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Latches are essential machine elements utilized by all sectors (military, automotive, consumer, manufacturing, etc.) with a growing need for active capabilities such as automatic release and reset, which require actuation. Shape memory alloy (SMA) actuation is an attractive alternative technology to conventional actuation (electrical, hydraulic, etc.) because SMA, particularly in the wire form, is simple, inexpensive, lightweight, and compact. This paper introduces a fundamental latch technology, referred to as the T-latch, which is driven by an ultrafast SMA wire actuator, that employs, a novel spool-packaged architecture to produce the necessary rotary release motion within a compact footprint. The T-latch technology can engage passively, maintain a strong structural connection in multiple degrees of freedom with zero power consumption, actively release within a very short timeframe ( Keywords: shape memory alloy, T-latch, active latch, rotary actuator, high-speed latch, SMA spooling, SMA packaging

A new family of piezoelectric actuators, called Recurves, exhibits high work per volume and have the extra benefit of performance and packaging tailorability. The focus of this paper is the dynamic performance of this novel actuation scheme. Two dynamic models, a detailed transfer matrix model and a simpler rod approximation model, are presented to predict the steady state frequency response of a general Recurve actuator driving a mass and spring load. Results from a [2.sup.3] design of experiments are given that validate these models and demonstrate the impact of the architectural design parameters on the dynamic behavior of a generic Recurve actuator.

Piezoelectric active diaphragms hold promise as an alternative to using passive diaphragms driven by voice coils for sound generation and noise cancellation applications. This paper presents an in-depth investigation of the acoustic response for curved polymeric piezoelectric active diaphragms. Simple analytical models were derived and experimentally validated to predict the structural dynamic and acoustic responses for generic polyvinylidene fluoride (PVdF) constant curvature active diaphragms with variable geometric parameters (width, radius, subtended angle, thickness). These models are useful for design purposes and for capturing the overall behavioral trends. To analyze the acoustic response mechanisms further, three-dimensional numerical models were also developed and experimentally validated. Parametric studies based upon these models reveal the potential of high acoustic outputs (over 100 dB in the far field) from optimized geometric configurations with subtended angles differing from the conventionally utilized flat, semicircular or circular configurations. These studies, corroborated by experiments on a variety of active diaphragm prototypes, conclude that the acoustic output is governed by the structural ring resonance, which can be designed such that the most efficient acoustic radiation is within the particular frequency range of operation. [DOI: 10.1115/1.1547461]

Distributed piezoelectric micromotor architectures have great potential because they combine the advantages of piezoelectric micromotors with the advantages of distributed architectures. However, to use a distributed architecture paradigm for piezoelectric micromotors, a basic motor building block is needed. To meet this need a piezoelectric micromotor building block, called a C-block, was developed. These C-blocks can be combined together in a variety of distributed architectures to expand their capabilities. This paper introduces a basic polymeric piezoelectric C-block micromotor design and a serial C-block micromotor architecture that demonstrates increased deflection capabilities. For both micromotor designs, simple manufacturing steps are described and analytical deflection models are presented. These micromotors were experimentally tested with prototypes ranging in size from a few millimeters to a few centimeters in scale. Results for an individual C-block micromotor and a serial C-block micromotor are presented. These results demonstrate the accuracy of the models and the feasibility of designing and fabricating polymeric piezoelectric micromotor architectures. [187]

The authors examine the use of smart materials in the design and construction of actuators. Topics include hybrid optimization techniques, piezoelectric configurations, and design tradeoffs.

The design of a piezoelectric-based microactuator to be used in the construction of an artificial hand is discussed. The microactuator is in the form of semicircular bimorph which consists of two layers of piezoelectric material connected electrically parallel. Several prototypes of this microactuator are tested through three different experiments. The results show that the microactuator's semicircular shape increases the force of the artificial hand.

The development of small actuators based on smart materials is one of the factors that has enabled the growth of smart structure technology. Most smart structure applications use piezoelectric actuators because of their small size and low energy requirements. However, such actuators do not cover all force-deflection capabilities. Proposals to fill the gap include curved piezoelectric bender actuators, known as C-blocks. A simple, steady-state theoretical deflection-voltage model for a C-block is presented.