A review on shape memory alloys with applications to morphing aircraft

Abstract

Shape memory alloys (SMAs) are a unique class of metallic materials with the ability to recover their original shape at certain characteristic temperatures (shape memory effect), even under high applied loads and large inelastic deformations, or to undergo large strains without plastic deformation or failure (super-elasticity). In this review, we describe the main features of SMAs, their constitutive models and their properties. We also review the fatigue behavior of SMAs and some methods adopted to remove or reduce its undesirable effects. SMAs have been used in a wide variety of applications in different fields. In this review, we focus on the use of shape memory alloys in the context of morphing aircraft, with particular emphasis on variable twist and camber, and also on actuation bandwidth and reduction of power consumption. These applications prove particularly challenging because novel configurations are adopted to maximize integration and effectiveness of SMAs, which play the role of an actuator (using the shape memory effect), often combined with structural, load-carrying capabilities. Iterative and multi-disciplinary modeling is therefore necessary due to the fluid-structure interaction combined with the nonlinear behavior of SMAs.

Development of a new iron-based shape memory alloy

“…One of application of such alloys is their use as load-bearing elements for weldless joint of structures, highpressure pipelines, elastic elements, etc. [10][11][12].…”

“…There are a number of iron-based shape memory alloys, and this effect is known in some austenitic steels [10][11][12][13][14][15]. However, disadvantages of the known alloys are low corrosion resistance, for example, due to the high content of manganese, low oxidation resistance, brittle phase formation, and insufficient viscosity and strength values.…”

Variable Camber Morphing Wings

“…Prova disto é a publicação de várias revisões bibliográficas, assim como de um livro a respeito do tema (Weisshaar, 2006;Thill et al, 2008;McGowan et al, 2009;Sofla et al, 2010;Taha et al, 2012;Valasek, 2012;Vasista et al, 2012;Weisshaar, 2013;Sinapius et al, 2014;Barbarino et al, 2014). (1975-1988o Smart Wing Program;o Aircraft Morphing Project (NASA Langley, 1994-2004; e o Morphing Aircraft Structures Program (DARPA, 2002(DARPA, -2007.…”

Investigation on thermo-mechanical behavior of shape memory alloy actuator

“…In this type of material two crystalline structures can be distinguished: (a) martensite (M) which is thermodynamically stable at a lower temperature and (b) austenite (A), which is the parent phase stable at a higher temperature. The SMA materials in the martensite phase have the crystal structure with a simple symmetry, such as tetragonal, rhombohedral, orthorhombic, monoclinic or triclinic depending on the composition of the alloy, whereas in the austenite phase they are more symmetrical, usually based on a cubic lattice [1,2]. SMAs are characterized by four temperatures, i.e.…”