Post-stressed concrete foundation may reduce machinery vibration

Post-stressing concrete mat foundation reduces excessive vibrations in machinery. The mat is stressed in compression after the machinery is mounted, thus closing any cracks in it, altering the distribution of the soil subgrade reaction on the mat, and changing the mat-subgrade natural frequency

Machinery vibration diagnostics

Vibration is a process that can not be measured, unlike its parameters. The machine can have high levels of vibration for three reasons: – there is a strong source of vibration inside the machine; – during spreading between source of vibration and the point of observation, vibration weakly damped or even increases due to good conductivity and transparency of the surrounding structures; – there are two previous reasons simultaneously. For solving the first problem we have to explore the physical nature of vibration inside the machine. For solving the second problem it's necessary to investigate the spread of vibrations out of the construction. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3387

Fault Diagnosis System of Rotating Machinery Vibration Signal

AbstractA high demand has been presented in the measuring and diagnosis of vibration signal of rotating machinery, which can reflect the running state information of rotating machinery equipment. This paper designs a new type of fault diagnosis system of rotating machinery vibration signal, which can measure the vibration acceleration and velocity signals accurately, and analyze the vibration severity and frequency division amplitude spectrum of vibration signal. Experiment showed that our system can diagnose typical mechanical fault

Vibration diagnostics of small hydroelectric power station machinery

This short paper describes a problematic of a small hydroelectric power station machinery vibration diagnostics. The vibration diagnostics of a power station machinery is very specific, machinery contains many possible damaged rotating parts including a turbine rotor. Non-stationary strength pulsing caused by water flow can be generated. The paper describes problems with the correct determination of a small hydroelectric power station machinery failure

Hydrostatic Vibratory Drive of the Test Stand for Excitation of the Amplitude-Modulated Vibrations

The article reviews the problems arising during the development of the test stand hydrostatic vibratory drive, which synthesize controlled amplitude-modulated vibrations required testing of vibration strength and vibrostability of technological devices. The newly developed modification can adequately simulate the transport vibration and vibration of the operating power-supply units of technological machinery vibration by means of implementing of a continuous frequency spectrum of the vibration exposure in the desired frequency range

Experimental investigation of unbalance and misalignment in rotor bearing system using order analysis

Unbalance and misalignment are the main causes of vibration in rotating machinery. Vibration analysis is the important tool for fault diagnosis in rotating machinery. In this paper, order analysis technique of vibration analysis for unbalance and misalignment fault diagnosis is proposed. In order analysis, both phase and amplitude are obtained. From phase and amplitude, the fault type and location are usually identified. Experimental results show order analysis is an effective technique for fault diagnosis

Machinery Vibration Monitoring Program at the Savannah River Site

The Reactor Maintenance's Machinery Vibration Monitoring Program (MVMP) plays an essential role in ensuring the safe operation of the three Production Reactors at the Westinghouse Savannah River Company (WRSC) Savannah River Site (SRS). This program has increased machinery availability and reduced maintenance cost by the early detection and determination of machinery problems. This paper presents the Reactor Maintenance's Machinery Vibration Monitoring Program, which has been documented based on Electric Power Research Institute's (EPRI) NP-5311, Utility Machinery Monitoring Guide, and some examples of the successes that it has enjoyed

Fault Detection in Rotating Machinery: Vibration analysis and numerical modeling

This thesis investigates vibration based machine condition monitoring and consists of two parts: bearing fault diagnosis and planetary gearbox modeling. In the first part, a new rolling element bearing diagnosis technique is introduced. Envelope analysis is one of the most advantageous methods for rolling element bearing diagnostics but finding the suitable frequency band for demodulation has been a substantial challenge for a long time. Introduction of the Spectral Kurtosis (SK) and Kurtogram mostly solved this problem but in situations where signal to noise ratio is very low or in presence of non-Gaussian noise these methods will fail. This major drawback may noticeably decrease their effectiveness and goal of this thesis is to overcome this problem. Vibration signals from rolling element bearings exhibit high levels of 2nd order cyclostationarity, especially in the presence of localized faults. A second-order cyclostationary signal is one whose autocovariance function is a periodic function of time: the proposed method, named Autogram by the authors, takes advantage of this property to enhance the conventional Kurtogram. The method computes the kurtosis of the unbiased autocorrelation (AC) of the squared envelope of the demodulated and undecimated signal, rather than the kurtosis of the filtered time signal. Moreover, to take advantage of unique features of the lower and upper portions of the AC, two modified forms of kurtosis are introduced and the resulting colormaps are called Upper and Lower Autogram. In addition, a new thresholding method is also proposed to enhance the quality of the frequency spectrum analysis. Finally, the proposed method is tested on experimental data and compared with literature results so to assess its performances in rolling element bearing diagnostics. Moreover, a second novel method for diagnosis of rolling element bearings is developed. This approach is a generalized version of the cepstrum pre-whitening (CPW) which is a simple and effective technique for bearing diagnosis. The superior performance of the proposed method has been shown on two real case data. For the first case, the method successfully extracts bearing characteristic frequencies related to two defected bearings from the acquired signal. Moreover, the defect frequency was highlighted in case two, even in presence of strong electromagnetic interference (EMI). The second part presents a newly developed lumped parameter model (LPM) of a planetary gear. Planets bearings of planetary gear sets exhibit high rate of failure; detection of these faults which may result in catastrophic breakdowns have always been challenging. Another objective of this thesis is to investigate the planetary gears vibration properties in healthy and faulty conditions. To seek this goal a previously proposed lumped parameter model (LPM) of planetary gear trains is integrated with a more comprehensive bearing model. This modified LPM includes time varying gear mesh and bearing stiffness and also nonlinear bearing stiffness due to the assumption of Hertzian contact between the rollers/balls and races. The proposed model is completely general and accepts any inner/outer race bearing defect location and profile in addition to its original capacity of modelling cracks and spalls of gears; therefore, various combinations of gears and bearing defects are also applicable. The model is exploited to attain the dynamic response of the system in order to identify and analyze localized faults signatures for inner and outer races as well as rolling elements of planets bearings. Moreover, bearing defect frequencies of inner/outer race and ball/roller and also their sidebands are discussed thoroughly. Finally, frequency response of the system for different sizes of planets bearing faults are compared and statistical diagnostic algorithms are tested to investigate faults presence and growth

Understanding Design Parameters That Affect Thermal Stability of High-Speed Turbo Machinery (Also Known As the Morton Effect)

Case StudyAt present, there are no commercially available codes in industry that have proven to reliably predict a rotors sensitivity to the Morton Effect. The Morton Effect refers to synchronous rotor instability due to non-uniform heating of shaft journals. The industrys inability to reliably predict this phenomenon has caused both plant start-up delays and shutdowns due to machinery vibration. The multiple case studies that will be presented assess this problem and summarize the solutions that were developed, tested and ultimately implemented to address the Morton Effect

Damage assessment in a reinforced concrete pedestal based on rotating machinery vibration analysis

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.A critical operational condition to be considered in the fatigue damage evaluation in reinforced concrete pedestals of power plants generation is the caused by the dynamic effects transmitted by the turbo-generator in terms of vibrations. The structural behavior of the turbo-generator under dynamics conditions is affected by its dimensional characteristics, the weight of each components and the performance of each supports on terms of stiffness and damping. In this study, a coupled finite element model FEM of the turbo-generator and reinforced concrete pedestal were developed in order to evaluate the dynamic behavior of the structure and the fatigue damage for different real operational conditions according to data obtained from field measurements. The FEM developed for the pedestal considers the inclusion of reinforcing steel structural elements within the concrete. The methodology was implemented to determine the critical zones to fatigue failure and an estimate of remaining fatigue life in the pedestal