Thermo/Mechanical Design, Modeling, and Testing of Shape Memory Actuated Minimal and Micro Invasive Probe Systems

2002 ◽  
Author(s):  
David R. Wulfman ◽  
Arthur G. Erdman ◽  
Paul J. Strykowski
Keyword(s):  
Shape Memory ◽  
Solid Phase ◽  
Mechanical Design ◽  
Phase Changes ◽  
Segment Length ◽  
Great Promise ◽  
Small Scale ◽  
Neutral Position ◽  
Total System ◽  
Physical Scale

Small scale probes implementing shape memory alloy (SMA) actuation show great promise in applications requiring remote and minimally invasive access to small environments. Such environments include physiological spaces like those located in human and animal bodies as well as cavities within mechanical systems. Probes examined here are generally snake like in appearance composed of one or multiple independent segments, which in turn are made up of one or multiple SMA actuators performing work against an elastic spine. As the actuator(s) of a given segment are activated, the spine bends causing the probe to bend in the area of that segment. When the actuator(s) are deactivated, the force generated in the bending of the spine returns the segment to its neutral position. Activation and deactivation of actuators is accomplished by heating and cooling respectively, enacting the solid phase changes that are characteristic to the shape memory effect. The gage of control over probe shape depends on the number of independent segments that are available per unit length and the degree of control an operator has over each of the segments. The work presented here discusses the constraints imposed on the design of SMA actuated probes, and how those constraints become more critical and limiting with reduced physical scale and refinement of motion control. Numerical and finite element models have been developed showing the interrelationship between mechanical design, the thermal and phase states of the SMA actuator(s), and the mechanical performance of the total system. Performance concerns examined include probe shape control and the limits of shape change as a function of physical scale. Comparative data is presented between behavior predicted by the models developed and performance observed during the testing of prototypes. It is concluded that segment length, linked to refinement of probe control, is limited by its thermal boundary conditions.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

Investigation of Micro-Sized Capsules at High Pressure by PALS Method

2017 ◽  
Vol 373 ◽  
pp. 284-287
Author(s):  
Bożena Zgardzińska ◽  
Maciej Tydda ◽  
Jan Wawryszczuk
Keyword(s):  
High Pressure ◽  
Solid Phase ◽  
Boundary Region ◽  
Argon Atmosphere ◽  
Phase Changes ◽  
Filling Material ◽  
Polymer Shell ◽  
Positron Annihilation Lifetime ◽  
The Core ◽  
Phase Pressure

The positron annihilation lifetime spectroscopy (PALS) was applied to investigate the properties of capsules composed of n-alkanes (filling material) and polymer (shell) in the broad range of pressures up to 450 MPa. These microcapsules aggregate into the grains having about 200 μm in diameter. Their properties were investigated as a function of pressure (p) at several selected temperatures: when the filling material is in liquid, rotator and solid phase. Pressure experiments were performed without gas access to the sample and in an argon atmosphere. Two o-Ps components were found, the longer-lived correspond to the filler material, and the shorter-lived one – to the shell. These components change with p; even a small pressure (6 MPa) reduces considerably the o-Ps lifetimes (τ). At 303 K the o-Ps lifetime in the core changes non-monotonically, and at 60 MPa τ is higher than at 20 MPa. The increase of pressure induces the phase changes in the filling material, and also produces the deformation of microcapsule aggregates and crash of small capsules at the grain boundary region. Internal structure of the microcapsules was observed by SEM.

Solid phase changes in chemically and biologically leached copper smelter slag

2017 ◽  
Vol 106 ◽  
pp. 97-101 ◽  
Author(s):  
Anna H. Kaksonen ◽  
Silja Särkijärvi ◽  
Jaakko A. Puhakka ◽  
Esa Peuraniemi ◽  
Saku Junnikkala ◽  
...  
Keyword(s):  
Solid Phase ◽  
Copper Smelter ◽  
Phase Changes ◽  
Smelter Slag

A Shape Memory Alloy-Based Morphing Axial Fan Blade—Part I: Blade Structure Design and Functional Characterization

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Annalisa Fortini ◽  
Alessio Suman ◽  
Nicola Aldi ◽  
Mattia Merlin ◽  
Michele Pinelli
Keyword(s):  
Shape Memory ◽  
Solid Phase ◽  
Functional Characterization ◽  
Structure Design ◽  
Operating Conditions ◽  
Surface Pattern ◽  
Fluid Temperature ◽  
Axial Fan ◽  
Polymeric Matrices ◽  
Air Stream

The possibility to realize adaptive structures is of great interest in turbomachinery design, owing to the benefits related to enhanced performance and efficiency. To accomplish this, a challenging approach is the employment of shape memory alloys (SMAs), which can recover seemingly permanent strains by solid phase transformations whereby the so-called shape memory effect (SME) takes place. This paper presents the development of a heavy-duty automotive cooling axial fan with morphing blades activated by SMA strips that works as actuator elements in the polymeric blade structure. Concerning the fan performance, this new concept differs from a conventional viscous fan clutch solution especially during the nonstationary operating conditions. The blade design was performed in order to achieve the thermal activation of the strips by means of air stream flow. Two polymeric matrices were chosen to be tested in conjunction with a commercially available NiTi binary alloy, whose phase transformation temperatures (TTRs) were experimentally evaluated by imposing the actual operating thermal gradient. The SMA strips were then thermomechanically treated to memorize a bent shape and embedded in the polymeric blade. In a specifically designed wind tunnel, the different polymeric matrices equipped with the SMA strips were tested to assess the fluid temperature and surface pattern behavior of the blade. Upon heating, they tend to recover the memorized shape and the blade is forced to bend, leading to a camber variation and a trailing edge displacement. The recovery behavior of each composite structure (polymeric matrix with the SMA strips) was evaluated through digital image analysis techniques. The differences between the blade shape at the initial condition and at the maximum bending deformation were considered. According to these results, the best coupling of SMA strips and polymeric structure is assessed and its timewise behavior is compared to the traditional timewise behavior of a viscous fan clutch.

Examination of phase changes in the CuAl high-temperature shape memory alloy with the addition of a third element

2018 ◽  
Vol 133 (2) ◽  
pp. 845-850 ◽  
Author(s):  
Mediha Kök ◽  
Şahin Ata ◽  
Zehra Deniz Yakıncı ◽  
Yıldırım Aydoğdu
Keyword(s):  
High Temperature ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Phase Changes

scholarly journals A Novel Self-Deployable Solar Sail System Activated by Shape Memory Alloys

Aerospace ◽  
2019 ◽  
Vol 6 (7) ◽  
pp. 78 ◽  
Author(s):  
Gianluigi Bovesecchi ◽  
Sandra Corasaniti ◽  
Girolamo Costanza ◽  
Maria Elisa Tata
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Environmental Conditions ◽  
Solar Sail ◽  
Operating Conditions ◽  
Small Scale ◽  
Space Vehicles ◽  
Solar Sails ◽  
Suitable Material ◽  
Transfer Mechanisms

This work deals with the feasibility and reliability about the use of shape memory alloys (SMAs) as mechanical actuators for solar sail self-deployment instead of heavy and bulky mechanical booms. Solar sails exploit radiation pressure a as propulsion system for the exploration of the solar system. Sunlight is used to propel space vehicles by reflecting solar photons from a large and light-weight material, so that no propellant is required for primary propulsion. In this work, different small-scale solar sail prototypes (SSP) were studied, manufactured, and tested for bending and in three different environmental conditions to simulate as much as possible the real operating conditions where the solar sails work. Kapton is the most suitable material for sail production and, in the space missions till now, activated booms as deployment systems have always been used. In the present work for the activation of the SMA elements some visible lamps have been employed to simulate the solar radiation and time-temperature diagrams have been acquired for different sail geometries and environmental conditions. Heat transfer mechanisms have been discussed and the minimum distance from the sun allowing the full self-deployment of the sail have also been calculated.

scholarly journals Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with VitaminB6Deficiency

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Chi-Fen Chen ◽  
Tsan-Zon Liu ◽  
Wu-Hsiang Lan ◽  
Li-An Wu ◽  
Chin-Hung Tsai ◽  
...  
Keyword(s):  
Spectrophotometric Method ◽  
Solid Phase ◽  
Correlation Coefficients ◽  
Urinary Metabolites ◽  
Hplc Method ◽  
Small Scale ◽  
Extraction Column ◽  
Xanthurenic Acid ◽  
Activation Coefficient ◽  
Coefficient Method

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n=80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 μmole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC’s AST/B6functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6deficiency-associated hyperhomocysteinemic condition.

Shape Memory Alloys in Automotive Applications

2014 ◽  
Vol 663 ◽  
pp. 248-253 ◽  
Author(s):  
Jaronie Mohd Jani ◽  
Martin Leary ◽  
Aleksandar Subic
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
External Force ◽  
Active Element ◽  
Mechanical Design ◽  
Competitive Market ◽  
Automotive Applications ◽  
Market Prices ◽  
Sma Actuators

Shape memory alloy (SMA) actuators have drawn much attention and interest due to their unique and superior properties, and are expected to be equipped in many modern vehicles at competitive market prices. The key advantage is that SMA actuators do not require bulky and complicated mechanical design to function, where the active element (e.g. SMA wire or spring) can be deformed by applying minimal external force and will retain to their previous form when subjected to certain stimuli such as thermomechanical or magnetic changes. This paper describes the SMA attributes that make them ideally suited as actuators in automotive applications and to address their limitations, feasibilities and prospects.

Mechanochromism of Piroxicam Accompanied by Intermolecular Proton Transfer Probed by Spectroscopic Methods and Solid-Phase Changes

2005 ◽  
Vol 127 (18) ◽  
pp. 6641-6651 ◽  
Author(s):  
Agam R. Sheth ◽  
Joseph W. Lubach ◽  
Eric J. Munson ◽  
Francis X. Muller ◽  
David J. W. Grant
Keyword(s):  
Proton Transfer ◽  
Solid Phase ◽  
Phase Changes ◽  
Spectroscopic Methods ◽  
Intermolecular Proton Transfer

Micro pulling down growth of very thin shape memory alloys single crystals

2017 ◽  
Vol 10 (01) ◽  
pp. 1740003 ◽  
Author(s):  
I. López-Ferreño ◽  
J. San Juan ◽  
T. Breczewski ◽  
G. A. López ◽  
M. L. Nó
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Single Crystals ◽  
Functional Materials ◽  
Small Scale ◽  
Cylindrical Shape ◽  
Minimum Diameter ◽  
Wide Range

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu–Al–Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100–200[Formula: see text]C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1[Formula: see text]mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down ([Formula: see text]-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The [Formula: see text]-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200[Formula: see text][Formula: see text]m in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

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