Piezoelectric Sensor of Mechanical Vibrations

Abstract

Creation of high-sensitive sensor of mechanical vibrations, capable of non-distorted transformation of the vibrations source energy into electric signal within a wide dynamic range, is necessary for determination of characteristics of the source as well as for obtaining the information on parameters of medium in which the vibrations propagate. Fast and successful usage of obtained data can be achieved with employment of programming algorithms of identification of type of a source of vibrations and finding their fundamental Eigen frequencies and quality factors of the structures at these frequencies. Calculations of the schematic-and-technical decisions, selection of elements, making of mock-ups, and working-out of variants of the sensor. Mathematical modeling, analysis and identification of dynamical parameters of the structures in which there are used the fundamental eigenfrequencies and the structures’ quality factors at these frequencies. The Fourier and wavelet analyses of the spectra. Algorythms of digital filtering (moving average of measured data). Sensors of mechanical vibrations and a system for collection, analysis, and digital processing of the output data arrays are created. New effective method for analysis of conditions of natural and artificial objects is suggested. Algorythm for identification of type of mechanical vibrations source is developed. Transducers of mechanical vibrations are developed using film-based piezoelectric sensors of new generation. System for storing and processing of the sensors’ output data arrays is developed and a technique for transferring and saving the information is formulated. Structural parameters such as fundamental eigenfrequencies and the structures’ quality factors at corresponding frequencies are applied for identification of conditions of natural and engineering objects. Methodology for expertise of both the natural-based (wind) and the test-pulses-assisted dynamical loading is developed. Sets of single-type sub-models suitable for modeling, by their superposition, of the whole process are considered, and optimal sets of the model’s free parameters are determined. Degree of the model’s closeness to data obtained within a selected metrics serves as a criterion of optimality. Algorithm for identification of type of a mechanical vibrations’ source is developed basing on the signals representation as wavelets. The sensor-measured total signal includes wavelets from multiple sources and, because of this, the task of separation of the aggregated signal into constituents is accomplished. To achieve this, regularities within the signal should be found which might be interpreted as wavelet. Enumeration of the wavelets is determined with excess; the algorithm employs rules in accordance with which the enumeration and wavelets parameters are selected with more accuracy, and connection of wavelets with certain vibration sources is specified. Performance of the proposed sensor is fully confirmed by experimental data. Successful tests targeted at determination of technical characteristics of the sensor of mechanical vibrations are conducted within a passive survey system of stationary security installation. Seismograms of an approaching pedestrian are obtained for the distance of 30 m. Characteristics of the piezoelectric sensor of mechanical vibrations make it possible a plenty of applications of technical decisions, laid into its basis, in various spheres of science and technology.