Elastic Fields By A Dislocation Loop In An Anisotropic Elastic Body With General Boundary/Interface Conditions And Its Applications

The boundary and interface problems have always been the subject of research in materials science,because they are directly related to the properties of the whole material,such as performance,delamination,force transfer and so on.Based on the latest results of Green's functions in anisotropic half-space and bimaterials,this thesis studies the interaction between elastic fields and material boundaries and interfaces caused by dislocation loops in an anisotropic body.The main work has been done in the following two aspects:1.Based on the latest research results of Green's functions in anisotropic half-space,the formulas of the displacement and stress fields induced by a dislocation loop in an anisotropic half-space elastic body under general boundary conditions are obtained.The Matlab programs are written for numerical calculations,and the effects of several different boundary conditions on the elastic fields induced by dislocation loops are studied in detail.Then,based on the elastic fields corresponding to three groups of boundaries,the dislocation loop distribution model of single crystals nano-indentation is established.The three sets of boundary conditions are traction-free contact,partially sticking contact and completely contact between the indenter and the pressed crystals.Through simulation,we observed for the first time significant differences in the magnitude of sink-in,pile-up,and residual stress components of the indentation profile under different boundary conditions,which can be used as a reference for future nano-indentation research.2.Based on the latest research results of Green's functions of anisotropic bimaterials,considering the influence of material interface conditions on the elastic fields,the simple line integrals of displacement and stress fields induced by dislocation loops under general interface conditions in anisotropic bimaterials are derived.The traditional formulas of bimaterials elastic fields only consider the case of perfect-interface,but the formulas given in this thesis fully consider the interface discontinuity of bimaterials.The displacement and stress fields caused by dislocation loops under the perfect-interface model and dislocationlike interface model in Fe-Cu system are calculated by Matlab.The results show that different interface conditions have great influence on the elastic fields induced by dislocation loops,which can be used in the interface design and research of composite materials.