介电微裂纹对铁电陶瓷有效电弹性质的影响

EFFECT OF DIELECTRIC MICROCRACKS ON THE EFFECTIVE ELECTROELASTIC PROPERTIES OF FERROELECTRIC CERAMICS

采用细观力学结合压电介质的Stroh方法,对介电微裂纹引起的铁电陶瓷性能改变进行研究。考虑电畴间的相互作用,忽略微裂纹和电畴之间的相互作用,对裂纹面电边界条件采用介电边界条件,计算在电场作用下微裂纹取向和微裂纹密度对铁电陶瓷压电系数及介电系数的影响。计算结果表明,随微裂纹密度增加,压电系数增大,而介电系数减小;微裂纹取向对压电系数有较大影响,但对介电系数无影响。

The influence of dielectric microeracks on the properties of ferroelectric ceramics is investigated by using the methods of micromechanics and Stroh approach, The interaction of domains is considered and the coupling between domains and microcracks is neglected, The dielectric boundary condition on the crack surfaces is employed to calculate the effects of microcrack density and orientation on the piezoelectric coefficient and dielectric permittivity under electric field loading. The calculations show that the orientation of micro-cracks has no influence on the effective dielectric permittivity, though they influence the piezoelectric coefficient significandy. It is found that the piezoelectric coefficient increases while the dielectric permittivity decreases as the microcrack density increases.