bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Fire-Flame Temperature and Duration on the Behavior of Reinforced Concrete Beams with Construction Joints
Authors: Abbood Ahmed A. , Kharnoob Majid M. 
Published: May 2024

Structural members' durability and strength depend on the member’s fire resistance. This study simulates the structural response of a reinforced concrete beam with a construction joint exposed to fire. The commercial finite element software ABAQUS was used to validate the laboratory findings. The testing program tested five reinforced concrete beams with the dimensions of (200x300x2700 mm), having identical reinforcing details and a concrete compressive strength (fc'=35 MPa). These beams had a 45° angled connection at the center. Four beams were exposed to fire flames at two temperature levels (600 °C and 800 °C) and for 1.0 and 2.0 hr. periods, respectively. The fifth beam is the control beam that was not exposed to fire. Laboratory results show that the worst exposure on the beam’s construction joint was at 800 °C with an exposure period of 2 hrs. This exposure reduces the bond between the joint’s two surfaces, creating a slipping effect in which disconnection occurs after loading. After 1 and 2 hours of exposure to fire at 600 °C, the residual flexural strength was 85% and 72% of that of the control beam, respectively. Whereas, beams exposed to fire for 1 and 2 hours at 800 °C showed flexural strengths lower than the control beam at 41% and 28%, respectively. Regarding the modulus of elasticity and compressive strength, they both showed residual values of (63.5, 59.2, 50.9, and 47%), and (28, 25, 19, and 16%), respectively.
Effect of Solution Heat Treatment of Nitinol (Ni55%-Ti45%) Manufactured via L-PBF
Authors: Agarwal Neha , Obeidi Muhannad Ahmed , Brabazon Dermot , Asal Karim , Faraoni Andrea , Pola Annalisa 
Published: May 2024

Abstract
The properties of nitinol, an alloy of nickel and titanium, include its good biocompatibility, corrosion resistance, damping capacity, fatigue strength, superelasticity, and shape memory characteristics. With other conventional methods, it has been challenging to achieve high precision and accuracy of the produced parts; however, laser powder bed fusion (L-PBF) has provided a useful new route for the processing of nitinol. While L-PBF offers many advantages, it also has drawbacks, including the potential for the formation of different phases and residual stress during rapid solidification. Post L-PBF heat treatment conditions aid in the generation of targeted stable phases. As reported by Lee et. al., the mechanical properties and transformation temperatures of the manufactured nitinol samples were largely influenced by the heat treatment. Fan et. al. showed an increase in the transformation temperatures by increasing the heat treatment temperatures after a solution heat treatment. Heat treatments that help in achieving the desired properties are two-step heat treatment processes. This study investigates the feasibility of applying a single-step solution heat treatment to Ni-rich nitinol and reports its effects on density, transformation temperatures, microstructures and microhardness for intended applications.
Unlocking Insights from In-Situ Meltpool Monitoring Data for Additively Manufactured NiTi Components
Authors: Monu Medad C.C. , Brabazon Dermot 
Published: May 2024

Abstract
The processing of Ni50Ti50 (at.%) alloy via powder bed fusion using a laser beam (PBF-LB) technique has been reported to significantly alter the atomic percentage of Ni in the final NiTi part when compared to the feedstock composition, and the ensuing variations in the phase characteristics and transformation temperatures. Residual stresses are also another challenge in the PBF-LB processing of NiTi. These PBF-LB challenges stem from the choice of laser scanning strategy, and process parameter selection typically defined by volumetric energy density (VED). Heat treatment also plays a crucial role in releasing residual stresses and effectively adjusting or tuning the final properties of as-built NiTi components.
Enhancing NiTi Implants through Binder Jetting: Microstructure, Impurity Control, and Post-processing Optimization
Authors: Pourshams Mohammad , Cullaz Timothee , Rocco Pete Angelo , Poorganji Behrang , Elahinia Mohammad 
Published: May 2024

Abstract
Additive manufacturing (AM), also known as 3D printing, has created new possibilities for designing and producing innovative NiTi medical implants. This technology offers significant advantages over traditional manufacturing methods, including the ability to produce complex geometries tailored to individual patient anatomy, potentially leading to better surgical outcomes and faster recovery times. These capabilities facilitate the creation of implants that are not only more biocompatible but also capable of promoting better osseointegration and reducing the risk of implant rejection.
Graphical Symbols to Communicate Shape Transformation for the Technical Documentation of Products
Authors: Pei Eujin , Leung Christopher 
Published: May 2024

Abstract
Advances in Additive Manufacturing using Shape Memory materials have found widespread use in medical, aerospace and automotive sectors. 4D Printed parts with shape memory and stimuli responsive materials can be programmed for transformation, actuation and self-assembly. This offers the potential to foster the development of specialized high- value products that can operate passively without an external power source and with fewer electromechanical components. To reach a high level of industrial maturity, standards are needed to accurately represent shape transformations to enable design engineers to accurately communicate the functional requirements for manufacturing; as well as for metrologists and test engineers to inspect for product quality control. However, a fundamental challenge exists: How do we ensure that the design, manufacturing and functional intent for 4D Printed parts are accurately and unambiguously communicated between stakeholders across the design, manufacturing, inspection and supply value chain? This paper proposes a new standard for technical product documentation, geometric product specification and engineering drawings within British Standard BS 8888. To illustrate how the proposed standard could be applied, a use-case with different shape transformation properties are considered in a workflow.
Kwink Patterns in Plastically Formed NiTi Martensite
Authors: Seiner Hanuš , Sedlák Petr , Frost Miroslav , Šittner Petr 
Published: May 2024

Abstract
Nickel-titanium B19’ martensite is a strongly plastically anisotropic material with only one available slip system, which is the [100](001)M slip. Despite this, B19’ martensite polycrystals can be homogeneously plastically formed, reaching up to very high plastic strains. The absence of other slip systems is compensated by plastic twinning, in particular by the frequently appearing irreversible (20-1)M twins. However, these twins act on the same (010)M lattice plane as the plastic slip, and thus, do not seem to be a very suitable complement to the slip in terms of the Von Mises criterion. In fact, exactly the same strains as by the (20-1)M twins can be achieved also by the [100](001)M slip itself, and thus, a question arises, whether they can be understood as plastic twins in the conventional sense.
In-Situ Characterization of Phase Interfaces in CuAlNi during Mechanical Cycling Using Dark-Field X-Ray Microscopy
Authors: Perez Celeste , Bucsek Ashley N. , Creuziger Adam 
Published: May 2024

Abstract
Interfacial stress fields play a critical role governing the hysteresis and functional fatigue of shape memory alloys. These stress fields manifest at austenite-martensite interfaces (i.e., habit planes) as a consequence of geometric incompatibility between the austenite and martensite phases. As the material approaches transformation, these interfacial stress fields act as an energy barrier, requiring extra energy to be driven into the system to overcome it, resulting in a hysteresis. In addition, increasing the energy in the system also increases dislocation generation, resulting in functional fatigue. In this research, we employ dark-field X-ray microscopy (DFXM), a high-resolution diffraction microstructure imaging technique, to characterize austenite-martensite interfaces and interfacial stress fields during mechanical cycling in a CuAlNi shape memory alloy. The results show, in 3D, the emergence and evolution of individual austenite-martensite interfaces and spatially mapped orientation and elastic strain, including the interfacial elastic strain fields at austenite-martensite interfaces. These findings will contribute to a better understanding of the origins of hysteresis and functional fatigue by investigating interfacial stress fields and dislocation generation at phase interfaces and their effects on macroscopic behavior.
3D In-Situ Characterization of Individual Grains in CuAlNi Shape Memory Alloys during Cyclic Loading Using X-Ray Topotomography
Authors: Moya Janice , Ludwig Wolfgang , Jin Yuefeng , Wright Jonathan , Creuziger Adam , Bucsek Ashley N. 
Published: May 2024

Abstract
The crystallographic theory of martensite (CTM) forms the foundation of our understanding of stress-induced reversible martensitic phase transformation cycling, relying on assumptions that exclude precipitates, grain boundaries, plasticity, and strained lattices. An ongoing challenge persists in adapting our understanding of CTM-based micromechanical theory (e.g., habit plane variant, or HPV, prediction and the origins of hysteresis and, subsequently, functional fatigue) to real, engineering-grade SMAs. Due to the complexity, elucidating the micromechanical phenomena requires novel high-resolution 3D in-situ characterization techniques.
Flexocaloric Effect in a Cu-Al-Ni Single Crystal
Authors: Vives Eduard , Valdés Emma , Porta Marcel , Pérez-Junyent Clàudia , Mañosa Lluís , Planes Antoni , Saxena Avadh 
Published: May 2024

Abstract
Caloric effects are reversible thermal changes that occur in a solid material in response to an external field, either magnetic, electric or mechanical. Materials with large caloric effects are candidates to be used for environmentally friendly, solid-state refrigerators. In the case of mechanocaloric effect, thermal changes are induced by a mechanical field. Most of the work to date has been carried out by the application and removal of uniaxial stress or hydrostatic pressure and the corresponding caloric effects are usually denoted as elastocaloric and barocaloric effects, respectively. Mechanocaloric effects are very large when they occur associated with a ferroelastic phase transition involving a collective atomic rearrangement as occurs in martensitic phase transitions that involve a change of symmetry of the unit cell. Recently, it has been theoretically suggested that the possibility of actuating with more complex mechanical fields such as bending or twisting should have a several advantages. In this work we present a study of flexocaloric effect in superelastic materials exhibiting structural transitions.
Investigating Elastocaloric Effect of NiTi Shape Memory Alloy Fabricated by Laser Powder Bed Fusion Technique
Authors: Kordizadeh Fatemeh , Mohajerani Shiva , Safaei Keyvan , Andani Nasrin Taheri , Pourshams Mohammad , Abdollahzadeh Mohammad Javad , Elahinia Mohammad 
Published: May 2024

Abstract
It has been shown that about 20% of the global electricity supply is used for refrigeration and cooling. Thus, the substantial global warming impact of refrigerants remains a crucial concern. In an attempt to solve this issue, caloric cooling technology has shown significant potential as an alternative to vapor-compression technology. Caloric cooling technology utilizes the latent heat of a solid-state phase transformation of a caloric material by applying an external trigger. The caloric cooling technologies can be broken down into four categories including magnetocaloric, electrocaloric, barocaloric, and elastocaloric. Among these four materials, the considerable elastocaloric effect and easy actuation of these materials make them an excellent alternative to the usual approach. The elastocaloric effect is defined by the adiabatic temperature change (△ Tad) in elastocaloric materials when uniaxial stress (load) is applied or removed in the adiabatic state. This phenomenon can be found in all shape memory alloy (SMAs) materials. To elaborate further, SMAs undergo a stress-induced transformation between austenite and martensite phases upon adiabatic loading and unloading. These phase transitions result in △ Tad (heating or cooling) within the materials. For example, during unloading, the endothermic reverse transformation from martensite to austenite leads to decreased temperature (cooling) within the sample. It has been well-defined in the literature that NiTi materials, a well- known type of SMA materials, are the best candidate in the elastocaloric industry due to their large latent heat and excellent mechanical properties and result in a large elastocaloric effect. There has been a limited number of studies that have explored the elastocaloric effect of NiTi. Additionally, it has been shown in the literature that the elastocaloric effect of this material can be optimized by adjusting the process parameters, providing a new route to investigate the elastocaloric effect of additively manufactured NiTi. It should be known that any change in the thermomechanical and mechanical behavior of NiTi materials results in a difference of the elastocaloric effect. To elaborate further, any process or building orientation controls that enhance the strength of the martensitic and austenitic phases will reduce slipping and enable recoverable strains to reach higher levels, resulting in a larger △Tad. In this comprehensive study, the effect of building orientation on the elastocaloric response was investigated and followed by an investigation of the effect of porous structures on the elastocaloric response.
Fatigue Life Assessment of Ni-Ti Stent-Like Devices: Investigation of a Fracture Mechanics Approach
Authors: Brambilla Alma , Berti Francesca , Patriarca Luca , Petrini Lorenza 
Published: May 2024

Abstract
Damage-tolerant approaches, relying on fracture mechanics, are powerful tools adopted in many engineering sectors to predict the initiation and propagation of fracture. In the last two decades, there has been a growing interest in extending these methods to shape memory alloy (SMA) components despite their greater complexities related to phase transformation and the thermomechanical coupling characterizing material response. SMA devices for actuation, damping, and energy absorption are the most appropriate applications of fracture mechanics, being large enough to sustain crack growth before fracture. Nevertheless, also the biomedical field is moving toward these methods for a more accurate prediction of device failure. This work investigates a damage-tolerant approach for predicting the fatigue fracture of Nickel-Titanium (Ni-Ti) stent-like devices. In the case of stenotic lower limb arteries, Ni-Ti SMAs are the top choice for designing self-expanding stents for mini-invasive deployment. The stents throughout their lifespan are subjected to cyclic loads mainly due to gait (106 cycles/year at 1 Hz) causing fatigue failures related to dramatic drawbacks. Since fatigue fracture is typically related to crack growth from manufacturing-related defects, this research aims to identify the basic ingredients needed to apply fracture mechanics, highlighting the critical aspects that should be considered given the particular features of the material and its application in the cardiovascular field.
Application of Shape Memory Alloys Inside a Ram Air Door Rotary Actuator
Authors: Pick Dean , Richman Ryan , Tran Daniel , Calkins Frederick , Nicholson Douglas E. , Jones Zachary , Steadele Jason 
Published: May 2024

Abstract
As the aerospace sector aims to decrease its greenhouse gas emissions from historical levels, vehicle lightweighting is seen as key to achieving meaningful reductions in the sector. Shape memory alloy (SMA) materials have been shown to have extremely high work density that, when applied in an actuator, can yield significant weight savings compared to electric motor and hydraulic powered alternatives.
Shape Memory Alloy Rotary Actuators for Aerospace: Part 1 Design and Testing
Authors: Nicholson Douglas E. , Calkins Frederick , Mabe James H. 
Published: May 2024

Abstract
Shape memory alloys (SMA) provide a compact, robust, light-weight and scalable rotary actuation technology suitable for many aerospace applications that require precise control and high torque. Over the last 25 years Boeing has fabricated, processed and characterized several hundred NiTi-based tubes with the objective of optimizing performance for aerospace applications. The effects of supplier, material composition, processing, heat treatment, training parameters and component size were characterized and mapped in NiTi and NiTiHf systems. The effects of lower and upper cycle temperature (LCT and UCT, respectively), applied torsional loading (including nominal, minimum, maximum, reversed and varying), rotational limits (blocking) and repeated thermal cycling (to over 100,000 cycles) were systematically investigated. Based on those results, torsional SMA components were fabricated for optimal performance and evaluated under repeated thermal cycling under load to assess their ability to meet actuator requirements for an applications’ required life cycle. Additionally, isothermal torque-deflection and constant torque thermal cycling test (similar to E3414) have been performed across all relevant actuator parameters. This paper reviews and summarizes test outcomes, providing additional insight into the design and characterization of SMA rotary actuator components in context of the SMA material, component processing, operational parameters and their intended use in applications.
Constitutive Model for NiTi Polycrystalline Alloys Undergoing Transformation and Plastic Deformation Processes
Authors: Frost Miroslav , Sedlák Petr , Seiner Hanuš , Valdman Jan , Moskovka Alexej , Šittner Petr 
Published: May 2024

Abstract
Great attention has been recently paid to the investigation of plastic deformation in NiTi. Experimental investigations of the mechanical response of NiTi polycrystalline samples within a broad stress-strain-temperature state space have revealed a complex response involving martensitic transformation, reorientation, and plastic deformation processes. The interactions between them result in complex coupled phenomena, such as transformation-induced plasticity, martensite stabilization through plastic deformation, and micro-strain heterogeneity induced by plasticity. Plastic deformation in NiTi not only generates irrecoverable strain at the macroscale, but it also induces substantial strain heterogeneity in the microstructure. This heterogeneity significantly affects the functional properties and may open up new technology pathways for designing sophisticated products. Tailored constitutive models that can reproduce the response in complex loading scenarios can be extremely beneficial.
Shape Memory Alloy Actuation Device Design Tool
Authors: Gantz Faith , Bolisay Linden , Palisoc Art , Young Marcus L. 
Published: May 2024

Abstract
Shape memory alloys (SMAs) are a novel solution to reducing the actuating system weight and mechanical complexities which consequentially comes with integration challenges. Some of these challenges are due to limited production accessibility and often need reengineering. A materials model turned into analytical routines would allow empirical data to predict the structural behavior of SMAs. An SMA design tool would bridge material science and engineering practices by guiding the users through an iterative design approach to improve integration efficiency for actuating devices. A user-friendly first-order approximation model was developed by the Consortium for the Advancement of Shape Memory Alloy Research and Technology (CASMART) to capture the macroscopic effects of forward and reverse transformation for various actuator types such as wires, springs, and torque tubes. This tool allows quick changes and iterations throughout the design process, which is particularly helpful in comparing actuator types. Although it is convenient to use, the ability to capture the SMA nonlinear and complex inelastic response is limited. Phenomenological-based models have been developed by incorporating classical theory of plasticity and by relating martensite volume fraction to the laws of thermodynamics. The phase transformation can be characterized as a rate-independent plasticity using the volume of martensite to govern the change in material properties between austenite and martensite. The development of the model itself incorporates other characteristics such as the degradation of performance due to plastic strain and the change in transformation strain during partial cycling. The challenge with these models is the complexity for the user. The starting point to create a user-friendly SMA design tool involved combining a phenomenological-based model with Finite Element Models (FEM). Integrating a complex 3D constitutive model with ABAQUS Finite Element Analysis (FEA) encompasses both conventional material parameters and unique shape memory alloy parameters.
A Novel Path Planning Framework for Constructing Compositional Gradients in Many-Element Systems
Authors: Price Samuel Grant , Cao Zhaoxi , McCue Ian 
Published: May 2024

Abstract
Shape memory alloys (SMAs) have found widespread use in superelastic components and as compact, lightweight actuators. However, current use cases require SMAs to be joined to structural alloys (e.g., A17075, Inconel 718, 316L). At present, this is done mechanically (e.g., bolting or crimping) adding significant weight and volume, which reduces the benefit of using an SMA. Attempts at metallurgical bonds, which would not incur the weight/volume penalties of mechanical joints, have fallen short, often producing joints with deleterious phases and poor joint efficiencies (defined as σjoint/σmaterial). This is largely because the elemental composition and phase structure of SMAs are highly dissimilar to nearly all structural alloys. As a result, most of the possible composition gradients connecting the SMA to the structural alloy led to the formation of undesirable phases, typically brittle intermetallics. Thus, for a metallurgical joint to be successful, it must have a final composition gradient that results in favorable (strong, ductile) phases, while avoiding unfavorable (weak, brittle) ones. This joint requires two features: (1) a target final gradient that is known (or predicted) to be favorable; and (2) a technique for guiding the joining process to such a targeted final gradient. This work focuses on developing the former.