Fatigue crack growth characteristics of Fe and Ni under cyclic loading using a quasi-continuum method.

Ren-Zheng Qiu,Te-Hua Fang,Yi-Chen Lin

doi:10.3762/bjnano.9.93

Abstract

A quasi-continuum (QC) method based on the embedded atom method (EAM) potential was employed to investigate the fatigue crack growth and expansion characteristics of single-crystal Fe and Ni under cyclic loading modes I and II. In particular, the crack growth and expansion characteristics of Fe and Ni under cyclic loading were evaluated in terms of atomic stress fields and force–distance curves. The simulation results indicated that under cyclic loading, the initially damaged area of the crack will coalesce again after compression or shear to the initial geometry leading to a strengthening of the material. If no coalescence appears, the crack spreads rapidly and the material breaks. Moreover, under the cyclic loading of shear at any orientation, the slip dislocation observed in the materials considerably affects the release of stress.

Highlights

When materials undergo cyclic loading, the growth of cracks in the material leads to fracture, which is referred to as fatigue
Considerable attention has been focused on the investigation of the fatigue crack growth behavior in single crystals under cyclic loading using molecular dynamics (MD), which is an effective tool for analyzing the mechanical deformation and mechanical properties of materials at the microscopic scale [1,2,3,4,5,6,7,8,9,10,11,12,13]
The fatigue crack growth and expansion characteristics of single-crystal Fe and Ni under the cyclic loading modes I and II were examined by a QC method

Summary

Introduction

When materials undergo cyclic loading, the growth of cracks in the material leads to fracture, which is referred to as fatigue. For facecentered cubic (FCC) metallic systems, Wu et al [10] have investigated the fatigue crack growth in single-crystal Ni under different cyclic loading regimes. They found that different crack propagation and stress distributions lead to changes in fatigue crack growth rates and crack opening displacements. Ma et al [11] have examined the effect of orientation on the fatigue crack propagation in single-crystal iron under cyclic loading, leading to differences in the crack growth rates and slip directions. The plastic deformation and double slip in single-crystal Ni and Cu

Methods

Results

Conclusion