科研之友
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摘要
The method of dislocation simulation of domain switching toughening is extended to the piezoelectric coupling field. As a typical example, domain switching toughening in the ferroelectric ceramic with a semi-infinite crack being perpendicular to spontaneous polarization direction subjected to negative electric field is evaluated by using dislocation simulation. The transformed strain nucleus simulated by an assembly of four different edge dislocations is constructed first, then the generalized stress intensity factor generated by four dislocations in strain nucleus is used to simulate the transformed particle toughening. Based on this solution, the formulations for toughening arising from ferroelectric domain switching are derived by the Green's function method. Taking BaTiO3 ferroelectric ceramic for example, the exact expression of generalized stress intensity factor is obtained, and it is discovered that the crack propagation can be promoted by domain switching induced by negative electrical load when crack surface is parallel to the isotropic plane, this result meets experimental phenomenon well. This method can also be used to evaluate domain switching toughening in ferroelectric ceramics under some other load and polarization types and those with some other cracks or holes.
