the vibration signals and acoustic emissions throughout this thesis. Due to the particular operating conditions of pitch bearings, this research states the need to create data sets to replicate the particular operating conditions in a controlled laboratory experiment. As a res ult, a datas et based on vibrations, and a second datas et based on acoustic emissions are generated.
The vibration datas et allows the validation of a novel algorithm for the low-speed bearing diagnosis, which is based on the concept of entropy by the definition of Shannon and Rényi. In com parison to the classical methods found in the literature, the diagnosis of low-speed bearings based on entropy-based indicators can extract more reliable information. Moreover, the research of the com bination of several indicators to improve the diagnosis revea Is that the entropy-based indicators can extract more information than regular indicators used in academia.
The datas et of acoustic emissions from low-speed bearings helps to contribute to the development of methods for diagnosis. In this research, the analysis of the energyfrom the signals reveals a dependencyon the intensityand the presence of damage. In addition, a relation between the waveform ofthe analyzed energy and the existence of damage is em phas ized.La energía eólica es una de las principales energías renovables consideradas para reemplazar los combustibles fósiles en la generación de electricidad a nivel mundial. Para mejorar y acelerar su implementación a gran escala, es vital reducir los costes asociados con el mantenimiento. Como las roturas de los componentes obligan a la turbina a detenerse durante largos períodos de reparación, la industria eólica necesita cambiar del anticuado mantenimiento preventiv o correctivo al mantenimiento basado en la condición (también llamado mantenimiento predictivo). El mantenimiento basado en la condición de los rodamientos pitch es especialmente desafiante, porque las condiciones de operación incluyen un alto estrés mecánico y bajas velocidades de rotación. Debido a que estas condiciones de operación impactan negativamente en los resultados de los métodos y técnicas estándar aplicados en los sistemas actuales de monitoreo basados en el estado, el mantenimiento basado en el estado de los rodamientos pitch sigue siendo un desafío. Por tanto, esta tesis se centra en la investigación de métodos y técnicas novedosas que obtengan información fiable sobre el estado de los rodamientos pitch para el mantenimiento basado en la condición. Inicialmente, se realiza el reconocimiento del estado del arte para reconocer los métodos y señales utilizados. Este paso avala la decisión de analizar las señales de vibración y las emisiones acústicas a lo largo de esta tesis. Debido a las condiciones de funcionamiento particulares de los rodamientos pitch, esta investigación reconoce la necesidad de crear un conjunto de datos para replicar las condiciones de funcionamiento particulares del rodamiento pitch en una experiencia de laboratorio controlado. Como resultado, se genera un conjunto de datos basado en vibraciones y un segundo conjunto de datos basado en emisiones acústicas. El conjunto de datos de vibraciones permite la validación de un algoritmo novedoso para el diagnóstico de rodamientos de baja velocidad, el cual se basa en el concepto de la entropía según la definición de Shannon y Rényi. En comparación con los métodos clásicos que se encuentran en la literatura, el diagnóstico de rodamientos de baja velocidad basado en indicadores basados en la entropía puede extraer información más confiable. Además, la investigación de la combinación de varios indicadores para mejorar el diagnóstico revela que los indicadores basados en la entropía pueden extraer más información que los indicadores habituales utilizados en la academia. El conjunto de datos de las emisiones acústicas de los rodamientos de baja velocidad ayuda a contribuir al desarrollo de métodos de diagnóstico. En esta investigación, el análisis de la energía de las señales revela una dependencia de la intensidad y la presencia de daño. Además, se enfatiza una relación entre la forma de onda de la energía analizada y la existencia de daño.
L'energia eòlica és una de les principals energies renovables considerades per reemplaçar els combustibles fòssils en la generació d'electricitat a nivell mundial. Per millorar i accelerar la seva implementació a gran escala, és vital reduir els costos associats amb el manteniment. Com els trencaments dels components obliguen a la turbina a aturar-se durant llargs períodes de reparació, la industria eòlica necessita canviar de l'antiquat manteniment preventiu o correctiu al manteniment basat en la condició (també anomenat manteniment predictiu). El manteniment basat en la condició dels rodaments de pas és especialment desafiant, perquè les condicions d’operació inclouen un alt estrès mecànic i baixes velocitats de rotació. A causa de que aquestes condicions d’operació impacten negativament en els resultats dels mètodes i tècniques estàndard aplicats en els sistemes actuals de monitorització basats en l'estat, el manteniment basat en l'estat dels rodaments de pas segueix sent un desafiament. Per tant, aquesta tesi se centra en la investigació de mètodes i tècniques noves que obtinguin informació fiable sobre l'estat dels rodaments de pas per al manteniment basat en la condició. Inicialment, es realitza el reconeixement de l'estat de l'art per reconèixer els mètodes i senyals utilitzats. Aquest pas avala la decisió d'analitzar els senyals de vibració i les emissions acústiques al llarg d'aquesta tesi. A causa de les condicions de funcionament particulars dels rodaments de pas, aquesta investigació reconeix la necessitat de crear un conjunt de dades per replicar les condicions de funcionament particulars del rodament de pas en un experiment de laboratori controlat. Com a resultat, es genera un conjunt de dades basat en vibracions i un segon conjunt de dades basat en emissions acústiques. El conjunt de dades de vibracions permet la validació d'un algoritme nou per al diagnòstic de rodaments de baixa velocitat, el qual es basa en el concepte de l'entropia segons la definició de Shannon i Renyi. En comparació amb els mètodes clàssics que es troben a la literatura, el diagnòstic de rodaments de baixa velocitat basat en indicadors basats en l'entropia pot extreure informació més fiable. A més, la investigació de la combinació de diversos indicadors per millorar el diagnòstic revela que els indicadors basats en l'entropia poden extreure més informació que els indicadors habituals utilitzats en la literatura. El conjunt de dades de les emissions acústiques dels rodaments de baixa velocitat ajuda a contribuir al desenvolupament de mètodes de diagnòstic. En aquesta investigació, l’anàlisi de l'energia de les senyals revela una dependència de la intensitat i la presència de dany. A més, s'emfatitza una relació entre la forma d'ona de l'energia analitzada i l’existència de dany.
Energia eolikoa mundu mailan elektrizitatea sortu eta erregai fosilak ordezkatzeko energia berriztagarri nagusietako bat da. Eskala handiko ezarpena hobetu eta bizkortzeko, ezinbestekoa da mantentze-lanekin lotutako kostuak murriztea. Osagaien hausturek turbina konponketa-aldi luzeetan gelditzera behartzen dutenez, industria eolikoak mantentze-lan prebentibo edo zuzentzaile zaharkitutik egoeran oinarritutako mantentzelanetara aldatu behar du (mantentze-lan prediktiboa ere esaten zaio). Pitch errodamenduen egoeran oinarritutako mantentzea bereziki desa atzailea da, tentsio mekaniko handiak jasaten baitituzte eta errotazio-abiadura txikietan egoten baitira abian. Operaziobaldintza horiek eragin negatiboa dutenez egoeran oinarritutako egungo monitorizazio sistemetan erabiltzen diren metodo eta teknika estandarren emaitzetan, pitch errodamenduen egoeran oinarritutako mantentze-lanak erronka bat izaten jarraitzen du. Tesi hau egoeran oinarritutako mantenurako pitch errodamenduen egoerari buruzko informazio dagarria lortzen duten metodo eta teknika berritzaileen ikerketan oinarritzen da. Hasieran, teknologiaren egungo egoera aztertzen da, erabilitako metodoak eta seinaleak ezagutzeko. Urrats honek tesi honetan zehar bibrazio-seinaleak eta emisio akustikoak aztertzeko erabakia bermatzen du. Pitch errodamenduen funtzionamendu baldintza bereziak direla eta, ikerketa honek adierazten du beharrezkoa dela datu multzo bat sortzea pitch errodamenduaren funtzionamendu baldintza partikularrak erreplikatzeko laborategi kontrolatuko testuinguru batean. Ondorioz, bibrazioetan oinarritutako datu-multzo bat eta emisio akustikoetan oinarritutako bigarren datu-multzo bat sortzen dira. Bibrazioen datu-multzoak abiadura txikiko errodamenduen diagnostikorako algoritmo berritzaile bat baliozkotzea ahalbidetzen du, zeina entropiaren kontzeptuan oinarritzen baita Shannon eta R enyiren de nizioaren arabera. Literaturan dauden metodo klasikoekin alderatuta, entropian oinarritutako adierazleek abiadura txikiko errodamenduen diagnostikorako informazio dagarriagoa atera dezakete. Gainera, diagnostikoa hobetzeko hainbat adierazleren konbinazioaren ikerketak agerian uzten du entropian oinarritutako adierazleek akademian erabiltzen diren ohiko adierazleek baino informazio gehiago atera dezaketela. Abiadura txikiko errodamenduen emisio akustikoen datu multzoak diagnostiko metodoak garatzen laguntzen du. Ikerketa lan honetan, seinaleen energiaren azterketak intentsitatearekiko eta kaltearen presentziarekiko dependentzia adierazten du. Gainera, aztertutako energiaren uhin-formaren eta kaltearen arteko erlazioa nabarmentzen da.
Enginyeria sísmica i dinàmica estructural
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Serra, López Roger. "Numerical and experimental investigation of spectral domain vibration based indicators for structural health monitoring." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/586170.
Анотація:
Structural health monitoring has been defined as the acquisition, validation and analysis of technical data to facilitate life- cycle management decisions. It is the result of a convergent path from many previous existing disciplines the two most influential being condition monitoring for rotary machinery and non-destructive testing. Vibration based testing presents the greatest stage of maturity of all non-destructive techniques applied to structural health monitoring. Although modal domain use is convention, spectral domain data is by nature more complete in information and requires less manipulation. The use of spectral-domain measurements brings the need to develop new damage detection indicators, as much of the literature existing is focused on modal derived damage indicators.
In this work, an integrated methodology for the evaluation of some spectral domain vibration based indicators for structural health monitoring is proposed. These indicators, namely the CFDAC and SCIs, are based on the correlation between covariance matrices of frequency response functions obtained from experimental modal analysis.
An extensive numerical campaign is performed on a simple structure (consisting on a 1-edge clamped square aluminium plate) over multiple structural alteration scenarios to assess the sensibility and stability of the proposed indexes in front of common acquisition parameters. The ability of the proposed indicators to assess structural alteration progression is also evaluated. This numerical analysis is used as well to observe the relationship between proposed indicators and the residual stiffness of the simple structure evaluated in terms of relative shift from the pristine condition. Finally, the numerical methodology proposed is applied to a different and more complex typology of structure, a 3d latticed and downscaled power transmission tower to investigate the validity of the methodology for other structural configurations.
Some of the cases studied in the numeric campaign are later reproduced in experimental scenarios using two specimens of aluminium plates and a downscaled prototype of a power transmission tower. Stability analysis on the indicators are reproduced and confirmed. For the aluminium plates, the relationship between indicators and residual stiffness is also obtained, showing close agreement with numerical data. Sensibility of the indicators to detect different damage typologies is found to be very similar to the one obtained in the initial numerical analysis. Results for the downscaled prototype model tower shown more dispersion than the results observed in the numerical investigation due to the influence of the boundary conditions in the model.
The research finally applies the structural damage alteration indexes studied to the detection of degradation in a real scale structure in an operational environment. An installation consisting of 3 full-scale medium-voltage power transmission towers is constructed. An experimental modal analysis campaign is performed on the central tower of the installation by introducing a series of intentionally made structural alterations on the structure. Spectral indicators developed are applied to the detection of those structural modifications with noticeable success. Cases involving changes in the structural components of the tower are successfully detected. Changes in the interface between power lines and their supports of the tower are hardly noticeable using this methodology.
Results of this investigation show that spectral domain damage indicators present some advantages over modal domain and temporal domain based indicators such as convenient condensing procedures without loss of information through the Fourier transform, added post-process simplicity and enhanced sensitivity to degradation that state of the art indexes.Es coneix com monitorització de la salut estructural a l'adquisició, validació i anàlisis de dades tècniques que faciliten la presa de decisions al llarg del cicle de vida d'un sistema. Aquesta tecnologia és resultat de la convergència tecnològica d'altres disciplines, com la monitorització operacional per màquines rotatòries i les tècniques d'assaig no destructiu. Els mètodes d'assaig basats en vibracions presenten el major grau de maduresa d'entre totes elles. Malgrat que la pràctica industrial sovint usa informació condensada en el domini modal, les dades en domini espectral son per naturalesa més completes i requereixen de menys post-procés. La utilització del domini espectral requereix desenvolupar nous indicadors d'alteració ja que la major part de la literatura existent se centra en indicadors basats en el domini modal. Es proposa una metodologia integrada per a la avaluació d'alguns indicadors d'alteració estructural en domini modal basats en vibració i aplicats a la monitorització de la salut estructural. Aquests indicadors, referits com a CFDAC i SCIs, estan basats en la correlació entre les matrius de covariància generades a partir de les funcions de resposta en freqüència obtingudes mitjançant anàlisi modal experimental. Es realitza una extensa campanya numèrica en una estructura senzilla (una placa d'alumini quadrada i encastada) a través d'una multitud d'estats estructuralment alterats per avaluar la sensibilitat i l'estabilitat dels indicadors enfront els paràmetres d?adquisició més comuns. En segon lloc, també s?avalua la capacitat dels indicadors per avaluar l'alteració estructural introduïda en cada cas. L'anàlisi numèrica s'utilitza a continuació per observar una possible relació entre els indicadors proposats i la rigidesa residual avaluada com a variació relativa respecte el seu valor intacte. Finalment, la metodologia numèric proposada s'aplica a una tipologia estructural diferent i més complexa, una estructura reticulada 3d que reprodueix una torre de transmissió d'energia elèctrica a escala per investigar la validesa de la metodologia en altres configuracions estructurals. Alguns dels casos estudiats a la campanya numèrica es reprodueixen experimentalment en un parell d?espècimens de placa d'alumini i en un prototip a escala de torre de transmissió elèctrica. Els anàlisis d'estabilitat numèrics sobre els indicadors es reprodueixen experimentalment, tot confirmant els resultats obtinguts. Per les plaques d'alumini, s'estudia la relació entre els indicadors i la rigidesa residual mostrant una correlació molt propera amb els resultats numèrics. La sensibilitat dels indicadors en la detecció de diferents tipologies de dany també s'observa molt similar als casos numèrics. Pere altra banda, els resultats experimentals sobre el prototip de torre a escala presenten més dispersió respecte a la corresponent campanya numèrica degut a la variabilitat en les condicions de contorn. Els indicadors proposats s'apliquen finalment en la detecció d'alteracions estructurals en una torre a escala real en condicions operacionals. Es construeix una línia que consisteix en tres torres de mitja tensió i s'executen anàlisis modals experimentals en la torre central de la mencionada instal·lació tot introduint una sèrie d'alteracions estructurals intencionals. Els indicadors espectrals presentats s'apliquen a la detecció de dites alteracions amb un èxit apreciable. Els casos que incorporen canvis en els membres de l'estructura son detectats amb èxit, mentre que la detecció en els casos que incorporen modificacions sobre les interfícies cable-estructura son més difusament detectables. Els resultats de la investigació mostren que els indicadors estructurals espectrals estudiats presenten algunes avantatges sobre els indicadors basats en domini com ara un procés de condensació més senzill sense pèrdua d'informació vibratòria (...)
4
Meuterlos, Maxime. "Développement de méthodes de normalisation des indicateurs de santé vibratoires pour la surveillance d'ensembles mécaniques basées sur les paramètres d’utilisation. Application à l’hélicoptère." Electronic Thesis or Diss., Lyon, INSA, 2023. http://www.theses.fr/2023ISAL0097.
Анотація:
Les systèmes VHMS (Vibration Health Monitoring System) installés sur les hélicoptères ont un rôle stratégique pour augmenter la sécurité en vol des opérateurs et passagers. Ces systèmes consistent à enregistrer des données opérationnelles en vol, en particulier de nature vibratoire, et à surveiller l’intégrité des ensembles mécaniques par le biais d’indicateurs issus du traitement des signaux. Le principe de base se fonde sur le postulat que l’apparition d’un mode de défaillance engendre une évolution caractéristique des valeurs des indicateurs. Une limite rencontrée par les systèmes VHMS est cependant liée à la forte dépendance des indicateurs aux conditions de vol qui, pour les hélicoptères, sont susceptibles de varier rapidement et de manière complexe. Ces variations, aujourd’hui difficilement maîtrisées, peuvent masquer la signature d’une défaillance mécanique. Il en résulte donc une ambigüité sur l’interprétation de l’origine d’évolution observée des indicateurs. Dans ce manuscrit, des méthodes de normalisation sont développées permettant d’estimer des indicateurs vibratoires normalisés, c’est-à-dire insensibles aux conditions de vol. Dans un premier temps, une revue des méthodes de normalisation couramment utilisées dans la littérature est présentée. Dans un deuxième temps, un cadre statistique paramétrique modélisant les indicateurs vibratoires est proposé et repose sur des modélisations cyclostationnaires du signal vibratoire. Ce cadre paramétrique sera utilisé pour construire deux approches de normalisation des indicateurs vibratoires. La première basée sur le clustering-classification permettant de lier les phases de vol de l’hélicoptère à la statistique de l’indicateur vibratoire. Puis, une deuxième basée sur la régression de paramètres de distributions de quantile conditionnées sur les paramètres de vol expliquant la variabilité des indicateurs de santé. En parallèle, une étude de sensibilité permettant d’identifier ses paramètres de vol est menéeThe VHMS (Vibration Health Monitoring System) installed on helicopters plays a strategic role in increasing the safety of operators and passengers during flight. These systems consist of recording operational data during flight, particularly vibration-related data, and monitoring the integrity of mechanical components through indicators derived from signal processing. The basic principle is based on the assumption that the appearance of a failure mode generates a characteristic evolution of indicator values. However, one limitation of VHMS systems is the strong dependence of indicators on flight conditions, which can vary rapidly and complex for helicopters. These variations, which are difficult to control, can mask the signature of a mechanical failure, resulting in ambiguity in interpreting the origin of the observed indicator evolution. In this manuscript, normalization methods are developed to estimate normalized vibration indicators, which are insensitive to flight conditions. First, a review of normalization methods commonly used in the literature is presented. Second, a parametric statistical framework modeling vibration indicators is proposed based on cyclostationary modeling of the vibration signal. This parametric framework will be used to construct two approaches to normalizing vibration indicators. The first approach is based on clustering-classification, linking the helicopter flight phases to the statistics of the vibration indicator. Then, a second approach is based on the regression of quantile distribution parameters conditioned on flight parameters that explain the variability of health indicators. In parallel, a sensitivity analysis is conducted to identify these flight parameters
5
Rzeszucinski, Pawel. "Development of reliable vibration-based condition indicators and their data fusion for the robust health diagnosis of gearboxes." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/development-of-reliable-vibrationbased-condition-indicators-and-their-data-fusion-for-the-robust-health-diagnosis-of-gearboxes(fa25db2f-89a5-420f-ba56-68ef7da874f9).html.
Анотація:
Performing condition monitoring related tasks on any machinery is an essential element of their rational maintenance. Endeavours to detect an incipient fault within a system serve multiple purposes from increasing the safety of people responsible for operating the machines through decreasing the running and operational costs, allowing time to plan for the inevitable repairs and making sure that the downtime of the machine is kept to an absolute minimum. All these tasks gain extra importance in a case when machines are operated in dangerous conditions putting people's lives in potential jeopardy - for instance in the field of operating a helicopter. The robust assessment of the condition of gearboxes used by helicopters has recently been given an increased attention due to a number of accidents which followed an undetected drive train component failure. The majority of the on-board mounted condition monitoring systems use vibration response signals which are specifically processed to obtain a single number which is representative of a condition of a given monitored drive train component. Those signal processing methods are called Condition Indicators (CIs). There are a number of such CIs which are already in use and they seem to adequately indicate faults in most of the cases. However in a number of instances it has been observed that the most popular parameters like Crest Factor or FM4 failed to dependably reflect the true condition of the gear causing serious accidents, some of which resulted in a number of lives being lost. For this reason the presented research is focused on investigating the limitations of the existing CIs and designing a set of improved CIs. The development process is based on overcoming the drawbacks of thetechniques used in existing CIs combined with the intelligence gathered while analysing the acceleration vibration signals which contained a gear or a bearing fault. Five new CIs are proposed and the details of their design are documented. Both the existing and the proposed CIs are applied on the available, uncorrelated datasets. The results of the comparison show that the newly developed CIs are capable of indicating a gear or a bearing fault in a more robust and dependable fashion. Each proposed CI alone may not be the most robust indicator of the actual condition of the monitored component hence the output from all proposed CIs is combined into a single indication through use of a novel data fusion model. The Combined CI created based on the data fusion model is observed to be more robust compared to each CI alone, hence it may increase the confidence level of the decision making routine and is expected to decrease the number of false alarms. The methods of the existing CIs, the proposed CIs and the data fusion techniques as well as the results of the comparison between the different approaches are present in this thesis.
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Pereira, Daniel Augusto 1983. "Detecção de falhas de sensores em estruturas flexíveis com controle ativo de vibração." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264923.
Анотація:
Orientador: Alberto Luiz SerpaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-24T00:36:50Z (GMT). No. of bitstreams: 1 Pereira_DanielAugusto_D.pdf: 10049171 bytes, checksum: 63439cd1c1df78b669ff99ba303ad488 (MD5) Previous issue date: 2013
Resumo: Partindo-se do princípio de que detectar falhas em sistemas realimentados pode ser considerada tarefa difícil, nessa tese é proposto um método para detecção de falhas de sensores em estruturas flexíveis sujeitas a controle ativo de vibração. O método é baseado num esquema com banco de estimadores para geração de resíduos e no uso de indicadores para a análise quantitativa desses resíduos. O esquema de banco de estimadores permite o isolamento das falhas. Os estimadores utilizados são observadores de saída, filtros de Kalman e filtros H-infinito. Já os indicadores propostos são versões modificadas da diferença entre os valores RMS das saídas medidas e estimadas, a soma do módulo do erro de estimativa, a soma quadrática do erro de estimativa e o modal assurance criterion. É proposto um reescalamento dos indicadores e também um novo indicador, definido pelo produto das versões modificadas e reescaladas dos indicadores clássicos. Inicialmente a técnica foi validada em simulações, primeiro com um modelo de elementos finitos de uma estrutura de placa e posteriormente com um modelo de placa identificado experimentalmente, ambos sob controle ativo de vibração. Experimentos com a estrutura de placa também foram realizados e comprovaram a eficácia da técnica
Abstract: Assuming that fault detection in feedback systems can be considered a hard task, it is proposed in this thesis a method for sensor fault detection in flexible structures subjected to active vibration control. The method is based on a scheme with bank of estimators for residual generation and indicators for quantitative analysis of residues. The bank estimators scheme allows the fault isolation. The estimators used are output observers, Kalman filters and H-infinity filters. The proposed indicators are modified versions of the difference between RMS values of measured and estimated outputs, the sum of the modulus of the estimation error, the quadratic sum of the estimation error and the modal assurance criterion. It is proposed a rescaling of the indicators and also a new indicator, defined by the product of the modified and rescaled versions of classical indicators. Initially the technique is validated in simulations, first with a finite element model of a plate structure and latter with an experimentally identified plate model, both under active vibration control. Experiments with the plate were also performed and proved the effectiveness of the technique
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
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Dogan, Gozde. "Development Of A 3-camera Vision System And The Saddle Motion Analysis Of Horses Via This System." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610877/index.pdf.
Анотація:
One of the purposes of this study is to develop a vision system consisting of 3 inexpensive, commercial cameras. The system is intended to be used for tracking the motion of objects in a large calibration volume, typically 6.5 m. wide and 0.7 m. high. Hence, a mechanism is designed and constructed for the calibration of the cameras.
The second purpose of the study is to develop an algorithm, which can be used to obtain the kinematic data associated with a rigid body, using a vision system. Special filters are implemented in the algorithm to identify the 3 markers attached on the body. Optimal curves are fitted to the position data of the markers after smoothing the data appropriately. The outputs of the algorithm are the position, velocity and acceleration of any point (visible or invisible) on the body and the angular velocity and acceleration of the body. The singularities associated with the algorithm are also determined.
Using the vision setup and the developed algorithm for tracking the kinematics of a rigid body, the motions of the saddles of different horses are investigated for different gaits. Similarities and differences between horses and/or gaits are analyzed to lead to quantitative results. Using the limits induced by the whole body vibration of humans, for the first time in the world, daily, allowable riding time and riding distances are determined for different horses and gaits. Furthermore, novel, quantitative horse comfort indicators are proposed. Via the experiments performed, these indicators are shown to be consistent with the comfort assessment of experienced riders.
Finally, in order to implement the algorithms proposed in this study, a computer code is developed using MATLAB®.
8
Van, Dyke Jason. "Modeling Behaviour of Damaged Turbine Blades for Engine Health Diagnostics and Prognostics." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20312.
Анотація:
The reliability of modern gas turbine engines is largely due to careful damage tolerant design a method of structural design based on the assumption that flaws (cracks) exist in any structure and will continue to grow with usage. With proper monitoring, largely in the form of periodic inspections at conservative intervals reliability and safety is maintained. These methods while reliable can lead to the early retirement of some components and unforeseen failure if design assumptions fail to reflect reality.
With improvements to sensor and computing technology there is a growing interest in a system that could continuously monitor the health of structural aircraft as well as forecast future damage accumulation in real-time.
Through the use of two-dimensional and three-dimensional numerical modeling the initial goals and findings for this continued work include: (a) establishing measurable parameters directly linked to the health of the blade and (b) the feasibility of detecting accumulated damage to the structural material and thermal barrier coating as well as the onset of damage causing structural failure.
9
Schallhorn, Charles Joseph. "Coherence-based transmissibility as a damage indicator for highway bridges." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2007.
Анотація:
Vibration-based damage detection methods are used in structural applications to identify the global dynamic response of the system. The purpose of the work presented is to exhibit a vibration-based damage detection algorithm that calculates a damage indicator, based on limited frequency bands of the transmissibility function that have high coherence, as a metric for changes in the dynamic integrity of the structure. The methodology was tested using numerical simulation, laboratory experimentation, and field testing with success in detecting, comparatively locating, and relatively quantifying different damages while also parametrically investigating variables which have been identified as issues within similar existing methods. Throughout both the numerical and laboratory analyses, the results were used to successfully detect damage as a result of crack growth or formation of new cracks. Field results using stochastic operational traffic loading have indicated the capability of the proposed methodology in evaluating the changes in the health condition of a section of the bridge and in consistently detecting cracks of various sizes (30 to 60 mm) on a sacrificial specimen integrated with the bridge abutment and a floor beam. Fluctuations in environmental and loading conditions have been known to create some uncertainties in most damage detection processes; however, this work demonstrated that by limiting the features of transmissibility to frequency ranges of high coherence, the effect of these parameters, as compared to the effect of damage, become less significant and can be neglected for some instances. The results of additional field testing using controlled impact forces on the sacrificial specimen have reinforced the findings from the operational loading in detecting damage.
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Hui, Yi. "Development and experimental validation of vibration based damage indicator on a specific twin-wall sandwich structure." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC032.
Анотація:
La surveillance de santé structurale (SHM) a attiré beaucoup d'attention dans de nombreux domaines tels que l'industrie civile, aéronautique, mécanique, etc., car il est important de surveiller l'état de la structure afin d'éviter des défaillances structurelles imprévues. Le processus d'identification des endommagements à quatre niveaux: existence, localisation, sévérité et prédiction de l'évolution des endommagements peut être partiellement réalisé si un propre indicateur est bien choisi. Il existe différents indicateurs d'endommagements dont la gamme d'application de la fréquence s'étend de la réponse vibratoire à basses fréquences aux régimes ultrasoniques dans la gamme méga hertz.Les structures sandwich sont largement utilisées dans diverses applications d'ingénierie en raison de son rapport rigidité / poids exceptionnellement élevé par rapport aux structures monocoques. Dans ce travail, une structure sandwich a été étudiée et des indicateurs basés sur la réponse vibratoire ont été conçus en utilisant ses caractéristiques de directivité de propagation et d'amortissement relativement élevé de la structure. Des investigations numériques sur différents scénarios d'endommagement (càd, différents types d'endommagement et leurs combinaisons) et une discussion associée sur la plage d'application ont d'abord été effectuées. La configuration expérimentale a été facilement réalisée à l'aide d'un vibromètre laser à balayage Doppler (SLDV). L'endommagement a été détecté avec succès par les indicateurs proposésStructural health monitoring (SHM) has attracted much attention in many engineering fields like civil, aeronautic, mechanical industry, etc. since it is important to monitor the healthy condition of the operational structure in order to avoid unpredicted structural failure which may have severe consequences. The four-level damage identification process: existence, localization, severity and prediction of damage evolution, can be partly realized if a suitable indicator is chosen. It exists different damage indicators whose application range of frequency spans from vibrational response at low frequencies to the ultrasonic regimes in the mega hertz range.The sandwich structures are widely used in various engineering applications due to its exceptionally high flexural stiffness-to-weight ratio compared to monocoque structures. In this thesis a specified twin-wall sandwich structure in polypropylene was studied and vibration-based indicators were designed by taking use of its relative high damping and propagation directivity characteristics. Numerical investigations on different damage scenarios (i.e., different types of defect and their combinations) and an associated discussion on the range of application were first carried out. Experimental configuration was easily realized with the help of a scanning laser doppler vibrometer (SLDV). Defect was successfully detected by the proposed indicators
Книги з теми "Vibration indicators":
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Smedley, Julia, Finlay Dick, and Steven Sadhra. Health surveillance. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199651627.003.0022.
Анотація:
Health surveillance: general principles 424Skin surveillance 426Respiratory health surveillance 428Classification of hearing loss 430Patterns of hearing loss 432Inorganic lead 434Organic lead 436Surveillance for hand–arm vibration syndrome 438• Health surveillance should only be introduced where the risk assessment indicates that it is required (Regulation 6, Management of Health and Safety at Work Regulations 1999) or it meets the criteria listed in the associated Approved Code of Practice:...
Частини книг з теми "Vibration indicators":
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Maier, Knut. "Lubricants — Indicators for Oil System Damage and Malfunction." In Vibration and Wear in High Speed Rotating Machinery, 49–61. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1914-3_4.
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Ribeiro, R. Rocha, L. A. C. M. Veloso, and R. M. Lameiras. "Machine Learning Vibration-Based Damage Detection and Early-Developed Damage Indicators." In Topics in Modal Analysis & Testing, Volume 8, 23–32. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-75996-4_4.
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Lukpanov, Rauan E., Serik B. Yenkebayev, Duman S. Dusembinov, and Denis V. Tsygulyov. "Assessment of the Impact of Vibration Indicators on the Foundation of the Existing Building During Pile Driving." In Lecture Notes in Civil Engineering, 229–38. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-85236-8_20.
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Diestmann, Thomas, Nils Broedling, Benedict Götz, and Tobias Melz. "Surrogate Model-Based Uncertainty Quantification for a Helical Gear Pair." In Lecture Notes in Mechanical Engineering, 191–207. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_16.
Анотація:
AbstractCompetitive industrial transmission systems must perform most efficiently with reference to complex requirements and conflicting key performance indicators. This design challenge translates into a high-dimensional multi-objective optimization problem that requires complex algorithms and evaluation of computationally expensive simulations to predict physical system behavior and design robustness. Crucial for the design decision-making process is the characterization, ranking, and quantification of relevant sources of uncertainties. However, due to the strict time limits of product development loops, the overall computational burden of uncertainty quantification (UQ) may even drive state-of-the-art parallel computing resources to their limits. Efficient machine learning (ML) tools and techniques emphasizing high-fidelity simulation data-driven training will play a fundamental role in enabling UQ in the early-stage development phase.This investigation surveys UQ methods with a focus on noise, vibration, and harshness (NVH) characteristics of transmission systems. Quasi-static 3D contact dynamic simulations are performed to evaluate the static transmission error (TE) of meshing gear pairs under different loading and boundary conditions. TE indicates NVH excitation and is typically used as an objective function in the early-stage design process. The limited system size allows large-scale design of experiments (DoE) and enables numerical studies of various UQ sampling and modeling techniques where the design parameters are treated as random variables associated with tolerances from manufacturing and assembly processes. The model accuracy of generalized polynomial chaos expansion (gPC) and Gaussian process regression (GPR) is evaluated and compared. The results of the methods are discussed to conclude efficient and scalable solution procedures for robust design optimization.
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Hasebe, Y., F. Kuratani, T. Yoshida, and T. Morikawa. "An Effective Indicator for Defect Detection in Concrete Structures by Rotary Hammering." In Vibration Engineering for a Sustainable Future, 211–17. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-48153-7_28.
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Xu, Zhi-wei, Li-xia Lin, Nan-hong Ding, and Lei Chen. "The External Prestress Effect of Curved Tendons on the Natural Vibration Characteristics of Steel Beams." In Advances in Frontier Research on Engineering Structures, 517–26. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8657-4_46.
Анотація:
AbstractIn order to explore the external prestress effect of the curved tendons on the stiffness and natural vibration characteristics of the steel beam, this paper deduced the calculation equation of the natural frequency on the external prestressed simply supported steel beam of the curved arrangement, which was based on the Hamilton principle. The natural frequency is calculated by combining the example of I-shaped simply supported steel beam, which was analyzed and verified by establishing the finite element model. The results show that: the calculation of the equation is well demonstrated by the finite element results, and the validity of model equation was verified. When the applied prestress increases, the natural vibration frequency decreases and the change range is not large, which indicates that the magnitude of the prestress has little effect on the natural frequency of simply supported steel beams.
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Yang, Lixiang, Yaobin Han, Xu Zhang, and Zhiwen Li. "Numerical Simulation for the Dynamic Response of Step Topography Subjected to Blasting Load." In Lecture Notes in Civil Engineering, 179–86. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2532-2_15.
Анотація:
AbstractThe vibration velocity and frequency of rock mass are closely related to the instability and failure of the building. The step topography has great influence on blasting vibration wave propagation. Therefore, it is of great significance to study the dynamic response of step topography subjected to blasting load. In this paper, the FLAC2D program is used to study the dynamic response of step topography subjected to blasting load. The plane strain mode is adopted in the calculation, and the blasting load is assumed to be a triangular pulse wave which is applied to one side of the calculating mode. The amplification effect of the height of the step is first studied. The calculation result shows that the amplification factor increases first and then decreases with the increase of the step height. The maximum value of the amplification factor is consistent with the results of the field test, which indicates the feasibility of the numerical simulation.
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Augustyn, Damian, and Marek Fidali. "Fuzzy Condition Indicator of Spindle of Machining Center Based on Vibration Parameters." In Applied Condition Monitoring, 203–11. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-31719-4_21.
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Wernsen, M. W. F., M. V. van der Seijs, and D. de Klerk. "An Indicator Sensor Criterion for In-Situ Characterisation of Source Vibrations." In Sensors and Instrumentation, Volume 5, 55–69. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54987-3_7.
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Kahouadji, Amar, Samir Tiachacht, Mohand Slimani, Amar Behtani, Samir Khatir, and Brahim Benaissa. "Vibration-Based Damage Assessment in Truss Structures Using Local Frequency Change Ratio Indicator Combined with Metaheuristic Optimization Algorithms." In Lecture Notes in Civil Engineering, 171–85. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-24041-6_14.
Тези доповідей конференцій з теми "Vibration indicators":
1
Bonamour, Pierre, Gianni Naccarato, Frederic Champavier, Ammar Mechouche, Nassia Daouayry, and Lucas Macchi. "Use of Machine Learning to Define Optimum HUMS Acquisition Strategy." In Vertical Flight Society 75th Annual Forum & Technology Display. The Vertical Flight Society, 2019. http://dx.doi.org/10.4050/f-0075-2019-14729.
Анотація:
Health and Usage Monitoring Systems (HUMS) measure vibrations levels and compute Vibration Condition Indicators to monitor Helicopters dynamic systems. Modern avionics record continuously a wealth of flight parameters. The influence of flight parameters on Vibration Condition Indicators was assessed using machine learning methods. Machine learning was used to derive Vibration Condition Indicators from flight parameters only. This derivation yielded quantitatively the influence of flight parameters. An illustration of this methodology is presented on main rotor speed. Variable rotor speed contributes to better acoustic performance but is a daunting challenge for HUMS vibration monitoring. Several Vibration Condition Indicators were modelled and their dependency to rotor speed was determined by machine learning parameter weight output. This allowed to optimize the acquisition parameters, the filtering of Vibration Condition Indicators and eventually to classify and choose the most relevant one based on machine learning and extensive replay of fleet data.
2
Sato, Hironao, Masahiro Oba, Takashi Hiromoto, Kiyofumi Sato, Toshiyuki Sonobe, Satoru Hayakawa, Koji Morikawa, Yasuo Moriyoshi, and Noriaki Sekine. "Experimental Study on the Relationship between Combustion and Vibration in a Gasoline Engine Part 2 Characteristics of Structure’s Exciting Force and Overall Research Summary." In Noise and Vibration Conference & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-1146.
Анотація:
<div class="section abstract"><div class="htmlview paragraph">Following Part 1 of the previous study, this paper reports the structure’s exciting force and summarize the overall research results. An experimental study was conducted to clarify the relationship between engine combustion and vibration, and to establish technology to suppress it. This study focused on the vehicle interior noise caused by combustion in which vibration transmission is the main component at high speed and high load region. A phenomenon in which both the combustion’s exciting force and the structure’s exciting force are combined is defined as vehicle interior noise caused by combustion. Conventionally, combustion and vibration are often discussed in terms of the average cycle, but considering the nonstationary property of vibration, in this paper analyzed the structure’s exciting force characteristics for vibration in cycle-by-cycle. Analysis was conducted using the combustion indicators clarified in the previous study. The engine vibration is affected by piston specifications even with the same heat release characteristics. Based on the analysis results, the piston rotation angle and translational displacement are defined as indicators of the structure’s exciting force. In this paper, after discussing the piston motion characteristics as the structure’s exciting force and the indicators of vibration suppression, the results clarified by the research combined with the previous study are summarized.</div></div>
3
Reich, Alton J., Steve J. Doherty, and Keith A. Williams. "Load Reduction on Valve Position Indicators in High Vibration Environments." In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71118.
Анотація:
The Arnold Engineering Development Center (AEDC) testing complex includes more than 50 wind tunnels, test cells, arc heaters, and other specialized test facilities. Of these, 27 units have capabilities that are unmatched in the United States, and 14 are unmatched in the world. These unique facilities create equally unique operating environments for instrumentation used for monitoring and control of test conditions. Several high flow-rate, supersonic wind tunnels utilize off-the-shelf angular displacement transducers (ADTs) for monitoring the position of 90° valves (i.e. butterfly valves) used to control the air flow-rate and bulk pressure during testing. Due to the high air flow rates in supply and exhaust ducts, there are significant structural vibrations to which the ADTs are subjected. These ADTs have experienced an unacceptably high rate of failure during testing. In the event of an ADT failure, alternative flow paths may, in some cases, be utilized. If an alternative path cannot be found, however, test operations must be suspended while the faulty sensor is replaced; leading to significant cost and schedule impacts associated with the down-time. This paper discusses an effort to understand the root cause of the ADT failures based on design information, and experience in the field. Several alternative mounting conditions were considered in order to reduce the vibrational loads acting on the ADT. A number of the alternatives consisted of utilizing different shaft couplings to couple the motion of the valve stems and the ADT sensor shaft. Experiments were performed at the University of Alabama’s Applied Controls Laboratory to test the effect of the different enclosures and shaft couplings. Preliminary results indicate that the shaft coupling, in particular, have a direct impact on shaft loads transmitted to the ADT. Test results and conclusions are presented.
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Непершина, О. П. "Deviation of indicators of blood plasma protein composition in vibration disease." In The second international youth Forum "OCCUPATION AND HEALTH". PT "ARIAL", 2018. http://dx.doi.org/10.31089/978-5-907032-51-4-2018-1-188-195.
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Camargo, Gisele de Fátima Lima, and Eurípedes Nóbrega. "STATISTICAL INDICATORS-BASED MACHINE LEARNING METHOD FOR CLASSIFICATION OF VIBRATION SIGNALS." In 26th International Congress of Mechanical Engineering. ABCM, 2021. http://dx.doi.org/10.26678/abcm.cobem2021.cob2021-0579.
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Penkova, Kateryna. "DETERMINATION OF OPERATIONAL RELIABILITY INDICATORS OF VIBRATION PLATFORM BASED ON FUZZY LOGIC." In DÉBATS SCIENTIFIQUES ET ORIENTATIONS PROSPECTIVES DU DÉVELOPPEMENT SCIENTIFIQUE, Chair Maksym Delembovskyi. European Scientific Platform, 2021. http://dx.doi.org/10.36074/logos-05.02.2021.v3.17.
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Lall, Pradeep, Peter Sakalaukus, Ryan Lowe, and Kai Goebel. "Leading indicators for prognostic health management of electrical connectors subjected to random vibration." In 2012 13th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm). IEEE, 2012. http://dx.doi.org/10.1109/itherm.2012.6231488.
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Badgley, Robert H., and Wayne A. Shade. "Vibration Analysis for Immediate Assessment of Battle-Damaged Gas Turbine Engines." In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-96.
Анотація:
Operation of aircraft in hostile combat areas exposes the aircraft to risks of substantial damage or loss. Engine damage can occur as a result of impact or penetration by projectiles or fragments, or by ingestion of impact debris. The risk level depends upon threat, aircraft type, and mission. Historical evidence indicates that damage is often survivable. Aircraft can often be repaired and returned to service. The damaged engine may still be able to operate. Normal action is to remove and replace a damaged engine, but replacement engines may not be available. A procedure is needed at the operational unit level to immediately assess the exact nature and extent of engine damage, as well as rapid (perhaps nonstandard) engine repair procedures for use at forward locations. Such repairs can include reblading of compressors and turbines, replacement of cracked or broken gear cases or gears, and replacement or repair of accessories. Without repairs, the aircraft fleet may quickly lose its effectiveness. Performance indicators, gas path and oil debris quantity and size, and vibration levels can help identify the location and extent of damage. Vibration analysis with portable, computerized equipment can identify damage in the engine’s compressor and turbine rotating components, as well as cracked, broken, or otherwise damaged accessory drive gearboxes and accessories. Vibration analysis either provides an immediate indication that all vibration indicators are within limits, or localizes the damage to specific components for immediate replacement or repair at the operating unit location.
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Kestel, Kayacan, Cédric Peeters, Jérôme Antoni, Shawn Sheng, and Jan Helsen. "Bearing Fault Detection on Wind Turbine Gearbox Vibrations Using Generalized Likelihood Ratio-Based Indicators." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-81294.
Анотація:
Abstract Studies in condition monitoring literature often aim to detect rolling element bearing faults because they have one of the biggest shares among defects in turbo machinery. Accordingly, several prognosis and diagnosis methods have been devised to identify fault signatures from vibration signals. A recently proposed method to capture the rolling element bearing degradation provides the groundwork for new indicator families utilizing the generalized likelihood ratio test. This novel approach exploits the cyclostationarity and the impulsiveness of vibration signals independently in order to estimate the most suitable indicators for a given fault. However, the method has yet to be tested on complex experimental vibration signals such as those of a wind turbine gearbox. In this study, the approach is applied to the National Renewable Energy Laboratory Wind Turbine Gearbox Condition Monitoring Round Robin Study data set for bearing fault detection purposes. The data set is measured on an experimental test rig of a wind turbine gearbox; hence the complexity of the vibration signals is similar to a real case. The outcome demonstrates that the proposed method is capable of distinguishing between healthy and damaged vibration signals measured on a complex wind turbine gearbox.
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Wilson, Dr, Daniel Martinez, and Daniel Wade. "Spectrum Reconstruction for Oil Cooler On Condition Monitoring." In Vertical Flight Society 75th Annual Forum & Technology Display. The Vertical Flight Society, 2019. http://dx.doi.org/10.4050/f-0075-2019-14611.
Анотація:
Machine learning is employed to reconstruct vibration spectra from the condition indicators recorded by a field data acquisition system. Those spectra are used to compute a custom condition indicator, enabling the expansion of an on condition part life extension program to many more rotorcraft. This alternate, machine-learning driven method for computing an existing condition indicator is submitted for rigorous testing and qualification, and for fielding to the fleet analytics system.
Звіти організацій з теми "Vibration indicators":
1
Tire Experimental Characterization Using Contactless Measurement Methods. SAE International, August 2021. http://dx.doi.org/10.4271/2021-01-1114.
Анотація:
In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.