Discussion of 'A Model of Fatigue Crack Growth in Polymers'.

摘要

A model was previously proposed by Hertzberg, Skibo, and Manson to account for the sensitivity of fatigue crack growth rates to frequency. The model was based on the hypothesis that the mechanical Beta transition controls the fatigue deformation and on the use of time-temperature relationships to determine the match between the Beta transition frequency and temperature and the frequency and temperature of the test. An alternate model was recently proposed by Williams, who interpreted the frequency sensitivity in terms of the sensitivity of fracture toughness (and Young's modulus) to frequency. In this communication, results of new experiments with nylon 66 are presented and discussed. Since Young's modulus was independent of test frequency for nylon 66, and for several other polymers, it was concluded that the author's earlier hypothesis was not invalidated. (Author)