A new solution for the determination of the generalized couplingcoefficient for piezoelectric systems

Recently, novel damping devices based on shunted piezoceramics have been investigated. Piezoceramics are therefore embedded into the mechanical structure and convert some part of the kinetic vibration energy into electrical energy. Subsequently, this energy is dissipated in the electrical network that is connected at the electrodes of the piezoceramics. The network is designed with the aim to maximize the dissipation, which results in a damping effect on the mechanical system. Alternatively, the converted energy can be stored and utilized to power electronic devices like sensors for health monitoring, called Energy Harvesting. In both cases, the converted energy and the damping performance depend on the so called generalized electromechanical coupling coefficient K. It is therefore crucial to maximize this factor. Besider the piezoelectric material properties, the coupling coefficient also depends on the vibration mode of the piezoceramics. Only for a constant mechanical strain distribution in the whole volume the generalized coupling coefficient K is equal to the material coupling k. In all other cases, K is smaller than k. This publication presents a general derivation of the generalized coupling coefficient K for an arbitrary, uniaxial deformation of the piezoceramics, which is based on the potential energy stored in the piezoceramics. The general result is applied to a piezoelectric bending bimorph and verified by a finite element model.