Shaped Actuators and Sensors for Local Control of Intelligent Structures.
Abstract:
The properties of the actuator to sensor transfer functions for various shaped strain actuator-sensor pairs on a Bernoulli-Euler beam are investigated. Analytical expressions for these transfer functions and their associated dereverberated transfer functions are derived. It is shown that the actuator-sensor pair can be designed such that its dereverberated transfer function will have a desirable corner frequency and high frequency rolloff rate. The analytical and dereverberated transfer functions of noncollocated actuator-sensor pairs are compared to those of the collocated pairs. General rules are found which determine the frequency at which the transfer function no longer has an interlaced pole-zero pattern. Finite element models are constructed which add damping, finite actuator thickness, and finite beam and actuator widths to the model. The actuator to sensor transfer functions are calculated for these models, and the effects of the added factors are determined. It is shown that the transverse bending modes of the three dimensional beam delay the rolloff of the actuator to sensor frequency transfer function by at least two decades. Finally, experimental data confirms the results of the three dimensional finite element model.