Control of jet noise continues to be an important research topic. Exhaust-nozzle chevrons have been shown to reduce jet noise, but parametric effects are not well understood. Additionally, thrust loss due to chevrons at cruise suggests significant benefit from active chevrons. The focus of this study is development of an active chevron concept for the primary purpose of parametric studies for j...

This study presents the status and results from an effort to design, fabricate, and test an adaptive jet engine chevron concept based upon embedding shape memory alloy (SMA) actuators in a composite laminate, termed a SMA hybrid composite (SMAHC). The approach for fabricating the adaptive SMAHC chevrons involves embedding prestrained Nitinol actuators on one side of the mid-plane of the composi...

In this study, a new Braille display is constructed based on the vibration of a Shape Memory Alloy (SMA) wire. To present Braille information, a vibration actuator is used instead of conventional Braille dots. According to the temperature-dependent characteristic shrinkage and the vest ration to the initial length of an SMA wire, a vibration actuator which can be driven by several [Hz]-100 [Hz]...

Most of the current ’applications’ of microelectromechanical systems can be found in the sensor field. The development of micro-actuators is severely hindered by the low power-to-volume ratio of most actuator technologies. Most of the presented micromotors also require reduction gearing and suffer from wear or fatigue problems. Shape Memory Alloy (SMA) actuators offer the advantage of extremely...

Shape memory alloys have been widely proposed as actuators, in fields such as robotics, biomimetics and microsystems: in particular spring actuators are the most widely used, due to their simplicity of fabrication. The aim of this paper is to provide a general model and the techniques for fabricating SMA spring actuators. All the steps of the design process are described: a mechanical model to ...

Although medical applications for shape memory alloys (SMA) now dominate in today’s market, there are many applications in the industrial sector which have reached large volume production that far surpass the material usage in the medical fields. In the early growth of shape memory alloy technology the most important applications were for fasteners and couplings, mainly in the military sector. ...

Surgeons performing endovascular interventions have high expectations with regard to the 15 improvement of their operating tools and, more specifically, of their catheters. Active catheters, in which the tip moves actively using shape memory alloy (SMA) actuators, constitute a promising approach. In this article, we review existing SMA-based active catheters present in the literature. We analyz...

Mechanical counter-pressure (MCP) space suits, which apply pressure to the wearer using tight-fitting materials rather than pressurized gas, offer numerous mobility and mass advantages over traditional gas-pressurized suits [1]. However, MCP design challenges related to pressure uniformity, pressure magnitude, and donning/doffing remain unsolved [2]. Previous MCP efforts have focused on passive...

Shape Memory Alloys (SMA) are good candidates to actuate endoscope heads but the cooling problem must be solved particularly in confined situations. For these reasons, a new SMA microactuator specially designed for active endoscopy applications has been developed in our laboratory. This work is a new step in the approach of using integrated thermoelectric cooling with SMA actuators. In fact, th...

Thin-film shape memory alloys (SMAs) have become excellent candidates for microactuator fabrication in MEMS due to their capability to achieve very high work densities, produce large deformations, and generate high stresses. In general, the material behavior of SMAs is nonlinear and hysteretic. To achieve the full potential of SMA actuators, it is necessary to develop models that characterize t...