Modal Analysis and Vibration Control of Smart Hull Structure in Underwater

Many research works have been conducted to investigate active vibration control of underwater structure using piezoelectric materials for the possible applications in the underwater vehicles and seashore structures. Recently, advanced anisotropic piezoceramic actuator named as Macro Fiber Composite (MFC) was developed in NASA Langley Research Center. MFC actuator is consisting of rectangular piezoceramic fibers and interdigitated electrode, which can provide great flexibility, large induced strain and directional actuating force. In this paper, vibration control performance of underwater smart hull structure with MFC actuator is evaluated. As a first step, dynamic modeling of underwater hull structure is conducted by using finite element technique and then modal characteristics of hull structure are investigated. For the verification of the proposed finite element model, numerical results of modal analysis are compared with those of experimental modal test results. In order to evaluate vibration control performance, linear quadratic Gaussian (LQG) controller is designed and experimentally implemented to the system. Control responses are evaluated in the water tank and presented in both time and frequency domain.