Analysis of Central Pivotal Load Effect on Circular Piezoelectric Unimorph Sensor

The piezo-electric unimorphs are used in most of oscillating systems and devices. The functional properties of unimorphs are dependent on geometry, materials used and mounting design. The dimensions and shape of unimorphs are usually calculated for usage application and are optimized using finite element method. This paper presents finite element analysis of a circular unimorph with the piezoelectric layer having diameter smaller than the elastic layer diameter. The unimorph is fixed on aluminum disc having cavity at the center to support edge of sensor. Electromechanical response of circular piezoelectric unimorph sensor with fixed edge under varying central pivotal load (up to 150 mN) is analyzed. It is observed that voltage sensitivity of unimorph sensor increases with increase in load and have decaying trend instead of flat response when pivotal load is introduced. Furthermore, a nonlinearity is introduced in the response curve at lower frequencies which shifts towards higher frequencies when pivotal load is increased increasing pivotal load beyond 100 mN results in shifting of nonlinearity outside frequency band of interest ie up to 10 kHz.