Molecular Dynamics Simulation of Crack Propagation in Single-Crystal Aluminum Plate with Central Cracks

Jun Ding,Bo Liu,Lu-Sheng Wang,Kun Song,Xia Huang

doi:10.1155/2017/5181206

Abstract

The crack propagation process in single-crystal aluminum plate (SCAP) with central cracks under tensile load was simulated by molecular dynamics method. Further, the effects of model size, crack length, temperature, and strain rate on strength of SCAP and crack growth were comprehensively investigated. The results showed that, with the increase of the model size, crack length, and strain rate, the plastic yield point of SCAP occurred in advance, the limit stress of plastic yield decreased, and the plastic deformability of material increased, but the temperature had less effect and sensitivity on the strength and crack propagation of SCAP. The model size affected the plastic deformation and crack growth of the material. Specifically, at small scale, the plastic deformation and crack propagation in SCAP are mainly affected through dislocation multiplication and slip. However, the plastic deformation and crack propagation are obviously affected by dislocation multiplication and twinning in larger scale.

Highlights

With the development of micro/nanoelectromechanical systems, the mechanical properties of metal materials at the nanoscale have attracted significant attention
Chen [5] observed the fracture failure process in industrial steelgrit bainite structure with microcracks under uniaxial tension by scanning electron microscopy (SEM), and the results revealed that the major fracture mechanism involved the formation, growth, and connection of microvoids
The temperature sensitivity of the material is relatively low, the dislocation width of facecentered cubic (FCC) structure is relatively large, and the influences of temperature on the capability of the material to resist deformation and plastic yield strength are relatively small, and these results are consistent with the results reported by Brochard et al [32]

Summary

Introduction

With the development of micro/nanoelectromechanical systems, the mechanical properties of metal materials at the nanoscale have attracted significant attention. Mahato et al [8] investigated the effects of model size and strain rate on the stress-strain relationship of single-crystal copper at the nanoscale by molecular dynamics method and obtained the critical strain rate of single-crystal copper They believed that dislocation nucleation was the major mechanism responsible for the material fracture. Numerous high-level researches have been carried out on factors affecting the mechanical properties of metal materials with microcracks under tensile load, deficiently, the effect of microscopic mechanism of dislocation and twinning on stress-strain relationship and crack propagation has rarely been reported. The crack propagation process in nanoaluminum plate with central cracks under tensile load was studied by molecular dynamics method; the effects of model size, crack length, temperature, and loading strain rate on material strength and crack propagation were systematically analyzed. Dislocation, twin crystal, and phase transition on material’s mechanical properties and crack propagation were discussed

Molecular Dynamics Simulation

C11 C12 C44 Mp

Results and Discussions

Yield point of model 6

Conclusions