Functional Characterization of NiTi Shape Memory Elements for Smart Micro-Actuation

2013 ◽  
Author(s):  
Carlo Alberto Biffi ◽  
Luca Bonacina ◽  
Adelaide Nespoli ◽  
Barbara Previtali ◽  
Ausonio Tuissi
Keyword(s):  
Shape Memory ◽  
Mechanical Response ◽  
Thermal Hysteresis ◽  
Functional Characterization ◽  
Functional Materials ◽  
Mechanical Tests ◽  
Calorimetric Analysis ◽  
Production Route ◽  
Definition Of

Shape Memory Alloys (SMAs) are smart and functional materials, which are considered good candidates for the activation of devices for the automotive, aerospace, biomedical and mechanical systems, thanks to the shape memory effect. In this work, a study on the mechanical response of NiTi SMA snake like elements has been proposed. The production route of these elements from thin sheets, was given by laser machining followed by chemical etching. The micro-elements were characterized by means of calorimetric analysis for the definition of the theoretical operating temperatures and by means of thermo-mechanical testing for the evaluation of their functional performances. Mechanical tests has been carried out to assess the tensile behavior of martensite and austenite separately, and to evaluate the thermal hysteresis under different constant loads. Moreover, Finite Element Modeling (FEM) has been also accomplished to study the numerical evaluation of the stress field that origins by the application of the different loads in both the martensitic and austenitic phases.

scholarly journals Mechanical Characterization of Nanocomposite Joints Based on Biomedical Grade Polyethylene under Cyclical Loads

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2681
Author(s):  
Annamaria Visco ◽  
Cristina Scolaro ◽  
Antonino Quattrocchi ◽  
Roberto Montanini
Keyword(s):  
Titanium Dioxide ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Laser Light ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Weight Content ◽  
Percentage Weight ◽  
Static Mechanical

Polymeric joints, made of biomedical polyethylene (UHMWPE) nanocomposite sheets, were welded with a diode laser. Since polyethylene does not absorb laser light, nanocomposites were prepared containing different percentages by weight of titanium dioxide as it is a laser absorbent. The joints were first analyzed with static mechanical tests to establish the best percentage weight content of filler that had the best mechanical response. Then, the nanocomposites containing 1 wt% titanium dioxide were selected (white color) to be subjected to fatigue tests. The experimental results were also compared with those obtained on UMMWPE with a different laser light absorbent nano filler (carbon, with greater laser absorbing power, gray in color), already studied by our research team. The results showed that the two types of joints had an appreciable resistance to fatigue, depending on the various loads imposed. Therefore, they can be chosen in different applications of UHMWPE, depending on the stresses imposed during their use.

scholarly journals Functional characterization of 3D protein structures informed by human genetic diversity

2019 ◽  
Vol 116 (18) ◽  
pp. 8960-8965 ◽  
Author(s):  
Michael Hicks ◽  
Istvan Bartha ◽  
Julia di Iulio ◽  
J. Craig Venter ◽  
Amalio Telenti
Keyword(s):  
Large Scale ◽  
Functional Characterization ◽  
Protein Structures ◽  
Large Scale Data ◽  
Allosteric Sites ◽  
Missense Variation ◽  
Binding Pockets ◽  
Definition Of ◽  
Scale Data

Sequence variation data of the human proteome can be used to analyze 3D protein structures to derive functional insights. We used genetic variant data from nearly 140,000 individuals to analyze 3D positional conservation in 4,715 proteins and 3,951 homology models using 860,292 missense and 465,886 synonymous variants. Sixty percent of protein structures harbor at least one intolerant 3D site as defined by significant depletion of observed over expected missense variation. Structural intolerance data correlated with deep mutational scanning functional readouts for PPARG, MAPK1/ERK2, UBE2I, SUMO1, PTEN, CALM1, CALM2, and TPK1 and with shallow mutagenesis data for 1,026 proteins. The 3D structural intolerance analysis revealed different features for ligand binding pockets and orthosteric and allosteric sites. Large-scale data on human genetic variation support a definition of functional 3D sites proteome-wide.

Manufacture and Electro-Thermomechanical Characterization of a SMA Copper-Based Cylindrical Connector

2010 ◽  
Vol 643 ◽  
pp. 29-35 ◽  
Author(s):  
Niédson José Da Silva ◽  
Jobson Alberto Silva ◽  
Rômulo Pierre Batista Dos Reis ◽  
Jackson de Brito Simões ◽  
Carlos José de Araújo
Keyword(s):  
Shape Memory ◽  
Thermal Activation ◽  
Functional Materials ◽  
Thermomechanical Properties ◽  
Contact Forces ◽  
Normal Contact ◽  
Electrical Connector ◽  
Electrical Connections ◽  
Cylindrical Element

The relevant and unique thermomechanical properties of shape memory alloys (SMA) have motivated researches for applications in several fields of engineering. The pseudoelasticity and shape memory effect (SME) are some behaviors displayed by these functional materials. The aim of the current work is the manufacture, physical characterization and investigation of electro-thermomechanical response of a SMA copper-based cylindrical element aiming the development of a smart electrical connector. The cylindrical element was manufactured by plasma melting and injection molding of a CuAlNi based SMA. During thermal activation, the SMA cylindrical element presented satisfactory movement of closure through the recovery of its shape, demonstrating a strong potential to generate normal contact forces useful for electrical connections.

scholarly journals Thermomechanical analysis of nitinol memory alloy behavior

2021 ◽  
Vol 102 (2) ◽  
pp. 161-167
Author(s):  
Nazarii Bykiv ◽  
Volodymyr Iasnii ◽  
Petro Yasniy ◽  
Robert Junga
Keyword(s):  
Strain Rate ◽  
Shape Memory ◽  
Phase Transformations ◽  
Functional Materials ◽  
Thermomechanical Analysis ◽  
Mechanical Tests ◽  
Scanning Calorimetry ◽  
External Temperature ◽  
Austenitic Transformation ◽  
Heating And Cooling

Shape memory alloys are functional materials characterized by the effect of shape memory and superelasticity. Due to these properties, they are widely used, particularly, in bioengineering, aeronautics, robotics and civil engineering. The temperatures of phase transformations and the influence of external temperature and strain rate on the functional and mechanical characteristics of Ni55.75Ti44.15 shape memory alloy are investigated in this paper. The temperature of alloy phase transformations is obtained by differential scanning calorimetry (DSC) in the temperature range from -70°C to 70°C. Diagrams of differential scanning calorimeters at different heating and cooling rates of Ni55.75Ti44.15 alloy is constructed and analyzed. Samples for mechanical tests are made of round rod 8 mm in diameter. The samples working area is 12.5 mm in length and 4 mm in diameter. Mechanical tests are carried out at temperatures close to the maximum value of the completion temperature of martensitic-austenitic transformation Af = 14.7°C. Diagrams of deformation under uniaxial tension are constructed and stresses of phase transformations, Young's modulus and relative elongations of transformation areas at different loading speeds and exterior temperatures are determined. Using Clausius-Clapeyron formula, it is shown that with simultaneous changes in temperature and strain rate, the stresses of phase transformations are largely due to changes in temperature rather than load rates. The coefficients of Clausius-Clapeyron equation for superelastic Ni55.75Ti44.15 alloy with shape memory, which are consistent with those known in the literature, are determined.

Functional Characterization of a Novel Shape Memory Alloy

2014 ◽  
Vol 23 (7) ◽  
pp. 2321-2326 ◽  
Author(s):  
M. Collado ◽  
R. Cabás ◽  
J. San Juan ◽  
I. López-Ferreño
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Functional Characterization

High-throughput characterization of shape memory thin films using automated temperature-dependent resistance measurements

2005 ◽  
Vol 894 ◽  
Author(s):  
Sigurd Thienhaus ◽  
Christiane Zamponi ◽  
Holger Rumpf ◽  
Jae Hattrick-Simpers ◽  
Ichiro Takeuchi ◽  
...  
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Throughput ◽  
Thermal Hysteresis ◽  
Wafer Level ◽  
Magnetic Shape Memory ◽  
Temperature Dependent ◽  
Characterization Of Materials

AbstractShape memory alloy (SMA) thin films are used as actuator materials in MEMS due to their unique properties. Binary thin films with a composition close to Ni50Ti50 are well-established materials, whereas ternaries like NiTiCu, NiTiPd, NiTiHf are less studied. Furthermore, new alloys are being developed which show a magnetic shape memory effect, e.g. Ni2MnGa. For the optimization of known, and the development of new, SMA thin films, a fast and reliable characterization technology is needed, which rapidly identifies the transformation temperatures (i.e. martensite and austenite start and finish temperatures) for a range of material compositions deposited on a whole wafer. In this paper, automated temperature-dependent resistance measurements are discussed as a means which yields the thermal hysteresis of the investigated thin films. Results of monitoring the uniformity of shape memory film depositions on the wafer level, as well as results on the use of this method as a tool for screening for new SMA films by characterization of materials libraries are reported.

Functional Characterization of Shape Memory CuZnAl Open-Cell Foams by Molten Metal Infiltration

2011 ◽  
Vol 20 (4-5) ◽  
pp. 544-550 ◽  
Author(s):  
S. Arnaboldi ◽  
P. Bassani ◽  
F. Passaretti ◽  
A. Redaelli ◽  
A. Tuissi
Keyword(s):  
Shape Memory ◽  
Molten Metal ◽  
Functional Characterization ◽  
Open Cell ◽  
Open Cell Foams ◽  
Metal Infiltration

scholarly journals Targeting Methyltransferases in Human Pathogenic Bacteria: Insights into Thymidylate Synthase (TS) and Flavin-Dependent TS (FDTS)

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1638 ◽  
Author(s):  
Cecilia Pozzi ◽  
Ludovica Lopresti ◽  
Giusy Tassone ◽  
Stefano Mangani
Keyword(s):  
Thymidylate Synthase ◽  
Pathogenic Bacteria ◽  
De Novo ◽  
Functional Characterization ◽  
Mechanisms Of Action ◽  
Human Pathogenic Bacteria ◽  
Thymidylate Synthases ◽  
Open Debate ◽  
Definition Of

In cells, thymidylate synthases provide the only de novo source of 2′-deoxythymidine-5′-monophosphate (dTMP), required for DNA synthesis. The activity of these enzymes is pivotal for cell survival and proliferation. Two main families of thymidylate synthases have been identified in bacteria, folate-dependent thymidylate synthase (TS) and flavin-dependent TS (FDTS). TS and FDTS are highly divergent enzymes, characterized by exclusive catalytic mechanisms, involving different sets of cofactors. TS and FDTS mechanisms of action have been recently revised, providing new perspectives for the development of antibacterial drugs targeting these enzymes. Nonetheless, some catalytic details still remain elusive. For bacterial TSs, half-site reactivity is still an open debate and the recent evidences are somehow controversial. Furthermore, different behaviors have been identified among bacterial TSs, compromising the definition of common mechanisms. Moreover, the redox reaction responsible for the regeneration of reduced flavin in FDTSs is not completely clarified. This review describes the recent advances in the structural and functional characterization of bacterial TSs and FDTSs and the current understanding of their mechanisms of action. Furthermore, the recent progresses in the development of inhibitors targeting TS and FDTS in human pathogenic bacteria are summarized.

Study of the Technical Capability of Sugarcane Bagasse Ash in Concrete Production

2016 ◽  
Vol 866 ◽  
pp. 53-57 ◽  
Author(s):  
Thiago da Cruz Sessa ◽  
Marcos Martinez Silvoso ◽  
Elaine Garrido Vazquez ◽  
Eduardo Linhares Qualharini ◽  
Assed Naked Haddad ◽  
...  
Keyword(s):  
Sugarcane Bagasse ◽  
Mechanical Tests ◽  
Cement Industry ◽  
Partial Replacement ◽  
Experimental Program ◽  
Concrete Production ◽  
Sugarcane Bagasse Ash ◽  
Definition Of ◽  
Mineral Mixtures

Cement industry has a great contribution to CO2 emissions in the world. In order to reduce the levels of CO2 emissions and the consequences of global warming, some researches have been developed aiming to reduce the cement volume produced through mineral mixtures. Sugarcane bagasse ash (SCBA) represents an important environmental liability of the alcohol industry in the northern state of Rio de Janeiro and its use as a partial replacement of Portland cement in concrete has shown great potential for use. This paper aims to analyze, through experimental procedures, the consistency and mechanic strength on concrete with low environmental impact, made from sugarcane bagasse ash, in substitution levels of 20% and 40%. The methodology of the experimental program, included the steps of characterizing the materials; definition of the reference concrete; molding and dosing of the reference concrete and concrete with SCBA; mechanical tests to evaluate the resistance in the reference test bodies; and analysis of the results. The method used from production and processing of the ash to the characterization of other materials in the concrete are also addressed in this study. The results indicate the feasibility of using sugarcane bagasse ashes in application of concretes in the construction industry.

Thermomechanical Characterization and Modeling of Ni60Ti40 SMA for Actuated Chevrons

Aerospace ◽  
2006 ◽  
Author(s):  
Darren Hartl ◽  
Brent Volk ◽  
Dimitris C. Lagoudas ◽  
Frederick Calkins ◽  
James Mabe
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Material Properties ◽  
Mechanical Response ◽  
System Behavior ◽  
Jet Engine ◽  
Fea Modeling ◽  
Primary Focus ◽  
Thermomechanical Characterization

This work describes the thermomechanical characterization and preliminary FEA modeling of commercial jet engine chevrons incorporating active Shape Memory Alloy (SMA) beam components. The SMA beams, when activated, induce the necessary bending forces on the chevron structure to deflect it into the fan flow and reduce noise. The primary focus of this work is the characterization of the SMA material (Ni60Ti40 wt%) chosen to actuate these chevrons and the preliminary modeling of the active chevron system behavior. To fully understand the material and calibrate the model, various thermomechanical experiments are performed on both untrained and trained standard SMA tensile specimens. Material properties for the shape memory alloy components are derived from this tensile experimentation. By using this data, a 3-D FEA implementation of a phenomenological SMA model is calibrated and used to analyze the response of a system motivated by the active chevron. The problem modeled consists of a pre-curved SMA beam clamped firmly against a straight aluminum substrate. The model proves to be an accurate tool for predicting the mechanical response of such a system subject to defined thermal inputs.

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