The Interaction Among Multi-defects In Multi-field Coupling Materials

As a kind of advanced functional material,multi-field coupling materials have good multi-field coupling characteristics and are very sensitive to external environment,such as force field,electric field,magnetic field and temperature field,and is widely used in various engineering structures.With its wide application,many research issues of multi-field coupling materials have been proposed for material workers and mechanical analysis.The inherent brittleness of multi-field coupling materials makes them inevitably produce various defects such as holes,cracks,dislocations,inclusions,etc.during the production,processing and using.These defects have a great impact on the safety performance of materials.The interaction between dislocations and material microstructures has an important influence on the mechanical properties and physical properties of materials.Therefore,the interaction among multiple defects in multi-field coupling materials has become one of the research hotspots.In this paper,the interaction between dislocations and different shapes of cracks in magnetoelectroelastic composites,quasicrystal and quasicrystalline piezoelectric materials are studied,which provides a theoretical reference for the practical application of materials.Firstly,based on the fundamental equations of magnetoelectroelastic material and the analytic function theory,by using the well-known complex variable techniques introduced by Muskhelishvili combined with the superposition principals,the closed form solution of the generalized stress field of the interaction between many parallel screw dislocations and a semi-infinite crack in an infinite magnetoelectroelastic solid are derived.Besides,the Peach-Koehler formula of n parallel screw dislocations is given.The numerical examples are provided to investigate the effect of the number of dislocations on the energy release rate when the dislocations are located at the real axis of equal distance,and the generalized stress field of the interaction between the crack and dislocations are also illustrated.Secondly,applying this research method to the study of the interaction between a finite crack and many screw dislocations in quasicrystalline materials,the generalized stress intensity factors and the force acting on the dislocation are obtained.The numerical examples are provided to discuss the influence of the dislocation position on the generalized stress field due to the existence of dislocations and crack.And the influences of the position and distribution of dislocations on the generalized stress field are explored.Finally,based on the fundamental equations of quasicrystalline piezoelectric materials,the anti-plane problem of a wedge-shaped crack interacting with many screw dislocations under far-field loading is considered,and the dislocation core is considered to be subjected to line force and line charge.The effects of wedge angle,dislocation position,dislocation distribution and the number of dislocations on field intensity factors,energy release rate and image force on the dislocation are illustrated by numerical examples.