RESEARCH OF ELECTROMECHANICAL TRANSDUCER’S FASTENING INFLUENCE TO THE ACCELERATION PIEZOSENSOR’S CHARACTERISTICS

Abstract

The research is carried out to obtain data necessary to improve calculation accuracy and for construction optimization in piezosensors of mechanical values. These sensors are widely used for control, monitoring and diagnostics of complex equipment and engineering structures. The task of the research is to study the features of working deformations in electromechanical piezotransducer in area of fastening to sensor base and to estimate their influence to the main metrological characteristics. The object of the research is electromechanical transducer in the form of cylindrical monolithic block made of piezoelectric ceramics with height-to-diameter ratio 0.33 to 2. This transducer is fixed on the sensor’s base which is affected by progressive acceleration of vibration oscillations from the controlled object. Using the ANSYS Multiphysics softwarepackage a mathematical model of the transducer with two fundamentally different types of fastening  “free sliding” and “rigid”  has been investigated. At the same time the mechanism of transverse mechanical shunting of transducer’s deformation in limit region of the rigid fastening was revealed. “Fastening effect coefficient” and its determination formula for various transducer’s height-to-diameter ratios are proposed for quantitative estimate of fastening conditions influence to transducer’s characteristics. Taking into account the properties of structural materials used in practice and the most frequently used elastic compression of elements a method was developed and experimental studies were carried out to determine the effect of transducer’s fastening in real sensor designs. It was found that base material properties and transducer dimensions ratio in real sensor design can cause changes in voltage conversion coefficient up to 15%, the charge conversion coefficient up to 22%, electric capacity up to 9% and longitudinal resonance frequency up to 16%. The influence of boundary fastening conditions decreases simultaneously with the increase of transducer’s relative height. The calculating data were obtained experimentally for the fastening effect coefficient when making the sensor’s base of metals with elastic modulus of 74300 GPa and density of 270017700 kg/m3. The results of research carried out can be taken into account when designing piezosensors of mechanical values.