Distributed Modal Identification and Vibration Control of Continua: Theory and Applications

1991 ◽  
Vol 113 (3) ◽  
pp. 494-499 ◽  
Author(s):  
H. S. Tzou

Conventional transducers and actuators are “discrete” in nature, i.e., they usually measure and control spatially discrete locations. These discrete devices become useless when they are placed at modal nodes or lines. In this paper, a generic “distributed” modal identification and vibration control theory for sensing and control of continua, e.g., shells, plates, cylinders, beams, etc., is proposed. The generic theory is derived for a thin shell coupled with two electroded piezoelectric layers. One piezoelectric layer serves as a distributed sensor and the other a distributed actuator. The sensor output, or a reference signal, is processed, amplified, and fed back into the distributed actuator. Due to the converse effect, the injected high voltage induces in-plane strains which result in counteracting moments used to suppress the shell oscillation. System dynamic equations and state equations are also derived. The theory shows that the distributed sensor can identify all vibration modes and the distributed actuators also control all modes. Simplification of the generic theory to other geometries is also demonstrated.

1991 ◽  
Vol 113 (3) ◽  
pp. 500-505 ◽  
Author(s):  
H. S. Tzou ◽  
C. I. Tseng

“Smart” continua with integrated sensor/actuator for structural identification and control have drawn much attention in recent years due to the rapid development of high-performance “smart” structures. The continua are distributed and flexible in nature. Thus, distributed dynamic measurement and active vibration control are of importance to their high-demanding performance. In this paper, continua (shells or plates) integrated with distributed piezoelectric sensors and actuators are studied using a finite element technique. A new piezoelectric finite element with internal degrees of freedom is derived. Two control algorithms, namely, constant gain feedback control and Lyapunov control, are implemented. Structural identification and control of a plate model with distributed piezoelectric sensor/actuator is studied. Distributed modal voltage and control effectiveness of mono and biaxially polarized piezoelectric actuators are evaluated.


Author(s):  
Aliakbar Bayat ◽  
Amir Jalali ◽  
Habib Ahmadi

In this study, the nonlinear vibration control of functionally graded laminated piezoelectric cylindrical shells under simultaneous parametric axial and radial external excitations is presented. The partial differential equations of shells are derived based on Hamilton’s principle, first-order shear deformation theory (FSDT), and nonlinear von Karman relations. The coupled nonlinear ordinary differential equations are obtained by Galerkin’s procedure and solved by the method of static condensation. Two piezoelectric layers are placed on the outer and inner surfaces of the cylindrical shell each as distributed sensor and actuator. Then the constant-gain negative velocity feedback strategy is employed. Regarding the nonlinear equations of motion, for the first time, the vibration analysis and active vibration control of smart FG cylindrical shells under combined parametric and external excitations are analyzed using the multiple scales approach. The effects of various parameters such as power index, external excitation’s amplitude, and control gain on the dynamic behavior of the system are investigated, using bifurcation diagrams, phase portraits, time histories, and Poincare maps. It is shown that quasi-periodic motion is the most common behavior of the system and controller gain and power index have inevitable effects on enhancing the quasi-periodic response of the system. Care should be exerted in selecting the parameters to have the desired response in the broad range of excitation frequency.


Author(s):  
Tsunehiro Wakasugi ◽  
Toru Watanabe ◽  
Kazuto Seto

This paper deals with a new system design method for motion and vibration control of a three-dimensional flexible shaking table. An integrated modeling and controller design procedure for flexible shaking table system is presented. An experimental three-dimensional shaking table is built. “Reduced-Order Physical Model” procedure is adopted. A state equation system model is composed and a feedback controller is designed by applying LQI control law to achieve simultaneous motion and vibration control. Adding a feedforward, two-degree-of-freedom control system is designed. Computer simulations and control experiments are carried out and the effectiveness of the presented procedure is investigated. The robustness of the system is also investigated.


2020 ◽  
Vol 20 (08) ◽  
pp. 2050095
Author(s):  
Yifan Lu ◽  
Qi Shao ◽  
Fei Yang ◽  
Honghao Yue ◽  
Rongqiang Liu

Different kinds of membrane structures have been proposed for future space exploration and earth observation. However, due to the low stiffness, high flexibility, and low damping properties, membrane structures are likely to generate large-amplitude (compared to the thickness) vibrations, which may lead to the degradation of their working performance. In this work, the governing equations are established at first, taking into account the modal control force induced by the polyvinylidene fluoride (PVDF) actuator. The optimal vibration control of the membrane structure is explored subsequently. A square PVDF actuator is attached on the membrane to achieve the vibration suppression. The influence of actuator position and control gains on the vibration control performance are studied. The optimal criteria for actuator placement and energy allocation are developed. Several case studies are numerically simulated to demonstrate the validity of the proposed optimization criteria. The analytical results in this study can serve as guidelines for optimal vibration control of membrane structures. Additionally, the proposed optimization criteria can be applied to active control of different flexible structures.


2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Tingrui Liu

Vibration control of the blade section of a wind turbine is investigated based on the sliding mode proportional-integral (SM-PI) method, i.e., sliding mode control (SMC) based on a PI controller. The structure is modeled as a 2D pretwisted blade section integrated with calculation of structural damping, which is subjected to flap/lead-lag vibrations of instability. To facilitate the hardware implementation of the control algorithm, the SM-PI method is applied to realize tracking for limited displacements and velocities. The SM-PI algorithm is a novel SMC algorithm based on the nominal model. It combines the effectiveness of the sliding mode algorithm for disturbance control and the stability of PID control for practical engineering application. The SM-PI design and stability analysis are discussed, with superiority and robustness and convergency control demonstrated. An experimental platform based on human-computer interaction using OPC technology is implemented, with position tracking for displacement and control input signal illustrated. The platform verifies the feasibility and effectiveness of the SM-PI algorithm in solving practical engineering problems, with online tuning of PI parameters realized by applying OPC technology.


AIAA Journal ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 118-127 ◽  
Author(s):  
Nebojsa Sebastijanovic ◽  
Tianwei Ma ◽  
Henry T. Y. Yang

Aerospace ◽  
2003 ◽  
Author(s):  
W. K. Chai ◽  
H. S. Tzou ◽  
S. M. Arnold

Certain ferroelectric materials possess dual electrostrictive and piezoelectric characteristics, depending on their specific Curie temperatures. These materials exhibit piezoelectric characteristics in the ferroelectric phase when the temperature is below the Curie point. However, they become electrostrictive in the paraelectric phase (non-polar phase) as the temperature exceeds the Curie point. The (direct) electrostrictive effect is a quadratic dependence of stress or strain on applied electric field. The nonlinear electromechanical effect of electrostrictive materials provides stronger actuation performance as compared with that of piezoelectric materials. Due to the complexity of the generic ferroelectric actuators, micro-electromechanics and control characteristics of generic electrostrictive/piezoelectric dynamics system deserve an in-depth investigation. In this study, electro-mechanical dynamic system equations and generic boundary conditions of hybrid electrostrictive/piezoelectric double-curvature shell continua are derived using the energy-based Hamilton’s principle, elasticity theory, electrostrictive/piezoelectric constitutive relations, and Gibb’s free energy function. Moreover, the second converse electrostrictive effect and the direct piezoelectric effect are all considered in the generic governing equations. Simplifications of the generic theory to other common geometries or specific materials are demonstrated and their electromechanical characteristics are also evaluated.


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