There are the facilities which a conventional vibration diagnosis technology is hard to apply in the processing assembly plant. For these facilities, we developed in the condition monitoring technology using the sound method and the current method. Furthermore, we developed the removal method of the inverter noise that was the disincentive of the vibration diagnosis.

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In the rotating machinery, the whirl motion of the rotor is inherently occurred due to its mass imbalance or thermal deformation during operation. That caused the vibration of the casing and/or bearing pedestal. The severe whirl motion of the rotor leads to the machine operating performance degradation or any kinds of the machine trouble. The vibration condition monitoring of the rotating machinery is one of the potential solutions to avoid the machine trouble and keep the safety operation. The self-powered wireless remote monitoring system is becoming a potential technology for future vibration condition monitoring of rotating machinery. This study aims at developing the wireless vibration acceleration sensor system for the vibration condition monitoring of the rotating machinery. In this paper, authors experimentally evaluated the feasibility of the commercial wireless device for the wireless vibration condition monitoring system.

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Recently wireless communication technologies became very robust, high reliability also having enough security. We developed wireless vibration measuring system using ISA100.11a regulation. In this time I will introduce our wireless vibration measuring system abstract and also wireless case study.

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Proactive maintenance of the rotary machine can be realized by using vibration data applying the "Chara-Map diagnostic system" based on Correlation Extraction Method. The amount of axis misalignment estimated by "Chara-Map diagnostic system" was verified in comparison with the actual measured amount of misalignment after stopping the machine. Therefore, the bearing alignment can be corrected at the optimum time according to the presumption of amount of the axis misalignment handily from the vibration data while driving. (Chara-Map :Character Mapping)

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Recent years, bearings frequently suffer from early damage caused by flaking. This is thought to be due to hydrogen embrittlement in connection with hydrocarbon decomposition when greases contact the nascent clean metal surface created under the current severer frictional situations. This study proposes the evaluation method of grease decomposition and hydrogen generation by a controlled atmosphere cutting apparatus. Mass spectrometry of this method provided the evidences of hydrogen generation and hydrocarbon decomposition in relation to the nascent metal surface appearance by cutting. The further investigation demonstrated additives in greases greatly influenced the grease decomposition and the hydrogen generation.

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This paper proposes a health monitoring system for damage detection on plate structures based on the vibration measurement using laser excitation. Ideal impulse force can be applied to a plate by laser excitation. By this ideal impulse force, vibration measurement can be accomplished in wide frequency range. Mode shape is locally changed at the damaged position. In this study, mode shapes are extracted through the vibration measurement using two LDVs. Then, the location of damage is identified by applying wavelet transform to the mode shapes because the wavelet transform can detect a local change of the mode shapes.

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It is common that the amplitude of the vibration displacement is inverse proportional to the frequency if the vibration velocity is constant in all the frequency range. Also the amplitude of the displacement is inverse proportional to the square of the frequency if the vibration acceleration is constant in all the frequency range. This paper proposes "half-velocity" and "half-acceleration" as new vibration values, and explains the measurement principle and the usefulness of these values. The amplitude of the "half-velocity" is inverse proportional to the one-half power of the frequency, and the amplitude of the "half-acceleration" is inverse proportional to the 1.5th power of the frequency.

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It is important to detect early abnormal sign to keep availability of industrial machines. We think about detecting machine-abnormal state using acoustic sensor. So, we study the method of acoustic feature extraction. We explain the method of feature extraction in case of measurement of time variation. We confirmed the difference between normal sound and abnormal sound on peak-frequency histogram representation.

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This study concerns non-contact excitation of planer objects by using near-field acoustic levitation, in which a planer object having relatively large size and weight is levitated on a ultrasonic vibration plate with 10-100 μm air gap. This phenomenon has been studied as a non-contact transportation technology for a fragile thin plate such as flat panel display glass substrate. In this study, we investigate the possibility of this phenomenon as a technology for non-contact excitation of planer objects. In this paper, we propose a non-contact excitation method to vibrate the levitated object at arbitrary low frequency by modulating the ultrasonic amplitude of the vibration plate. An experimental study of non-contact excitation of plate specimens near the natural frequencies suggests that the system consisting of the vibration plate, the air gap, and the levitated plate can be modeled as a two-degree-of-freedom dynamical system.

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Robots using for the bridge inspection to aim at the labor saving and lowering the maintenance cost is desirable for the management and maintenance of many old bridges because the conventional method will impose a burden on the economy. We had created a four-wheel driving robot for trial purposes that can inspect cracks and corrosion in steel bridge substructures. If the robot will be used in real environment, it needs cameras which are used to control the robot for the bridge inspection. In this study, we verified the cameras adapted to BIREM. Finally, it was found suitable camera equipped with wide-angle lens.

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With the conspicuous advances in adhesion technologies, structural adhesion joints have been used more often replacing conventional mechanical joints such as bolted and riveted joints. Nondestructive techniques, which can detect and monitor the development of adhesive failures in-situ to evaluate the health state of adhesive joints would become increasingly important. This paper investigates the detection of the failures in the adhesive joints in a structure by applying the nonlinear piezoelectric impedance modulation method, a sensitive baseline-free structural health monitoring methodology developed by the authors. This technique evaluates failures in the structure under a pump excitation at low frequency, by measuring the current response of a piezoelectric patch on the structural surface driven by a high frequency probe voltage. Beam specimens with structural adhesive joint in healthy and debonded conditions are experimentally examined, and the resultant damage evaluation indices are investigated in terms of the probe voltage amplitudes.

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This study concerns damage localization method based on nonlinear wave modulation phenomenon. The detection technique based on nonlinear wave modulation is one of sensitive technique as nondestructive detection technique. When the structure including contact-type failure is vibrating at low-frequency, the pair of contact surfaces is tapping and clapping. In this condition, the scatter characteristics of high-frequency waves, such as wave transmissivity and reflectivity, in the vicinity of the contact-type failure may fluctuate in synchronization with low-frequency vibration. Since the demodulation wave propagates through the structure with the group velocity, it is possible to estimate location of the contact-type failure. When impact excitation is used as low-frequency vibration, we are able to observe the initial achieved waves which is occurred at the location of the contact-type failure. In this paper, we use the dispersion wave as high-frequency waves, so we need to evaluate the propagation characteristics of demodulated swave by theoretical analysis based on Bernoulli-Euler beam. Especially, the equation which describes propagation characteristics of demodulated waves is applied and the relationship of dispersion of equation of demodulated waves is determined. Finally, we evaluate the relationship between propagation distance and the collapse of the wave packet and verified the limit of the proposed method caused by the collapse of the wave packet in theory.

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We have developed and upgraded portable 950keV X-band(9.3GHz) linac X-ray sources for on-site nondestructive testing. We successfully performed on-site inspection by the 950keV system some times, namely internal part of distillation tower, reinforced concrete pier and other.

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It is mentioned more critically that the source location of a damage initiation is often considered as the main goal of acoustic emission technique. Principally, AE technique is applying for finding the damage source by getting the time delay of AE signal propagations. AE sensors are used in the system based on calculating linear source location algorithms. In the present research a ductile cast iron specimen has been used for monitoring its damage characteristics in fatigue loading failure. AE sensors have been kept attached to the specimen until its complete damage by crack developments. Before applying the technique, several proof of concept test of pencil lead breaks(PLBs) have been conducted. According to the PLBs verifying data, the failure location of ductile cast iron (pearlite type) by the fatigue loading has been characterized. In both cases, the source location of structural damage have been successfully identified.

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Damage characteristics of pearlite ductile cast iron due to fatigue crack have been investigated by acoustic emission (AE) technique. As perlite type spheroidal graphite cast iron has high strength as well as excellent workability and damping capacity, it has been widely used as automobile and many other machine parts. However, the damage initiation and propagation of this type of this type of spheroidal graphite cast iron might depend not only on the graphite size but also on the distribution of the graphite cast nodules. Therefore, the cracks are initiated from the larger or coarser graphite nodules. In this study, the failures of pearlite ductile cast iron caused by cracks and micro-cracks have been investigated sequentially by AE technique as a non-detective evaluated and characterized by analyzing AE parametric investigations and found remarkable results as well.

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The thermal and nuclear power plants have been imposed a stable supply of electricity. To certainly achieve this, we built the plant condition monitoring system based on the heat and mass balance calculation. If there are some performance changes on the turbine system components of their power plants, the heat and mass balance of the turbine system will change. This system has ability to detect the abnormal signs of their components by finding the changes of the heat and mass balance. Moreover it helps operators understand problem situation.

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Needless to say, various rotational machines support today's industry. It follows that maintenance of these machines is extremely important to ensure their performance. Maintenance keeps facilities or machines able to operate, and can be defined as measures to restore a trouble or a fault. Maintenance is broadly divided into the two categories breakdown maintenance and preventive maintenance. In the case of breakdown maintenance, machines are fixed after the occurrence of troubles, so machines unpredictably stop operating. On the other hand, preventive maintenance is like car inspection; that machines are overhauled at intervals in according to a prescribed schedule. However, in breakdown maintenance it may be necessary to change parts which have not broken yet but are expected to break with time. Therefore, preventive maintenance is costly, but can result in cost saving. In contrast, recently a condition monitoring maintenance method has been adopted as preventive maintenance, in which inspection and repair are determined by monitoring machine condition. Such maintenance can allow machines to continue operation and save maintenance cost. ISO watching vibration as condition monitoring is widely applied to various rotational machines (motors, pumps, etc.). In this standard, we judge velocity of machine vibrations while the machine is driven according to a standard corresponding to the size of the machine. However, when the operational situation prevents rigid fixation of a machine to the ground, the machine is flexibly fixed. As a result, the machine vibration is higher amplitude than that of a machine that is rigidly fixed, and application of the existing evaluation standard becomes difficult. Therefore, the evaluation standard is relaxed for some machines. This study proposes new criterion that consider for stiffness and damping of a flexible support base that contains springs or rubber sheets. In this study we prepare an experimental system of one disk rotor that is supported by ball bearings at both ends, and compare vibration with a flexible support base and that with a rigid support base, by simulation and experiment.

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This study aims at quantifying malfunctioning in the reciprocating compressor and establishing a new monitoring technique. We proposed a mathematical model (eleven degrees of freedom) in which deterioration and damage are expressed by changing model parameters. In addition, we can elucidate the cause of the resonance peak that occurs during operation by examining the frequency characteristics of the reciprocating compressor and the natural vibration characteristics by the use of numerical analysis. Then, we perform parameter identification using the natural frequency characteristics and examine the model parameter estimation method, which uses the relationship between the natural frequency characteristics and the frequency characteristics during operation. As a result, it was confirmed that the estimation method enables to express vibration characteristics using the error function about the natural frequency characteristics. In addition, it was possible to estimate the vibration characteristics by using the proposed model.

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