• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2023, Vol. 59 ›› Issue (16): 90-106.doi: 10.3901/JME.2023.16.090

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Notch Fatigue Life Prediction under Size Effect:Stress Gradient-based Theory of Critical Distance

HE Jinchao1, ZHU Shunpeng1,2,3, NIU Xiaopeng1, LIAO Ding1, WANG Qingyuan2,3,4   

  1. 1. School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731;
    2. MOE Key Laboratory of Deep Earth Science and Engineering, Sichuan University, Chengdu 610065;
    3. Failure Mechanics and Engineering Disaster Prevention and Mitigation, Key Laboratory of Sichuan Province, Sichuan University, Chengdu 610065;
    4. Advanced Research Institute, Chengdu University, Chengdu 610106
  • Received:2022-09-16 Revised:2023-03-12 Online:2023-08-20 Published:2023-11-15

Abstract: Fatigue fracture is one of the most common failure modes of metallic materials. The stress gradient effect induced by the notch features are the key problem in anti-fatigue design of engineering components. Therefore, developing reliable notch fatigue methods is significant for maintaining service integrity of engineering structures. In view of this, a notch fatigue life prediction model combining the theory of critical distance and the Weibull distribution is developed. In addition, both the influence of stress gradient effect and the size effect on the critical distance are considered. Specifically, under given loading cycles, the critical distance decreases with the increase of the stress gradient. Therefore, a relative stress gradient modified critical distance model is proposed to quantify the size effect. Finally, experimental data of nickel-based alloy GH4169 and aluminium alloy Al 2024-T351 are utilized for model validation and comparison, and results indicated that the proposed model shows better predictive ability than the traditional method.

Key words: notch, fatigue, critical distance, stress gradient, size effect

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