Active vibration control of plate-like structures with discontinuities and discontinuous boundary conditions

The motivation of this dissertation involves the application of methods to actively control the vibrations on an experiment rack shelf similar to those in use on the International Space Station (ISS). The initial goal of the research described in this work is to control the vibration of a simulated rack shelf that is constructed from a solid aluminum rectangular plate bolted along segments of the short sides and free on the long sides. Once the structural vibration and control issues related to this uniform simulator have been addressed, the control system development will be extended to the more realistic experiment rack shelf like that used on the ISS. The primary contributions of this dissertation include advances to vibration modeling and control of structures with discontinuous boundary conditions as well as the development and study of a new method for controlling discontinuous structures using piezoelectric actuators.; In this work the control model is set up using analytical method as well as experimental method. Two control strategies, collocated output feedback control and modal control, are designed based on the control model. A dSPACE system is used to develop a rapid control prototype. Based on the experimental results, the two control strategies are shown to be effective in controlling the first several modes of the rack shelf system at frequencies below 800Hz. The second goal of this work is to study the modeling and control of a shelf more similar to that used on the space station. The shelf structure is uniform on the top side and discontinuous on the bottom side. As an initial step, a one-dimensional beam structure with rib discontinuities is investigated. Instead of being bonded on the uniform side of the beam, the actuator is placed on the discontinuous side spanning two adjacent rib discontinuities. Through numerical examples, the characteristics of the voltage-generated piezoelectric forces are examined in both the frequency domain and the time domain. The numerical study shows that when the actuator spans two discontinuities, there is potential for greater control authority than when that same actuator is placed on the uniform side of the structure.