On the Use of Finite Element Codes for Structures with Passive Piezoceramic Devices

Limiting structural response by increasing damping with passive devices it is attractive because these elements, even if they fail to work properly, will never introduce mechanical energy into the structure. Thus although active control results more efficient, nevertheless possible malfunction of the control system or the changed properties of mechanical components, during lifetime, may cause the control system itself to trouble the structure dynamics. That is especially true in space, where external operations are difficult or even impossible and the system must work for lifetimes of years in the space environment (radiations, space debris, etc.). In this paper piezoceramic materials, suitably loaded with either resistors or resistors and inductors, are considered. The similarity of the piezo device complex stiffness with the ones used for viscoelastic material models allows one to simulate, with relative ease, the behaviour of a structure equipped with passive piezo devices by the use of general purpose finite element codes. Finite element models of a beam and one model of a plate are considered as test cases. Estimations of the damping coefficients, introduced by the passive devices, are in excellent agreement in the different models of the beam considered and are consistent in the case of the plate.