Numerical Simulations Of Crack Propagation Of Single Crystal Aluminum Based On Cohesive Zone Model

Crystals accounted for the majority of the solid material in the nature. The study andapplication of single crystal material attracts more attentions with the development ofnanomaterials science, compared with the polycrystalline material, its physical propertiesare more sensitive and also exhibit significant anisotropy，and the orientation of crystalshould also be taken into account as an important factor. A large number of studies haveshown that the mechanical behavior of crystalline materials can be corresponding to themicroscopic changes in thermodynamics, to study the mechanical properties of crystal bymolecular dynamics method has significant physical significance.Cracking is a common form of macro defects in crystal. It seriously affects thepreparations and applications in practical engineering of crystal. The fracture behavior ofsingle crystal aluminum with cracks was discussed in this paper by combining moleculardynamics and finite element method. First, using molecular dynamics simulations tostudy the tensile behavior of single crystal aluminum, record the curve ofload-displacement, determine its elastic properties and the parameters of cohesive zonemodel, the analysis the field evolution of single crystal aluminum with cracks, thedevelopment of micro-cracks initiation and the macroscopic crack propagation behaviorwith finite element method.The results show that：(1) Single crystal aluminum is orthotropic anisotropy materialwhich contains nine independent elastic constants, and the elastic matrix decided bymolecular dynamics is approximately symmetrical.(2) Some branch cracks appear duringthe crack propagation process, but they will eventually tend to close with thedevelopment of the main crack and the redistribution of stress field.(3) Obvious stressconcentration is found at the crack tip, the stress intensity factor and energy release ratecalculated by the finite element results are correspond to the fracture toughness ofcohesive zone model.(4) The elastic modulus, elastic limit and fracture toughness ofcohesive zone model will have an impact on the fracture properties of the material.