A review of shape memory alloy research, applications and opportunities

With the increased emphasis on both reliability and multi-functionality in the aerospace industry, active materials are fast becoming an enabling technology capturing the attention of an increasing number of engineers and scientists worldwide. This article reviews the class of active materials known as shape memory alloys (SMAs), especially as used in aerospace applications. To begin, a general overview of SMAs is provided. Their useful properties and engineering effects are described and the methods in which these may be utilized are discussed. A review of past and present aerospace applications is presented. The discussion addresses applications for both atmospheric earth flight as well as space flight. To complete the discussion, SMA design challenges and methodologies are addressed and the future of the field is examined.

https://journals.sagepub.com/doi/pdf/10.1243/09544100JAERO211

Aerospace applications of shape memory alloys

http://milad-engc.persiangig.com/Recent.pdf

Recent research advances on the dynamic analysis of composite shells: 2000-2009

A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

Distributed Power Harvesting Systems Using DC Power Sources

Method for distributed power harvesting using DC power sources

The present invention is a wing having telescoping segments deployed via an actuator composed of a heat activated material. The actuator is a coiled tube of shape memory alloy (SMA) with large force-displacement characteristics activated thermally by either a fluid or an electrical charge. Actuator motion extends an inner wing segment from an outer wing segment when the coiled tube is compressed. Compression is achieved by heating the coiled tube so as to cause a phase transformation from Martensite to Austenite. The inner wing segment may be retracted by a mechanical device or second SMA coil when the coiled tube is cooled and returned to its Martensite phase.

Telescopic wing system

A flextensional transducer assembly having a single flextensional cell with a transducer housed with a platten The transducer expands and contracts in a transverse direction to cause inverse movement in the platten in the axial direction The platten may include either an elbow at the intersection of walls or corrugated pattern along the top and bottom walls The platten is manufactured from one piece using Electrical Discharge Machining A load is applied to the platten to then slot in the transducer into the platten before releasing the load to mechanically capture the transducer

Flextensional transducer assembly and method for its manufacture

The invention described herein is a novel power circuit capable of electrically driving devices whose mechanical action is accomplished by induced strain transducers. The power circuit neither recycles nor dissipates the energy returned from the near lossless transducer, instead redirects power either to another transducer of the same type or to the transducer itself. The invention is based on a balanced capacitive loading method wherein the load itself acts as the energy storage element in the energy balance system. In the preferred mode, the circuit directs power to a symmetric couple where both loads in the couple consist of one or more transductive elements. The invention eliminates the need for a large power-supply bypass capacitor in driving reactive loads thereby reducing the peak power handled by the d.c. power section.

Device and method for driving symmetric load systems

The paper presents a theoretical formulation for spherical shells reinforced by meridional and circumferential stiffeners Active damping of the shell is introduced through control action of piezoelectric coupled pairs bonded to the meridional stiffeners The induced loads can include radial pressure and a thermal field that are independent of the circumferential coordinate Neglecting local deformations between adjacent meridional stiffeners, the response of the shell will be axisymmetric The analysis employs the Donnell-Mushtari-Vlasov version of Love's theory of shells together with a smeared stiffeners technique The paper also considers a particular case of shell mounted piezoelectic coupled pairs without conventional stiffeners A closed form solution is derived for spherical panels without conventional stiffeners within the range of the meridional coordinate between 75° and 90° using a version of the Geckeler approximation

Axisymmetric dynamics of composite spherical shells with active piezoelectric/composite stiffeners

The present invention provides methods and systems for controlling transductive structures to achieve a desired performance objective. According to one aspect, the present invention provides a controller which simulates a synthetic admittance or impedance when coupled to a bicoupled device and effectively cancels the reactance of the bicoupled device. Cancelling the reactance of the bicoupled device allows energy to be reflected back into an energy storage portion of the circuit resulting in an energy efficient damping and/or control system.

Gareth J. Knowles

Papers

Telescopic wing system

Flextensional transducer assembly and method for its manufacture

Device and method for driving symmetric load systems

Axisymmetric dynamics of composite spherical shells with active piezoelectric/composite stiffeners

Device and method for controlling transductive systems