A modified strength degradation model of 45 steel under cyclic loading

ABSTRACT

In this paper, a modified degradation model is proposed to simulate the residual strength of 45 steel under cyclic loading, which is then applied to analyse the rule of strength degradation of the metal. The degradation data of 45 steel tests shows the relationship between the ratio of cycle number and residual strength. The model is built by considering a series of cycle ratio errors between loading times and fatigue life on the basis of the Schaff theory and power degradation model criterion. The model is applied to numerical simulation of 35CrMo, with the outcome being presented to illustrate the applicability and efficiency of the model. Moreover, the results provide some theoretical references for the fatigue life analysis of metals.

KEYWORDS:

• Strength degradation
• fatigue
• 45 steel
• numerical simulation
• reliability

Nomenclature

$R\left(n\right)$	=	residual strength
${\sigma }_{max}$	=	maximum stress $\left(MPa\right)$
$\sigma$	=	load stress $\left(MPa\right)$
${\sigma }_b$	=	static tensile strength $\left(MPa\right)$
$n$	=	loading times
$N$	=	fatigue life
$k$	=	ratio of loading times to fatigue life

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [51675324].

Notes on contributors

Yang Qu

Yang Qu is pursuing her Master’s degree at Shanghai University of Engineering Science. Her research area is focused on fatigue life prediction and reliability design theory.

Xintian Liu

Xintian Liu is currently working as an associate professor of vehicle engineering at Shanghai University of Engineering Science (China) since 2007. His research area is focused on fatigue life prediction and evaluation, reliability design theory and vehicle system dynamics. He received his Ph.D. degree in power machinery and engineering from University of Shanghai for Science and Technology (China) in 2016. He received his master degree in vehicle engineering from Shanghai Jiaotong University (China) in 2007.

Minghui Zhang

Minghui Zhang is pursuing his Master’s degree at Shanghai University of Engineering Science. His research area is fatigue life prediction and reliability design theory.

Zhiqiang Liang

Zhiqiang Liang is pursuing his Master’s degree at Shanghai University of Engineering Science. His research area is fatigue life prediction and reliability design theory.