Applied Mathematics and Mechanics (English Edition) ›› 2004, Vol. 25 ›› Issue (11): 1271-1276.

• 论文 • 上一篇    下一篇

PENDULUM WITH LINEAR DAMPING AND VARIABLE LENGTH

蔡建平1,3, 杨翠红2, 李怡平3   

  1. 1. Department of Mathematics, Zhangzhou Teachers College, Zhangzhou, Fujian 363000, P. R. China;
    2. Department of Mathematics, Central China Normal University, Wuhan 430079, P. R. China;
    3. Department of Mathematics, Zhongshan University, Guangzhou 510275, P. R. China
  • 收稿日期:2003-02-27 修回日期:2004-06-28 出版日期:2004-11-18 发布日期:2004-11-18

PENDULUM WITH LINEAR DAMPING AND VARIABLE LENGTH

CAI Jian-ping1,3, YANG Cui-hong2, LI Yi-ping3   

  1. 1. Department of Mathematics, Zhangzhou Teachers College, Zhangzhou, Fujian 363000, P. R. China;
    2. Department of Mathematics, Central China Normal University, Wuhan 430079, P. R. China;
    3. Department of Mathematics, Zhongshan University, Guangzhou 510275, P. R. China
  • Received:2003-02-27 Revised:2004-06-28 Online:2004-11-18 Published:2004-11-18

摘要: The methods of multiple scales and approximate potential are used to study pendulums with linear damping and variable length. According to the order of the coefficient of friction compared with that of the slowly varying parameter of length, three different cases are discussed in details. Asymptotic analytical expressions of amplitude, frequency and solution are obtained. The method of approximate potential makes the results effective for large oscillations. A modified multiple scales method is used to get more accurate leading order approximations when the coefficient friction is not small. Comparisons are also made with numerical results to show the efficiency of the present method.

Abstract: The methods of multiple scales and approximate potential are used to study pendulums with linear damping and variable length. According to the order of the coefficient of friction compared with that of the slowly varying parameter of length, three different cases are discussed in details. Asymptotic analytical expressions of amplitude, frequency and solution are obtained. The method of approximate potential makes the results effective for large oscillations. A modified multiple scales method is used to get more accurate leading order approximations when the coefficient friction is not small. Comparisons are also made with numerical results to show the efficiency of the present method.

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