Stress Ratio and Notch Effects on the Very High Cycle Fatigue Properties of a Near-Alpha Titanium Alloy

Materials

Bin Zhong¹  Qi Huang²  Chao He³  Qingyuan Wang³  Yong-Jie Liu³  Kun Yang³  Zhi-Yong Huang⁴ 

[1] Beijing Institute of Aeronautical Materials, Aviation Industries of China, Beijing 100095, China;Department of Civil Engineering, Sichuan College of Architectural Technology, Deyang 618000, China;Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province, College of Architecture and Environment, Sichuan University, Chengdu 610065, China;School of Aeronautics and Astronautics, Sichuan University, Chengdu 610064, China;

关键词: VHCF;    multi-point surface crack initiation;    notch;    mean stress;    fatigue strength prediction;   

DOI  :  10.3390/ma11091778

来源: DOAJ

【 摘 要 】

Ultrasonic fatigue tests up to 1010 cycles were performed on a turbine engine titanium alloy (Ti-8Al-1Mo-1V) at the stress ratio (R) of −1 with smooth specimens and at R = −1, 0.1 and 0.5 with notched specimens. As a result, with increase of fatigue life, the source of reduced fatigue life caused by multi-point surface crack initiation changes from crack propagation stage to crack initiation stage in the high cycle fatigue regime. Notch effect further promotes the degeneration of high cycle and very high cycle fatigue strength at R > −1. The bilinear model, extended from the Goodman method, can better estimate the mean stress sensitivity of this titanium alloy. The fatigue mean stress sensitivity and fatigue-creep mean stress sensitivity of this material increased with the increase of fatigue life. The new model, based on the Murakami model, can provide more appropriate predictions for notch fatigue strength.

【 授权许可】

Unknown