Constitutive modelling of ferroelectric composites with a PSZ matrix

Constitutive relations of ferroelectric composites with a transformable par tially stabilized-zirconia (PSZ) matrix are developed based on the mean fie ld theory. The effect of phase transformation of the matrix on the electrom echanical coupling behaviour is highlighted. The general constitutive relat ions are specialized to a model ferroelectric composite in which lead-zirco nate-titanate (PZT) inclusions are oriented in three mutually orthogonal di rections, in order to illustrate the interaction. The analysis shows that i f the composite is partly or completely polarized, t --> m phase transforma tion call be induced by an applied electric field due to electromechanical coupling. t --> m phase transformation can increase the toughness of the fe rroelectric composite if the absolute values of the residual stress/strain and the residual electric displacement in the composite after the t --> m p hase transformation are larger than those before it.