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Mathematical Problems in Engineering
Volume 2014, Article ID 352676, 8 pages
http://dx.doi.org/10.1155/2014/352676
Research Article

Analysis of Fatigue Life of PMMA at Different Frequencies Based on a New Damage Mechanics Model

1Research Institute of Unmanned Aircraft, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
2State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

Received 12 March 2014; Revised 28 April 2014; Accepted 4 May 2014; Published 11 June 2014

Academic Editor: Jose Merodio

Copyright © 2014 Aifeng Huang et al. 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.

Abstract

Low-cycle fatigue tests at different frequencies and creep tests under different stress levels of Plexiglas Resist 45 were conducted. Correspondingly, the creep fracture time, - curves, cyclic creep, and hysteresis loop were obtained. These results showed that the fatigue life increases with frequency at low frequency domain. After analysis, it was found that fatigue life is dependent on the load rate and is affected by the creep damage. In addition, a new continuum damage mechanics (CDM) model was established to analyze creep-fatigue life, where the damage increment nonlinear summation rule was proposed and the frequency modification was made on the fatigue damage evolution equation. Differential evolution (DE) algorithm was employed to determine the parameters within the model. The proposed model described fatigue life under different frequencies, and the calculated results agreed well with the experimental results.