CuO added Pb0.92Sr0.06Ba0.02（Mg1/3Nb2/3）0.25（Ti0.53Zr0.47）0.75O3 ceramics were studied to prepare high-quality multilayer piezoelectric actuators with pure Ag electrodes at 900 ℃. CuO addition not only reduced th...CuO added Pb0.92Sr0.06Ba0.02（Mg1/3Nb2/3）0.25（Ti0.53Zr0.47）0.75O3 ceramics were studied to prepare high-quality multilayer piezoelectric actuators with pure Ag electrodes at 900 ℃. CuO addition not only reduced the sintering temperature significantly from 1260 ℃ to 900 ℃ but also improved the ceramic density to 7.742 g/cm3. The 0.7 wt.% CuO added ceramic sintered at 900 ℃ shows the remnant polarization （Pr） of 40 μC/cm2, 0.28% strain at 40 kV/cm, and the piezoelectric coefficient （d33） of 630 pC/N. This ceramic shows a strong relaxor characteristic with a Curie temperature of 200 ℃. Furthermore, the 0.7 wt.% CuO added ceramic and pure Ag electrodes were co-fired at 900 ℃ to prepare a high-quality multilayer piezoelectric actuator with a d33 of over 450 pC/N per ceramic layer.展开更多
Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure. In this paper, the stress ...Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure. In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical con?guration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric ?eld distribution, are analyzed by moir′e interferometry experiment and ?nite element numerical simulation. Based on the above analysis, two optimized geometrical models are presented for the purpose of geometrical con?guration selection, with which stress concentration can be reduced signi?cantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is e?ectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model II is 93.1% smaller than that in the conventional model. It is proved that stress concentration can be e?ectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.展开更多
The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field ...The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field concentrations ahead of the electrodes in the multilayer piezoelectric actuators are examined. By considering a representative unit in realistic multilayers, the problem is formulated in terms of electric potential between the electrode tips and results in a system of singular integral equations in which the electric potential is taken as unknown function. Effects are investigated of electrode spacing and piezoelectric coupling on the singular electroelastic fields at the electrode tips, and closed-form expressions are given for the electromechanical field near the electrode tips. Exact solution for un-coupled dielectrics is provided, where no piezoelectric coupling is present.展开更多
Piezoelectric bar-shaped resonators were proposed to act as hardness sensors in the 1960 s and stiffness sensors in the 1990 s based on the contact impedance method.In this work, we point out that both multilayer and ...Piezoelectric bar-shaped resonators were proposed to act as hardness sensors in the 1960 s and stiffness sensors in the 1990 s based on the contact impedance method.In this work, we point out that both multilayer and unimorph（or bimorph） piezoelectric actuators could act as stiffness/modulus sensors based on the principle of mechanical contact resonance. First, the practical design and the performance of a piezoelectric unimorph actuator–based stiffness sensor were presented. Then the working principle of piezoelectric multilayer actuator–based stiffness sensors was given and verified by numerical investigation. It was found that for these two types of resonance-based sensors, the shift of the resonance frequency due to contact is always positive, which is different from that of the contact impedance method. Further comparative sensitivity study indicated that the unimorph actuator–based stiffness sensor is very suitable for measurement on soft materials, whereas the multilayer actuator–based sensor is more suitable for hard materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472118,51602156,52177072,and 11274174)the Fundamental Research Funds for the Central Universities,China(Grant Nos.30916011104 and 30916011208)
文摘CuO added Pb0.92Sr0.06Ba0.02（Mg1/3Nb2/3）0.25（Ti0.53Zr0.47）0.75O3 ceramics were studied to prepare high-quality multilayer piezoelectric actuators with pure Ag electrodes at 900 ℃. CuO addition not only reduced the sintering temperature significantly from 1260 ℃ to 900 ℃ but also improved the ceramic density to 7.742 g/cm3. The 0.7 wt.% CuO added ceramic sintered at 900 ℃ shows the remnant polarization （Pr） of 40 μC/cm2, 0.28% strain at 40 kV/cm, and the piezoelectric coefficient （d33） of 630 pC/N. This ceramic shows a strong relaxor characteristic with a Curie temperature of 200 ℃. Furthermore, the 0.7 wt.% CuO added ceramic and pure Ag electrodes were co-fired at 900 ℃ to prepare a high-quality multilayer piezoelectric actuator with a d33 of over 450 pC/N per ceramic layer.
基金Project supported by the National Natural Sciences Foundation of China (No.10232030).
文摘Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure. In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical con?guration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric ?eld distribution, are analyzed by moir′e interferometry experiment and ?nite element numerical simulation. Based on the above analysis, two optimized geometrical models are presented for the purpose of geometrical con?guration selection, with which stress concentration can be reduced signi?cantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is e?ectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model II is 93.1% smaller than that in the conventional model. It is proved that stress concentration can be e?ectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.
文摘The present paper develops an analytical model for multi-electrodes in multi-layered piezoelectric actuators, in which the electrodes are vertical to and terminated at the edges of the medium and electroelastic field concentrations ahead of the electrodes in the multilayer piezoelectric actuators are examined. By considering a representative unit in realistic multilayers, the problem is formulated in terms of electric potential between the electrode tips and results in a system of singular integral equations in which the electric potential is taken as unknown function. Effects are investigated of electrode spacing and piezoelectric coupling on the singular electroelastic fields at the electrode tips, and closed-form expressions are given for the electromechanical field near the electrode tips. Exact solution for un-coupled dielectrics is provided, where no piezoelectric coupling is present.
基金financial support of the National Natural Science Foundation of China (Grant11090331)Support from the Chinese National Programs for Scientific Instruments Research and Development (Grant 2012YQ03007502)
文摘Piezoelectric bar-shaped resonators were proposed to act as hardness sensors in the 1960 s and stiffness sensors in the 1990 s based on the contact impedance method.In this work, we point out that both multilayer and unimorph（or bimorph） piezoelectric actuators could act as stiffness/modulus sensors based on the principle of mechanical contact resonance. First, the practical design and the performance of a piezoelectric unimorph actuator–based stiffness sensor were presented. Then the working principle of piezoelectric multilayer actuator–based stiffness sensors was given and verified by numerical investigation. It was found that for these two types of resonance-based sensors, the shift of the resonance frequency due to contact is always positive, which is different from that of the contact impedance method. Further comparative sensitivity study indicated that the unimorph actuator–based stiffness sensor is very suitable for measurement on soft materials, whereas the multilayer actuator–based sensor is more suitable for hard materials.
