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.