bluuebunny/crossref_metadata_2025_split huggingface dataset:
SMA-Based Multi-Ring Self-Centering Damping Devices for Seismic Retrofit of Structures
Authors: Salehi Mohammad , DesRoches Reginald , Hodgson Darel E. , Kim Parnell T. 
Published: May 2022

Abstract
One of the effective methods to retrofit seismically vulnerable building structures is the use of supplemental energy dissipation devices. Such devices may decrease the seismic displacement and acceleration demands of the retrofitted structures, thereby mitigating damage to both structural and non-structural components. Due to the unique mechanical properties of superelastic (SE) Nitinol, such as high strength, significant elasticity, substantial energy absorption, and excellent fatigue resistance, various forms/shapes of SE Nitinol have been used to develop self-centering damping devices. SE Nitinol rings are particularly effective because they offer large ductility, can resist compression without buckling, allow multi-directional loading, and are cost-effective. Recently, an innovative class of self-centering damping devices incorporating SE Nitinol rings, termed SMA-based multi-ring (SBMR) devices, has been developed and numerically evaluated by the authors. Each SBMR damping device consist of at least one SE Nitinol ring and at least one supplemental energy dissipating (ED) ring. The rings are concentrically and tightly positioned inside one another such that they deform together. The ED rings are made of metals with high hysteretic damping capacity, such as mild steel or shape memory (SM) Nitinol. Under diametric deformation, both the SE and ED rings absorb energy, whereas the SE ring(s) are primarily intended to provide self-centering. Due to their shape, the SBMR devices may be installed in building frames through a variety of approaches, among which cross bracing is particularly efficient. This presentation evaluates the performance of SBMR devices through an extensive experimental study. This presentation discusses an extensive experimental study on four SBMR damping devices with different ring configurations. The initial test results for two single SM and SE Nitinol rings along with a double-ring device demonstrated the stability of the hysteretic responses of the proposed devices and their effectiveness in providing a balanced combination of damping and self-centering capabilities.
Auxetic Superelastic TiNiCuCo Sputtered Thin-Films For Stretchable Electronics
Authors: Curtis Sabrina M. , Dengiz Duygu , Bumke Lars , Quandt Eckhard 
Published: May 2022

Abstract
Auxetic shape memory alloy (SMA) materials are candidates for ballistics, deployable antennas, actuators, stretchable electronics, and biomedical devices. Auxetic materials are periodic structures characterized by a negative Poisson's ratio, meaning they expand laterally when stretched longitudinally. The work presented here shows the mechanical properties of auxetic structures are significantly improved by using sputtered superelastic shape memory alloy materials compared to traditional materials (e.g., Cu, Si). In particular, sputtered freestanding TiNiCuCo SMAs offer advantages as substrates for stretchable electronics. Two novel auxetic structures with enhanced expandability and compressibility are presented, fabricated from sputtered TiNiCuCo. The novel geometries presented in this work are based on the combination of the auxetic rotating rectangle structure where the rotating hinges are replaced by two common stretchable interconnects (e.g., serpentines and Archimedean spirals). The influence of functional fatigue on the electrical properties, thermal-induced and stress-induced phase transformations of the novel stretchable auxetic TiNiCuCo thin-films are presented.
Elastocaloric Potential in Copper-Based SMAs through a Combinatorial Approach
Authors: Ouyang Gaoyuan , Hilliard Ben , Cui Jun 
Published: May 2022

Abstract
Elastocaloric applications exploit the latent heat from a shape memory alloy (SMA) through its stress-induced phase transformation. The elastocaloric potential of a SMA depends on its latent heat, critical transformation stress, hysteresis, heat capacity and conductivity, and, most importantly, its cost-effectiveness. Increasing the latent heat and improving the transformation characteristics are critical to increasing the elastocaloric potential in copper-based SMAs, which depend heavily on their compositions and processing conditions. This paper reports on a comprehensive compositional optimization effort to maximize latent heat while maintaining the near room temperature transition window and minimizing hysteresis for copper-based SMAs. The effort uses a high throughput combinatorial approach to prepare and scan multiple samples with different compositions. The transformation characteristics of grouped samples were determined simultaneously using a novel differential thermal analysis (DTA) method via thermal imaging. Differential scanning calorimetry (DSC) was used to examine the down-selected compositions for verification.
Continuous Operating Elastocaloric Device: Model and Experiments
Authors: Cheng Siyuan , Li Xueshi , Zhang Jiongjiong , Zhou Guoan , Zhu Yuxiang , Yao Shuhuai , Sun Qingping 
Published: May 2022

Abstract
Elastocaloric refrigeration using superelastic NiTi shape memory alloys (SMAs) has attracted much attention recently because it has a large energy saving potential, no environmental effects, and a low cost. Achieving the continuous operating of elastocaloric devices, i.e., separating the cold and hot areas on the NiTi alloys physically, helps the efficient release and absorption of heat and avoid the reciprocal parts and intervals of outputs in the system. In this paper, an analytical model and proof-of-concept experiments for continuous operating (elasto)caloric devices are presented. The experimental concept was developed based on a set of rotating NiTi sheets with which the copper heat sink and heat source contact cyclically.
Influence of Active Af on the Fatigue Performance of Peripheral Stents Subjected to Physiological Loading Conditions
Authors: Frotscher M. , Kiekbusch M. , Mews S. , Knopp A. , Serowietzki D. 
Published: May 2022

Abstract
The temperature difference between active austenite finish temperature, Af, and the intended operating temperature in the range of 3.2 °C to 20.8 °C. has been reported to have an influence on the fatigue lifetime of a pseudoelastic shape-memory device. The negative effect on fatigue life increases with the temperature difference between active Af and, in case of a biomedical device, 37 °C body temperature. In this study, samples were prepared and processed in a manner to replicate aspects of the complex manufacturing process, device design, and geometry of state-of-the-art stents, and physiological loading conditions. Following explantation from the mock vessels after fatigue testing, the stents were inspected using optical microscopy to detect and document the location and number of strut fractures. The fatigue results were compared and assessed for statistical significance between the groups with various active Af temperatures. The variations in the heat treatments, as part of the manufacturing process, resulted in three distinct groups of samples with varying target active Af temperatures. These variances corresponded to differences in fatigue damage.
Fatigue Testing of a New Generation Commercial Scale Ultra-Low Inclusion NiTi Alloy
Authors: Pequegnat Andie , Heitmann Walter , Chapman Kyle 
Published: May 2022

Abstract
The effects of inclusions within a Nitinol alloy on the fatigue performance has been largely accepted by the Nitinol community. With significant reduction in size and density of non-metallic inclusions, the statistical probability of an inclusion being at the region of high stress and facilitating fatigue failure is much reduced. A new generation of commercial scale, ultra-low inclusion Nitinol material has been developed. The purpose of this study was to characterize this new alloy and demonstrate the improved fatigue performance. It was shown that a significant improvement fatigue performance can be realized with the new commercial scale ultra-low inclusion NiTi alloy. The results further suggest that inclusion size and density play a critical role in fatigue performance.
SMAnalytics – An Automated Software for the Analysis of Shape Memory Alloy Test Data
Authors: Bigelow Glen S. , Benafan Othmane , Toom Zachary D. 
Published: May 2022

Abstract
This presentation reports on work to create user friendly software to aid in automated data analysis of tests to characterize the shape memory response of alloys. This effort has developed and produced software capable of automated analysis of test data produced using standard test methods and variations of these methods. This software provides a uniform method for analyzing data, which reduces analysis time and reduces error/variation due to different user and organization analysis methods. The software will allow analyzed data to be reported in the ASTM format for material certification, or as compiled data that can be directly imported into the NASA Shape Memory Material Database.
An Overview of ASTM Standard Test Methods for Shape Memory Alloy Actuation Materials
Authors: Nicholson D.E. , Benafan O. , Bigelow G.S. , Sczerzenie F. , Forbes D. , Van Doren B. , Mabe J.H. , Demblon A. , Karaman I. 
Published: May 2022

Abstract
Standard test methods for Uniaxial Constant Force Thermal Cycling (UCFTC) and Uniaxial Pre-strain and Free Recovery (UPFR) have been published under ASTM as E3097 and E3098, respectively. These two test methods capture the two most important responses in shape memory alloys (SMAs) for actuation, which is load-biased shape memory effect and classical shape memory effect. These test methods measure the transformation properties such as transformation temperatures, actuation strain, and residual strain to provide data for the characterization and selection of SMA materials, quality control, design allowables, and actuator design. In light of this recent development, additional test methods are still needed to fully support the transition of SMA actuators to production use. First, there is a recognized need for a test method that defines and evaluates the evolution of actuation properties and actuation lifecycle during repeated UCFTC. Second, rotary SMA actuation has been demonstrated as a practical and valuable actuator form as highlighted recently during flight test of the spanwise adaptive wing and reconfigurable vortex generators and in remote controlled actuated wind tunnel models. To this end, two new test methods have been proposed to ASTM that extend the applicability of E3097 to repeated UCFTC and torsional testing, respectively. This paper provides an update on the development of SMA standardized test methods for actuator applications highlighting their need and envisioned approaches.
Fatigue Strain Verification for Cardiovascular Implantable Nitinol Devices
Authors: Tripathy Sakya , Senol Koray , Cao Hengchu , Dominick Douglas , Wu Ming H. 
Published: May 2022

Abstract
Strain-based criteria is most often used for characterizing the fatigue reliability of Nitinol cardiovascular devices. Fatigue testing of Nitinol specimens has also relied on finite element analysis (FEA) to compute cyclic strain amplitudes and mean strains. Recently, the digital image correlation (DIC) technique has been shown to have high resolution to experimentally determine the local material strains of Nitinol fatigue specimens. In this study, the authors explored the feasibility of alignment between DIC strain measurement, and the strain calculated by the continuum mechanics approach used in the FEA technique. The agreements and discrepancies are discussed with their implications on fatigue reliability assessment of Nitinol cardiovascular devices.
Thermodynamical Model of NiTi SMA Including Plastic Deformation Mechanisms
Authors: Sedlák Petr , Frost Miroslav , Seiner Hanus , Heller Ludek , Sittner Petr 
Published: May 2022

Abstract
This paper presents an extension of a well-established constitutive model for NiTi covering both reversible (elastic, martensitic transformation, martensite reorientation) and irreversible (plastic) deformation mechanisms. Besides the inclusion of mechanisms of plastic deformation in both austenitic and martensitic phases in an independent manner, the model also newly captures more complex coupled phenomena of martensitic transformation and plastic deformation, such as transformation-induced plasticity, stabilization of martensite by plastic deformation, or plasticity-induced microstrain heterogeneity leading to functional fatigue. Despite a large number of different mechanisms involved in the model, which is reflected by a considerable number of internal parameters introduced for the description of the evolving microstructure of the material, the model still brings a basic, simple phenomenological understanding of the coupled transformation-plasticity proceeding in NiTi. After successful implementation to FEM software, the model provides new possibilities for simulations of NiTi components' behavior and processing.
Hyperelastic Behavior of Knitted TiNi Mesh under Uniaxial Tension
Authors: Baigonakova G.A. , Marchenko E.S. , Yasenchuk Yu F. , Kovaleva M.A. 
Published: May 2022

Abstract
TiNi-based alloys belong to the class of materials with shape memory effects and superelasticity, which are currently being actively studied and successfully used in engineering and medicine. In these alloys, their natural ability to undergo large inelastic deformations and return to their original shape by increasing temperature or relieving stress takes place. The key characteristic of these phenomena is thermoelastic martensitic transformations (MT). The problem of biocompatibility of implants is relevant, as the number of operations using implants in various fields of medicine is growing rapidly. Currently, several studies are underway on the deformation behavior of biological tissues and various implant materials. Wires made of TiNi are one of the most important metal biomedical materials used in endovascular surgery, orthodontics, soft tissue plastics in the form of stents, catheters, orthodontic archwires, metal-knitted materials. Textile implants should be singled out from a wide range of structures made of thin TiNi wire, with the help of which complex surgical problems are solved. A variety of mesh structures made of titanium nickelide are characterized by a particular complexity of deformation characteristics, the manifestation of which in the implant-bio-tissue interface is difficult to predict. To create the appropriate mechanical behavior of an implant in the form of mesh structures, it is necessary to study their deformation behavior. Therefore, to describe the functioning of a superelastic implant in the interface with a biological tissue, the aim of this work is to study the deformation behavior of wire samples 40, 60, and 90 µm thick from the TiNi alloy and metal knit made from them by the method of uniaxial tension. TiNi wires exhibit the effect of superelasticity at a relative strain of 4-6%. Under uniaxial tension of knitted mesh made of these wires, the effect of superelasticity was not detected. It has been found that the cyclic tension diagrams of knitted mesh show behavior inherent in hyperelastic materials. The total tensile load is unevenly distributed in the knitwear, in contrast to the uniformly distributed load when testing the wire.
Tensile Deformation of B19′ Monoclinic Martensite in Nanocrystalline NiTi Wires
Authors: Šittner P. , Molnárová O. , Bian X. , Heller L. , Seiner H. 
Published: May 2022

Abstract
When deformed in martensite state, NiTi undergoes pseudoplastic deformation taking place via motion of intervariant interfaces (called martensite reorientation or detwinning), followed by plastic deformation of the B19′ monoclinic martensite. The state of the art view is that: (i) the martensite reorientation proceeds via detwinning of &lt;011&gt; type-II twin laminates created by the martensitic transformation upon cooling and (ii) the reoriented martensite deforms plastically via dislocation slip. Although this view might be correct for single crystals and large grain size polycrystals, doubts existed whether it applies also for nanocrystalline NiTi which displays (001) compound twinned microstructures after stress free cooling from the austenite. The authors performed systematic experimental investigations of martensitic microstructures (postmortem TEM) and textures (in-situ HEXRD) evolving during tensile tests on nanocrystalline NiTi wires until fracture. The results indicate that the widespread view of the martensite reorientation as "detwinning" is incorrect. Plastic deformation of martensite proceeds via peculiar deformation mechanism involving (20-1) and (100) deformation twinning assisted by [100]/(011) dislocation slip. It enables the nanocrystalline NiTi wire to deform plastically at ~1 GPa engineering stress up to very large plastic strains ~50% and refines the austenitic microstructure down to nanoscale. Upon unloading and heating, reverse martensitic transformation takes place leaving large recoverable as well as unrecovered strains and high density of {114} austenite twins in the microstructure.
Compression Behaviors of Different Geometry-Designed NiTi Refrigerants
Authors: Zhou Guoan , Sun Qingping 
Published: May 2022

Abstract
A promising elastocaloric cooling technology (one of the solid-state cooling technologies) does not require any potentially harmful vaporous refrigerants. Its basic working principle, the martensitic transformation and its reverse transformation of shape memory alloys (SMAs) such as NiTi, NiTiCu, and NiFeGaC is one of the first-order non-diffusible phase transitions between a high-temperature phase (the austenite phase) of a B2 cubic structure and a low-temperature phase (the martensite phase) of a B19′ monoclinic structure. This paper investigates the compression behaviors of different NiTi regenerator structures through fatigue tests. An optimized 3-layer sample shows promise to be used in elastocaloric cooling prototypes and gives insight into the structural optimization of regenerators.
Laser Improved NiTi Surface for Biomedical Applications
Authors: Racek Jan , Hauschwitz Petr , Bičišťová Radka , Brajer Jan , Huyhn Jaroslav , Minárik Peter 
Published: May 2022

Abstract
The surface structure of medical implants and their chemical state are extremely important for their lifetime and reliability. There are problems with the degradation of NiTi implants due to structural fatigue, localized tribo-corrosion, and inconsistent hemocompatibility. These issues potentially can be solved by surface texturing by controlled short laser pulse treatments with a multibeam approach explored in this study. One of the unique surface textures in nanoscale is represented by introducing laser induced periodic surface structures (LIPSS) into the implant surface. The LIPSS formation involves the excitation of surface plasmon polaritons and material surface reorganization. Ripples with periodicity less than 1 ?m along with the catalytic activity of oxide surface with "rutile nanohairs" can significantly reduce bacterial film adhesion while promoting surface endothelialization and hemocompatibility. The morphological texturing of the surface allows for tuning the wetting properties from extreme hydrophobicity to hydrophilicity. Reduction of friction and wear of material surfaces can be achieved by introducing textures that reduce the contact friction area. The geometry of the LIPSS and dimples maintains an adhesive film of liquid among moving parts. Short laser "beam-shaped" pulses were applied in this work to NiTi surfaces. The results indicate that LIPSS processing of NiTi surface with controlled height profiles and periodicity gives rise to chemisorbed hydrocarbon molecules on rutile oxide layer, which leads to super-hydrophobicity and a beneficial antibacterial effect. Ultrashort laser pulse micromachining does not affect the microstructure and martensitic phase transformation. The corrosion resistance of LIPSS textured NiTi surface is not degraded, and the process reduces friction area and maintains an adhesive film of liquid between the moving parts.
Heightened Tameness and Accelerated Handling-Habituation in 3×Tg-AD Mice on a B6;129 Genetic Background
Authors: Hu Wen , Dai Chun-Ling , Niu Jiahui , Iqbal Khalid 
Published: May 2022

Background: The triple transgenic mouse model of Alzheimer’s disease (3×Tg-AD) has gained popularity in Alzheimer’s research owing to the progressive development of both amyloid- β and tau pathologies in its brain. Prior handling-habituation, a necessary preparation procedure that reduces anxiety and stress in rodents, was seldom described in the literature involving these mice and needs to be addressed. Objective: We sought to determine whether 3×Tg-AD mice differ from B6;129 genetic control mice in terms of tameness and prior habituation to handling. Methods: We devised hand-staying and hand-boarding assays to evaluate tameness in 3×Tg-AD and B6;129 genetic control mice at 2.5, 7, and 11.5 months of age, representing cognitively pre-symptomatic, early symptomatic and advanced symptomatic stages of the disease, respectively. We monitored the progress of handling-habituation across 8–15 daily handling sessions and assessed the animal behaviors in elevated plus maze. Results: We found that 3×Tg-AD mice were markedly tamer than age-matched control mice at the baseline. Whereas it took 2–3 days for 3×Tg-AD mice to reach the criteria for full tameness, it took an average of 7–9 days for young genetic control mice to do so. Prior handling-habituation enhanced risk assessment and coping strategy in mice in elevated plus maze. Completely handling-habituated mice exhibited comparable anxiety indices in the maze regardless of genotype and age. Conclusion: These findings collectively point to inherently heightened tameness and accelerated handling-habituation in 3×Tg-AD mice on a B6;129 genetic background. These traits should be carefully considered when behaviors are compared between 3×Tg-AD and the genetic control mice.
Fuzzy multi-agent assistance system for elderly care based on user engagement
Authors: Rojas-Domínguez Alfonso , Lino-Ramírez Carlos , Gutiérrez-Hernández David , Puga Héctor , Zamudio Víctor 
Published: May 2022

An intelligent system intended to provide assistance to an elderly user in their home is presented. This multi-agent system is designed to monitor the interaction between the user and other agents, and regulate itself based on the estimated level of mental engagement of the user in order to contribute to help them maintain adequate levels of awareness and interaction with their home environment. The agents are devices programmed to preserve the security, comfort and health of the user, who is also conceptualized as one of the agents in the system. The user engagement level is estimated through fuzzy inference, that is, by means of a set of fuzzy membership functions and rules applied over the interaction of the user with different categories of agents. The system incorporates several dozen agents and is tested using two different datasets of real interactions between users and devices in their home environments. A uniform parameter configuration yielded very positive results for diverse scenarios and subsequently the parameters of the system were automatically optimized to show that improved performance, in the form of a more efficient system regulation and increased certainty in adjustment estimation, is obtained.