Cyclic loadings and crystallization of natural rubber: An explanation of fatigue crack propagation reinforcement under a positive loading ratio

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:528

Article

Saintier, N.¹  Cailletaud, G.²  Piques, R.² 

[1] Arts & Metiers ParisTech, Esplanade Arts & Metiers, LAMEFIP, F-33405 Talence, France

[2] CNRS, UMR 7633, Ecole Natl Supierieure Mines Paris, Ctr Mat PM FOURT, F-91003 Evry, France

关键词: Natural rubber;    Fatigue;    Crystallization;    Crack branching;   

DOI  :  10.1016/j.msea.2010.09.079

来源: Elsevier

【 摘 要 】

Natural rubber is known to have excellent fatigue properties. Fatigue crack propagation studies show that, under uniaxial tension loading, fatigue crack growth resistance increases with the loading ratio, even if the peak stress increases. Studies dealing with crack initiation confirm this trend. If strain induced crystallization is believed to play a major role in this reinforcement process, it is not clear yet by which mechanism this reinforcement takes place. Using SEM investigation, it is shown here that the reinforcement process is associated with strong crack branching in the crack tip region. From experimental results it is shown that under particular reinforcing loading condition a cyclic strain hardening process can be observed on the natural rubber which is able to overcome classically observed softening effects. A cumulative strain induced crystallization process is proposed to explain the stress ratio effect on fatigue crack initiation and propagation properties of natural rubber. (C) 2010 Elsevier B.V. All rights reserved.

【 授权许可】

Free