bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physics-Based Microstructure Modeling for Grain Tailoring and Refinement in Wire Arc Additively Manufactured Ti-6Al-4V Alloy
Authors: Özel Tuğrul , Shokri Hamed , Hosseinzadeh Hamed 
Published: February 2023

Abstract
This paper presents the advances in wire arc additive manufacturing (WAAM) processes and efforts in grain tailoring during the process for desired size and shape. WAAM can cause fabrication and post-processing time reduction in comparison with traditional processes. However, the high cooling rates and thermal gradient of the fusion-based metal additive manufacturing process often leads to an almost exclusively columnar grains microstructure (especially in titanium-based alloys), which can result in anisotropic mechanical properties and are, in consequence, undesirable. The issue of large directional grains can be addressed either with the addition of potent nuclei, a solute that promotes constitutional supercooling or a combination of the two. Nuclei are naturally present in liquid metals and are the starting point of every grain. Introducing additional potent nucleant particles by inoculation would facilitate grain refinement by increasing the total number of grains and therefore reducing the average grain size. To study the importance of solutes like Cr. and/or nuclei phases like TiB on final grains size and topology of the printed Ti-6Al-V titanium alloy with WAAM method, coupled thermal and microstructure simulations conducted. Simulation results show that the final microstructure of Ti-6Al-4V alloy at points without adding nucleants (solute and nuclei phase) will be columnar. By adding some solutes (Cr), the final microstructure is finer but still remains columnar. Although the final microstructure is equiaxed for all scenarios, adding solute and nuclei phases will change the final average size of the grains and hence achieve grain refinement.
Automated Design of FDM-Printable Snake-Like Compliant Mechanisms With Predefined End-Effector Poses
Authors: Schiele Simon , Rehekampff Christoph , Schroeffer Andreas , Schweigert Laurin , Lueth Tim C. 
Published: February 2023

Abstract
High prices and complex control are still an inhibitor to the wider use of robotic systems. Additive Manufacturing in combination with automated design, on the one hand, enables the low-cost production of robots and mechanism and, on the other hand, creates new possibilities for fabricating innovative systems, such as continuum robots and compliant mechanisms. The problem thereby is not the manufacturing itself but the design of the necessary individual models specified for certain additive manufacturing processes, which is complex and needs expert knowledge. This work deals with the design of snake-like compliant mechanisms and proposes an automated framework to design mechanisms for specified end-effector poses. Using rolling-contact flexure joints designed for fused deposition modeling (FDM) 3D printing, flexible segments are developed, which can be assembled to form a task-specific mechanism. Only with the specification of the end-effector configurations and few geometric boundary conditions all surface models for printing this mechanism with FDM are generated automatically. Furthermore, an approach to improve the accuracy of these mechanisms, regardless of the used 3D printer, is presented.
Industrializing Residential Construction Using Artificial Intelligent (AI) Robotics
Authors: Abaza Hussein , Clark Austin , Schwartz Aaron , Durce Henry J. , Guerra-Zubiaga David A. 
Published: February 2023

Abstract
This research investigates using AI robotics in automating wooden residential construction. Residential building construction still depends on manual labor. Automation is used to construct certain buildings such as wood trusses, cabinets, doors, windows, and mechanical systems. However, there is a great need for automating the assembly of the building construction. This research builds a framework on how robotics can automate the construction of significant building components and assemble them in the field. In this approach, walls, roofs, and floors assemble in the area. Several attempts have been made to use robots for wood framing. However, these automation attempts focused only on the structural parts of the wooden construction. The scope of this research includes using multiple robots with conveying belts to incorporate the assembly of the main building components, including the wooden framing, exterior sheathing and siding, electric wiring and trim, plumbing pipes, thermal insulation, vapor barrier, waterproofing, trim, windows, and doors, and first coat painting. Building assemblies will be transported to the field and fit together. The system will integrate mass customization strategies which includes Product Family Architecture and Personalization Design. This approach will improve quality assurance, reduce labor costs, reduce construction time, and reduce material waste. As a proof of concept, the research simulates the use of a robot to assemble walls components. The results showed that using AI Robotics to automate wooden residential construction is possible and practical. The advancement in AI robots overcame the inconsistencies in building materials and achieved the goals of this project.
Evaluation of Needle Driver Designs for Robot-Assisted Needle Insertions Under MRI Guidance
Authors: Liu Guanyun , Wang Yanzhou , Li Gang , Cleary Kevin , Iordachita Iulian 
Published: February 2023

Abstract
This paper presents the evaluation of two detachable MR-Conditional needle driver designs for our 4-degree-of-freedom (DOF) robotic platform for MRI-guided spinal injections. Compared to their predecessor, the new designs open up the possibility of intraoperative needle driver attachment, and in order to evaluate the feasibility of such an approach, force and torque requried during the needle driver attachment process are captured to evaluate which of the two designs are better suited for such purpose. A simulated clinical scenario is also carried out to measure the possible position change of the 4-DOF robot with respect to the patient due to intraoperative tool attachment, thus providing future guidance to the proposed clinical workflow in the framework of body-mounted robotic surgical devices.
Generating Multi-Pixel Thermal Images Through an Acousto-Thermal Effect
Authors: Li Teng , Li Jiali , Bo Luyu , Tian Zhenhua 
Published: February 2023

Abstract
In this study, we attempted to systematically integrate the acousto-thermal effect and acoustic holography to explore the feasibility of generating controlled thermal fields in a tissue-mimicking material. To enable this capability, our method firstly generates multiple acoustic focal points by using an acoustic hologram-based lens and then constructs a thermal field with multiple elevated-temperature areas based on the acousto-thermal effect. To design the acoustic lens, multiple points are distributed on a constraint plane, which is used as the input for determining the desired phase map based on an iterative phase propagation approach. To characterize the performance of our hologram for generating an acoustic field with concentrated energy at multiple points, on one hand, numerical simulations were performed. On the other hand, experiments were performed by using a 3D printed hologram to generate multiple acoustic focal points and further enable the acousto-thermal effect at multiple target locations of a phantom slice. The thermal image recorded by an infrared camera shows multiple elevated-temperature areas. Moreover, the locations of these elevated-temperature areas agree with the locations of acoustic focal points. We expect this study can contribute to the noncontact control of thermal fields for biomedical applications.
Numerical Simulation of Accidental Leakage and Diffusion of Liquid Hydrogen in the Laboratory
Authors: Li Hao , Cao Xuewen , Teng Lin , Wu Yi , Bian Jiang 
Published: February 2023

Abstract
Benefit from the advantages of wide sources and zero carbon emission, hydrogen is considered to be the most potential renewable energy to replace the traditional fossil energy. With the increase in the number of hydrogen refueling stations and other hydrogen energy application terminals, liquid hydrogen has attracted widespread attention as an efficient form of hydrogen energy storage and transportation, and many universities and enterprises have carried out laboratory-scale experiments related to liquid hydrogen. The accidental leakage of liquid hydrogen is prone to frostbite due to its extremely low-temperature characteristics, and the wide flammable range (4–75 vol%), low minimum ignition energy (0.017 mJ) and strong diffusivity of hydrogen make it very easy for combustion and explosion accidents to occur after leakage. To carry out the safety analysis of accidental leakage of liquid hydrogen in laboratory space, a two-dimensional Mixture model is established by using the Computational Fluid Dynamics (CFD) method to study the phase change, diffusion, and thermophysical characteristics of liquid hydrogen after leakage. The calculation model simulates the vertical leakage of liquid hydrogen to the ground and continuous diffusion at a speed of 0.2 m/s for 1 s at a distance of 20 cm from the ground under different ventilation conditions and cofferdam setups in the laboratory space. The characteristics of liquid hydrogen flow and hydrogen cloud diffusion are studied, the safety risks are evaluated and suggestions are given. The results show that: (1) After the liquid hydrogen leaked hits the ground, it flows rapidly around the ground, accompanied by violent phase change, which ended within 4.8 s after the leakage. During this period, the evaporated hydrogen continues to gather to the ceiling under the action of buoyancy and is continuously discharged from the laboratory space. (2) The safety of laboratory space with active ventilation is better than that of passive ventilation. The two cases of active ventilation and the case of double passive vents involved in this paper all decrease rapidly after the total mass of hydrogen in the space reaches the peak value, which decreases to less than 0.1 kg in 2.65 s, 27.45 s and 39.85 s respectively. In the case of single passive vent, the hydrogen is discharged slowly due to the backflow of air from the vent, even 120 s after the leakage, the hydrogen quality remained at a high level. (3) After the liquid hydrogen leaks to the ground, it rapidly expands around with phase change, and a considerable amount of liquid hydrogen is entrained into the air, which has great low-temperature harm. Compared with the case without cofferdam, the case with unilateral cofferdam and bilateral cofferdam reduces the low-temperature harm area near the ground by 32.6% and 77.9% after 1 s of leakage, and the installation of the cofferdam caused the hydrogen cloud to diffuse upwards and accelerate the hydrogen discharge space.
Towards Verification and Validation of Modeling Dyneema Using the Embedded Finite Element Method
Authors: Martin Valerie , Hannah Thomas , Ellis Stephen , Kraft Reuben 
Published: February 2023

Abstract
In this research, the embedded element method is investigated as a method for creating a finite element model for fiber reinforced composites. Bundles of polyethylene fibers are represented by truss elements and embedded in a continuum element matrix material by tying the displacement of the two meshes together. This type of mesh can be created more quickly than layered models while still maintaining directional layers than can capture the indirect tension mechanism that is important to compression failure[1–4]. Here, we show that by varying the number of fibers represented by a single truss element, the size of the finite element model can be scaled up or down for macro or micro scale modeling without changing the material properties or modeling method being used.
Experimental Characterization of the Nonlinear Boundary Conditions Applied by Two Different Designs of Spacer Grids on PWR Fuel Rods
Authors: Ferrari Giovanni , Painter Brian , Franchini Giulio , Karazis Kostas , Amabili Marco 
Published: February 2023

Abstract
Spacer grids in Pressurized Water Reactors (PWRs) hold fuel rods in place by means of springs and rigid stops during the operation of the reactor core; in addition, they are used to improve the mixing of the coolant, improving heat transfer. The constraint exerted by spacer grids influences the amplitude of the vibrations reached by fuel rods under the action of the turbulent coolant flow; in turn, these vibrations may result in Grid-To-Rod Fretting (GTRF), the main cause of failure for nuclear fuel rods. As a result, considerable effort is dedicated to the design of spacer grids.
In this perspective, the boundary condition exerted by two prototypical spacer grids on fuel rods was characterized experimentally. First, a traditional spacer grid, employing both compliant and stiffer elements (springs and dimples) to retain fuel rods was tested; afterwards, an innovative spacer grid, employing springs only, was tested. The rotational constraint on the bending of fuel rods was measured imposing angular displacements varying sinusoidally in time to rigid tubes inserted in the spacer grids. The spacer grids were immersed in water and the direction of the excitation was varied with respect to the spacer grids. The displacements were measured by means of Laser Doppler Vibrometers (LDV), while the resulting alternating compressive forces were measured through a load cell installed on the electrodynamic exciter that applied the time-varying displacements. Force-displacement loops revealed in both cases a hysteretic behavior described well by nonlinear hysteretic models such as Caughey’s bilinear model. The behavior of either spacer grid is not affected by the frequency of the sinusoidal excitation, but it is affected strongly by the amplitude of the latter. In particular, the hysteresis area increases substantially with the amplitude of displacement for both spacer grids, while the terminal stiffness decreases for spacer grid 1.
Such nonlinear conditions may be related to the strongly softening behavior shown by the large-amplitude vibrations of fuel rods supported by spacer grids, which happen at lower resonant frequencies and with larger damping values for increasing vibration amplitudes. The inclusion of hysteretic boundary conditions improves substantially the simulation of the forced vibrations of fuel rods supported by spacer grids. The vibrations of fuel rods supported by dimple-less spacer grids result much more damped than those if fuel rods supported by traditional spacer grids. Additional damping acts in the sense of safety and may be related to a larger hysteretic dissipation at the boundary conditions when dimple-less spacer grids are used.
Impact of Imperfect Kolsky Bar Experiments Across Different Scales Using Finite Elements
Authors: Hannah Thomas , Kraft Reuben H. , Martin Valerie , Ellis Steve 
Published: February 2023

Abstract
Typical Kolsky bars are 10–20mm in diameter with the lengths of each main bar being on the scale of meters. To push 104 and higher strain rates smaller diameter bars, accompanied by shorter lengths, are needed. As the diameters of the bars decreases the precision in the alignment of the system must increase to maintain the same relative tolerance as the larger experimental systems. Conversely, as the size of the bars decreases so does the magnitude of gravity based frictional forces due to the decreased mass of the system. Finite Element (FE) models are typically generated assuming a perfect experiment with exact alignment and no gravity. Additionally, these simulations tend to take advantage of the radial symmetry of an ideal experiment which removes any potential for modeling non-symmetric effects but has the added benefit of a reduced computational load. In this work, we discuss some of the results of these fast-running symmetry models to establish a baseline and demonstrate the first-order use case of such methods. We then take advantage of high-performance computing techniques to generate several three-dimensional, half symmetry simulations using Abaqus® allowing modeling of gravity and misalignment. The imperfection is initially modeled using the static general process followed by a dynamic explicit simulation in which the impact portion of the test is conducted. This multi-step simulation structure creates a system that can properly investigate the impact of these real-world, non-axis symmetric effects. These simulations fully explore the impacts of these experimental realities and are described in detail to allow other researchers to implement a similar FE modeling structure to aid in their experimentation and diagnostic efforts. Both a 12.7 mm and 3.16 mm diameter bar system are evaluated to quantify the degree that these various experimental imperfections have across two size scales of Kolsky bar systems.
Evaluation of Delay of a Teleultrasound Robotic System for Musculoskeletal Imaging
Authors: Noguera Cundar Adriana Paola , Fotouhi Reza , Ochitwa Zachary 
Published: February 2023

Abstract
Teleoperated systems are used in multiple fields since they allow the user to remotely work in locations where it would otherwise be infeasible due to cost, safety, or accessibility. However, due to the vast distances involved, teleoperated systems suffer from degraded communication between the operator and end device. This often takes the form of either delay or loss in the control signal. Understanding this degradation is necessary to advance the development of teleoperated systems.
The objective of this research is to identify how normal operation of a teleoperated device is altered by delay in the communication signal and how system performance can be improved.
A 4-degrees-of-freedom (4-DOF) teleultrasound robot was used to measure the time delay between a command and its response as well as the position error resulting from the time delay.
The delay was measured by both a video recording and a network analysis software. The position error was measured by comparing physical coordinates of the actual robot with position of a simulated robot. These tests were then moved from a Wireless Local Area Network (WLAN) to a Virtual Local Area Network (VLAN) to see if there is a noticeable change from the different network topology.
This study verified that the communication channel between the operator and robot is a significant source of delay. In the experimental WLAN setup, the system experienced an average of about 300 milliseconds of delay. It was verified that signal degradation affects operation of the system. The error in displacement was found to have a quadratic relation with signal delay. It was found that a VLAN network performed better than a WLAN network, with about 40% reduction in average delay time and 70% reduction in maximum displacement error. Contribution of this work was on quantifying effects of delay in position of a 4-DOF end-effector in a teleultrasound robot.
Optimization of Design Parameters for Large Diameter N07718 Hex Bolts in Hot Forging Using Finite Element Analysis
Authors: Upchurch Carl , Peng Xiaobo , Jiang Lai , Park Jaejong 
Published: February 2023

Abstract
The demand for bolting components is expected to grow as fasteners remain a standard method of assembling parts. UNS N07718 is a Nickel-based chromium superalloy, which is the most popular grade of choice for its high yield strength. Forged UNS N07718 bolts of larger diameter have been growing in demand. In this paper, a non-conforming forging process for a 1.375″ N07718 hex flange bolt was analyzed. With the original design parameters, defects were detected at the base of the bolt hex during the post-processing inspection. To eliminate the defects in the bolts, finite element analysis (FEA) tool DEFORM Forming Express 3D was used to evaluate and optimize the design parameters of the bolt in the forging process. The quantitative and qualitative outputs of the FEA model were provided in the paper. Physical testing was performed using ASTM industry standards to validate the design configurations. The initial solution in this process has resulted in part failure. Re-evaluation of the process with gained knowledge results in a successful forging. Both failure and final solution were presented such that the lessons learned in the failure process may help understand both the advantages and disadvantages of applying FEA models.
Effect of Whirling Motion on the Fluid Induced Instability Force in Axial Compressor Rotors
Authors: Sheng Xia , Indraneel Tandalam Shashikant , Kim Jay 
Published: February 2023

Abstract
Possibilities of aerodynamics induced instability of turbomachinery rotor systems have been studied over the years. The fluid force induced by the motion of the rotor, which is a combination of the whirling motion and the rotation motion, results in an unbalanced force in the tangential direction of the whirling motion, which in turn influences the motion to cause the instability. In the past, only one type of the cross-coupled forces, the force proportional to the shaft deflection, was considered because it is the most obvious form to recognize. However, the influence of the whirling motion of the rotor has been ignored in the past studies as this motion is very difficult to precisely obtained experimentally. CFD simulations can be utilized instead to achieve it. A set of full 3D unsteady CFD simulations are presented to predict fluid induced cross-coupled force on the compressor rotor. Motions of rotor whirl and rotor self-spin are superimposed to prescribe the rigid body motion of the rotor. Mesh morphing solver is used to achieve remeshing process for the blade tip region mesh changes due to the unsteady motion of the blade. The approach for the CFD model is validated and the simulation results are explained. Based on the simulation results, an overall approach for the stability analysis of turbomachinery system is proposed.
Experimental Investigation of Taper Angle and Airflow Rate on Air-Injected Bubble Squeezing in a Tapered Microgap
Authors: Shukla Maharshi Y. , Kandlikar Satish G. 
Published: February 2023

Abstract
Squeezing bubbles in a tapered microgap has proved to be effective for improving flow stability in flow boiling. A previous study from our research group has successfully demonstrated using tapered microgap for transforming pool boiling into a self-sustained flow boiling-like system for cooling CPU through thermosiphon. To overcome the imaging challenges with nucleating vapor bubbles, the present work investigates the squeezing behaviour of air-injected bubbles between a tapered microgap with taper angles of 5°, 10°, and 15°. The air bubbles are injected at a rate of 3 ml/min, 15ml/min, and 30 ml/min in a pool of water. The bubble squeezing is recorded at 2000fps using a Photron high-speed camera. The experimental analysis compares the displacement and velocity of the advancing and receding bubble interfaces. The analysis found that in certain test cases, multiple bubbles coalesced while exiting the tapered microgap. In all the test cases, the receding interface of the bubble slingshots after detaching pushes the bubble out of the tapered microgap. The result from the current study provides an insight into the bubble flow and squeezing behavior that can be used for optimizing taper microgap geometries to enhance critical heat flux and heat transfer coefficient of two-phase, and air-injected single-phase heat transfer systems.