Analysis Of Some Defects In Quasicrystals Piezoelectric Bi-material

As a new functional and structural material,quasicrystals(QCs)has been extensively used in many fields due to its special structure and excellent properties.However,the defects(such as dislocations,cracks,holes,etc.)in the quasicrystals structure have great influence on the properties and applications of quasicrystals materials.Therefore,it is of great significance to investigate the quasicrystals material with defects.Based on the basic equation of quasicrystals piezoelectric materials,the quasicrystals piezoelectric bi-material with defects are analyzed by using complex variable function method,which provides the theoretical basis for further study on the fracture mechanics of quasicrystals piezoelectric materials.The main work is as follows:1.First of all,the solution of a screw dislocation in infinite quasicrystals piezoelectric bi-material is investigated.The analytical expressions of the electroelastic field and the image force acting on the dislocation are obtained,moreover,the interaction between the screw dislocation and interface is analyzed.Then the solution of a screw dislocation in the semi-infinite quasicrystals piezoelectric bi-material is obtained.The distribution characteristics with regard to the phonon stresses,phason stresses and electric displacements in infinite and half infinite quasicrystals piezoelectric bi-material are analyzed in detail,and the effects of the phonon-phason fields coupling elastic constants on the image force are discussed by numerical examples.2.Based on the above research work,the problem of the interaction between a screw dislocation and the wedge shaped cracks in the infinite quasicrystals piezoelectric bi-material is studied.The analytical expressions of the electroelastic field,the intensity factors at the crack tip as well as the image force on dislocation are presented.The effects of the geometrical parameters of dislocation location and wedge angle,the phonon-phason fields coupling elastic constant on the image force andintensity factors are analyzed by numerical examples.Moreover,the distribution characteristics of phonon stress,phason stress and electric displacement in the bi-material are discussed in detail.On the basis of obtained solution,some special cases are discussed.3.The interaction between a screw dislocation and the elliptical hole with two asymmetrical cracks in the infinite quasicrystals piezoelectric bi-material is discussed by constructing a new conformal function method.The analytical expressions of the electroelastic field are obtained.The fracture criteria such as intensity factors and image force are given,besides,on the basis of the obtained solution,some special cases are analyzed.Then the influence of geometric parameters of dislocation location and the phonon-phason fields coupling elastic constants on the image force and the intensity factors are discussed by numerical examples.