Nonlinear oscillations in physical systems
Nonlinear oscillations in physical systems
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DOI:
10.1115/1.3172988
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发表时间:
1987-03
期刊:
影响因子:
--
通讯作者:
C. Hayashi;D. Mook
中科院分区:
文献类型:
--
作者:
C. Hayashi;D. Mook
By popular demand, this book is a reprint of the 1964 issue. Nonlinear oscillations revolve about systems whose differential equations cannot be solved exactly. However, great strides have been accomplished in employing approximate solutions. This provides adequate information concerning nonlinear oscillations. This volume is meant to furnish approximate solutions for these nonlinear differential equations. As stated by the author, "That the problems discussed in this book are mostly concerned with forced oscillations; furthermore in most of the text, only systems with one degree of freedom are treated. However, a wide variety of oscillations may occur in these systems under the influence of external forces." This book fulfills the author's intentions and opens up a vast story that makes interesting reading. Although originally pointed towards electrical engineers, it remains a good reference for mechanical engineers plus researchers interested in other disciplines. The book consists of four parts with a total of 13 chapters, 6 appendices, and an excellent bibliography. Part I, entitled "Physical methods of nonlinear analysis," contains 3 chapters. The initial chapter presents analytical methods. This includes the powerful perturbation method (autonomous and nonautonomous systems). Examples are provided using Duffing's and Van Der Pol equations. We progress to the iteration method (successive iteration), averaging method (autonomous and nonautonomous), and the principles of harmonic balance with reference to the describing function method. Comparisons are made in the solution of Duffing's equation between perturbation and harmonic balance. Both furnish almost identical answers. Chapter 2 reports on topological methods which are powerful schemes of investigating various phenomena of nonlinear oscillations. The study of autonomous systems rests upon topological methods. Beginning with integral curves and singular points in the static plane, we continue with the classification of singular points according to the character of the integral curves. The author plunges ahead into canonical forms of the differential equations, singular points of higher order plus an interesting study of limit cycles. The text shows 5 different types of singular points in state space. The next important methods are (a) isocline method (graphical), (b) Lienard's method dealing with self-excited oscillation, (c) higher order approximates (use of eigenvalue and approximations instead of initial values), (d) double delta methods, (e) slope line method of graphical construction, and (f) second order equations of autonomous and nonautonomous systems. Illustrative examples explain these methods using Duffing and Van Der Pol equations. Chapter 3 speaks about stability of nonlinear systems. Liapunov stability opens this chapter. This leads to Routh-Hurwitz criteria, Floquet's theorem, Mathieu's equations, and their respective functions. In the unstable region, Hill's infinite determinant and Whittaker method are the most prominent. The former delves into the stability problem and improved approximation of the characteristic exponent in the odd unstable regions (first and third) and even (second). This chapter contains a large number of illustrative examples. Part II studies forced oscillations in steady state. Chapter 4 treats stability of periodic oscillations in second order systems. Since the principle of superposition is no longer applicable to nonlinear systems, other means of determining stability is required. Different conditions for stability of second order systems are necessary and encompasses various types of variational equations. It points a finger at the various stability conditions. Chapter 5 focuses on harmonic oscillations. Here, higher harmonics can be neglected because the fundamental component possesses a period, the same as that of the predominant external force. After deriving the fundamental equation, this continues with periodic states of equilibrium and its stability plus harmonic oscillations with unsymmetric nonlinear characteristics. The chapter concludes with a demonstration of an electrical circuit having unsymmetrical characteristics. Chaper 6 speaks about higher harmonic oscillations. Beginning with higher harmonic oscillations in series-resonance circuits, it migrates to parallel resonance circuits. Chapter 7 deals with important topics of subharmonic oscillations. Relationships between nonlinear characteristics and order of subharmonic oscillations of this study, i.e., quadratic, cubic and fifth order forcing functions are considered. Each of them contribute to a subharmonic order of 1/3. This is extended to dissipative and nondissipative systems. This follows with nonlinear characteristics determined by quintic function. The chapter concludes with nonlinear characteristics represented by a symmetric quadratic function which produces a 1 /2 harmonic oscillation. Experimental investigations complement the above subjects. Part III delves into forced oscillations in the transient state. Chapter 8 opens up with harmonic oscillation and considers periodic solutions and their stability in the transient stage. Harmonic oscillations are analyzed by means of integral curves with and without dissipative systems. In the next chapter, we jump ahead into subcontinua and subharmonic