bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechatronic System Design and Construction of a CNC Machine for Cutting Styrofoam Parts for RC Planes
Authors: Roa Prada Sebastián
Published: February 2023

Flying radio controlled, RC, planes has become both a sport and a form of entertainment that attracts an increasing number of practitioners worldwide. RC plane hobbyists design and build reduced-scale airplanes, unmanned aircrafts or replicas of existing full-scale ones, and fly them as often as possible to develop the necessary skills to go from basic flights to complex maneuvers and acrobatics and to race against other planes. Unfortunately, many practice flights do not go as planned and end with physical damage to the aircrafts. Companies dedicated to the production and marketing of RC planes require Computerized Numerical Controlled, CNC, machines to cut different parts for these model aircrafts due to their geometrical complexity, such as the case of the wings. Airplane wings must be light, strong and at the same time they have a tridimensional shape which is difficult to obtain by means of conventional manufacturing processes such as milling. Styrofoam is a convenient material for the fabrication of RC plane wings. The most common way to cut Styrofoam parts is by means of a taut hot wire. In order to achieve the complex shape of the wing, starting with a block of Styrofoam, the motion of the two ends of the taut hot wire must be carefully controlled and synchronized, to keep the tension in the wire and to obtain the desired shape in the part being manufactured. The best way to get this precise control for the two ends of the wire is by means of computerized numerical control. The aim of this research is to illustrate the steps for the mechatronic system design and construction of a machine for cutting RC plane Styrofoam parts to be used in the manufacturing of the aircrafts and the fabrication of spare parts for repairs after crash landings. The details for the development of each step of the mechatronic system design methodology are illustrated. The steps include design requirement specification, conceptual design, CAD modeling, structural analysis, sensors and actuators specification, assembly and testing. Once the functioning of the machine is validated, the quality of the manufactured parts must be tested so that they can be fitted to the corresponding aircrafts. The results demonstrated that the application of the methodology for the design of mechatronic systems facilitates the development of a robust device, such as a CNC machine, which synergistically combine the advantages of precision mechanics, electronics, control systems and computers to manufacture high quality parts for the RC planes industry.
Aerosol Dispersion Modeling With a Low-Cost Flow Simulation Tool: Analysis of Performance and Boundary Condition Sensitivity
Authors: Hirn Mallory , Rodriguez Andrew , Owkes Mark , Dacunto Philip , Ng Andrew , Rogers John , Benson Michael
Published: February 2023

Understanding the dispersion of potentially infectious aerosols released from breathing and speaking is critical to maintaining a healthy indoor environment. This study used a low-cost commercial off-the-shelf flow simulation tool (SolidWorks Flow Simulation) to model aerosol dispersion within a university classroom and assessed its utility by comparing results to those from physical experiments. A SolidWorks model of a university classroom was created using parameters from a series of full-scale carbon dioxide tracer gas release experiments previously conducted in the physical classroom at both low (520 cfm) and high (900 cfm) flowrates. Steady state concentrations at 13 monitoring points throughout the room were obtained from the flow simulation tool and compared to the experimental results using four performance measures for dispersion model evaluation [15]. The performance measures for the baseline model fell within published acceptance criteria for Fractional Mean Bias (FB), Normalized-Mean Square Error (NMSE), Fraction of Cpredicted within a factor of two of Cobserved (FAC2), and Normalized Absolute Difference (NAD). A sensitivity analysis revealed that the most critical boundary condition for creating an optimum model in both cases was the student heat flux. Adding a simulation of body heat from the silhouettes improved the FAC 2 in the low flow case from 0.08 to 1.0, the NMSE from 1.19 to 0.14, the FB from 0.91 to 0.30, and the NAD from 0.45 to 0.15. Given the ability of SolidWorks Flow Simulation to function as a viable first pass modeling method at a low cost, this accessible tool could be used by a variety of interested parties to quickly predict the spread of aerosols, gases, and other passive scalars under a variety of ventilation and physical arrangement conditions. This software tool may already be available to many academic institutions and provides a reasonable expectation of accuracy.
Latent Representation and Characterization of Scanning Strategy on Laser Powder Bed Fusion Additive Manufacturing
Authors: Imani Farhad , Chen Ruimin
Published: February 2023

Despite the transformative capability of laser powder bed fusion (LPBF) additive manufacturing to create components with intricate geometry, the large-scale adoption remains a barrier owing to the process complexity and significant build quality concerns. In-process melt pool imaging offers an unparalleled capability to tackle the problems by evaluating the impact of prominent process parameters (e.g., laser power, laser velocity, and hatch spacing) on build quality. However, the current investigations overlook the effect of other influential factors such as scan strategies. Because of the multitude and high-dimensionality in melt pool images, the extraction of manual features to characterize and intertwine diverse scan strategies (e.g., orthogonal serpentine, pre-scanned boarder, and clockwise spiral) is cumbersome or inefficient. While end-to-end deep neural networks realize automated feature extraction from melt pool images, they are limited in providing meaningful signatures for the characterization of various scan strategies. This paper presents a systematic image-guided analysis based on variational autoencoder (VAE) that enables the semantic representation of image data on low-dimensional latent space to characterize similarities between scan strategies. Further, hyperdimensional computing as a cognitive solution is integrated to differentiate various scan strategies according to latent features. Experimental results on the real-world case study based on 30,000 in-situ melt pool images show that VAE is significantly effective in interpretable characterization associated with 12 different scan strategies. In addition, the cognitive model differentiates scan strategies using the latent representation with an accuracy of 81.20 ± 0.8%.
Rapid and Low-Cost Fabrication of Microfluidic Devices Using Liquid Crystal Display-Based 3D Printing
Authors: Shan Yujie , Sahu Praveen , Sundararajan Raji , Mao Huachao
Published: February 2023

Microfluidic devices have been widely investigated for various applications, specifically in the biomedical field, which involve manipulating cells at a sub-micron scale. However, the conventional lithography process with polydimethylsiloxane (PDMS) micro-molding process (soft lithography) involves numerous steps demanding high-end equipment and a cleanroom fueling up the cost and making it a time-consuming process. This paper presents a low-cost yet versatile way to fabricate long microfluidic channels using liquid crystal display (LCD)-based vat photopolymerization 3D printing. The accuracy, resolution and repeatability of the printing process were characterized using various parameter settings.

We validated the developed process by 3D-printing four different microfluidic devices with 100 μm wide channels. Subsequently, we successfully demonstrated the formation of a single streamline of breast cancer cells in a microchannel with long and smooth edges. The scanning electron microscopy (SEM) characterization shows a high-quality fabricated channel. This proposed approach aligns with the ongoing efforts toward a versatile, flexible, and fast option for producing the diagnostic device.
Development of a Continuous Improvement Tool for Outgoing Erasmus: First Results
Authors: Carvalho Violeta , Rocha Carla , Campinos Jorge , Teixeira Senhorinha , Rodrigues Cristina
Published: February 2023

Erasmus mobility is a valuable opportunity for students to explore not only new cultures and costumes but also learning practices and experiences. Every year, at the University of Minho there are many undergraduate students interested in the Erasmus program, however, there are several reasons that prevent them from moving forward. Aiming to help clarify students’ questions and fears about the Erasmus experience, the Department of Production and Systems - DPS of the University of Minho decided to create a continuous improvement tool. The first step consisted of evaluating what motivated students to perform Erasmus whose results are analyzed in the present study. For this purpose, a questionnaire was developed and implemented with engineering students at the DPS who applied to the Erasmus program for the 2021/2022 academic year. The main personal reasons to study abroad pointed out by students were the fact that they think they will like the experience and that it will be interesting for them, as well as the fact that it is personally important for them. Despite this, many students consider Erasmus something they should do. Furthermore, it was found that the Erasmus coordination of the DPS played a fundamental role in their decision to conduct the Erasmus mobility.
Experimental Investigation of Solar-Thermal Desalination Platform Leveraging Dynamic Flash Evaporation and Swirl Flow Separator
Authors: Thyagarajan Ashok , Dhir Vijay , Banerjee Debjyoti
Published: February 2023

Commercial thermal desalination plants usually leverage static flash evaporation and vapor separation processes that occur separately in large chambers. Depending on the level of purity — the product can be used for potable water (for human consumption), for agriculture or ranching, or as input for industrial processes (such as in injection wells in oil and gas production operations). Currently, static methods such as Multi Stage Flash (MSF) or Multi Effect Distillation (MED) are widely used (in addition to Reverse Osmosis) for desalination. These static methods occupy large land area (large footprint). This in turn drives up the capital and production costs of the resulting purified water obtained in these techniques.

Desalination processes that leverage evaporation and vapor separation in the same chamber (dynamically) have smaller form factors which confers lower cost of desalination. Thus, the motivation of our study is to develop a novel apparatus to simultaneously generate vapor by flash evaporation and separate the produced vapor in the same apparatus. The novel apparatus is geared for desalination of sea water, remediation of produced water from process-industries and other sources of saline water (such as brackish water) that are deemed unfit for human consumption. The end goal of the project is to develop a solar-thermal desalination platform by leveraging hot saline water as input from solar ponds.

In this experimental study, the thermal-hydraulic performance of a prototype (lab-scale) dynamic vapor generation and swirl flow phase separation apparatus is explored for determining the efficacy of this novel concept. Heated water from a constant temperature supply tank (that is comparable to a solar pond in real life) is passed through injection passages into the flow-separation apparatus. As the water flows through the injection passages, vapor bubbles are generated inside the flow passages due to local superheating of the liquid caused by frictional pressure drop. Conversion of liquid into vapor continues as the liquid-vapor mixture flows through the injector ports and eventually the mixture enters a larger separation tube tangentially. Due to the tangential injection of the two-phase mixture, a centrifugal force acts to separate the water and vapor inside the separation tube. The liquid is pushed to the periphery (i.e., the walls) of the separation tube while the vapor forms a stable core at the center. A vapor retrieval tube is then positioned at the center of the vapor core to extract vapor which is then condensed inside the condenser.

The formation of the vapor core is demonstrated for different operating conditions (supply liquid flow rates) and maximum superheat (temperature difference between supply tank and condenser) ranging between 45–52°C. Based on this study, the optimal operating conditions for maximizing the thermal conversion upstream of the test section are presented.
Multi-Regional Design and Analysis of Biomass-Driven Combined Cooling, Heating and Power Systems for Rural Communities
Authors: Schicker Philippe C. , Cho Heejin
Published: February 2023

The challenges during the aftermath of natural disasters in remote locations, such as unreliable power supply from the grid during crucial times, coupled with ever-increasing energy needs, demand new and innovative solutions to limited energy production. Local, on-site power generation, such as combined cooling, heating, and power (CCHP) systems, may safeguard against grid fluctuations, outages, and provide additional security through grid independence. CCHP systems can provide more reliable and resilient energy supply to buildings and communities while also providing energy-efficient, cost-effective, and environmentally sustainable solutions compared to centralized power systems. Biomass-driven CCHP systems have been recognized as a potential technology to bring increased efficiency of fuel utilization and environmentally sustainable solutions. Biomass as an energy source is created through agricultural and forestry by-products and may thus be efficiently and conveniently transported to remote rural communities. This paper presents a design and implementation analysis of biomass (primarily wood pellets)-driven CCHP systems for a rural community across the United States. The U.S. Department of Energy Climate Regions map was used to determine areas of interest. For this study, all three climates moist, dry, and marine as well as all major climate zones (2–6) were included. To effectively compare small towns across the U.S., the selection process was based on certain criteria: A population of approximately 1,500 people, the existence of a rural hospital, two kinds of schools (E.g., an elementary and a high school), and small businesses. The following places meet those conditions and are located in differentiating climate zones: (2A) Keystone Heights, FL, (3A) Ackerman, MS, (3B) Quincy, CA, (3C) Mariposa, CA, (4A) Hardinsburg, KY, (4C) Coupeville, WA, (5A) Alma, NE, (5B) Lovelock, NV, (6A) Colebrook, NH, (6B) Choteau, MT. Each location was investigated based on the merits of on-site CCHP systems and potential grid independence. The viability of wood pellets (WP) as a suitable fuel source is explored by comparing it to a conventional natural gas-driven and grid-connected system. To measure viability, three performance parameters — operational cost (OC), primary energy consumption (PEC), and carbon dioxide emission (CDE) — are considered in the analysis. The results demonstrate that in many climate regions wood pellet-fueled CCHP systems create significant economic and environmental advantages over traditional systems. Additionally, on-site energy production and the potential for grid independence, especially in the aftermath of natural disasters provide critical services and added upsides of traditional systems. The main factors in increasing the viability of CCHP systems are the appropriate sizing and operational strategies of the system and the purchase price of biomass with respect to the price of traditional fuels.
Development of Kinematic and Dynamic Model of an Omnidirectional Four Mecanum Wheeled Robot
Authors: Brown Noah , Pierce Trey , Ma Gloria , McCusker James , Cuckov Filip
Published: February 2023

This paper focuses on the development of the kinematics and dynamics model of an omnidirectional four Mecanum wheeled robot for the purposes of motion control. The kinematic model is implemented to calculate the RPM of each wheel and control the motors. The model allows for the evaluation of drift of the body and a feedback loop implemented in conjunction with odometry to adjust the trajectory of the robotic platform. This considers route length, pose efficiency, necessity of acceleration, and smoothness of motion.

This analysis focuses on the determination of effects from slippage of the roller on the shaft connecting it to a wheel while considering the physical geometry of the robotics platform. In doing so, a more accurate kinematic and dynamics model for an omnidirectional platform is created and simulation is conducted in MATLAB/Simulink environment. The inverse kinematics is also presented in this paper. The authors illustrate the validity of this extensive model through experimental and analytical position tracking of the physical system in eight planar directions: forward/backward, laterally, and along 45-degree angle, as well as in two rotating directions. The dynamics model can be used to understand the performance of the mobile robot and further be used to design the control algorithm for object avoidance.
Experimental and Computational Analysis of Additively Manufactured Nonlinear Springs for Verification of a Predictive Model
Authors: Steel Kyle , Clarke Charisma , Romero-Ramirez Edwar , Carbajal Gerardo
Published: February 2023

A System of Arbitrary General Equations, SAGE, is a new mathematical description technique for modeling generic nonlinear systems with similar ease to linear approximation techniques but capturing data normally only obtainable through intensive nonlinear solving techniques. In this study, SAGE predicts the frequency response of fifteen manufactured nonlinear harmonic mechanical systems, categorized as an eccentric rotor system, and a horizontal pendulum system, all sprung with double spiral torsional springs additively manufactured in PLA, chosen for its nonlinear stress-strain material properties, with solid concentric, hollow, aligned rectilinear, honeycomb, and gyroid infill patterns, chosen to introduce a nonuniform spring geometry. Nonuniform spring geometries and nonlinear material properties give rise to nonlinear spring rates. The nonlinear harmonic mechanical systems are subjected to a cyclic forcing equation sweeping the frequency range of 0 Hz to 2 Hz to obtain a frequency response plot. ANSYS Multiphysics Engineering Simulation software was used to plot the frequency responses of the nonlinear harmonic mechanical systems modeled as a double spiral torsion spring attached to a point mass representing the properties of the physical system. The ANSYS, SAGE, and experimentally obtained frequency response plots are compared to demonstrate the ability of the developed model to display nonlinear behaviors effectively.
Study of the Graphene Energy Absorbing Layer and the Viscosity of Sodium Alginate in Laser-Induced-Forward-Transfer (LIFT) Bioprinting
Authors: Zhou Shuqi , Li Jianzhi , Xu Ben
Published: February 2023

Laser induced forward transfer (LIFT) bioprinting has been viewed as a new and actively developed three-dimensional bioprinting technology due to its high accuracy and good cell viability. The printing quality is highly dependent on the jet formation and its stability in the LIFT bioprinting process. The objective of this study is to investigate the effect of a graphene Energy Absorbing Layer (EAL) and alginate hydrogel (SA) (w.t. 1% and 2%) viscosity on jet generation in the LIFT bioprinting process. Since SA exhibits a shear-thinning behavior, it is a non-Newtonian fluid. The effect of EAL thickness and SA’s viscosity were addressed for various experimental conditions. After the laser irradiated on the quartz substrate, small holes caused by laser interaction appeared in the interaction area on the EAL. The EAL substrate with multiple holes was examined using an optical microscope, and the morphology of holes was observed and compared. The images of jet generation showed that graphene EAL can assist in the transfer of SA with a low laser energy absorption rate. The viscosity of the SA also plays a significant role in the generation of a stable jet for SA transfer. For the cases with the same laser energy input, the jet generated using higher viscosity bioink had a smaller initial velocity, which eventually led to a shorter jet length. The findings in this study will facilitate the development of new EAL in LIFT bioprinting.
Four-Wheel Independent Steering Swerve Drive for First Robotics Competition
Authors: DeNoma Benjamin , Kendall Michael , Poulos Nicholas , Dong Janet , Frank Ray
Published: February 2023

Swerve drive is a drive train that is designed to be omnidirectional, with the ability of a robot to move in any direction at any moment. A swerve drive module is composed of two motors, a gearbox, encoders, and a wheel. One of the motors drives the wheel, while the other motor controls the steering. The gearbox is what controls the rotation of the wheel. The encoders are placed in various places to detect the rotational position of the drive wheel. By combining these components, the swerve drive module can be programmed to rotate as fast as the encoders are able to read. The drawbacks of swerve drive include weight and cost. These drawbacks keep this drive train out of reach of many applications, including the FIRST Robotics Competition (FRC). The FRC is an international high school robotics competition. Each year, teams of high school students, coaches, and mentors work during a six-week period to build robots capable of competing in that year’s game that weigh up to 125 pounds. Our intention for this project is to design, prototype, build, and test a drive system comprised of four independent steering modules that are more cost-effective, compact, and have less weight than what is currently available on the market. It is expected that such a drive system with four swerve drive modules will provide a viable option for the teams with their robots in the FRC. It not only allows young adults in high school teams to expose to complex yet affordable drive systems but also gives them the opportunity to build or program this drivetrain for their robots.

A team of three seniors took on this task to develop four viable swerve drive modules that are cost-effective, and light weighted to fulfill their senior capstone requirement. The project was broken into 3 major sub-sections: structure/frame, steering train, and drive train. This paper will discuss the development of such swerve drive using the engineering design process, including the illustration and description of three feasible design concepts and the selection of the best of three options. The integration of the best drive train design into the robot structure is also illustrated and discussed. The testing of the robot drive will be demonstrated, including speed, maneuverability, and structure analysis. The developed four swerve drive modules later were mounted to the robot built by a local high school team (Colerain High School) in their FRC in March 2022. The team experience and competition results during their FRC will be summarized at the end of this paper. It is evident that the swerve drive is the best overall option for the robotics teams from a competitive and compact design standpoint due to its complete maneuverability combined with the necessary torque and speed with less weight to compete at a high level.
Development of a Predictive Model and Optimization for the Kerf Properties and Delamination Length in AWJM of Kevlar Epoxy Composite
Authors: Kumar Puneet , Salunkhe Sachin , Shanmugam Ragavanantham , Bhuyan Basanta Kumar , Dahiya Anil Kumar , N. Yuvaraj
Published: February 2023

Kevlar epoxy composite is a strong and light weight fiber reinforced polymer (FRP) composite material. It has wide applications in various domains such as aerospace, marine, automotive, military, and sports’ goods (Campbell, 2010). This paper describes the research work involved in studying the influence of process parameters on surface roughness and kerf taper and development of predicative model for the response in abrasive water jet machining (AWJM) of Kevlar epoxy composite. Design of experiments has been performed using response surface methodology and then based on experimental analysis predictive models have been developed to estimate surface roughness and kerf taper. In the present work, four process parameters namely stand-off distance, water pressure, traverse rate and abrasive mass flow rate are considered to study their influence on response characteristics. Experiments are performed according to response surface methodology design. The regression models have been developed to predict surface roughness, kerf taper and maximum delamination length in AWJM of Kevlar epoxy composite. Optimization of process parameters is performed to minimize surface roughness, kerf taper and delamination. Desirability function approach is used for optimization.
Modeling Analysis on Combined Effects of VVT/VCR Engine Technology to Reduce Fuel Consumption of Light-Duty Parallel Hybrid CNG Trucks
Authors: Sok Ratnak , Kusaka Jin , Nakashima Hisaharu , Minagata Hidetaka
Published: February 2023

Potential fuel consumption (FC) improvements of a parallel hybrid, light-duty, compressed natural gas (CNG) truck are numerically predicted using the combined benefits of a variable valve timing (VVT) and variable compression ratio (VCR) engine. A CNG hybrid electric vehicle (CNG-HEV) simulation model is developed in commercial software based on conventional delivery trucks in the Japanese market. The hybrid powertrain model includes a pre-transmission e-motor, high voltage battery, and production-typed 3.0 L CNG engine. Power splitting between e-motor and engine is controlled by a rule-based control strategy. Under the JE05 drive-cycle, engine maps such as torque, fuel and flow rate, and engine friction were measured under different intake valve timings in the 4-cylinder, twin-turbocharged spark-ignition engine with customized pistons to reach a compression ratio (CR) of 17. For VCR operations, the performance maps were recorded under CR14, CR15, and CR17 using standard valve timings. Simulated FC of the CNG-HEV under the JE05 driving cycle is improved by 10.9% and 15.7% using standard and optimal intake valve timings, respectively, against a conventional powertrain vehicle. By combining optimal VVT/VCR engine operations with a selected battery sizing, the predicted FC of the CNG-HEV could be achieved up to 18.2% against the conventional powertrain.
Performance Evaluation of a Solar Thermal Collector With Custom-Made Reflector: An Experimental Study in Midwest Region
Authors: Nokhosteen Arman , Ozkaya Onur , Sobhansarbandi Sarvenaz
Published: February 2023

Aiming to meet the challenges of worldwide energy demand, solar energy is one of the fastest growing renewable energy sectors which can be used for providing heat to the end user on both residential and industrial scales. Amongst the various thermal systems used for providing solar heat, evacuated tube collectors are the most promising and play a crucial role in solar water heating (SWH) systems, therefore, increasing their efficiency and thermal output is extremely beneficial, especially in cold climates. In this study, an optimized parabolic reflector trough is designed in-house to eliminate the dependence of the system to sun’s availability and reduce the solar scattering. This solution will not only concentrate on increasing efficiency, but also modularity is a design targets to aid in increasing the market penetration of solar water heating systems. The system is tested in Midwest region of the United States and results are compared with regular solar water heater. The results show that maximum and minimum fin temperature enhancement of 19°C and 10°C were achieved, respectfully, with employing the solar reflector. Furthermore, as a result of the achieved enhancement, the proposed SWH system is more primed to be coupled with latent heat storage materials with higher melting temperature and latent heat of phase change.
Study of Rotational Heat Transfer Coefficients in Enclosed Flow Over High-Speed Rotors
Authors: Ayyadevara Narayana Teja , Kavali Ravi Kumar , Subramanian Balaji
Published: February 2023

A state-of-the-art integrated heating and cooling facility is established to conduct accelerated tests on large, vertically-oriented alloy rotors, spinning at high speeds. Accelerated testing for such components is accomplished by imposing a cyclically varying thermal stress field in addition to the existing mechanical stress field to estimate the impact on their creep and fatigue life. The cyclic thermal stresses are generated by repeatedly subjecting a rotor to mechanical loading, through alternate transient heating and cooling processes. These transient heating and cooling cycles are carefully designed to maintain specific temperature gradients in the rotor. Such accelerated testing helps provide an accurate estimate of the expected life of a rotor under actual field operating conditions.

Thermal effects seen during cooling of large rotor shafts rotating at high speeds, by forced convection is an important subject area, both in academia and industry. In the present application, this feature gains importance in the development of new rotor-alloy materials for utilization in turbines of modern thermal power plants operating at advanced ultra-supercritical conditions. During the cooling phase of the thermal cycle, cylindrical alloy rotors spinning at high speeds (up to 3000 rpm) are enclosed in a cylindrical cavity and are cooled from high temperatures (∼800 °C) with inert gas, by means of forced convection. There is a need to perform many such cooling cycles to establish alloy material characteristics. The direction of cooling gas flow is neither longitudinal nor transverse to the rotor orientation, making this a unique cooling phenomenon. A comprehensive study is undertaken to predict rotor surface cooling, based on a combination of influencing parameters like gas mass flow, annular dimension, and rotor speeds. It is essential to arrive at the best combination of these parameters for obtaining the desired Rotational Heat Transfer Coefficient (RHTC) data. Mean RHTC for each case gives an insight into rotor cooling rates for this unique cooling disposition. Several simulations have been conducted using Computational Fluid Dynamics (CFD) to obtain temperature profiles along the rotor surface and cross-sections during the cooling period. This is supplemented by experimentation with sufficient instrumentation on these rotors. Establishing accurate correlations from the outputs obtained numerically would lead to considerable savings in terms of fixed costs, experimentation time, energy consumed and human resources deployed. This exercise will support tests on multiple such rotor alloy materials in a shorter time frame, thus speeding up the development of next-generation thermal power plants with the highest order of plant efficiency and reduced emissions.
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

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

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

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

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

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

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

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

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

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.