Abstract
The fatigue resistance of coarse-grained (CG) metals can be greatly improved by introducing a nanograined surface layer. In this study, the Weibull distribution is used to characterize the spatially-random fracture properties of specimens under axial fatigue. For the cylindrical solid specimen, the heterogeneity of element sizes may lead to unfavorable size effects in fatigue damage initiation and evolution process. To alleviate the size effects, a three-dimensional cohesive finite element method combined with a local Monte Carlo simulation is proposed to analyze fatigue damage evolution of solid metallic specimens. The numerical results for the fatigue life and end displacement of CG specimens are consistent with the experimental data. It is shown that for the specimens after surface mechanical attrition treatment, damage initiates from the subsurface and then extends to the exterior surface, yielding an improvement in the fatigue life. Good agreement is found between the numerical results for the fatigue life of the specimens with the nanograined layer and experimental data, demonstrating the efficacy and accuracy of the proposed method.
Highlights
Since the fatigue resistance of metal is strongly dependent on its surface properties, much attention has been paid to the surface modification [1]
The flow stress of the CG specimen is from the experiments [46], that of the nanograined layer (NGL) is estimated from experiments of the SMATed 316L stainless steel (SS) [47]
The heterogeneity of element sizes in a cylindrical solid may result in size effects in the fatigue process when the conventional global Monte Carlo method is employed
Summary
Since the fatigue resistance of metal is strongly dependent on its surface properties, much attention has been paid to the surface modification [1]. A number of experiments have been conducted to investigate the effects of the NGL on the fatigue behavior of SMATed metallic specimens. This is of importance for the practical applications of nanostructured metals. Based on the scatter of concrete tensile strength and bond strength, Hartig and Häussler-Combe employed MCS to study the statistics of crack widths [30] It is quite difficult for the MCS to deal with the high nonlinearity related to the fracture process because of the high computational cost associated with a large number of finite elements [31].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
