Structural born vibration is the most concern issue for industry. Traditionally, the accelerometer is usually used as the major monitoring device for vibration. As the mechanism getting more and more complexity, more compact, tinier and more lighting, the traditional accelerometers are suffered from the loading effect. Its accuracy of measurement is suspected and cannot match the modern measurement requirement. Hence, the studies of fiber optic vibration sensors become an urgent issue in this era. The reflection wavelength of a fiber Bragg grating¡]FBG¡^is sensitive to the variation of the strain and temperature. Our sensor configuration is made of an interferometer and fiber Bragg grating. The vibration induces a strain of the fiber Bragg grating, and it makes a phase difference between those two light beams in the interferometer. A demodulation circuit is needed to detect the phase difference caused by the vibration. In this project, the aim is focused on the vibration measurement for some complicated rotational machines or structures. A fiber optic accelerometer will be designed and studied as a vibration monitor for the other subprojects. In this the thesis, two kinds of vibration sensor head are designed and studied, the first is a bending loss sensor head and the other is an optic fiber Bragg grating sensor head. The results are narrated as follows¡G¡]1¡^ The dynamic range of the bending loss sensing head is about 50 dB.¡]2¡^The dynamic range of the optic fiber Bragg grating sensing head is 38 dB with test frequency range between 100 ~ 400 Hz, the noise level is around 1.95 ¡Ñ 10-2 rad.

Fiber optic temperature and vibration sensors were designed and built to take readings in the harsh environment of a steel mill. The sensors are insensitive to electromagnetic noise; making them well suited for the use in such an environment. The temperature sensor uses an optical filter technique. A piece of intrinsic silicon is inserted between two optical fibers and 1064nm wavelength light is transmitted through the silicon. As the temperature increases, the silicon becomes more highly absorbing. The vibration sensor uses an optomechanical technique. Light is transmitted across a short air gap between two optical fibers. One of the fibers acts as cantilever while the other is fixed. As the cantilever vibrates, the transmitted power fluctuates, which enables the detection of the frequency and amplitude of the vibration. Sensors were initially tested under laboratory conditions, and subsequently field tested at ArcelorMittal Dofasco. The temperature sensor has a sensitivity of 0.4°C over the temperature range from 22°C to 120°C. The vibration sensor has a sensitivity of 2.87mV /g peak over a frequency range from 0 to 1250 Hz. / Thesis / Master of Applied Science (MASc)

In line with its commitment to safe nuclear power generation, the Koeberg Nuclear Power Station (KNPS) replaced the outdated vibration monitoring system with a modern on-line vibration monitoring system. This will allow plant personnel to monitor components on a continuous basis which will provide faster response time in the scenario of excessive vibrations of the primary components. This study focuses on the analysis of the vibration of the primary components of the KNPS by analysing the frequency spectra of the vibration signals of the primary components and comparing these to reference signatures obtained during similar operating conditions. The condition of the vibration sensors will also be evaluated. In order to obtain a deeper understanding of the vibration behaviour and hence vibration signatures of the KNPS primary reactor components, a simplified mathematical model of the primary components is developed, based on the system of elasto-dynamic equations. The equations are solved numerically and used to simulate the KNPS vibration monitoring system. The mechanical system is modelled. Time series are generated and Fast Fourier Transforms (FFT) are calculated to simulate the new KNPS monitoring system. In the simulation mechanical degradation of the primary components as well as sensor degradation is simulated. The purpose of this study is to indicate whether mechanical degradation has occurred in the primary components of the plant and to validate the vibration signals. At the same time the study aims to lay a foundation for future monitoring and interpretation of vibration signatures by simulating the vibration and the monitoring signals. It was found that the primary components had not been affected by mechanical degradation as no deviations in resonances were detected in the frequency signatures. A small number of vibration sensors were found to have deteriorated; hence replacement / maintenance was proposed. The mechanical model and the simulation of the monitoring signals proved to be useful to understand and interpret the vibration of the KNPS primary components. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.

In line with its commitment to safe nuclear power generation, the Koeberg Nuclear Power Station (KNPS) replaced the outdated vibration monitoring system with a modern on-line vibration monitoring system. This will allow plant personnel to monitor components on a continuous basis which will provide faster response time in the scenario of excessive vibrations of the primary components. This study focuses on the analysis of the vibration of the primary components of the KNPS by analysing the frequency spectra of the vibration signals of the primary components and comparing these to reference signatures obtained during similar operating conditions. The condition of the vibration sensors will also be evaluated. In order to obtain a deeper understanding of the vibration behaviour and hence vibration signatures of the KNPS primary reactor components, a simplified mathematical model of the primary components is developed, based on the system of elasto-dynamic equations. The equations are solved numerically and used to simulate the KNPS vibration monitoring system. The mechanical system is modelled. Time series are generated and Fast Fourier Transforms (FFT) are calculated to simulate the new KNPS monitoring system. In the simulation mechanical degradation of the primary components as well as sensor degradation is simulated. The purpose of this study is to indicate whether mechanical degradation has occurred in the primary components of the plant and to validate the vibration signals. At the same time the study aims to lay a foundation for future monitoring and interpretation of vibration signatures by simulating the vibration and the monitoring signals. It was found that the primary components had not been affected by mechanical degradation as no deviations in resonances were detected in the frequency signatures. A small number of vibration sensors were found to have deteriorated; hence replacement / maintenance was proposed. The mechanical model and the simulation of the monitoring signals proved to be useful to understand and interpret the vibration of the KNPS primary components. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.

This thesis encompasses measuring and rating of vibrations in electric machines. The theoretical part begins with a short description of possible causes of vibrations, which is followed by a discussion about what consequences the vibrational effects have on electrical devices. Then there is a description of available vibration sensors. The bigger part is then devoted to analysis of vibratory signal in both time and frequency domains. The practical part is divided into two chapters. The first one describes laboratory demonstration of control drive with DC motor, which is expanded by measurement of vibrations. The second chapter deals with measurement and analysis of said vibrations in the demonstration.