Atenuação de vibrações em pás de helicópteros utilizando circuito piezelétrico semi-passivo

Abstract

The use of smart materials in vibration control problems has been investigated in several researches over the last years. Although di erent smart materials are available, the piezoelectric one has received great attention due to ease of use as sensors, actuators, or both. The main control techniques using piezoelectric materials are the active and passive ones. Passive piezoelectric networks are adjusted for speci c target frequencies and, therefore, the e ective bandwidth of such systems is small. Although active systems can achieve good vibration control performance, the amount of external power and added hardware are important issues. The synchronized switch damping (SSD) technique was developed in order to address the issues of passive damping methodologies as well as the issues of active control systems. The SSD can be classi ed as semi-passive technique or semi-active technique that introduce the nonlinear treatment of the piezoelectric element voltage output and induce an increase in mechanical to electrical energy conversion and, consequently, the shunt damping e ect. In this work, the semi-passive piezoelectric control of a rotating cantilever beam response is presented and compared with other controllers. The nonlinear electromechanical model of a rotating beam with embedded piezoceramics is derived based on the variational-asymptotic method (VAM). The coupled non-linear rotary system is solved in the time-domain by using a generalized-alpha integration method in order to guarantee numerical stability. The simulations are performed for a wide range of rotating speeds. First, a set of load resistances (ranging from short circuit condition to open circuit condition) is considered. The e ect of optimum load resistance (for maximum damping) on the elastic behavior of the beam is investigated for increasing rotating speed. Later, the synchronized switch damping on short (SSDS) technique is employed to damp the nonlinear oscillations of the rotating beam with increasing rotating speed. Results show that the SSDS technique can be a useful method of control for nonlinear rotating beams such as helicopter blades.

Aplicação de transdutores piezoelétricos para o controle da instabilidade de whirl-flutter

“…Os materiais inteligentes são aqueles possuem a capacidade de ativar suas funções de forma intrínseca e extrínseca a partir de respostas aos estímulos ou mudanças ambientais [1]. Outra forma de definição é a apresentada por [2] na qual se afirma que os materiais inteligentes são aqueles que apresentam acoplamentos entre diversos domínios físicos. Pode-se dizer que um material possui acoplamento quando a mudança de uma variável de estado de um determinado domínio físico engendra uma mudança em outra variável de estado de outro domínio físico.…”

“…Pode-se dizer que um material possui acoplamento quando a mudança de uma variável de estado de um determinado domínio físico engendra uma mudança em outra variável de estado de outro domínio físico. No caso, da presente pesquisa, foca-se nos materiais do tipo piezoelétrico que são aqueles que possuem o acoplamento entre os domínios elétrico e mecânico [2].…”