Selection of the geometric and materials parameters in piezoelectric sensors level

In the last years, smart materials are often used in industry equipment. Examples of smart materials are piezoelectric plates, widely used for elimination of vibrations in mechanical systems. They have large forces and small displacements and they also have the ability to change shape upon the application of power to the surface of the piezoelectric. Articles about piezoelectric systems are often presented [1-4, 6], but still there is not mathematical model containing both the elastic properties, piezoelectric and dielectric properties of piezoelectric working in sensor levels. Such analysis is very important for correctly design of geometrical and materials parameters of this sensors. Development of methods for the analysis of simple systems with different conditions of piezoelectric fix is important for determination of piezoelectric plate characteristics. The main industry object of this article is piezoelectric level sensors which detect the level of liquids, fluids or solids including powders. This kind on sensor is just on-off sensor it is means that it can detect when the forks of the sensor are covered or free. The work is only part of the mathematical analysis of piezoelectric level sensors. It was made together with a representative of the industry in order to facilitate the selection of electric parameters of signal generator for level sensor. Until now, the company where sensors were produced has to manual tune the frequency of the generator so that the vibration fork of sensor were correct. Currently, using the derived mathematical formula by authors, a direct assessment of the resonant frequency of a fork, taking into account the number of platelets in the stack as well as the material of which are made are possible. This paper indicates solution engineering problem which is the choice of parameters of piezoelectric plates by using scientific methods of mathematical description.