Finite element analysis of cracks in ferroelectric ceramic materials

A constitutive law governing the behavior of ferroelectric ceramics is pres ented. The constitutive law includes the effects of ferroelectric and ferro elastic polarization reorientation, It is both multiaxial and non-proportio nal. This material model is implemented in a finite element code developed for this work. The material model determines changes of remanent strain and remanent polarization induced by the stress and electric field. The finite element code is used to analyze the effect of an elliptical hole in a ferr oelectric plate. The effects of aspect ratio and ratio of the permittivity of the hole interior to that of the plate material are determined. As the e llipse shrinks to a crack, the electric field and stress concentrations inc rease. As the permittivity of the ellipse interior approaches that of the f erroelectric material, the electric field concentration diminishes. Ferroel ectric and ferroelastic switching are shown to have a large effect on the m agnitude of the field concentrations. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.