چكيده به لاتين
This study aims to improve Sound Transmission Loss (STL) in aircraft structure designed as doubly curved shells, using a robust piezoelectric H_∞ controller. The aircraft shell is made of aluminum with two piezoelectric patches (PZT-5H) as a sensor and actuator that are attached to the shell. The first order shear deformation theory is used to model the shell while considering piezoelectric constitutive equations, establishing four sources of uncertainty: temperature, Mach number, elevation angle, and azimuth angle, which impact the acoustic characteristics of the aircraft system. Hamilton's principle is used to derive the equations of motion representing the shell displacements, acoustic pressure, and electric displacement. Simulations indicate the existence of the effects of the uncertainties on both the shell response and the piezoelectric patches. The Genetic Algorithm is employed to optimize the positions of the piezoelectric actuator and sensor to enhance controller controllability and observability while preventing control spillover. A generalized plant is formulated to establish the H_∞ controller for acoustic insulation improvement. Performance weights include a low-pass filter for shell response, a pass-band filter for actuator signals, and a band-stop filter for disturbance signals are established to enhance performance. The closed loop results show improvement in STL and transverse displacement respectively. Thus, the proposed control system shows a high authority up to three natural bending frequencies. The system also shows high stability and performance characteristics. This study, for the first time, provides a comprehensive investigation into enhancing the acoustic characteristics of aircraft structures under uncertainty conditions.
