The very low frequency primary vibration calibration system in Taiwan has been improved. In order to provide local semiconductor foundry a more reliable way to calibrate the MEMS accelerometer, three kinds of accelerometers that are ADXL, PCB 356A15 and QA3000 were tested via such vibration calibration system. Unlike PCB 356A15 and QA3000, the MEMS type accelerometer, ADXL, was only performed well under 100 Hz. All the three kinds of accelerometers were connected to NI wireless modules in order to reduce the inconvenience of wires during vibration monitoring. The result suggests that we...
It is an important means for determining the conditions and making fault analysis of the aero-engine by measuring its vibration. Because the different features give different analysis results for vibration fault, in order to integration these information, the results of the different Back Propagation (BP) neural networks were fused by applying the Dempster-Shafer (D-S) evidential theory of the information fusion and the basic belief assignment function was established according to the statistical parameters of the networks. The analysis results from the aero-engine vibration signals show...
Three-axis MEMS accelerometers are typically characterized in terms of their cross-sensitivity matrix. We present an analysis and protocol to characterize them in terms of their intrinsic properties, which we define as the responsivity of each accelerometer along its axis of maximum response in a gravitational field and the angles between each of these axes. An analysis and test protocol is developed to determine these properties using a gimbal to rotate each axis of the device orthogonally to the gravitational field. We propose that this approach is better suited for laboratory...
Focus of the paper is to propose a simpler and intuitive parameter for monitoring and possibly detecting incoming failure conditions of rotating machinery or its components during their stationary operation and subject to misalignment of the rotor (due to increasing eccentricities, uneven mass distribution, propagating cracks, etc.). Such a parameter, which can be considered as a damage index, is obtained by processing the vibration signals acquired from static supporting elements of the machinery. In order to show the feasibility of the idea, the authors performed a series of measurements...
Following, and in addition to several papers, exercises and thorough research concerning the topic of primary calibration of back-to-back vibration transducers in the frequency range > 5 kHz, this paper aims to raise the question if the conventional method using slotted mass, is mandatory when using modern commercial calibration standard vibration exciters in fully optimized system setup.
Phase response is a key performance parameter of vibration transducers, which is usually measured by the primary calibration. The typical primary calibration method used analog mixer and lowpass filter to modulate heterodyne laser interferometer signal. There is some time delay caused by the analog devices, which will introduce some phase delay for the measurement of phase response of transducers. This paper proposed a novel time delay measurement method of the analog devices based on high definition oscilloscope (HDO) and phase unwrapping sine approximation method (PUSAM).
Multi-exciter vibration systems provides access to simultaneous multicomponent calibration of motion transducers. Vibration control is an essential prerequisite to generate accurate spatial orbit motion for transducer calibration. Relationship of shapes and orientations of spatial orbits and amplitudes and phases of acceleration components is discussed. Multi-exciter vibration control for both cross-coupling compensation and amplitudes and phases control of acceleration components is investigated. The experimental results show that the proposed control method can efficiently reduce...
This paper describes how to calibrate accelerometers in a temperature range from -55 °C to +100 °C. Compared earlier solutions the suggested approach is able to cover the wide frequency range 10 Hz to 10 kHz and the temperature range -55 °C to 100 °C while the calibration is still traceable.
A study is presented in this paper able to identify and to quantify the effects of sensor characteristics and of data processing aspects on the uncertainty of the features used for Condition Monitoring (CM) applications, based on a hybrid approach. The precision of the sensors and the modalities to perform the FFT and obtain the related features are evaluated, to improve the coherence of information deriving from the data obtained by means of a physics-based model and that gained from the experiments. Validation of the features related to both classes is expected to improve the fusion...