Alexander F. Vakakis – författare

A collection of papers on nonlinear normal modes and localization in dynamical systems. The reader should find analytical and computational techniques for studying normal modes and localization phenomena in nonlinear discrete and continuous oscillators. In addition, examples are provided of applications of these concepts to diverse problems of engineering and applied mathematics, such as nonlinear control of micro-gyroscopes, dynamics of floating offshore platforms, buckling of imperfect continua, order reduction of nonlinear systems, dynamics of nonlinear vibration absorbers, spatial localization and pattern formation in extended systems, singular asymptotics and nonlinear modal interactions and energy pumping in coupled oscillators.

This monograph is the first in the new area of targeted nonlinear energy transfer in mechanical and structural systems. This concept was initially discovered by the two leading authors in 1999, and was further developed exclusively by the entire author group in the last 6 years. Since then, additional groups of researchers in the USA, Russia, UK and France have started working on this concept and applying it. It is estimated that in the years to come, the concept of targeted nonlinear energy transfer will be considered and applied by numerous groups of researchers and practitioners internationally. This monograph presents theoretical methods, computational results and experimental demonstrations of this concept applied to discrete and continuous coupled nonlinear oscillators. Moreover, it demonstrates the wide applicability of targeted nonlinear energy transfer to a wide range of problems, including: (1) Vibration and shock isolation in mechanical systems; (2) Seismic mitigation; (3) Aeroelastic and structural instability suppression; (4) Drilling operations; (5) Packaging devices. This is a groundbreaking and unique volume, providing new design paradigms in a variety of fields.

This monograph evolved over a period of nine years from a series of papers and presentations addressing the subject of passive vibration control of mechanical s- tems subjected to broadband, transient inputs. The unifying theme is Targeted - ergy Transfer – TET, which represents a new and unique approach to the passive control problem, in which a strongly nonlinear, fully passive, local attachment, the Nonlinear Energy Sink – NES, is employed to drastically alter the dynamics of the primary system to which it is attached. The intrinsic capacity of the properly - signed NES to promote rapid localization of externally applied (narrowband) - bration or (broadband) shock energy to itself, where it can be captured and dis- pated, provides a powerful strategy for vibration control and the opens the pos- bility for a wide range of applications of TET, such as, vibration and shock i- lation, passive energy harvesting, aeroelastic instability (?utter) suppression, se- mic mitigation, vortex shedding control, enhanced reliability designs (for ex- ple in power grids) and others. The monograph is intended to provide a thorough explanation of the analytical, computational and experimental methods needed to formulate and study TET in mechanical and structural systems. Several prac- cal engineering applications are examined in detail, and experimental veri?cation and validation of the theoretical predictions are provided as well. The authors also suggest a number of possible future applications where application of TET seems promising. The authors are indebted to a number of sponsoring agencies.

This book covers the latest ideas and approaches in strongly nonlinear dynamical and acoustical systems and discusses appropriate modelling tools and practical examples highlighting the non-standard and non-stationary aspects of this challenging, yet so promising area. The contributions investigate and present the intentional use of nonlinearity in the most challenging field of acoustics, the latest developments in transient dynamics of strongly nonlinear systems, the subtle numeric problems arising while exploring nonlinear normal modes, the fascinating topic of nonlinear dynamics of wind musical instruments, the novel developments in the field of global nonlinear dynamics, some multi-faceted mathematical challenges in the dynamics of hysteretic systems, and lastly offers theoretical, numeric and experimental insights into the intricate dynamics of systems with contact nonlinearities. The need for such a work is underscored by the fact that accounting for, understanding of, and designing with nonlinearities is becoming an emerging universal trend in engineering practice, and is predicted to be even more so in the future. The book demonstrates that the idea of exploiting strong nonlinearity in dynamical and acoustical systems has transitioned from few early theoretical works to a diverse theoretical and experimental body of current research.

This book covers the latest ideas and approaches in strongly nonlinear dynamical and acoustical systems and discusses appropriate modelling tools and practical examples highlighting the non-standard and non-stationary aspects of this challenging, yet so promising area. The contributions investigate and present the intentional use of nonlinearity in the most challenging field of acoustics, the latest developments in transient dynamics of strongly nonlinear systems, the subtle numeric problems arising while exploring nonlinear normal modes, the fascinating topic of nonlinear dynamics of wind musical instruments, the novel developments in the field of global nonlinear dynamics, some multi-faceted mathematical challenges in the dynamics of hysteretic systems, and lastly offers theoretical, numeric and experimental insights into the intricate dynamics of systems with contact nonlinearities. The need for such a work is underscored by the fact that accounting for, understanding of, and designing with nonlinearities is becoming an emerging universal trend in engineering practice, and is predicted to be even more so in the future. The book demonstrates that the idea of exploiting strong nonlinearity in dynamical and acoustical systems has transitioned from few early theoretical works to a diverse theoretical and experimental body of current research.

This landmark book deals with nonlinear normal modes (NNMs) and nonlinear mode localization. Offers an analysis which enables the study of various nonlinear phenomena having no counterpart in linear theory. On a more theoretical level, the concept of NNMs will be shown to provide an excellent framework for understanding a variety of distinctively nonlinear phenomena such as mode bifurcations and standing or traveling solitary waves.

There are many monographs in the existing literature devoted to the static and dynamic behavior of plates and shells. Plates and shells are enco- tered often in engineering applications being integralparts of a wide range of constructions, such as machines, vehicles, airplanes, rockets, ships, bridges, buildings, and containers, to name a few. In addition to the usual requi- ments posedby engineersrelatedtolightweightness,su?cientrigidityor?- ibility, and robust stability properties, there is an additional class ofapriori dynamicalpropertiesrequiredbymodernengineeringapplicationswheren- homogeneity and non-uniformity of structural components is often the norm incertainapplications. Inaddition,strictoperationalrequirementsinmodern engineering applications towards higher speeds, lighter construction, robust andreliableperformance,dictatessmallermarginsoferrorordeviationsfrom prescribed performances in adverse or uncertain forcing environments. This, in turn, requires the development of new analytical and computational tools capable of addressing challenging and not very well developed topics, such as, nonlinearities a?ecting the system performance, the e?ects of unmodeled dynamics on the stability of operation, and the role of uncertainties in the systemparametersonthestructuralresponse.Asaresult,thereisanongoing e?ort to address such issues, leading to the development of new analytical and computational tools, some of which are discussed in this monograph. The monograph follows an approach based on an integrated treatment of analysis and computation. Such a hybrid approach, coupled with computer algebra, can lead to results that cannot be obtained by other standard th- ries in the ?eld. We show, that in a wide class of problems only a carefully prepared numerical experiment followed by purely mathematical conside- tionscan?nallyleadtothesoughtresults. Thenumerousanalyticalconstr- tions are illustrated by examples of application and computational results.

There are many monographs in the existing literature devoted to the static and dynamic behavior of plates and shells. Plates and shells are enco- tered often in engineering applications being integralparts of a wide range of constructions, such as machines, vehicles, airplanes, rockets, ships, bridges, buildings, and containers, to name a few. In addition to the usual requi- ments posedby engineersrelatedtolightweightness,su?cientrigidityor?- ibility, and robust stability properties, there is an additional class ofapriori dynamicalpropertiesrequiredbymodernengineeringapplicationswheren- homogeneity and non-uniformity of structural components is often the norm incertainapplications. Inaddition,strictoperationalrequirementsinmodern engineering applications towards higher speeds, lighter construction, robust andreliableperformance,dictatessmallermarginsoferrorordeviationsfrom prescribed performances in adverse or uncertain forcing environments. This, in turn, requires the development of new analytical and computational tools capable of addressing challenging and not very well developed topics, such as, nonlinearities a?ecting the system performance, the e?ects of unmodeled dynamics on the stability of operation, and the role of uncertainties in the systemparametersonthestructuralresponse.Asaresult,thereisanongoing e?ort to address such issues, leading to the development of new analytical and computational tools, some of which are discussed in this monograph. The monograph follows an approach based on an integrated treatment of analysis and computation. Such a hybrid approach, coupled with computer algebra, can lead to results that cannot be obtained by other standard th- ries in the ?eld. We show, that in a wide class of problems only a carefully prepared numerical experiment followed by purely mathematical conside- tionscan?nallyleadtothesoughtresults. Thenumerousanalyticalconstr- tions are illustrated by examples of application and computational results.

The papers in this volume address advanced nonlinear topics in the general areas of vibration mitigation and system identification, such as, methods of analysis of strongly nonlinear dyanmical systems; techniques and methodologies for interpreting complex, multi-frequency transitions in damped nonlinear responses; new approaches for passive vibration mitigation based on nonlinear targeted energy transfer (TET) and the associated concept of nonlinear energy sink (NES); and an overview and assessment of current nonlinear system identification techniques.

The papers in this volume address advanced nonlinear topics in the general areas of vibration mitigation and system identification, such as, methods of analysis of strongly nonlinear dyanmical systems; techniques and methodologies for interpreting complex, multi-frequency transitions in damped nonlinear responses; new approaches for passive vibration mitigation based on nonlinear targeted energy transfer (TET) and the associated concept of nonlinear energy sink (NES); and an overview and assessment of current nonlinear system identification techniques.

The papers in this volume address advanced nonlinear topics in the general areas of vibration mitigation and system identification, such as, methods of analysis of strongly nonlinear dyanmical systems; techniques and methodologies for interpreting complex, multi-frequency transitions in damped nonlinear responses; new approaches for passive vibration mitigation based on nonlinear targeted energy transfer (TET) and the associated concept of nonlinear energy sink (NES); and an overview and assessment of current nonlinear system identification techniques.

This book contains a collection of original papers on nonlinear normal modes and localization in dynamical systems from leading experts in the field. The reader will find new analytical and computational techniques for studying normal modes and localization phenomena in nonlinear discrete and continuous oscillators. In addition, examples are provided of applications of these concepts to diverse problems of engineering and applied mathematics, such as nonlinear control of micro-gyroscopes, dynamics of floating offshore platforms, buckling of imperfect continua, order reduction of nonlinear systems, dynamics of nonlinear vibration absorbers, spatial localization and pattern formation in extended systems, singular asymptotics and nonlinear modal interactions and energy pumping in coupled oscillators.

The nonlinear normal modes of a parametrically excited cantilever beam are constructed by directly applying the method of multiple scales to the governing integral-partial differential equation and associated boundary conditions. The effect of the inertia and curvature nonlin­ earities and the parametric excitation on the spatial distribution of the deflection is examined. The results are compared with those obtained by using a single-mode discretization. In the absence of linear viscous and quadratic damping, it is shown that there are nonlinear normal modes, as defined by Rosenberg, even in the presence of a principal parametric excitation. Furthermore, the nonlinear mode shape obtained with the direct approach is compared with that obtained with the discretization approach for some values of the excitation frequency. In the single-mode discretization, the spatial distribution of the deflection is assumed a priori to be given by the linear mode shape ¢n, which is parametrically excited, as Equation (41). Thus, the mode shape is not influenced by the nonlinear curvature and nonlinear damping. On the other hand, in the direct approach, the mode shape is not assumed a priori; the nonlinear effects modify the linear mode shape ¢n. Therefore, in the case of large-amplitude oscillations, the single-mode discretization may yield inaccurate mode shapes. References 1. Vakakis, A. F., Manevitch, L. I., Mikhlin, Y. v., Pilipchuk, V. N., and Zevin A. A., Nonnal Modes and Localization in Nonlinear Systems, Wiley, New York, 1996.

This monograph evolved over a period of nine years from a series of papers and presentations addressing the subject of passive vibration control of mechanical s- tems subjected to broadband, transient inputs. The unifying theme is Targeted - ergy Transfer – TET, which represents a new and unique approach to the passive control problem, in which a strongly nonlinear, fully passive, local attachment, the Nonlinear Energy Sink – NES, is employed to drastically alter the dynamics of the primary system to which it is attached. The intrinsic capacity of the properly - signed NES to promote rapid localization of externally applied (narrowband) - bration or (broadband) shock energy to itself, where it can be captured and dis- pated, provides a powerful strategy for vibration control and the opens the pos- bility for a wide range of applications of TET, such as, vibration and shock i- lation, passive energy harvesting, aeroelastic instability (?utter) suppression, se- mic mitigation, vortex shedding control, enhanced reliability designs (for ex- ple in power grids) and others. The monograph is intended to provide a thorough explanation of the analytical, computational and experimental methods needed to formulate and study TET in mechanical and structural systems. Several prac- cal engineering applications are examined in detail, and experimental veri?cation and validation of the theoretical predictions are provided as well. The authors also suggest a number of possible future applications where application of TET seems promising. The authors are indebted to a number of sponsoring agencies.