Affiliations: Department of Engineering Mechanics, Tsinghua University, Beijing, P. R. China
Note:  Address for correspondence: Shouwen Yu, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P. R. China. E-mail: email@example.com.
Abstract: Ferroelectric materials is one of important smart materials using as actuators and sensors. Electric fatigue and damage of radiation may induce pinched polarization hysteresis loops and asymmetric strain hysteresis loops of ferroelectric materials, respectively. The damage level can be reflected by the evolution of hysteresis loops. This paper formulates a novel constitutive model to characterize the hysteresis deformation behavior of ferroelectric ceramics by electric fatigue. The results show that the alignment of the defect dipoles acts as an internal bias field and increases the coercive field, while the domain-wall pinning can prohibit domain switching and causes degradation of remanent polarization. Then the damage criterion of the ferroelectric materials due to electric fatigue is proposed. The temperature in the ferroelectric and ferromagnetic materials may rise due to energy dissipation under loading. Thermal effects on the mechanical behavior in ferroelectric/ferromagnetic materials are investigated. Using the magnetic saturation model, the temperature fields around the tip of a narrow elliptic hole are calculated under different conditions. It is found that the magnitude of temperature increment strongly depends upon the geometrical shape of the hole, the frequency and wave shape of the magnetic loading.