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Electromagnetic actuators have been commonly deployed in robotics technology for obtaining expressions and other motion. However, the current technology is unable to meet the requirement of space limitation and at the same time provide high displacement and force (22–25 mm and force 2–7 N). The loss of space due to bulky motors prohibits the possibility of installing processing and control cards inside the skull of humanoid robot which is required to realize a smart expressive face. Our study shows the feasibility of utilizing piezoelectric ultrasonic motors and fiber matrix composites as an alternative to electromagnetics. The results are very promising and clearly demonstrate the promise of piezoelectric technology. A sample skin was developed from artificial room temperature vulcanized silicone material with piezoelectric unimorphs embedded inside it. For actuation, ultrasonic motors were implemented to drive anchor points of our humanoid robot-Albert to demonstrate facial expressions like opening and closing of eyes, smiling and squinting. Characterization of macro fiber composite for both sensing and actuation was also conducted and results are highly encouraging. [ABSTRACT FROM AUTHOR]

The density of hollow particle (microballoon) filled composites called syntactic foams can be varied by two methods. The first method is the variation in microballoon volume fraction and the second method is the variation in the microballoon wall thickness, while keeping their volume fraction the same. A comparison of compressive properties of syntactic foams having microballoons of four different wall thicknesses in five volume fraction each is presented here. It is found that the compressive strength and modulus vary linearly with respect to the foam density. Dielectric constant, dielectric loss and electrical impedance are measured for four syntactic foam compositions with respect to temperature and frequency. Dielectric constant and loss are found to decrease with increase in frequency and with decrease in temperature in the range of 40–140°C. [ABSTRACT FROM AUTHOR]

This study reports the mechanism for the enhancement of resistivity in the (Ba x Sr 1 - x )(Cu 1/3 Nb 2/3 )O 3 system. In previous investigations, it has been found that the resistivity of this system decreases significantly with increasing temperature and applied electric field which inhibits the measurement of dielectric properties. The decrement in the resistivity was associated with the eutectic transformation from cuprous to cupric oxide, which occurs in the vicinity of 1075°C at a partial pressure of 0.21 atm of O 2 during sintering. It was found that by decreasing the sintering temperature to 975°C by addition of ZnO and B 2 O 3 , the resistivity of the system increases by 2 orders of magnitude. The stability under the applied field and temperature is also enhanced permitting the dielectric measurement. The dielectric constant and loss measurement as a function of temperature confirmed that this system has high Curie temperature of more than 600°C. [ABSTRACT FROM AUTHOR]

We report the presence of an intermediate ferroelectric orthorhombic FE o phase in oriented 0.92Pb(Zn 1/3 Nb 2/3 )O 3 -0.08PbTiO 3 single crystals. High field-long time poling was done in order to stabilize the inherent symmetry of the crystal. Pyroelectric and dielectric measurements were conducted on <001>, <011> and <111> oriented crystals. Pyroelectric and dielectric peaks corresponding to a ferroelectric rhombohedral FE r to FE o phase transition was observed for <111> oriented piezocrystals at ∼80°C. [ABSTRACT FROM AUTHOR]

This paper reports the uniaxial and hydrostatic pressure dependence of the electromechanical property of the 0.68 Pb(Mg 1/3 Nb 2/3 )O 3 -0.32PbTiO 3 (PMNT), single crystals. A significant decrease was observed in the mechanical quality factor ( Q m ) under both uniaxial and hydrostatic pressures. This decrease was most dramatic under uniaxial conditions. The decrement in the magnitude of the Q m with pressure can be attributed to the stress induced transformation into ferroelectric tetragonal state whose c -axis is oriented at 90° from the direction of the applied stress and increased polar fluctuations within the poled piezoelectric state. The low value of Q m under uniaxial conditions may present a significant thermal stability problem under moderate drive levels. [ABSTRACT FROM AUTHOR]

We report an ultra-low start-up speed windmill that consists of a 72 mm diameter horizontal axis wind turbine rotor with 12 alternating polarity magnets around its periphery and a 60 mm × 20 mm × 0.7 mm piezoelectric bimorph element having a magnet at its tip. This wind turbine operates at very low Reynolds number of around 2×104, but still it has reasonably high power coefficient of about 11% at the optimal tip speed ratio of 0.7. It was found to produce peak electric power of 450 μW at the rated wind speed of 4.2 mph. An extremely low start-up wind speed of 2.4 mph was achieved by operating the bimorph in actuator mode. [ABSTRACT FROM AUTHOR]

In this paper, we discuss how the material parameters of piezoelectric phase affect the magnetoelectric properties of the laminate composite especially focusing on the role of loss factors and electromechanical resonance of piezoelectric phase. By analyzing experimental results of magnetoelectric laminate composite consisting of Pb(Zr,Ti)O3-based piezoelectric layer and Metglas ferromagnetic layers, we demonstrate that the losses of piezoelectric materials play an important role in controlling the magnetoelectric sensitivity of the laminate composite. Further, we show that direct magnetoelectric effect is maximized at anti-resonance frequency while the converse magnetoelectric effect is maximized at resonance frequency of the laminate composite. [ABSTRACT FROM AUTHOR]