ASSESSMENT METHODOLOGY OF FATIGUE CRACK GROWTH LIFE CONSIDERING THE HISTORY OF THE ELASTO-PLASTIC DEFORMATION AND THE ACCUMULATED DAMAGE

Abstract

 The authors invented an unconventional material model and proposed a methodology for the investigation of the crack propagation phenomenon under the elasto-plastic state utilizing the model. However, previous works are conducted only under the positive stress ratio 𝑅. Additionally, the effects of the elasto-plastic deformation and the accumulated damage accompanying crack growth have not been sufficiently considered, nor the impact of these factors on the evaluation accuracy. This paper suggested the unconventional method considering the history of deformation and the accumulated damage accompanying crack growth to follow the complexity of the contact changes after crack initiation. The accuracy of this methodology was verified for the crack propagation tests by SENT specimen conducted under the two different stress ratios 𝑅 and maximum loads. The obtained results exhibit good accuracy in predicting four experiments under different loading conditions.