Implementation of multi-layer active structural-acoustic transmission control

Abstract

Structural-acoustic vibration is one of the major sources of payload failure during launch. Past research on the topic of structural-acoustic vibration control has focused on actuating a single structural layer to minimize the amount of energy flowing across the boundary. This thesis investigates the use of a dual layer approach to address the structural-acoustic problem and compares the results to a single layer approach.Four different controller configurations were used to experimentally determine which configuration is best suited for multi-layer transmission control. The four controller configurations were the Multi-Input Multi-Output (MIMO) Controller, the Successive Loop Closure (SLC) Controller, the Interference Controller and the Power Diode Controller. The MIMO Controller used a single state-space controller to actively control the two active plates, while the other three configurations used a single controller to actively control each plate. The SLC Controller and the Interference Controller are different because the design order of the two plate controllers for the Interference Controller is reversed compared to the SLC Controller. The Power Diode Controller implements a power diode on one of the two structural plates. The power diode is designed to attenuate acoustic transmission across the plate in one direction only as compared to typical controllers that attenuate acoustic transmission across the plate in both directions.Although the four controller configurations were different, they shared a common goal-to minimize the system's response over the 40-1000 Hz broadband frequency region. The SLC Controller performed the best by posting a 2.08 dB reduction across the broadband region, compared to a 1.06 dB reduction posted by the worst performing controller. These reductions only refer to the differences in open and closed loop performances of the dual layer configuration. Compared to a passive single layer system with the same thickness as the two separate layers combined, the SLC Controller posted a 3.02 dB reduction for the broadband metric.