Semi Active Vibration Control Using Piezoelectric Based Switched Stiffness

“Piezoelectric-Based Vibration-control Systems: Applications in Micro/Nano Sensors and Actuators” covers: Fundamental concepts in smart (active) materials including piezoelectric and piezoceramics, magnetostrictive, shape-memory materials, and electro/magneto-rheological fluids; Physical principles and constitutive models of piezoelectric materials; Piezoelectric sensors and actuators; Fundamental concepts in mechanical vibration analysis and control with emphasis on distributed-parameters and vibration-control systems; and Recent advances in piezoelectric-based microelectromechanical and nanoelectromechanical systems design and implementation.

Semi-active vibration reduction techniques switch a piezoelectric transducer between an open circuit and a shunt circuit in a way that reduces vibration. The steady-state vibration amplitude is reduced by exploiting the change in stiffness between states, manipulating the converted electrical energy, or both. Semi-active techniques typically require four switches per vibration cycle. Control laws such as state switching and synchronized switch damping require switches to occur at every displacement extrema. Due to the complexity of analyzing a system with discrete switches, these control laws were developed based on intuition. The few analyses that attempt to determine an optimal switching law mathematically only evaluate the system at resonance. This thesis investigates the effects of switch timing on vibration reduction and the frequency dependence of the optimal switch timing control law. Regardless of the switch timing, sensing uncertainties, noise, and modeling errors can cause the switches to occur away from the designed moment. Thus, this work also quantifies the expected degradation in vibration reduction performance due to variations in the designed switch time. Experimental, numerical, and analytical solutions agree that the optimal switch timing of these semi-active techniques depends on frequency. A closed-form solution for the optimal switch timing is derived in terms of well-known, non-dimensional parameters.

Vibrations are a part of our environment and daily life. Many of them are useful and are needed for many purposes, one of the best example being the hearing system. Nevertheless, vibrations are often undesirable and have to be suppressed or reduced, as they may be harmful to structures by generating damages or compromise the comfort of users through noise generation of mechanical wave transmission to the body. the purpose of this book is to present basic and advanced methods for efficiently controlling the vibrations and limiting their effects. Open-access publishing is an extraordinary opportunity for a wide dissemination of high quality research. This book is not an exception to this, and I am proud to introduce the works performed by experts from all over the world.

Es folgt eine experimentelle Validierung dieser neuartigen Strategie zur Schwingungssteuerung vorgestellt und ein drehender Prüfstand entwickelt. Der Prüfstand verwendet zwei ringförmig angeordnete Elektromagnetplatten zusammen mit einer Ankerwelle als zwei mechanische Schalter, um die Verbindung oder Trennung von zwei Spiralfedern mit einem Lastträgheitsmoment zu erreichen. Die Speicherung von Schwingungsenergie und die Schwingungsreduktion werden auf diesem Versuchssystem getestet. Neben einer harmonischen Störung wird auch eine Anfangsgeschwindigkeit ungleich Null berücksichtigt. Um in diesem Fall die Schwingungsreduktion zu verbessern, wird ein neues Schaltgesetz vorgeschlagen. Mit Hilfe der Phasenebene wird das transiente und stationäre Ratterverhalten von 4S analysiert. Das Schaltgesetz ermöglicht eine schnelle Umwandlung der anfänglichen kinetischen Energie, die in beiden Federn zu gleichen Teilen gespeichert wird. Dies ist numerisch und experimentell validiert. .

Structural vibration control is an important issue and has received considerable research attention in many industry applications. Researches investigated various approaches to reduce undesirable vibrations. The smart materials can control and suppress vibration in an efficient and “intelligent” way without causing much additional weight. The majority of research in smart damping materials has focused on the control of composite structure using embedded or bonded piezoelectric transducers. The advantages of piezoelectric materials include high achievable bandwidth, compactness, lightness, easy implementation and good electromechanical coupling characteristics, thus making them appropriate for actuators and sensors applications. Recently, a non-linear semi-passive vibration control technique, so-called Synchronized Switch Damping (SSD), has been developed. SSD technique relies on a cumulative build-up of the voltage resulting from the continuous switching of the piezoelectric voltage and it was shown that the performance is strongly related to this total voltage amplitude available. Based on SSD techniques, a new global approach for improved vibration damping of smart structure, based on global energy redistribution by means of a network of piezoelectric elements is proposed in this thesis. The objective of this work is to propose a new approach to increase the piezoelectric voltage (also related to the damping operative energy) in order to improve the damping performance. In the proposed semi-active approach, the extra energy used to improve this voltage is gathered on the various modes of the structure using an interconnected piezoelectric element network. Two original network topologies are developed for transferring energy. One is named SSDT for “Synchronized Switch Damping by energy Transfer”. The second is defined as SSDD for “Synchronized Switch Damping with Diode”. Performance evaluations and comparisons are performed on a model representative of a clamped plate equipped with piezoelectric elements in the case of multimodal motion. Compared to the Modal-SSDI method used as a baseline, simulation results and a global theoretical model are proposed demonstrating the relationship between the achievable damping improvement and the ratio of transferred energy to the structure mechanical energy, thus proving the capability of a network of piezoelectric elements for global energy management and redistribution in order to improve the vibration damping of smart structures.

This book presents select papers presented during the 6th National Symposium on Rotor Dynamics, held at CSIR-NAL, Bangalore, and focuses on the latest trends in rotor dynamics and various challenges encountered in the design of rotating machinery. The book is of interest to researchers from mechanical, aerospace, tribology and power industries, engineering service providers and academics.

Provides an introduction to active vibration control, active sound control, and active vibroacoustic control, respectively. This book also talks about actuator/sensor placement, deals with robust control of vibrating structures, and discusses finite element modelling of piezoelectric continua.

Vibrations are a part of our environment and daily life. Many of them are useful and are needed for many purposes, one of the best example being the hearing system. Nevertheless, vibrations are often undesirable and have to be suppressed or reduced, as they may be harmful to structures by generating damages or compromise the comfort of users through noise generation of mechanical wave transmission to the body. the purpose of this book is to present basic and advanced methods for efficiently controlling the vibrations and limiting their effects. Open-access publishing is an extraordinary opportunity for a wide dissemination of high quality research. This book is not an exception to this, and I am proud to introduce the works performed by experts from all over the world.

Recently, considerable attention has been focused on vibration control technology using "smart" or "intelligent" materials, which have inherently actuating and sensing capabilities. Typically these materials are employed to the vibration control of lumped parameter systems or distributed parameter structures by controlling the mass-distribution, stiffness change and the dissipation change. This may be accomplished by semi-active control or active control methods associated with the smart material actuators. Among many candidates of smart materials, magneto-rheological materials and piezoelectric materials are frequently adopted for vibration control. Magneto-rheological fluid and elastomer are especially utilized for vibration control of lumped parameter systems such as automotive damper, while the piezoelectric materials are used for vibration control of flexible distributed parameter structures with salient characteristics, such as fast response time. This book can be used as a textbook for graduate students or as a reference book for potential researchers who are interested in vibration control utilizing new methods associated with smart materials actuators. This book will provide some novel insights for advanced vibration control technology to many readers.