This paper presents the design and analysis of a cantilever beam resonator that is driven by a piezoelectric material. In this paper, we shall look at the effects of miniaturizing the resonator. The beam is a bimorph structure with a Lead Zirconate Titanate (PZT) layer and a stainless steel substrate layer. The PZT layer is electroded in segments to form a sensor and actuator pair for feedback to drive the resonator. Key issues are the effects of design choices on the gain required to cause self-oscillation. These choices are placement and sizing of the sensor and actuator. The study is based on an analytical model of the beam. Results show that the gain required for self-oscillation is highly dependent on the actuator and sensor size and location, the mode of vibration and the overall resonator size.
There are a number of designs that have been proposed for MR and ER fluid actuators. While studies have shown that the fluids themselves behave similarly (in terms of constitutive behavior), the design issues are clearly different. ER fluids require electric fields to control their behavior, while MR fluids require magnetic fields. The goal in each case is to maximize the field to achieve the highest possible change in fluid properties in the working volume. Design challenges are faced in trying to maximize this field in an actuator. This paper will focus on design issues for MR fluid actuators. The focus will be on how to get the most out of the field that is produced. One critical issue is how to produce high force with a low magnetic field. Magnetic field alignment and actuator geometry are investigated as design issues. Experimental data shall be presented for two distinct actuator designs.