Analysis Of Defect In Functionally Graded Piezoelectric Materials Based On Multi-field Coupling Effects

The functionally graded piezoelectric material is a new kind of heterogeneous composite material,which has been widely used in aerospace,military,and other fields.Due to the complex manufacturing process and service environment,a large number of defects will be produced in the use of functionally graded piezoelectric material.Therefore,it is very important to study the functionally graded piezoelectric material with defects under the multifields.In this paper,the finite element software ABAQUS is used to study the problem of single defect and multi defects of functionally graded piezoelectric materials under the action of single and multi electric-mechanical fields.The problem of the three-dimensional defect of piezoelectric materials is further studied.Finally,the problem of functionally graded piezoelectric materials with two-dimensional defect and three-dimensional defect under thermal and thermoelectric fields is studied.The main contents include:Firstly,based on the constitutive relation,geometric relation and boundary condition of functionally graded piezoelectric materials under the action of multi-fields,the gradient of materials is divided by the principle of the layering method.In this paper,the finite element model of a single hole in a functionally graded piezoelectric plate is established.The variation of the stress and potential distribution around the defect under the action of different gradient parameters,different defect shapes,different defect sizes,and different gradient functions under the mechanical,electric and electromechanical coupling fields are discussed.The geometric process function is proposed as a gradient function to adjust the properties of functionally graded piezoelectric material.The effects of different gradient functions on the stress and electrical displacement around the defect are obtained.Secondly,for the multi-holes problem in functionally gradient piezoelectric materials,under the action of mechanical field,electric field and electromechanical coupling field,the influence of parallel distribution,collinear distribution,and different arrangement,the change of defect size and the number of defects on the distribution of stress and potential displacement around the multiple defects is discussed,respectively.The enhancement effect and the shielding effect of the multiple defects interaction is further analyzed.Thirdly,based on problems with the different three-dimensional defects in practical engineering,the finite element models of the through defect,corner defect,surface defect,and embedded defect are established.Under the coupling action of mechanical field,electric field and electromechanical coupling fields,The distribution of stress and electrical displacement around different types of three-dimensional defects is obtained by using finite element method,and the influence of shape factor of defect on stress and electrical displacement around the defect is discussed.Meanwhile,the verification is made under the action of mechanical field by using the isogeometric analysis.Finally,under the action of thermal field and thermoelectric field,the gradient parameters of single hole model in functionally gradient piezoelectric materials are analyzed.The effects of gradient parameters on the thermal stress and electrical displacement around the defect are studied.Furthermore,the influence of arrangement model,defect size and defect shape on the stress and electric displacement around the defects under thermal load is studied.At the same time,the research shows that the application of the electric field can also effectively reduce thermal stress.