Large scale testing of nitinol shape memory alloy devices for retrofitting of bridges

Johnson, Rita; Padgett, Jamie E.; Maragakis, Manos; DesRoches, Reginald; Saiidi, Mehdi S.

doi:10.1088/0964-1726/17/3/035018

Cited by 101 publications

(60 citation statements)

References 20 publications

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“…NiTi memory elements have been used (among other things) in: stents [21]; catheters [22]; actuators for robotic and biomimetic systems [23]- [27]; morphing aircraft structures [20]; orthopedic implants [20]; systems for structural health monitoring [28]; robotic pumps [29]; and even as integrated elements in clothing [30]. SMAs offer high blocking stresses (200 MPa), high specific power (>100 kW/kg), and can be actuated using Joule heating via an applied current [12].…”

Section: Theory and Modeling Of Niti Coil Actuatorsmentioning

confidence: 99%

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

Holschuh

Obropta

Newman

2015

IEEE/ASME Trans. Mechatron.

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Abstract-This paper describes the modeling, development, and testing of low spring index nickel titanium (NiTi) coil actuators designed for use in wearable compression garments, and presents a prototype tourniquet system using these actuators. NiTi coil actuators produce both large forces (>1 N) and large recoverable displacements (>100% length) that are well suited for compression garment design. Thermomechanical coil models are presented that describe temperature and force as a function of non-dimensionalized coil geometry, extensional strain, and applied voltage. These models suggest that low spring index coils maximize activation force, and an analytical model is presented to predict garment counter-pressure based on actuator architecture. Several low spring index (C = 3.08) coils were manufactured, annealed, and tested to assess their de-twinning and activation characteristics. Results suggest both annealing and applied stress affect activation thresholds. Actuator force increases both with extensional strain and applied voltage up to 7.24 N. A first-generation compression tourniquet system using integrated actuators with direct voltage-control of applied pressure is presented, demonstrating >70% increase in applied pressure during activation. This approach enables new, dynamic garments with controllable activation and low effort donning and doffing, with applications ranging from healthcare solutions to advanced space suit design.

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Section: Theory and Modeling Of Niti Coil Actuatorsmentioning

confidence: 99%

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

Holschuh

Obropta

Newman

2015

IEEE/ASME Trans. Mechatron.

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“…SMAs have been extensively studied, and their shape memory and elastic properties have proven useful in a wide variety of applications, ranging from robotic actuators and prostheses to bridge restraints, valves, deformable glasses frames, biomedical devices, and even wearable garments 30,[45][46][47][48][49] . The memory effect has been demonstrated in several alloy types, though the most common and commercially available alloy produced is NiTi (approximately 55% Nickel and 45% Titanium), under brands such as Nitinol® and Flexinol®.…”

Section: Analysis Of Active Materialsmentioning

confidence: 99%

Materials and Textile Architecture Analyses for Mechanical Counter-Pressure Space Suits using Active Materials

Holschuh

Obropta

Buechley

et al. 2012

AIAA SPACE 2012 Conference &Amp; Exposition

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Mechanical counter-pressure (MCP) space suits have the potential to improve the mobility of astronauts as they conduct planetary exploration activities. MCP suits differ from traditional gas-pressurized space suits by applying surface pressure to the wearer using tight-fitting materials rather than pressurized gas, and represent a fundamental change in space suit design. However, the underlying technologies required to provide uniform compression in a MCP garment at sufficient pressures for space exploration have not yet been perfected, and donning and doffing a MCP suit remains a significant challenge. This research effort focuses on the novel use of active material technologies to produce a garment with controllable compression capabilities (up to 30 kPa) to address these problems. We provide a comparative study of active materials and textile architectures for MCP applications; concept active material compression textiles to be developed and tested based on these analyses; and preliminary biaxial braid compression garment modeling results. Nomenclature DEA= dielectric elastomer actuator EAP = electroactive polymer EMU = extravehicular mobility unit EVA = extravehicular activity MCP = mechanical counter-pressure NASA = National Aeronautics and Space Agency SMA = shape memory alloy SMP = shape memory polymer

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“…Here, the frequency tuning capabilities of a tensegrity inspired structure are explored, using SMA NiTi wires as actuators. SMAs have been widely used to mitigate vibrations, both in passive control systems and adaptive control systems, taking advantage of the superelastic effect, in the former case [34][35][36][37][38], and of the shape-memory effect, in the latter case [39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Design and experimental testing of an adaptive shape-morphing tensegrity structure, with frequency self-tuning capabilities, using shape-memory alloys

Santos

Rodrigues

Micheletti

2015

Smart Mater. Struct.

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Abstract. The present paper explores the capabilities of a tensegrity-inspired tower with regard to frequency tuning by shape morphing. To change the configuration of the proposed structure, shape-memory-alloy actuators are used. This actuation principle also takes advantage of the variation of the elastic modulus of shape-memory alloys associated with the martensitic transformation. The temperature modulation of the shape-memory-alloy wires is successfully achieved by Joule heating, through a proportional-integral-derivative controller, to change between a low-temperature shape and a high-temperature shape. The implementation of a short-time-Fourier-transform control algorithm allows for the correct identification of the dominant input frequency, associated with the dynamic excitation. This information is used to automatically change the configuration of the structure in order to shift its natural frequency away from that of the dynamic excitation. With this frequency tuning, one obtains a reduction of the accelerations throughout the structure up to about 80%. The good performance of the proposed control approach gives promising indications regarding the use of tensegrity systems, in combination with shape-memory alloys, for shapemorphing applications, and, in particular, for self-tuning structures.

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Large scale testing of nitinol shape memory alloy devices for retrofitting of bridges

Cited by 101 publications

References 20 publications

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

Low Spring Index NiTi Coil Actuators for Use in Active Compression Garments

Materials and Textile Architecture Analyses for Mechanical Counter-Pressure Space Suits using Active Materials

Design and experimental testing of an adaptive shape-morphing tensegrity structure, with frequency self-tuning capabilities, using shape-memory alloys

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