bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration Transmission Characteristics of Multi-Materials With Hard and Soft Layers Utilizing Photo-Patterning Polymerization
Authors: Inoue Tatsuya , Fukuno Koichi , Fukunishi Haruka , Terashima Osamu , Hayashi Mikihiro , Yamada Shuho
Published: January 2025

This study investigated the vibration reduction effects of polymer materials with hard and soft layers, designed to mimic the surface shapes and characteristics of plants and animals. Initially, numerical analysis using the finite element method was conducted to determine the number of soft layers. The results revealed that having four or nine soft layers could provide a high vibration-reduction effect. Based on these findings, prototype polymer materials were created and tested for their vibration reduction effects by using a shaker. Polymer materials with either four or nine soft layers exhibited a significant vibration reduction, indicating that the effect depended on the number of soft layers. It was also found that this polymer material is effective in reducing the vibrations transmitted to the soles of passengers’ feet while they are inside a vehicle and that these vibrations are caused by road inputs during vehicle driving. It was found that designing hard and soft layers with appropriate values for the number of soft layers may be an effective method for reducing vibrations over a wide range of frequencies.
Exploring the Influence of Acetone Vapor Processing and Subsequent Drying Methods on the Fatigue Performance of 3D Printed ABS Parts
Authors: Bae Heechang , Rada Eric , Scheff Tyler , Michaelis Matthew , Hossain Awlad
Published: January 2025

Fused Deposition Modeling (FDM), a method in additive manufacturing and 3D printing, is extensively utilized where materials are melted, extruded, and layered to fabricate a desired object. Recently applications of FDM technologies have surged extending not only to rapid prototyping but also to the mass production of finalized products. Components in 3D printing are often formed in distinct layers which inherently introduces structural unpredictability due to discontinuities, voids and insufficient inter-layer adhesion. In earlier research we effectively explored the discrepancies in ultimate strength and fatigue life among 3D printed Acrylonitrile Butadiene Styrene (ABS) components crafted with various build/layer orientations. That research successfully underscored the ultimate strengths and fatigue life including SN Curves. Nonetheless there is a pressing necessity for additional research aimed at enhancing the fatigue life of the 3D printed ABS components. This study explores the impact of surface treatment on the fatigue life of 3D printed ABS components across various layup orientations. Herein the Acetone Vapor Smoothing (AVS) method was employed as the surface treatment for the components. Our findings indicate that the AVS method can mitigate stress concentrations on the surface and structural uncertainty in the 3D printed ABS components thereby amplifying fatigue strength. These findings, however, were attained after manipulating Acetone vapor exposure and optimizing drying procedures since Acetone compromised the layer bonding of the ABS diminishing its tensile strength and fatigue life. This research outlines the optimal conditions for Acetone Vapor exposure time and drying procedure.
Modelling and Simulation of Solenoid Driven Electro-Pneumatic Actuator
Authors: Ercis O. Fatih
Published: January 2025

This paper presents the modelling and simulation of a servo electro-pneumatic actuator utilizing solenoids. Many control actuation systems employ electro-hydraulic or electro-mechanical servo actuators. However, electro-pneumatic servo actuators using solenoids are becoming more popular due to their lower cost and simpler structure. Pneumatic actuators are preferred due to their low cost, simple structure, fast response, low electromagnetic interference, high force/weight ratio. In this study, poppet type on-off solenoid valves, driven by pulse width modulation (PWM), are used to achieve servo control of the pneumatic actuator. A feedback sensor is attached to the output shaft of the actuation mechanism. The actuator is powered by a pressurized gas tank, with gas pressure regulated by a pneumatic pressure regulator. Both non-linear and linear mathematical models of the pneumatic actuator are developed and compared at a specific operating point using MATLAB/Simulink software. Furthermore, a closed loop servo system is established in Amesim simulation environment. The detailed models of the solenoid valve, friction, and pneumatic pressure regulator are implemented in the Amesim model. The simulation results reveal the non-linear behavior of the compressed gas. Additionally, the 3dB bandwidth is calculated to be 23 Hz. Beyond this frequency, unpredictable harmonic motions are observed.
Characterization of Energy Dissipation and Material Failure Mechanisms In High-Velocity Impact of Magnesium Alloys
Authors: Jin Rong , Sun Xingsheng
Published: January 2025

High-velocity impact analysis is crucial in defense, aerospace, and materials science, involving scenarios ranging from projectiles hitting land vehicles to supersonic aircraft traveling in dusty environments. This work presents a detailed computational analysis of high-velocity impacts using the Smoothed Particle Hydrodynamics (SPH) method. Impact events include a stainless steel projectile against a magnesium alloy target plate, with impact velocities ranging from 1.2 km/s to 2.4 km/s. We employ carefully calibrated plasticity, fracture, and equation of state models to characterize the behaviors of both projectile and target over a wide range of strain rates and temperatures. Our simulation results include the evolution of the von-Mises effective stress and temperature fields at different impact velocities. Several key material failure mechanisms are observed, such as spalling and adiabatic shearing. We partition and quantify the dissipation of the impact kinetic energy into the kinetic and internal energies of both the projectile and the target. Finally, we analyze the time histories of the corresponding proportions during the impact events and the distributions of energies across all material points at key time points. We find that at all impact velocities, the target’s kinetic energy peaks when the shock wave reaches the back face and stabilizes after complete penetration. As the impact velocity increases, the kinetic energy of the target and the internal energy of the projectile contribute more significantly to the dissipation of the impact energy, while the contribution of the target internal energy decreases.
Heat Transfer of High-Temperature in Rotating Aerocraft Jet Engine Turbine Blades
Authors: Amano Ryoichi S.
Published: January 2025

Pin-fin is an excellent structure to insert in the narrow trailing edge of a gas turbine blade to achieve effective cooling. The optimization of the pin-fin design is important to finding the optimal pressure drop. The present study considers two different pin-fin designs, i.e., partial spherical and dome shapes with different pin-fin arrays. The experimental and simulation studies were performed with different rotation numbers. The experimental study with different Reynolds numbers was completed. A computational study was conducted with a simulation. The investigation was completed based on the cooling channel’s heat transfer coefficient, friction factor, and thermal performance. The cooling channel with dome-shaped pin-fins showed better thermal performance than other cooling channels.
Mechano-Bactericidal Surfaces Fabricated by Inverted Glancing Angle Deposition (I-GLAD)
Authors: Qu Chuang , Walsh Kevin
Published: January 2025

This paper explores the nanofabrication of mechano-bactericidal antimicrobial surfaces using inverted glancing angle deposition (I-GLAD). Inspired by natural mechanisms, needle-like structures are employed to eliminate microbes by rupturing them upon contact, thereby preventing the development of antimicrobial resistance. However, creating artificial mechano-bactericidal antimicrobial surfaces presents challenges due to the intricate three-dimensional nanofeatures involved. Leveraging the capabilities of Inverted-Glancing Angle Deposition (I-GLAD), an advanced physical vapor deposition technique, this work aims to produce large-area surfaces featuring sub-10 nm tip-sized nanoneedles for mechano-bactericidal purposes. Compared to conventional nanofabrication techniques, the I-GLAD process offers a cost-effective and time-efficient approach to creating such antimicrobial surfaces. The manuscript discusses the inverting ability of the process, highlighting the necessity of a maximum incident angle of over 79 degrees for successful inversion, as demonstrated by tape testing results. Furthermore, by incorporating transparent materials (such as SiO2) in the I-GLAD process, the nanoneedle structures act as a transitional medium between air and the parylene substrate, effectively reducing surface reflection and rendering the antimicrobial surfaces transparent. Experimental tests confirm the transparent nature of these surfaces. Both opaque and transparent I-GLAD films hold promise for diverse applications across various fields in our daily lives.
The Study of Hyperparameters in the Prediction of Remaining Useful Life
Authors: Gandur Nazir Laureano , Ekwaro-Osire Stephen
Published: January 2025

Despite the extensive body of literature on RUL prediction techniques, there is still a need to understand how hyperparameters affect these predictions’ error and aleatoric and epistemic uncertainty. Motivated by this need, the research question was: Does applying machine learning architecture enhance uncertainty quantification in RUL prognostics? Two objectives are pursued to address this question: first, to analyze the impact of hyperparameters on modeling the data, and second, to explore the temporal propagation of the hyperparameters’ influence on RUL.

To achieve these objectives, this research leverages vibration data obtained from experiments conducted on bearings. Employing a neural network framework, the study quantifies uncertainty in RUL prediction. Different hyperparameters were studied to determine how they affect uncertainty and error. Furthermore, the paper goes to the temporal analysis of hyperparameter impact by delving into the dynamics of these influences over time and examining how the hyperparameter effect propagates, as represented by a probability density function of RUL. The hyperparameter analysis reveals how different settings influence the model’s uncertainties and error metrics. Finally, it was determined that the selection of an optimizer is critical when developing RUL prediction models for predictive maintenance tasks.
Digital Shadow-Based Detection of Blockage Formation in Water-Cooled Power Electronics
Authors: Hainey Richard , Priddy Braden , Sado Kerry , Downey Austin R. J. , Khan Jamil , Fought Haskell , Booth Kristen
Published: January 2025

In maintaining the quality of coolant within water-cooled electronic systems, attention must be given to potential blockage formations. These blockages typically occur when suspended particulates form deposits within component chambers, leading to restricted flow, which can result in overheating issues, decreased performance, and cooling failure. To address this, a thermal digital shadow has been designed and validated to accurately simulate and detect blockage formation within the cooling system of a real-world physical twin. During operation, the digital shadow characterizes system parameters — flow rate, initial temperatures, individual components, and waste heat production — from the physical twin to more accurately replicate system characteristics. For validation, simulated blockages are created in the physical twin and digital shadow, and the results are compared. At 50% blockage, a significant temperature surge is observed, with subsequent surges increasing as the blockage develops, the largest occurring at 87.5% blockage formation. The data gathered shows how a digital shadow can support real-time monitoring and predictive maintenance, enabling proactive interventions to prevent thermal accumulation from damaging the affected components. Serving as the groundwork for future development, this digital shadow system can assist in creating a robust digital twin system for blockage detection and decision-making within water/liquid-cooled electronic systems.
A Study of Optimal Mesh for Computational Fluid Dynamics in Cerebral Aneurysms
Authors: Garigapuram Prithvinath Reddy , Katore Srushti
Published: January 2025

A cerebral aneurysm is a cerebrovascular condition affecting about 3 to 5 percent of the population, posing significant health risks. Rupture can result in death, with aneurysms greater than 7mm considered high risk and those less than 3mm low risk. However, size alone doesn’t determine rupture risk; location, shape, and individual health also play crucial roles. Computational fluid dynamics (CFD) analysis has advanced preventative medicine by providing valuable insights into aneurysm growth, rupture risk, and behavior, aiding early diagnosis and treatment. The accuracy of CFD depends on mesh quality in capturing flow properties. Improper meshing introduces challenges like lack of mesh independence and artificial flow disturbances, impacting accurate hemodynamic assessment. Computational costs increase with mesh size without necessarily improving accuracy due to numerical instability. Thus, meticulous meshing is crucial for reliable CFD simulations. This study investigates meshing effects on CFD results using ANSYS 2023 R2 Fluent with polyhedral meshes. A comparative study of five patient models assesses the impact of varying mesh quality on simulation accuracy. Uniform boundary conditions (blood pressure 120/80 mm Hg, healthy velocity inputs) are used to evaluate flow dynamics, wall shear stress (WSS), and pressure distribution, establishing an efficient and accurate simulation approach for aneurysm modeling.
Transient Evolution of Interface and Temperature in Twin Roll Casting Process Using Coupled Phase Field and Thermo-Fluid Model
Authors: Soni Akshay , Bag Swarup , Robi P. S. , Amin M. Ruhul
Published: January 2025

A The production of thin strips by utilizing twin roll casting process requires proper control over process parameters. Excellent quality of the strip is only visible when process is operated under steady state condition. However, defects such as porosity, irregularities in strip surface, and frequent breakage in strip are observed during the process. These defects arise prominently due to unstable liquid metal-air interface during initial transient stage of the process. The stability of the interface can be tailored by selecting process parameter that consequently mitigates the possibilities of defects. The current study focuses on the transient evolution of liquid metal-air interface during the initial stage of the process. A two-dimensional transient coupled thermo-fluid model using phase field is devised for investigating free surface profile of the liquid melt and possibility of air entrapment within the liquid metal. In addition, growth of solidified shell, time required to stabilize the exit surface temperature, and thermal profile are also incorporated in the study. The investigation of the process indicates that higher casting and inlet melt velocity creates unstable interface. Hence to obtain stable and gradual formation of interface, optimum casting speeds with low inlet melt velocity is proposed.
Morphokinematic Impacts on Hydrodynamics and Performance of Tuna-Inspired Robots
Authors: Kelly John , Zhu Joe , Bart-Smith Hilary , Dong Haibo
Published: January 2025

Many recent developments have been made in the performance of bioinspired underwater vehicles, however, there is still a significant performance gap between the high-performing fish in nature and their engineered counterparts. A multitude of parameters govern performance in biological fish swimming, including the morphology of the fish and the kinematics of the swimming motion. In this research, we utilize computational fluid dynamics to study the effect of morphological and kinematic parameters on the performance and hydrodynamics of Tunabot Flex, a high-performance tuna-inspired robotic platform. A reconstructed virtual model is used for fluid simulations, completed with an in-house immersed boundary method-based direct numerical flow solver. Results characterize the flow of the Tunabot flex platform, including thrust generation and vortex wake analysis. The effects of the body thickness on the performance are studied, revealing a critical flow separation mechanism that accelerates the detriment resulting from a wider body. Finally, the kinematics are varied by adjusting the virtual joint angles corresponding to the real Tunabot flex joints. These results allow for a better understanding of body flexibility, morphological, and kinematic parameters and their role in Tuna-like locomotion, allowing for better-informed engineering design.
Time-Dependent Solution of Unsteady Compressible Flow Equations for Nanoscale Heat and Mass Transfer in Wide-Ranging Diverse Applications
Authors: Sinha Ramlala P.
Published: January 2025

A new innovative stable time-dependent compressible flow solution over the order of nanoseconds is provided here for wide-ranging critically important challenging applications. Specifically, a solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube, closed at one end with a piston oscillating at very high resonant frequency at the other end, has been obtained numerically, assuming one dimensional, viscous, and heat-conducting flow, by solving the appropriate fluid dynamic and energy equations. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. In successfully predicting the time-dependent results/data, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, nanoscale heat and mass transfer, diverse range of advanced fluidics, biofluidics / bioengineering, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and high energy nuclear explosion blast wave propagations in one dimensional and/or radial spherical coordinates with or without including energy generation / addition terms. No other solution exists for such applications.
The Fabrication Process of Surface Acoustic Wave (SAW) Devices Using Maskless Photolithography With a Validation of Traditional Masked Photolithography for Microfluidic Applications
Authors: Parvez Mohammad Salman , Hussain Shadhin , Young Chadwin , Lee Jeong-Bong
Published: January 2025

IDT (Interdigitated Electrodes or Transducers) fabricated Surface Acoustic Wave (SAW)-based devices have been popularly used in microfluidic applications. The mask-based photolithography system is commonly used for fabricating IDTs on SAW devices. But the process does not provide much freedom for changing the design, once the mask is made. On a different note, Lithium Niobate (LiNbO3)is very fragile and brittle which can be broken or can induce stress that may impact the piezoelectric properties due to hard contact of the Chromium mask during UV exposure. A novel maskless photolithography process is introduced for such devices to mitigate these limitations. In terms of cost, this maskless approach is cheaper than creating a new mask each time for a change in design parameters. This process is also suitable for the “lift-off” and “etching” techniques regardless of “Bright-field” or “Dark-field” masks with the same computer-aided drawing (CAD). In this study, the dosage rate has been estimated for the maskless process by converting the dosage parameters from the masked photolithography process. Finally, the devices made by the maskless photolithography process have been characterized with a Vector Network Analyzer (VNA), and the results are validated through comparison with the conventional mask-based photolithography process.
Synergy Based Design of a Hand Exoskeleton With Dual Actuation for Three Finger Groups
Authors: Portillo Perla , Saldajeno Ezekiel John , Sharifi Mojtaba
Published: January 2025

Each year, numerous individuals experience strokes and other medical conditions that result in the loss of hand movement. To regain this movement, they often undergo physical therapy, which can be both costly and time consuming due to the complex musculoskeletal structure of the hand and the high level of skill required for rehabilitation. The intricate nature of the hand makes it challenging for some patients to quickly restore movement. To address this challenge, researchers have developed assistive devices, such as hand exoskeletons, to facilitate the rehabilitation process. These exoskeletons use external power sources to control and move the user’s fingers, enabling them to perform routine or therapeutic exercises. In addition, hand exoskeletons can reduce the cost of physical therapy by allowing users to perform exercises independently, without continuous physical assistance from a therapist.

This study aims to design a novel, synergy-based mechanism for a hand exoskeleton that can move three groups of five fingers using only two actuators. The two synergies employed are the primary ones identified in the literature based on hand anatomy. The three finger groups are defined as follows: Set 1 consists of the pinky and ring fingers, Set 2 includes the middle and index fingers, and Set 3 comprises the thumb. The developed hand exoskeleton utilizes two linear actuators to move these finger groups, enabling the hand to perform grasping motions effectively.
Modeling and Simulation of 7000-Series Aluminum Extrusion Process for Complex Curtain Structure Profile
Authors: Nguyen Thanh-Cong , Hsu Quang-Cherng , Truong Tat-Tai
Published: January 2025

The extensive range of applications for aluminum alloys in the 7000 series is linked to their excellent mechanical properties; however, this also restricts their formability, especially with the extrusion process. Practical extrusion die design depends on the traditional “test-and-revise” process to cover all the complicated influence factors, which costs a lot of time and resources. Recently, researchers have investigated the aluminum extrusion process by applying simulation software to overcome those challenges. This study aims to utilize different approaches to virtual simulations, including steady-state simulations with the finite element method and transient simulations based on the finite volume method. It gave overall comparison results to gain a better understanding of the 7000-series aluminum extrusion process for complex curtain structure profiles. Details of the material flow in the die and the extrusion force in both types of simulations have been compared and analyzed. The notable difference in force prediction between transient and steady-state simulations for AA7005 (up to 457 tons) compared to AA7075 (only 41 tons) highlights the critical influence of input parameters, particularly the flow stress data. In addition, transient simulations required a significantly longer amount of time to run than steady-state simulations, typically around 10 times.
Thermally Induced Stress and Deflection in Cantilever Beam
Authors: Mohammadzadeh Ali , Haidar Salim M. , Norouzi Mahdi
Published: January 2025

In the absence of mechanical loads, temperature gradients could cause significant stresses in a solid body. In turn, this could lead to failure of mechanical and structural parts. In a typical undergraduate mechanical engineering curriculum, students are introduced to the concept of mechanical stress in solid bodies during sophomore or early junior year of their studies. They have no exposure to heat transfer and temperature field in a solid body until later in the curriculum. As such, students’ study of thermally induced stresses is limited just to statically indeterminant axial loads due to uniform temperature rise, and in the absence of temperature gradient in the body. Therefore, they are not aware of thermal stresses induced solely by temperature gradients in a solid body and the harmful effects they can cause even in the absence of mechanical loads. In this paper we present a complete model for introducing our students to this important aspect of design of structural parts and mechanical components. It would also make for a great term-long project in either heat transfer class or machine design course. It is believed that students in either of these two senior-level courses possess the technical maturity both in stress and heat conduction analyses to handle such a project.
Enhancing the Structural Performance of 3D Printed Objects Through G Code Optimization via FEA in the FDM Process
Authors: Shahriar Saquib , Islam Razaul , Park Jaejong
Published: January 2025

Additive manufacturing, an innovative process that assembles materials layer by layer from 3D model data, is recognized as a transformative technology across diverse industries. Researchers have extensively investigated the impact of various printing parameters of 3D printing machines, such as printing speed, nozzle temperature, and infill, on the mechanical properties of printed objects. Specifically, this study focuses on applying Finite Element Analysis (FEA) in G code modification in Fused Deposition Modeling (FDM) 3D Printing. FDM involves extruding a thermoplastic filament in layers over a build plate to create a three-dimensional object. In the realm of load-bearing structures, the Finite Element Analysis (FEA) process is initiated on the target object, employing the primary load to identify areas with high-stress concentrations. Subsequently, optimization techniques are used to strategically assign printing parameter combinations to improve mechanical properties in potentially vulnerable regions. The ultimate objective is to tailor the G code, a set of instructions for the printer, to strengthen particular areas and improve the printed object’s overall structural integrity. To evaluate the suggested methodology’s efficacy, the study conducts a comprehensive analysis of printed objects, both with and without the optimized G code. Simultaneously, mechanical testing, such as tensile testing, demonstrates quantitative data on structural performance. This comprehensive analysis aims to identify the impact of G code alteration on the finished product. Preliminary experimental results using simple tensile specimens indicate notable improvements in structural performance. Importantly, these improvements are achieved without any discernible mass increase, optimizing material usage and reducing the cost of additive manufacturing. The modified G code targets to strengthen critical areas using updated printing parameters without a net increase in the overall material consumption of the object. This finding holds significant implications for industries reliant on additive manufacturing for load-bearing components, offering a promising avenue for improved efficiency and durability. Integrating advanced techniques, such as G code modification and finite element analysis (FEA), as the additive manufacturing landscape evolves presents a pathway toward optimizing mechanical properties. By contributing valuable insights and laying the groundwork for further exploration and refinement of these methodologies, this study paves the way for enhanced structural performance in various additive manufacturing applications. Ultimately, it encourages innovation and progress in the field, propelling the industry toward new heights of efficiency and reliability.
Elastic and Thermal Properties of Additively Manufactured Continuous Fiber Composites
Authors: Inan Efe E. , Saigal Anil
Published: January 2025

This paper presents a new framework for predicting both elastic and thermal properties of additively manufactured continuous fiber composites as functions of printing parameters. Guided by tensile testing and bespoke thermal conductivity measurements of samples produced by the Markforged Mark Two printer, the framework leverages classical laminate theory (CLT) to offer a convenient and systematic approach to the evaluation of the stiffness and thermal conductivity matrices of 3D printed composite parts.

The thermal conductivity, in particular, of additively manufactured continuous fiber composites is not well documented. Composite materials are highly sought after for applications like electronics packaging, where heat dissipation is an important consideration. The ability to additively manufacture composites for such applications presents previously unattainable opportunities for prototyping for these use cases. Using this framework, important thermal performance metrics like heat dissipation rate can be easily evaluated, allowing for optimizing the printing parameters to better suit the desired application.
Protecting Workers Performing Machine Maintenance: Comparing Modalities
Authors: Hamilton John , Morse John
Published: January 2025

Machine maintenance brings humans into exposure to hazards in unique ways. Modalities to reduce risk vary globally. In the United States the government attempts to protect workers performing maintenance via regulations imposed on employers. The relevant regulation for general industry is titled “The control of hazardous energy (lockout/tagout)”, also known as Lockout/Tagout or LOTO. LOTO relies on training of and compliance by the employees, and enforcement of the LOTO program by the employers. The cost of compliance in time spent can be high and therefore LOTO is sometimes not complied with.

The European Union has a machine directive specifying safety requirements for industrial machines to meet before those machines can be sold. There is no EU regulatory requirement for LOTO like that used in the US. Some maintenance tasks that are legally allowed in Europe without LOTO would be a violation in the US. Whereas in Europe workers can be protected via alternative methods while performing some maintenance tasks, that same maintenance procedure would have to be performed under LOTO in the US to comply with regulations.

Even under the LOTO standard, given the high cost of compliance in some instances, it is reasonably foreseeable to machine designers that LOTO may not be followed. The addition of alternative means of protection through machine design can enhance machine safety whether LOTO is followed.

This paper will explore LOTO and alternative means of protection, compare LOTO and the use of alternative methods, identify strengths and weaknesses of both, and consider case studies regarding LOTO.
Micro-Mechanical Property Evaluation of Heat-Treated Metal 3D Printed Parts Affected by Process Interruptions
Authors: Chigurupati Poojith Chowdary , Dababneh Fadwa , Taheri Hossein , Jones Michael
Published: January 2025

Metal additive manufacturing techniques enable rapid prototyping and on-demand manufacturing while improving supply chain resiliency. Changes in microstructure and micro-mechanical characteristics of 3D printed metal parts occur due to the influence of process interruptions on melting-solidification cycles during the layer evolution in additive manufacturing processes. The process interruption can deteriorate the structural integrity of the 3D printed parts and generate micro-flaws in the interruption region. There are a variety of techniques which can remove or reduce the amount or size of micro-flaws. Manufacturing post-processing techniques such as Heat-Treatment methods can enhance the mechanical properties of the parts. Since variations commonly happen at the layer level, the investigation of mechanical properties must be done such that these variations can be effectively identified, evaluated, and used to inform post-processing needs. Hence, this study investigates the influence of process interruption on the micro-mechanical properties of the metal 3D printed parts for stainless steel parts with and without post-processing. Accordingly, various stainless steel 316L parts are fabricated using powder-bed fusion additive manufacturing process. Manufacturing processes included different process lags. Nano-indentation testing is used to measure the elasticity and hardness. Measurements are recorded in a matrix grid form covering the interruption region of the manufacturing process. Measurement results of measurement are analyzed to detect potential variations caused by the process interruption. To investigate the influence of the post-processing procedures on the enhancements of mechanical properties of the parts, a group of parts were heat-treated in a vacuum furnace. Micro-mechanical properties were also measured for the parts with heat-treated post-processing. Results indicate that process interruptions and lags alter the mechanical properties of the parts; however, the variation can be reduced using post-processing procedures.
Reduced Order Modeling of Flow Over Spanwise Periodic Rough Surfaces
Authors: Huang Yuting , Hutchins Nicholas , McKeon Beverley
Published: January 2025

Resolvent analysis is utilized to model the temporal mean of experimental measurements of a turbulent boundary layer over streamwise aligned, spanwise alternating rough surfaces, where large counter-rotating rolls are observed. Without detailed knowledge of the roughness geometry, the resolvent modes are generated using a smooth wall boundary condition and a spatio-temporal mean extrapolated using an analytical model. A least squares fit is then performed using the resolvent modes on the streamwise time averaged hot wire measurements, achieving good agreement with the experimental results. The spanwise and wall-normal velocity components predicted from the resolvent modes achieves a qualitative agreement with particle image velocimetry (PIV) measurements, correctly predicting the location, shape, and direction of the secondary counter-rotating rolls while under-predicting its magnitude. An eddy-viscosity model is then added into the streamwise momentum equation in the resolvent framework to augment its predictive capabilities, significantly improving the predicted magnitude of the spanwise and wall-normal velocity components. Finally, all three velocity components from the PIV measurement are utilized in the least squares regression, achieving good agreement with the experiments while reducing the degree of freedom to 0.18% of the experimental data. This work showcases the ability to use resolvent modes that can be computed with effectively negligible cost to model flow features unavailable from the experimental data and to efficiently represent experimentally measured flow fields over rough surfaces of industrial interests.
Generation of MATLAB Simscape Models Using Large Language Models for Training Reliability Evaluation Methods
Authors: Hummel Patrick , Grimstad Joachim , Xia Yuchen , Morozov Andrey
Published: January 2025

The approach presented in this paper makes use of the natural language processing capabilities of large language models in order to generate MATLAB Simscape models based on specification texts. This process is based on a well-defined state machine and begins with the creation of abstract system models that may be iterated on using natural language. The abstract models are then converted to more detailed models by adding parameters and blocks required for simulation. Fault tolerance may optionally be improved by automatically applying design patterns that increase redundancy using voter and comparator blocks, among others. The abstract models are then converted into MATLAB Simscape models using traditional algorithms. The generated models can be used to train artificial intelligence systems designed for reliability evaluation. A selection of publicly available large language models is systematically evaluated based on capability regarding this task. A software prototype demonstrates the feasibility of using generative artificial intelligence to assist with the modeling of systems in MATLAB Simscape as a proof-of-concept. Current limitations and future research potential is discussed.
Finite Element Modeling and Additive Manufacturing of High-Density Polyethylene Micro/Nano-Hydroxyapatite Composites for Biomedical Implants
Authors: Al-Kharusi Moosa S. M. , Al Owiemri Mohammed S. , Al Jahwari Farooq K. S.
Published: January 2025

This study examines the development and characterization of High-Density Polyethylene (HDPE) composites enhanced with micro and nano-Hydroxyapatite (HA), aimed at optimizing their utility in biomedical implants through the integration of Finite Element Modeling (FEM) and additive manufacturing techniques. Initial fabrication utilized a twin-screw extrusion process to create a variety of composite formulations, which were then molded and subjected to comprehensive mechanical testing to assess their suitability for orthopedic applications. These tests revealed that nano-HA particularly enhances the mechanical strength and stiffness of the composites, thus improving their load-bearing capabilities which are crucial for implant success. In parallel, FEM was applied using ANSYS to simulate the behavior of these composites under tensile stress, allowing for the validation of experimental results and adjustment of composite configurations for optimal performance.

Further exploration involved the application of additive manufacturing techniques to produce complex implant geometries using the extruded HDPE/HA filaments. This method demonstrated the potential of tailored therapeutic solutions, catering to individual patient needs and advancing the state of custom implant design. The adaptability of HDPE/HA composites to 3D printing underscores their significant role in facilitating the production of durable, precise, and patient-specific implant structures. Through iterative testing and simulation, the study not only confirmed the mechanical enhancements provided by HA fillers but also optimized the processing conditions for effective 3D printing of biomedical implants.

Conclusively, this research highlights the synergy between advanced computational modeling and novel manufacturing processes in the creation of next-generation biomedical implants. The dual approach of FEM and 3D printing allows for the meticulous refinement of material properties and implant designs, presenting a significant advancement in the field of reconstructive surgery. By providing enhanced material solutions that offer both superior performance under physiological conditions and customization capabilities, this study contributes to the broader efforts to improve patient outcomes in orthopedic applications.
Design and Development of Inertially Excited Fully Compliant Robot
Authors: Lozano Raul , Walker Britt , Tekes Ayse
Published: January 2025

Compliant mechanisms, or flexible machines, deform largely under an external force, displacement, torque, or excitation and mimic motions commonly observed in nature. Due to their unique characteristics, such as the ability to be manufactured as a single piece, no friction between neighboring parts, no backlash, and thus enhanced performance, they are widely used in robot design. In this study, we developed a fully compliant locomotive robot consisting of a top plate, four masses, a rail, four links, support structures, initially preloaded compliant beams, and a disk. Two carts (masses) slide along the rail, with one end of the legs connected to each cart via a small length-flexure hinge, and the other ends converging at the center through a flexure hinge. The initially preloaded compliant beams are vertically attached between the top and bottom masses on each side. Engineers typically design active or passive vibration isolators to dampen undesired vibrations caused by unbalanced masses in a rotating system. However, in our design, we utilized the undesired vibrations to inertially excite the robot. A DC motor, positioned within the support structure and connected to the disk, allows for the addition of small loads to the rotating disk with eccentricity, creating controllable vibrations in amplitude and frequency. While the preloaded beams maintain the robot’s vertical position, they also act as compression springs, facilitating motion transfer. We developed the mathematical model of the locomotive robot using Lagrange equations and analyzed the motion in MATLAB Simulink.
LH2 Tanks in Fire Incidents - the Cryogenic High Temperature Thermal Vacuum Chamber Enables In-Depth Insights
Authors: Eberwein Robert , Scarponi Giordano Emrys , Cozzani Valerio , Otremba Frank
Published: January 2025

Liquefied Hydrogen (LH2) and Liquefied Natural Gas (LNG) establish themselves as important energy carriers in the transport sector. Their storage requires tanks with thermal super-insulations to keep them at cryogenic conditions for a long time. These insulation systems have proven itself in various applications over a long time. However, these insulations are still new in land transportation, where accidents involving collisions, fires, and their combination are to be expected. This study summarizes the results of the ongoing research program in which insulations commonly used in industry were analysed through experimental and numerical studies under fire-like conditions. It was found that there are strong differences among the various insulation systems. Several safety concerns and research gaps exists for layered insulations, which are typically used in land transport. To further analyse these insulation systems, a new test concept called Cryogenic High Temperature Thermal Vacuum Chamber (CHTTVC) was developed and manufactured. This concept enables the testing of large insulation samples under industrial conditions and the consideration of cryogenic conditions relevant for the investigation of various phenomena. The results are important for the evaluation of accident scenarios, the improvement of thermal super-insulations, and the development of emergency measures.
Hybrid Thermal Management Method of Li-Ion Batteries Using Heat Pipes and PCM for Electric Vehicles
Authors: Sharifi Nourouddin , Millard Christian , Etufugh Ugochukwu , Shabgard Hamidreza
Published: January 2025

This study presents an experimental investigation into a new hybrid cooling method for 18650 lithium-ion batteries utilized in electric vehicles (EV). The experimental setup comprises a heating section, a phase change material (PCM) reservoir, and a cooling section. The heating section replicates the heat generated by the batteries and includes two cylindrical aluminum housings (with dimensions matching those of an 18650 battery), two cartridge heaters, and an aluminum heat sink. The PCM reservoir is constructed using 3D-printed PLA components. A designated airflow channel is designed for the cooling section. Three copper-water heat pipes (HPs) are utilized to transfer heat from the heaters to the air flow channel through the aluminum housings, the heat sink, and the PCM reservoir. Aluminum fin jackets are affixed to the HPs within the PCM reservoir and the airflow channel to improve heat transfer. Two cooling scenarios — with and without PCM — are investigated. Temperatures at various locations within the setup are measured and compared under multiple power settings of the heat cartridge and air velocities. It was found that for a moderate total power of 16W, the steady-state battery temperatures are reduced by about 14%, 10%, and 4% when using the PCM compared to the case without the PCM for air velocities of 2 m/s, 3 m/s, and 4 m/s, respectively.
Deconvolution of Atomic Force Microscopy Data From the Effects of Destructive Indentation in Soft Material Systems
Authors: Westby Maximillian , Yekani Fard Masoud , Norkus Tyler , Boutin William
Published: January 2025

Atomic force microscopy (AFM) is a crucial tool for nanoscale material characterization of soft materials. However, AFM data is easily convoluted by many real, non-ideal artifacts. Researchers have identified some of them and developed techniques to deconvolute AFM data. Yet, several effects remain poorly understood. One of these effects has been identified as destructive AFM indentation. In particle-matrix composites, hard particle inclusions are responsible for varying degrees of stiffness across the sample, making nondestructive AFM indentation challenging. This paper utilizes finite element analysis (FEA) and AFM to study the impact of polymer matrix damage caused by destructive indentation on AFM data. AFM indentation is simulated on a polymer matrix FE model at varying depths. The Derjaguin-Muller-Toporov (DMT) contact model is validated for the FE geometry and applied to probe-matrix interactions for small indentation depths. Experimental data from AFM performed on PNCs reinforced with 0.5 wt.% multi-walled carbon nanotube (MWCNT) and CNT buckypaper (BP) is used to supplement FEA. Force-displacement data obtained through FEA is used to determine the indentation force and yield strength at the nanoscale following Hertzian contact theory and Tresca’s yield criterion. Subsequent destructive indentations are simulated to study their effect on force-displacement data.
Assessment of Refrigerant Management Practices in Automotive Air Conditioning Service Centers: Compliance, Challenges, and Environmental Implications
Authors: Galindo Ronald M.
Published: January 2025

The unintentional or intentional venting of refrigerants into the atmosphere by automotive air conditioning service centers instead of utilizing refrigerant recovery equipment poses a significant threat to the ozone layer, in accordance with the Montreal Protocol, Environmental Protection Agency (EPA) regulations, and Republic Act 8749 (R.A. 8749), also known as the “Philippine Clean Air Act.” This study assesses the refrigerant management practices within accredited automotive air conditioning service centers in Metro Cebu, Philippines, focusing on operations, awareness, and compliance with environmental regulations. Using a descriptive survey technique, the assessment covers various areas of refrigerant management, including sourcing, handling, storage, inventory, recovery, recycling, reclamation, equipment, and parts disposal. The findings indicate that while accredited automotive air conditioning service centers in Metro Cebu demonstrate partial compliance with operational standards such as quality, process efficiency, capacity management, inventory control, and workforce competence, there exist significant gaps in compliance with EPA and R.A. 8749 guidelines. Specifically, refrigerant management practices related to sourcing, handling, storage, inventory control, recovery, recycling, reclamation, and equipment and parts disposal are not fully implemented in accordance with regulatory standards.