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`Abstract and Applied AnalysisVolume 2013 (2013), Article ID 329638, 3 pageshttp://dx.doi.org/10.1155/2013/329638`
Letter to the Editor

## Comment on “Nonlinear Response of Strong Nonlinear System Arisen in Polymer Cushion”

School of Mathematics and Computer Science, Yangtze Normal University, Chongqing 408100, China

Received 10 April 2013; Accepted 26 May 2013

Copyright © 2013 Jun Zhou. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### 1. Introduction

In [1], the following nonlinear oscillator was studied: Similar nonlinear oscillators arising in packing systems and textile engineering are available in [27].

In [1], (1) is approximated by Taylor’s series for the nonlinear terms: By using Taylor’s expansion function of MATLAB’s symbolic function, the nonlinear terms , , and are expanded to 8th order. After careful calculation, (2) should be corrected as where .

#### 2. Variational Iteration Method

In [1], the following variational iteration algorithm was constructed: which should be corrected as In order to simplify the solution process, we denote Equation (5) becomes We begin with and use the following relationships: By (7), we have where Consider the following identity: From (10), we obtain where ( = 1~4) are defined above.

#### 3. Discussion and Conclusion

The result of in [1] should be corrected as that given in (13). In [1], actually the following variational iteration algorithm is used: which is called the variational iteration algorithm in [8, 9]; for the present problem, the variational iteration algorithm in [10] is much more effective, which reads The variational iteration method is especially effective in solving nonlinear oscillators.

#### References

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