scholarly journals Active Control of Rotor Vibrations by Means of Piezoelectric Actuators

2001 ◽  
Author(s):  
Costantino Carmignani ◽  
Paola Forte ◽  
Emiliano Rustighi
Keyword(s):  
Active Control ◽  
Piezoelectric Actuators ◽  
Mobile Bearing ◽  
Numerical Results ◽  
Hydrodynamic Bearing ◽  
Harmonic Displacement

Abstract This work deals with the development of an adaptive hydrodynamic bearing made of a mobile housing mounted on piezoelectric actuators. The device is placed near one of the two bearings supporting a slender shaft. Imposing a harmonic displacement on the mobile bearing, in two orthogonal directions, a rotating force, and hence a correcting moment, can be produced on the shaft so as to reduce the bending caused by the unbalance. The first tests carried out are encouraging and the agreement of experimental and numerical results is satisfactory.

Active Control of Elastodynamic Vibrations of a Flexible Mechanism With Piezoelectric Actuator

1999 ◽  
Author(s):  
Ching-I Chen
Keyword(s):  
Control Theory ◽  
Active Control ◽  
Piezoelectric Actuator ◽  
Control Strategies ◽  
Piezoelectric Actuators ◽  
Structural Vibration ◽  
Control Technique ◽  
Vibration Modes ◽  
Time Sharing ◽  
Transient Dynamic

Abstract This study focused on the application of active vibration control strategies for flexible moving structures which degrade into transient dynamic vibration problem. These control strategies are based primarily on modal control methods in which the flexible moving structures are controlled by reducing their dominant vibration modes. This work numerically investigated active control of the elastodynamic response of a four-bar mechanical system, using a piezoelectric actuator. A controller based on the modified independent modal space control theory was also utilized. This control theory produced overall excellent performance in terms of achieving the desired closed-loop structural damping. The merits of this technique include its ability to manage the spill-over effect, i.e. eliminate the magnitude of vibrations associated with uncontrolled modes, using only a few selected modes for control. This control was accomplished using a time sharing technique, which reduces the number of piezoelectric actuators required to control a large number of vibration modes. Furthermore, this algorithm implements a procedure for determining the optimal locations for the piezoelectric actuators. The dynamics of a steel four-bar linkage was selected with a flexible coupler separated by six elements and one piezoelectric actuator was used in the numerical simulation. The optimal actuator position was located at the third element from the right to the left. Results in this study demonstrated that a highly desired the structural vibration damping could be achieved. This control technique can be applied to transient dynamic systems.

Subharmonic and Chaotic Motions of a Hybrid Squeeze-Film Damper-Mounted Rigid Rotor With Active Control

2002 ◽  
Vol 124 (2) ◽  
pp. 198-208 ◽  
Author(s):  
Chieh-Li Chen ◽  
Her-Terng Yau ◽  
Yunhua Li
Keyword(s):  
Lyapunov Exponent ◽  
Active Control ◽  
Chaotic Motion ◽  
Numerical Results ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Maximum Lyapunov Exponent ◽  
Rigid Rotor ◽  
Squeeze Film Damper

The hybrid squeeze-film damper bearing with active control is proposed in this paper. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. A PD (proportional-plus-derivative) controller is used to stabilize the rotor-bearing system. Numerical results show that, due to the nonlinear factors of oil film force, the trajectory of the rotor demonstrates a complex dynamics with rotational speed ratio s. Poincare´ maps, bifurcation diagrams, and power spectra are used to analyze the behavior of the rotor trajectory in the horizontal and vertical directions under different operating conditions. The maximum Lyapunov exponent and fractal dimension concepts are used to determine if the system is in a state of chaotic motion. Numerical results show that the maximum Lyapunov exponent of this system is positive and the dimension of the rotor trajectory is fractal at the nondimensional speed ratio s=3.0, which indicate that the rotor trajectory is chaotic under such operation condition. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain is applied to control this system. It is shown that the rotor trajectory will leave chaotic motion to periodic motion in the steady state under control action.

Characterization and Mathematical Modelling of Geometric Effects on Piezoelectric Actuators

2019 ◽  
Vol 201 (1) ◽  
pp. 201-217
Author(s):  
Hareem Jawaid ◽  
Waqar Ahmed Qureshi ◽  
Riffat Asim Pasha ◽  
Rizwan Ahmed Malik
Keyword(s):  
Mathematical Model ◽  
Structural Analysis ◽  
Mathematical Modelling ◽  
Piezoelectric Actuator ◽  
Piezoelectric Actuators ◽  
Numerical Results ◽  
Hydraulic Valves ◽  
Geometric Effects

This paper focuses on the characterization and static structural analysis of piezoelectric actuator to investigate the sequential increasing effect of piezoelectric patches. The effect on the tip deflection is observed analytically, numerically and experimentally. By varying the quantity and the geometry of piezoelectric patches/beams, the actuation effect is analyzed. A mathematical model has been developed for the unequal lengths of patches and beam. The analysis is carried out numerically to examine the tip deflection under various parameters. The results are analyzed and verified experimentally. The results are found to be in accordance with the analytical and numerical results. This permits the desired configuration of an actuator in applications like hydraulic valves for actuating and controlling the flow of liquid as per need.

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