Analysis of the effects of compressive stresses on fatigue crack propagation rate

✍ Scribed by J. Zhang; X.D. He; S.Y. Du

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 167 KB
• Volume: 29
• Category: Article
• ISSN: 0142-1123
• DOI: 10.1016/j.ijfatigue.2006.12.007

✦ Synopsis

In this study, the effects of compressive stresses on the crack tip parameters and its implication on fatigue crack growth have been studied. Elastic-plastic finite element analysis has been used to analyse the change of crack tip parameters with the increase of the applied compressive stress level.

The near crack tip opening displacements and the reverse plastic zone size around the crack tip have been obtained. The finite element analysis shows that when unloading from peak tensile applied stress to zero applied stress, the crack tip is still kept open and the crack tip opening displacement gradually decreases further with the applied compressive stress. It has been found that for a tension-compression stress cycle these crack tip parameters are determined mainly by two loading parameters, the maximum stress intensity K max in the tension part of the stress cycle and the maximum compressive stress r maxcom in the compression part of the stress cycle.

Based on the two parameters, K max , and r maxcom , a fatigue crack propagation model for negative R ratios only has been developed to include the compressive stress effect on the fatigue crack propagation rate.

Experimental fatigue crack propagation data sets were used for the verification of this model, good agreements have been obtained.