Study on Free Oscillations of Systems with Even Nonlinearities by Means of the Method of Multiple Scales

2007 ◽  
Vol 10-12 ◽  
pp. 193-197
Author(s):  
J.M. Wen ◽  
Z.C. Cao

An analytical technique, namely the method of multiple scales, is applied to solve the differential equations of free oscillations with even nonlinearities in a mass-spring system. Unlike other perturbation methods, the method of multiple scales is effective in determining the transient response as well as determining the approximation to the frequency of the nonlinear system. In this paper, the periodic solutions of the even nonlinear differential equations have been obtained by using the method of multiple scales. Compared with the numerical examples, the approximate solutions are in good agreement with exact solutions. The numerical and analytical solutions have clearly shown that there exists the so-called drift phenomenon in the free oscillations of systems with even nonlinearities without any external excitation.

Volume 2 ◽  
2004 ◽  
Author(s):  
Mohammad Shoeybi ◽  
Mehrdaad Ghorashi

An investigation on the nonlinear vibrations of a system with two degrees of freedom when subjected to saturation is presented. The method is especially applied to a system that consists of a DC motor with a nonlinear controller and subjected to a harmonic forcing voltage. Approximate solutions are sought using the method of multiple scales. Also, singular point analysis is used to study stability of solutions. These findings are then compared with the corresponding numerical results. Good agreement between the two is observed.


2013 ◽  
Vol 274 ◽  
pp. 324-327
Author(s):  
J.F. Nie ◽  
M.L. Zheng ◽  
G.B. Yu ◽  
J.M. Wen ◽  
B. Dai

To obtain exact analytical solutions of differential equations of gear system dynamics due to the difficulty of solving complicated differential equations. Only the approximate analytical solutions can be determined. The method of multiple scales is one of the most powerful, popular perturbation methods. The dynamic model which describes the torsional vibration behaviors of gear system has been introduced accurately in this paper. The differential equation of gear system nonlinear dynamics exhibiting combined nonlinearity influence such as time-varying stiffness, tooth backlash and dynamic transmission error (DTE) has been proposed. The theory of multiple scales method has been presented in solving nonlinear differential equations of gear systems and the frequency response equation has been obtained. The fact that the approximate analytical solution by using the method of multiple scales is in good agreement with the exact solutions by numerically integrating differential equations has proved that the method of multiple scales is one of the most frequently used methods in solving differential equations, especially for large and complicated differential equations.


2017 ◽  
Vol 72 (6) ◽  
pp. 547-557 ◽  
Author(s):  
M.M. Fatih Karahan

AbstractA new perturbation method, multiple scales Lindstedt–Poincare (MSLP) is applied to jerk equations with cubic nonlinearities. Three different jerk equations are investigated. Approximate analytical solutions and periods are obtained using MSLP method. Both approximate analytical solutions and periods are contrasted with numerical and exact results. For the case of strong nonlinearities, obtained results are in good agreement with numerical and exact ones.


2017 ◽  
Vol 72 (1) ◽  
pp. 59-69 ◽  
Author(s):  
M.M. Fatih Karahan ◽  
Mehmet Pakdemirli

AbstractStrongly nonlinear cubic-quintic Duffing oscillatoris considered. Approximate solutions are derived using the multiple scales Lindstedt Poincare method (MSLP), a relatively new method developed for strongly nonlinear oscillators. The free undamped oscillator is considered first. Approximate analytical solutions of the MSLP are contrasted with the classical multiple scales (MS) method and numerical simulations. It is found that contrary to the classical MS method, the MSLP can provide acceptable solutions for the case of strong nonlinearities. Next, the forced and damped case is treated. Frequency response curves of both the MS and MSLP methods are obtained and contrasted with the numerical solutions. The MSLP method and numerical simulations are in good agreement while there are discrepancies between the MS and numerical solutions.


2018 ◽  
Vol 7 (3) ◽  
pp. 31
Author(s):  
Rosa Virginia Hernández ◽  
Luis Fernando Mariño ◽  
Mawency Vergel

En este artículo se presenta la caracterización del conocimiento semántico evidenciado por un grupo de estudiantes en la representación externa a problemas de ecuaciones diferenciales lineales de segundo orden como modelos matemáticos. El trabajo fue cuantitativo de tipo exploratorio y descriptivo utilizando un cuestionario en la recolección de información. El soporte teórico que dio sentido al estudio fue el modelo de dos etapas propuesto por Mayer R. para la resolución de problemas matemáticos, el ciclo de modelación bajo la perspectiva cognitiva según Borromeo Ferri y la teoría de las representaciones de Goldin y Kaput. La investigación se centró específicamente en la fase de representación del modelo. Entre los principales hallazgos se destaca que cada participante hace su propia representación externa a conceptos como: sistema masa-resorte, peso, masa, punto de equilibrio, constante de elasticidad, punto de equilibrio, ley de Hooke, fuerza amortiguadora, fuerza externa, ley de Newton, entre otros. Se evidencian también dificultades en el tránsito del lenguaje natural al lenguaje matemático y la representación externa de cada una de los signos, símbolos o expresiones matemáticas inmersas en el problema de palabra, debido a que el resolutor tiene que construir un modelo mental de la situación real y plasmarlo en un modelo matemático. Lo anterior pone de manifiesto la importancia que tiene el conocimiento semántico en la etapa de traducción cuando se intentan resolver problemas como situaciones reales a modelar.Palabras clave: resolución de problemas, ciclos de modelación, problemas de palabra, representaciones externas, conocimiento extra matemático, modelación matemática. AbstractThis article presents the characterization of the semantic knowledge evidenced by a group of students in the external representation to problems of second order linear differential equations as mathematical models. The work was quantitative exploratory and descriptive using a questionnaire in the collection of information. The theoretical support that gave meaning to the study was the two-stage model proposed by Mayer R. for solving mathematical problems, the modeling cycle under the cognitive perspective according to Borromeo Ferri and the theory of representations of Goldin and Kaput. The research focused specifically on the representation phase of the model. Among the main findings is that each participant makes his own external representation to concepts such as: mass-spring system, weight, mass, equilibrium point, constant of elasticity, equilibrium point, Hooke's law, damping force, external force, law of Newton, among others. Difficulties are also evident in the transition from natural language to mathematical language and the external representation of each of the signs, symbols or mathematical expressions involved in the word problem, because the resolver has to construct a mental model of the real situation and translate it into a mathematical model. This demonstrates the importance of semantic knowledge in the translation stage when trying to solve problems as real situations to be modeledKeywords: problem solving, modeling cycles, word problems, external representations, extra mathematical knowledge, mathematical modeling.ResumoEste artigo apresenta a caracterização do conhecimento semântico evidenciado por um grupo de estudantes na representação externa a problemas de equações diferenciais lineares de segunda ordem como modelos matemáticos. O trabalho foi quantitativo exploratório e descritivo usando um questionário na coleta de informações. O suporte teórico que deu sentido ao estudo foi o modelo de dois estágios proposto por Mayer R. para resolver problemas matemáticos, o ciclo de modelagem sob a perspectiva cognitiva de acordo com Borromeo Ferri e a teoria das representações de Goldin e Kaput. A pesquisa focalizou especificamente a fase de representação do modelo. Entre os principais achados, cada participante faz sua própria representação externa para conceitos como: sistema de massa-mola, peso, massa, ponto de equilíbrio, constante de elasticidade, ponto de equilíbrio, lei de Hooke, força de amortecimento, força externa, lei de Newton, entre outros. As dificuldades também são evidentes na transição da linguagem natural para a linguagem matemática e a representação externa de cada um dos signos, símbolos ou expressões matemáticas envolvidas na palavra problema, porque o resolvedor tem que construir um modelo mental da situação real e traduzi-lo para um modelo matemático. Isso demonstra a importância do conhecimento semântico na fase de tradução ao tentar resolver problemas como situações reais a serem modeladas. ______________________________________________________ Palavras-chave: resolução de problemas, ciclos de modelagem, problemas de palavra, representação externa, conhecimento extra matemático, modelagem matemática


Author(s):  
Safia Meftah

The question discussed in this study concerns one of the most helpful approximation methods, namely, the expansion of a solution of a differential equation in a series in powers of a small parameter. We used the Lindstedt-Poincaré perturbation method to construct a solution closer to uniformly valid asymptotic expansions for periodic solutions of second-order nonlinear differential equations.


2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Shaheed N. Huseen ◽  
Said R. Grace

A modifiedq-homotopy analysis method (mq-HAM) was proposed for solvingnth-order nonlinear differential equations. This method improves the convergence of the series solution in thenHAM which was proposed in (see Hassan and El-Tawil 2011, 2012). The proposed method provides an approximate solution by rewriting thenth-order nonlinear differential equation in the form ofnfirst-order differential equations. The solution of thesendifferential equations is obtained as a power series solution. This scheme is tested on two nonlinear exactly solvable differential equations. The results demonstrate the reliability and efficiency of the algorithm developed.


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