Michael J. Brennan

Bio: Michael J. Brennan is an academic researcher from Sao Paulo State University. The author has contributed to research in topics: Vibration & Vibration isolation. The author has an hindex of 50, co-authored 329 publications receiving 9582 citations. Previous affiliations of Michael J. Brennan include University of Southampton & University of São Paulo.

The Duffing Equation: Nonlinear Oscillators and their Behaviour

Abstract: List of Contributors. Preface. 1 Background: On Georg Duffing and the Duffing Equation (Ivana Kovacic and Michael J. Brennan). 1.1 Introduction. 1.2 Historical perspective. 1.3 A brief biography of Georg Duffing. 1.4 The work of Georg Duffing. 1.5 Contents of Duffing's book. 1.6 Research inspired by Duffing s work. 1.7 Some other books on nonlinear dynamics. 1.8 Overview of this book. References. 2 Examples of Physical Systems Described by the Duffing Equation (Michael J. Brennan and Ivana Kovacic). 2.1 Introduction. 2.2 Nonlinear stiffness. 2.3 The pendulum. 2.4 Example of geometrical nonlinearity. 2.5 A system consisting of the pendulum and nonlinear stiffness. 2.6 Snap-through mechanism. 2.7 Nonlinear isolator. 2.8 Large deflection of a beam with nonlinear stiffness. 2.9 Beam with nonlinear stiffness due to inplane tension. 2.10 Nonlinear cable vibrations. 2.11 Nonlinear electrical circuit. 2.12 Summary. References. 3 Free Vibration of a Duffing Oscillator with Viscous Damping (Hiroshi Yabuno). 3.1 Introduction. 3.2 Fixed points and their stability. 3.3 Local bifurcation analysis. 3.4 Global analysis for softening nonlinear stiffness ( < 0). 3.5 Global analysis for hardening nonlinear stiffness ( < 0). 3.6 Summary. Acknowledgments. References. 4 Analysis Techniques for the Various Forms of the Duffing Equation (Livija Cveticanin). 4.1 Introduction. 4.2 Exact solution for free oscillations of the Duffing equation with cubic nonlinearity. 4.3 The elliptic harmonic balance method. 4.4 The elliptic Galerkin method. 4.5 The straightforward expansion method. 4.6 The elliptic Lindstedt Poincare method. 4.7 Averaging methods. 4.8 Elliptic homotopy methods. 4.9 Summary. References. Appendix AI: Jacob elliptic function and elliptic integrals. Appendix 4AII: The best L2 norm approximation. 5 Forced Harmonic Vibration of a Duffing Oscillator with Linear Viscous Damping (Tamas Kalmar-Nagy and Balakumar Balachandran). 5.1 Introduction. 5.2 Free and forced responses of the linear oscillator. 5.3 Amplitude and phase responses of the Duffing oscillator. 5.4 Periodic solutions, Poincare sections, and bifurcations. 5.5 Global dynamics. 5.6 Summary. References. 6 Forced Harmonic Vibration of a Duffing Oscillator with Different Damping Mechanisms (Asok Kumar Mallik). 6.1 Introduction. 6.2 Classification of nonlinear characteristics. 6.3 Harmonically excited Duffing oscillator with generalised damping. 6.4 Viscous damping. 6.5 Nonlinear damping in a hardening system. 6.6 Nonlinear damping in a softening system. 6.7 Nonlinear damping in a double-well potential oscillator. 6.8 Summary. Acknowledgments. References. 7 Forced Harmonic Vibration in a Duffing Oscillator with Negative Linear Stiffness and Linear Viscous Damping (Stefano Lenci and Giuseppe Rega). 7.1 Introduction. 7.2 Literature survey. 7.3 Dynamics of conservative and nonconservative systems. 7.4 Nonlinear periodic oscillations. 7.5 Transition to complex response. 7.6 Nonclassical analyses. 7.7 Summary. References. 8 Forced Harmonic Vibration of an Asymmetric Duffing Oscillator (Ivana Kovacic and Michael J. Brennan). 8.1 Introduction. 8.2 Models of the systems under consideration. 8.3 Regular response of the pure cubic oscillator. 8.4 Regular response of the single-well Helmholtz Duffing oscillator. 8.5 Chaotic response of the pure cubic oscillator. 8.6 Chaotic response of the single-well Helmholtz Duffing oscillator. 8.7 Summary. References. Appendix Translation of Sections from Duffing's Original Book (Keith Worden and Heather Worden). Glossary. Index.

Finite element prediction of wave motion in structural waveguides.

Abstract: A method is presented by which the wavenumbers for a one-dimensional waveguide can be predicted from a finite element (FE) model. The method involves postprocessing a conventional, but low order, FE model, the mass and stiffness matrices of which are typically found using a conventional FE package. This is in contrast to the most popular previous waveguide/FE approach, sometimes termed the spectral finite element approach, which requires new spectral element matrices to be developed. In the approach described here, a section of the waveguide is modeled using conventional FE software and the dynamic stiffness matrix formed. A periodicity condition is applied, the wavenumbers following from the eigensolution of the resulting transfer matrix. The method is described, estimation of wavenumbers, energy, and group velocity discussed, and numerical examples presented. These concern wave propagation in a beam and a simply supported plate strip, for which analytical solutions exist, and the more complex case of a viscoelastic laminate, which involves postprocessing an ANSYS FE model. The method is seen to yield accurate results for the wavenumbers and group velocities of both propagating and evanescent waves.

Potential benefits of a non-linear stiffness in an energy harvesting device

Abstract: The benefits of using a non-linear stiffness in an energy harvesting device comprising a mass–spring–damper system are investigated. Analysis based on the principle of conservation of energy reveals a fundamental limit of the effectiveness of any non-linear device over a tuned linear device for such an application. Two types of non-linear stiffness are considered. The first system has a non-linear bi-stable snap-through mechanism. This mechanism has the effect of steepening the displacement response of the mass as a function of time, resulting in a higher velocity for a given input excitation. Numerical results show that more power is harvested by the mechanism if the excitation frequency is much less than the natural frequency. The other non-linear system studied has a hardening spring, which has the effect of shifting the resonance frequency. Numerical and analytical studies show that the device with a hardening spring has a larger bandwidth over which the power can be harvested due to the shift in the resonance frequency.

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

A review of the recent research on vibration energy harvesting via bistable systems

Abstract: The investigation of the conversion of vibrational energy into electrical power has become a major field of research. In recent years, bistable energy harvesting devices have attracted significant attention due to some of their unique features. Through a snap-through action, bistable systems transition from one stable state to the other, which could cause large amplitude motion and dramatically increase power generation. Due to their nonlinear characteristics, such devices may be effective across a broad-frequency bandwidth. Consequently, a rapid engagement of research has been undertaken to understand bistable electromechanical dynamics and to utilize the insight for the development of improved designs. This paper reviews, consolidates, and reports on the major efforts and findings documented in the literature. A common analytical framework for bistable electromechanical dynamics is presented, the principal results are provided, the wide variety of bistable energy harvesters are described, and some remaining challenges and proposed solutions are summarized.