bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Health Monitoring of Wind Turbine Blades Utilizing Guided Waves
Authors: Lu Runye , Shen Yanfeng
Published: January 2025

Wind turbine blades (WTBs), as crucial components of wind turbine generators, are susceptible to structural damage due to severe weather conditions during operation periods. This paper proposes an active structural health monitoring (SHM) system, leveraging guided waves for the WTBs diagnosis. It comprises electro-magnetic actuators, piezoelectric sensing units, and data acquisition and signal processing modules. An algorithm incorporating spectral wave energy and cross-correlation is developed for precise damage detection. To validate the system and algorithm, a simplified SHM system is implemented on a laboratory-scale WTB prototype. Artificial damage simulated by the bonded mass block can be accurately detected and located. For the subsequent phase, a full-scale test is conducted on a XX-192 WTB (anonymity of XX for confidential purpose), exceeding 90 meters in length and fixed on a foundation tower as a cantilever beam under fatigue tests. The practical durability and stability of the system is demonstrated, subjected to over 500,000 flapping and edging cyclic loadings. The system precisely detects the artificial delamination in the fashion of a bonded composite sample on the WTB, achieving the detection of a small delamination area of 80 mm* 30 mm. The paper culminates in summary, concluding remarks, and suggestions for future work.
Estimating Scaled Cloud Height in Pulse Jet Mixed Vessels
Authors: Pease Leonard F. , Bamberger Judith Ann , Daniel Richard C. , Minette Michael J.
Published: January 2025

To suspend and mix radioactive slurries without pumps or impellers, the performance of pulsed jet mixed vessels has been investigated. The slurry in the pulse tubes is expelled impinging upon the vessel floor and lifting solids to a “cloud height” in a cyclic process. Experiments measuring cloud height for a variety of waste simulants have been conducted for vessel configurations that varied vessel diameter, fill height and pulse tube number, volume, and nozzle diameter.

The elevation to which suspended particles rise is termed the cloud height and derives from a balance between the fluid forces of the jet and the gravitational forces acting on the particle ensemble. Here we use scaling to estimate the cloud height based on conservation of mass and momentum and jet similarity.

We find that the cloud height varies with the nozzle exit velocity to the 2/3 power in agreement with observations.
Development of a Geometric Accuracy Machine Vision Application for Metal Castings
Authors: Jones Michael , Chigurupati Poojith Chowdary , Taheri Hossein
Published: January 2025

Metal castings provide critical products to several industries such as aerospace, medical, and automobile. A prominent level of geometric accuracy is required in high-value casting components to ensure an adequate level of quality. While traditional methods of measuring critical features on metal castings such as laser scanning measurements have proven effective to determine geometric accuracy, these techniques are often time consuming and require costly equipment and labor time. The aspect of geometry measurement in Industry 4.0 involves the application of advanced digital technologies to streamline the measurement of geometric features through machine vision techniques. Machine vision systems utilize cameras and image processing algorithms to capture and analyze visual data from manufactured parts to accurately measure geometric features, enabling real-time inspection and quality control. While previous research has been conducted into the accuracy and efficiency of laser scanning methods and gauge measurement methods, little research has been conducted in the application of machine vision for geometric accuracy of metal castings. In this study, a machine vision application is introduced and utilized to analyze, measure, and evaluate parts based on the critical geometry of two castings. The geometry measurements have been done on as-built components using caliper and machine vision techniques. The results of the machine vision application are compared to manual measurements using a caliper. The study demonstrated the effectiveness of machine vision technology in accurately measuring geometric features of metal casting components. Potential for the introduction of this application of machine vision to the metal casting industry in the context of industry 4.0 is also discussed and an implementation framework is introduced as well.
Aerodynamic Analysis of a Dielectric Elastomer Membrane in the Gust Environment
Authors: Raihan Gazi Abu , Chakravarty Uttam
Published: January 2025

The design of the wings of UAVs using dielectric elastomer membranes is critical for analyzing and enhancing their maneuverability, particularly in turbulent atmospheric conditions, popularly known as gust environments, necessitating advanced design innovations. This study presents a comprehensive aerodynamic analysis of a dielectric elastomer membrane (VHB 4910) subjected to sinusoidal profile gust environments. A fluid-structure interaction model, coupling the finite element model of the membrane with a computational fluid dynamics model of the surrounding airflow, is developed to study the coupled effect of the gust and its structural response. Aerodynamic coefficients are derived from forces calculated in numerical simulations for unsteady gust velocities. Results demonstrate the aerodynamic and structural response of the membrane which is similar to the Dryden and von Karman gust models demonstrating minimal discrepancies in the gust velocity profile. This study offers valuable insights into the aerodynamics and maneuverability of UAVs in gust environments, contributing to the advancement of UAV design for improved stability and performance under adverse atmospheric conditions. Results from the computational simulations reveal that the electroactive membrane demonstrates varying aerodynamic response in unsteady sinusoidal load potential in enhancing aerodynamic performance under variable gust conditions. By actively adjusting its shape in real-time, the membrane effectively reduces drag and increases lift, thereby improving the overall aerodynamic efficiency.
Simultaneous Perturbation Algorithm Tuned Oscillation Controller for Automotive Driveline With Kalman Filtering-Based Compensation for Dead-Zone Nonlinearity
Authors: Yonezawa Heisei , Yonezawa Ansei , Kajiwara Itsuro
Published: January 2025

Advanced active control algorithms have addressed the reduction of vehicle driveline oscillations with the purpose of improving component lifespan and drivability. However, the majority of the current works require the important controller parameters to be determined subjectively, placing a significant burden on designers to make adjustments. This study offers an effective model-based driveline vibration controller tuning technique that specifically takes nonlinear backlash’s negative effects into account. Initially, a driveline model is created that incorporates a dead-zone impact of backlash. To reduce a driveline’s low-frequency resonance, a baseline controller reflecting H2 control theory is used. To handle the backlash nonlinearity, the controller is coupled with a control mode switching-based compensation. For identifying whether the system is in the backlash mode or the contact mode, the state vector is estimated by a Kalman filter. The Kalman filter-based state estimation enables switching of the two control modes systematically and stably. A computationally efficient approach, namely the simultaneous perturbation stochastic approximation (SPSA), finds out the best values of their significant design parameters that are incorporated in the active control system. Multiple comparative simulations confirm the effectiveness of the proposed active oscillation controller adjusted by the SPSA. The resilience is assessed for several patterns of driveline dynamics variations. Consequently, it is discovered that the improved vibration suppression performance is stemming from the backlash compensation.
Efficient Controller Tuning Technique for Model-Free Active Vibration Control Based on Virtual Controlled Object
Authors: Yonezawa Ansei , Yonezawa Heisei , Kajiwara Itsuro
Published: January 2025

Vibration control based on a virtual controlled object (VCO) is a simple and practical model-free active vibration suppression strategy. To utilize VCO-based model-free control, controller tuning plays the critical role. This study presents a computationally efficient tuning strategy for the VCO-based model-free active vibration controller. A state equation for model-free controller design is derived based on an actuator model and the VCO. The parameters of the VCO are determined so as to achieve the vibration suppression in the predetermined controlled frequency band. Then, we introduce the reference controlled object (RCO). The control performance of the VCO-controller is evaluated through the vibration control simulation for the RCO. Iteratively executing the vibration suppression simulation for the RCO, the suitable design parameters of the VCO-controller are searched on the basis of the simultaneous perturbation stochastic approximation (SPSA) algorithm. The nonlinear parametrization technique enhances the tuning efficiency. The validity of the tuning scheme is demonstrated by applying it to the design problem of the VCO-based model-free linear quadratic regulator (LQR). The numerical simulations verify the applicability of the VCO-LQR tuned by the proposed approach to wide variety of controlled objects other than the RCO.
Mechanical Property Evaluation of Sublimation Agents on Nanostructure Stability in Semiconductor
Authors: Hanawa Yosuke , Zhang Jianliang , Sasaki Yuta , Sawada Koichi , Yoshida Junichi , Xu Minghan , Mohit Mohammaderfan , Sasmito Agus P. , Sakuma Atsushi
Published: January 2025

Collapsing nanostructures due to the surface tension of cleaning solutions pose a significant problem during the drying process in semiconductor manufacturing. The sublimation drying method has been proposed as a potential solution, but achieving collapse-free drying has been challenging. This study investigated the correlation between the mechanical properties of sublimation agent thin films and the collapse rate of nanostructures during sublimation drying. First, various mechanical properties — such as Young’s modulus, viscosity coefficient, plateau stress, and rupture stress — of eight sublimation agent thin films were determined by conducting indentation tests using a spherical indenter. Next, sublimation drying of Si substrates with nanostructures was conducted using these sublimation agents, and the pattern collapse rate of the nanostructures was assessed. The study found a correlation between the rate of viscous change during the phase transition of the sublimation agent from liquid to solid and the collapse rate of nanostructures. However, no correlation was found between other mechanical properties and the collapse rate. These results suggest that the viscous change during the solidification of the sublimation agent exerts stress on the nanostructures, leading to pattern collapse. This study highlights the importance of considering the viscous change during sublimation agent solidification for enhancing nanostructure stability in semiconductor manufacturing.
Investigation of Copper Interconnects Suffered Reliability Physics for Advanced Packaging Architecture
Authors: Chuang Jui-Chang , Lee Chang-Chun
Published: January 2025

This study offers an insight into copper interconnects subjected to diverse physical loading conditions associated with the thermal, electrical, and mechanical domains. In order to estimate primary contributions among stress, temperature and electrical effects, a novel specimen has been designed to analyze the influence under multiple loading through images of distinct failure defects in this study. Three geometric variations in line widths for copper interconnects have been designed, specifically 15 μm, 10 μm, and 5 μm. This research examines the reliability physics of copper interconnects in advanced packaging architectures, assessing the effects of electromigration (EM), electromigration combined with thermomigration (TM), and stress migration (SM), alongside three distinct physical loading scenarios. The analytic results indicated that electrical resistance of copper interconnection is increased rapidly with reliability physics especially temperature condition. Copper interconnects with a width of 5 μm exhibit a 19.32% increase in electrical resistance under combined EM and TM effects, relative to solely EM effect. This experiment provides a method to estimate electrical resistance change under various reliability physics loading for advanced packaging structures featuring diverse copper interconnection design.
Comparative Numerical Analysis of Tool Tilt Effects in Friction Stir Processing of AZ91: Exploring SPH Applications
Authors: Marode Roshan Vijay , Lemma Tamiru Alemu , Pedapati Srinivasa Rao , Sallih Nabihah , Awang Mokhtar , Hassan Adeel
Published: January 2025

A comparative investigation is carried out on the impact of TTA on the FSP of AZ91 using a novel mesh-free SPH technique. The main objective is to interpret thermo-mechanical behavior by examining temperature distribution, material flow, and microhardness within the SZ. Comparing FSP with and without tool tilt revealed that the 2.5° TTA results in higher and more uniform temperatures throughout the SZ. A minimal % difference of 0.93% and a maximum of 7.86% were noticed when the temperature distribution at the shoulder edge was compared between both cases. It also causes increased material flow, zero surface defects, and a more refined and uniform microstructure. The 2.5° TTA increased overall microhardness compared to the BM and 0° TTA, with the advancing side showing higher microhardness. Around 13% improvement in the microhardness than the 0° TTA was observed due to the strengthening phenomena such as grain boundary strengthening. Thus, the application of SPH has precisely captured the thermal and mechanical characteristics for the impact of TTA on the FSP of AZ91 and proved that employing SPH in numerical simulations provides valuable insights and can further aid in optimizing process parameters to reach desirable microstructural and mechanical characteristics.
Preliminary Study on the Tribological Performance of Ceramic on Laser-Textured Polymer Contacts for Artificial Hip Applications
Authors: Vaidyanathan Sandhya , Vazquez Juan Manuel , Salguero Jorge , Iglesias Patricia
Published: January 2025

More than one million people worldwide undergo total hip arthroplasty (THA) annually, and this number is expected to increase as the global population ages. Despite being a common and effective intervention for conditions such as osteoarthritis or traumatic injuries, THA may require surgical revision in an important number of cases due to tribological problems between the bearing surfaces. Adding textures to the surfaces in contact has garnered increased attention in the tribological community as a method to reduce friction and wear of bearing surfaces. Intentionally created dimples on either or both contacting surfaces can serve as lubricant reservoirs, enhance hydrodynamic lubrication, capture wear debris and/or reduce contact between the two bearing surfaces. Numerous studies have proven the efficacy of reducing friction when textured surfaces are used in metal pairs for various applications. However, the number of studies on ceramic-on-polyethylene surfaces, one of the most common pairs found in hip replacement, is particularly limited, especially when considering the texturing of the softer surface. In this study, the tribological behavior of different laser textured polyethylene surfaces are investigated against ceramic. Friction and wear properties of ultra-high molecular weight polyethylene (UHMWPE) blocks textured with different texture densities are studied against alumina (Al2O3) balls using a ball-on-flat reciprocating tribometer under lubricated conditions. Results show a decrease in friction and wear as the texture density decreased.
Computing Natural Frequencies and Mode Shapes of a Reddy Beam
Authors: Sinha Alok
Published: January 2025

This paper presents an algorithm to find natural frequencies and mode shapes of an uniform Reddy beam. In this method, spatial state equations are developed. Then, the spatial state transition matrix is computed, which is independent of the boundary conditions of the beam. Then, natural frequencies and mode shape equations are easily derived for any boundary conditions in terms of elements of the state transition matrix evaluated at the right end of the beam. Here, these equations are derived for pinned-pinned and clamped-clamped beams. Numerical difficulties in implementing this method are recognized, and a reduced order spatial state space model is developed by analyzing the nature of roots of the sixth order characteristic equation. Numerical results are presented for rectangular beams and compared to those for Timoshenko beams.
Bayesian Neural Network for Mechanical Parameter Distribution in Complex Connections of Laboratory Steel Grid Structures Using Modal Data
Authors: Mehrkash Milad , Santini-Bell Erin
Published: January 2025

Modeling complex connections in mechanical systems is computationally intensive, often leading to simplified simulations that neglect geometrical and mechanical details. While low-fidelity models can suffice for many engineering purposes, uncertainties in predictions pose challenges, especially for connection parameters. Accurately characterizing these parameters is vital for structural integrity and performance. Bayesian neural networks offer a robust framework for parameter estimation, particularly with limited data and significant uncertainties, preventing overfitting and enhancing generalization. This study estimates mass and stiffness parameter distributions in semi-rigid complex connections of a steel structure. This study provides probabilistic insights into parameter uncertainties by integrating Bayesian neural networks with experimental modal data. A Hybrid Monte Carlo (HMC) technique refines parameter estimates, improving reliability. Complex connections are simplified for low-fidelity simulations, with parameter estimation based on finite element model updating and beam element modeling. Numerical simulations demonstrate the approach’s efficacy compared to deterministic methods, highlighting its robustness in capturing uncertainties. Insights from parameter distributions offer valuable mechanical design and assessment guidance, with implications for structural health monitoring and condition assessment methodologies.
In Silico Analysis of Flow-Mediated Drug Transport for Thrombolytic Therapy in Acute Ischemic Stroke
Authors: Rovito Nick , Mukherjee Debanjan
Published: January 2025

Acute Ischemic Stroke (AIS) is a life threatening condition that occurs when an artery within the brain is blocked by a pathological blood clot, called a thrombus. The most popular treatment approach for AIS relies on intravenous administration of a drug named tissue plasminogen activator (tPA) to dissolve fibrin fibers within the clot. Despite the widespread use of tPA, treatment outcomes are often unsuccessful. This is commonly attributed to local clot-flow interactions and their effect on drug delivery into a thrombus. Yet, detailed characterization of flow-mediated drug transport within and around the thrombus remains a challenge, especially when the thrombus is far downstream from the administration site. Here, we address this challenge by using an in silico finite element model to investigate how hemodynamics affects drug delivery and lysis in a fully occluding thrombus within an anatomically realistic brain vascular segment. Specifically, we developed a computational methodology for coupling unsteady pulsatile hemodynamics with advection and diffusion of tPA, and a fibrinolysis reaction model, to elucidate the complex dynamics underlying drug delivery and clot dissolution within realistic patient-specific vasculature. In our study, the thrombus is modeled as an immersed homogeneous porous media. A pulsatile inflow profile, based on prior simulation data, is specified as boundary conditions at the left and right internal carotid arteries and the basilar artery. The flow is advected to the 6 major cerebral arteries. Our coupling scheme leverages a stabilized finite element method, using a fictitious domain approach to represent the effect of the clot on blood flow using a Brinkman model, where interior permeability is modeled as a function of clot porosity. A staggered multiphysics scheme couples this with a stabilized finite element framework for advection-diffusion equations. The average concentration of tPA is input into a five-species biochemical reaction model of the fibrinolysis cascade that describes porosity as a function of the temporal evolution of lysis proteins during tPA infusion. We demonstrate that our methodology can effectively capture this flow-transport-reaction-dissolution coupling, generate detailed spatiotemporal predictions of lysis drug delivery and action, and generate key computational descriptors that are otherwise challenging to obtain in vivo or in vitro.
Primary Resonance of Electrostatically Actuated Cantilever Resonators: Uniform vs. Nonuniform
Authors: Caruntu Dumitru , Flores Rigoberto
Published: January 2025

This work investigates the amplitude-frequency and amplitude-voltage responses of electrostatically actuated uniform and nonuniform micro-electro-mechanical systems (MEMS) cantilevers. A comparison between uniform and nonuniform cantilevers’ responses is conducted. The AC frequency is near half cantilever’s first natural frequency. The bifurcation diagrams (responses) for uniform and nonuniform MEMS cantilevers are predicted. The nonuniform cantilever is a cantilever with linearly varying thickness and constant width. In this investigation two reduced order models (ROMs), with one and two modes of vibrations, are developed. Three methods are used to solve the two ROMs for both MEMS cantilevers. 1) The method of multiple scales (MMS) which is a perturbation method is used to solve the ROMs using only one mode of vibration in order to predict the amplitude-frequency and amplitude-voltage responses. ROMs using two modes of vibration are solved using 2) AUTO 07P, a software for continuation and bifurcation, for predicting the amplitude-frequency and amplitude-voltage responses, and 3) MATLAB ordinary differential equations solver ode15s, to numerically integrate the system of differential equations of ROM and predict time responses of the structure.
Thermal Characterization of Nonconductive Micro-Scale Fibers via Transient Electrothermal Technique
Authors: Spirnock William , Hake Alison , Ban Heng
Published: January 2025

While polymers are generally regarded as thermal insulators, previous work has demonstrated that ultra-high molecular weight polyethylene fibers (UHMWPE) have not only high mechanical properties but also a high thermal diffusivity. However, little data exists detailing the thermal properties of newer grades of UHMWPE which is crucial for the accuracy of computational modeling used in various strength applications. In this work, the thermal diffusivity of a new grade of UHMWPE fiber, Dyneema SK99, is measured using a well-established thermal characterization method known as the transient electrothermal technique (TET). The TET was performed in vacuum to mitigate the effect of convection heat transfer and radiation heat loss was minimized by heating the samples less than 5°C. Measurements were performed on multiple fiber lengths in order to estimate the diffusivity value without radiation. The thermal diffusivity of the Dyneema SK99 fiber was found to be 3.22 × 10−5 m2s−1. The TET uncertainty is approximated for thermal diffusivity based on prior work, however the exact uncertainty for the Dyneema fiber will be measured more specifically in future work.
Single Droplet Combustion of Alternative Fuels
Authors: Powell Karah , Shi Yunye
Published: January 2025

Due to an increase in emissions, alternative fuels are often being considered for fuel reliant systems. Biodiesel is often produced from vegetable oil feedstock. Evaluating the combustion characteristics of pure vegetable oil is beneficial in determining how the vegetable oil would benefit as a biodiesel addition or in other combustion systems. Glycerol and methanol are byproducts of biodiesel. There is potential in using methanol and glycerol in combustion systems rather than recycling the alcohols back in for biodiesel production. Ethanol is a promising alternative fuel that is currently in use in combustion systems. Using ethanol as a comparison for other alternative fuels is beneficial for evaluation.

Because almost all engines involve fuel atomization, it is critical to study single droplet combustion by experiments to fully understand combustion characteristics. In this study, single droplets of canola oil, olive oil, methanol, ethanol, and glycerol were investigated.

Canola oil and olive oil have similar droplet combustion dynamics. Both fuels engaged in a bubbling stage during the burning process. Methanol was the quickest to ignite. Once ignited, methanol had a similar burning rate to that of ethanol. Glycerol required the longest preheating period before ignition and the longest burning time.
Drag Reduction by Riblet-Structures With Limited Tip Sharpness – An Experimental and Numerical Survey
Authors: Hartung Konrad M. , Oehlert Karsten
Published: January 2025

In wall-bounded flows, to which most technical applications belong, viscous drag restricts the aerodynamic efficiency. Riblets, functional surface structures inspired by the dermal denticles of fast swimming sharks, are capable of reducing the wall shear stress and thus increase the efficiency by interacting with the overlying turbulent flow phenomena. As the dimensions of these functional surface structures are usually within the micrometer range, their manufacturing still poses great challenges. This especially applies for the riblet tip width also referred to as the riblet tip sharpness, which is a crucial parameter for riblet performance. Within the present study, laser-manufactured trapezoidal riblets with limited tip sharpness in the range of 0.079 ≤ t/s ≤ 0.150 are investigated and compared to ideal riblet formations. The wall shear stress reduction is model-based predicted based on the vicious theory approach, solving the Navier-Stokes-Equations for a Couette flow. Moreover, for model validation, wind tunnel measurements were carried out. Investigations were performed on flow-exposed laser structured flat plate test specimens. In agreement, the results show that in the case of lower tip sharpness (t/s > 0.1), a higher drag reduction than previously assumed can be achieved, provided that the riblet height to spacing ratio is near its optimum value of h/s = 0.5.
Theoretical and Numerical Analysis of a Squirrel Cage Fan
Authors: Fritsche Manuel , Epple Philipp
Published: January 2025

A squirrel cage fan consists of a radial impeller with short, forward-curved blades and a spiral casing. This type of fan is widely used industrially, e.g. in building or automotive air conditioning and ventilation systems (HVAC) or other applications where high air mass flow rates and small dimensions are required. However, these squirrel cage fans have a comparatively low efficiency, and they represent a challenge in the design process. Because the short, forward-curved blades do not ensure a controlled flow guidance through the blade channel. The flow in squirrel cage fans is predominantly unsteady, turbulent and three-dimensional. In addition, even at the best efficiency point (BEP), unavoidable flow separations and vortex formation occur in the blade channels as well as in the spiral casing.

In the present contribution, a comprehensive principle study with detailed analysis of the state of the art and subsequent investigations. The blade shape of the impeller was systematically varied and the influence on the fan’s performance has been worked out. The influence of the blade length and the blade angle at the impeller inlet and outlet has been examined. In addition, the influence of splitter blades has been also examined. The numerical investigations were performed using 3D-RANS solved with the numerical solver ANSYS CFX. A detailed grid study was performed and the developed CFD simulation model was validated with existing measurement data from a well-known squirrel cage fan. The investigated parameter variations showed a significant influence on the performance of the squirrel cage fan. The analytical and numerical investigation as well as the results are shown and analyzed in detail.
Mitigation of Energetic Deployment in Modular Composite Shells With Localized Folds
Authors: Shabeer Saad , Connor Matthew , Stroud Austin , Lee Andrew J.
Published: January 2025

This paper investigates how the elastic instability in fiber-reinforced composite shell structures can be tailored with multiple localized folds for the purpose of mitigating energetic dynamic deployment. Generating a proper balance of strain energy through packaging is critical for achieving reliable and controllable self-deployment as necessitated in engineered space systems. This is realized by packaging composite tape springs, which is a prototypical space structure, with combinations of multiple localized folds that individually vary from being unstable to stable depending on the fold direction and magnitude. The degree of stability for each fold is controlled with the composite shell layup, the cross-sectional shape, and the fold angle. Motion capture experiments demonstrate that the excessively disordered deployment of a cantilevered tape spring from a single unstable fold is largely mitigated when a second fold with a stable equilibrium state is adjacently introduced. This novel approach is extended to a 3D arrangement of tape springs that are coupled with additively manufactured joints. A collapsible triangular prism is assembled and two of these modules are stacked to form a lightweight truss structure that can deploy in the axial direction. Motion captured deployment experiments reveal that the shock events from the disappearance of unstable folds are largely attenuated when a second fold with a stable state is induced in the prism column.
Microstructural Evolution Laws of Integrated Billet Production by Piercing and Rolling in Three-Roll Skew Rolling Process for 42CrMo Flange Nuts
Authors: Chen Yusen , Shu Xuedao , Xia Yingxiang , Li Zixuan , Xu Haijie , Zhang Song , Wang Jitai
Published: January 2025

This study primarily focuses on examining the microstructural evolution during the integrated manufacturing process of 42CrMo large-scale flange nut blanks, utilizing a three-roll skew rolling and piercing technique. Through secondary development, we have integrated constitutive and microstructural models into our analysis. Utilizing numerical simulation, this research delves into the temperature variation throughout each stage of the flange nut forming process facilitated by three-roll skew rolling and piercing. The study meticulously examines various rolling stages of the workpiece to uncover the distribution patterns of dynamic recrystallization grain size and the volume fraction of dynamic recrystallization. Furthermore, employing point tracking techniques, the temporal evolution of both axial and radial grain sizes has been elucidated.

The finite element simulation results suggest that the grain size of flange nut crystals, which are integrated through piercing and rolling, diminishes from an initial average of 150μm to approximately 30μm, achieving a grain refinement rate of up to 80%. The application of the integrated process involving three-roll skew rolling and piercing for the production of flange nuts not only facilitates the one-step formation of flange nut blanks but also notably refines the internal grain size of the rolled components and ensures a more uniform distribution. Consequently, this enhances the mechanical properties of the rolled components, thereby offering a theoretical foundation for the high-quality manufacturing of large-scale flange nut blanks through the integrated forming process of three-roll skew rolling and piercing.
Dynamic Analyses of Sandwich Structures Through Variable-Fidelity Beam Models
Authors: Azzara Rodolfo , Filippi Matteo , Carrera Erasmo
Published: January 2025

This work discusses some advances in the nonlinear dynamic analysis of sandwich structures. Based on the Carrera Unified Formulation (CUF), geometrically linearized and full nonlinear governing equations are derived to investigate vibrations, transient responses, and dynamic instabilities of loaded and unloaded sandwich beams. According to CUF and using all terms of the full Green-Lagrange strain tensor, the proposed methodology can detect simple and complex nonlinear phenomena, including those related to deep nonlinear regimes. Particular attention is given to characterizing the response of sandwich structures under various conditions, including mechanical or thermal loads and parametric excitations. Low kinematics models can be adopted whenever stable conditions exist with no loss of generality. In contrast, in the case of unstable regimes, and when the stress state is complex, high-order kinematics and full displacement-strain relations must be used to describe vibrations. The results, discussed and compared with commercial software solutions, demonstrate the excellent accuracy and reliability of the proposed numerical methodology.
Mechanical Properties Evaluation of Wire-Arc Additively Manufactured Steel Through Automated Ball Indentation Testing
Authors: Prakash Raghu V. , Zhou Wei
Published: January 2025

Wire Arc Additive Manufacturing (WAAM) is one of the directed energy deposition (DED) techniques used for material build-up for cost-effective repair and rebuild of engineering parts used in aerospace, marine and oil and gas industries. It can be considered as an extension of arc welding technique and uses layer-by-layer building strategy — so can be considered to be representative of additive manufacturing technique. The build-up layers have heterogeneous properties in view of the rapid cooling of previous layer and reheating when a new layer is deposited. Assessment of mechanical properties such as tensile strength and in some specific cases the fatigue strength is important to assure compatibility between parent material and WAAM section.

In this paper, the tensile properties of typical low carbon steel, ER70S-6 produced through WAAM process is evaluated through automated ball indentation test technique. A Tungsten Carbide (WC) spherical ball of 1.57 mm diameter is used to indent the WAAM built-up sample using a programmed load, unload step sequence on a MTS 810 servo-hydraulic test system. The test is conducted under actuator displacement control and the load-displacement response is recorded for further processing. As the test system compliance can affect the indentation depth response, a local crack opening displacement gage is used to measure the depth of penetration close to the indenter. About five steps of loading and unloading are carried out to obtain the plastic depth of penetration during each unloading segment. The data is processed as per the analysis procedures suggested by Haggag [1]. The true stress-true strain response of the material is thus obtained and compared with the parent material data from the literature.

Cyclic indentation studies have been carried out on the same sample to assess the fatigue life of WAAM material. Fatigue cycling under load control is carried out at a low frequency of 0.5 Hz and the depth of penetration is measured as a function of the number of cycles of loading. In addition, the load-crack opening displacement is logged continuously to derive the global stiffness of the material as a function of the number of cycles of loading. This information is used to estimate the failure life for a given cyclic loading condition. Based on such failure data collected from multiple load cycling experiments, a failure life curve is derived for this material.
Energy, Economic, and Environmental Assessment of an Energy Pile-Based Solar-Assisted Residential Ground Source Heat Pump System in a Canadian Cold Climate
Authors: Beragama Jathunge Charaka , Dworkin Seth B. , Wemhöner Carsten , Mwesigye Aggrey
Published: January 2025

The building sector’s high energy consumption and related emissions signify the urgency for cleaner space conditioning technologies. While ground source heat pumps (GSHPs) and solar-assisted ground source heat pumps (SAGSHPs) offer cleaner and more efficient solutions, their wide adoption is hindered by the high initial costs. This study investigates the energy, economic, and environmental aspects of energy pile-based GSHP and SAGSHP systems in a Canadian cold climate. A finite volume numerical model of the energy pile is developed, validated and coupled with a realistic building energy load profile and photovoltaic/thermal solar collector model to evaluate the energy performance of the systems. The economic and environmental performance of the system is compared with two conventional space conditioning technologies, i.e. electric baseboard heater + air conditioner and natural gas furnace + air conditioner. The results indicate that the payback period of the GSHP and the SAGSHP systems is in the range of 6–17 years when the ground heat exchanger is incorporated into the building foundation during construction. This highlights the potential of energy piles to drastically cut down the initial cost of ground-coupled heat pump systems. Moreover, based on Alberta’s grid emission factors as of 2023, the GSHP and SAGSHP systems lower emissions by 50.2–68.2% and 88.6–91.8% compared to baseboard heater + air conditioner and 47.6–66.6% and 82.1–87.2 % compared to natural gas furnace + air conditioner, respectively.
A Pedagogical Exercise of Integrating AI Image Generator Tool: A Pilot Experience in Design Product Education
Authors: Rojas Juan-Carlos
Published: January 2025

This pilot study explores the integration of technological tools, particularly Artificial Intelligence (AI) Interactive Generative Technologies (IGTs), into pedagogical exercises within design product education (DPE). The aim is to present the impact of this integration on traditional creative exercises. The results of the exercise reveal promising results, suggesting that the use of AI IGTs enhances students’ motivation and application of design principles in less time compared to traditional methods. Through a structured exercise involving the creation of a design firm and the subsequent application of AI IGTs to generate design solutions, students demonstrated natural engagement and proficiency. The study underscores the importance of integrating technological trends, such as AI IGTs, into design education to bridge the gap between academic learning and professional practice. However, several areas for improvement and further research are identified, including the standardization of exercise approaches, optimal tool selection, and comprehensive evaluation of student perception, and learning outcomes. This study contributes to the ongoing discourse on the evolving pedagogical approaches in design education and highlights the potential of AI IGTs to revolutionize the learning experience for future designers.
Development of an Open-Source Magnetic Modular System for End-Effectors in 3D Printed Humanoid Robots
Authors: Michels William , Van Milligen James , Radhakrishnan Pradeep
Published: January 2025

Humanoid robots that are being developed for at-home use require versatile end-effectors or hands to perform tasks ranging from handling fruits to complex medical equipment. At Worcester Polytechnic Institute (WPI), efforts have been underway to develop toddler-sized humanoid robots, based on the Poppy platform, for various at-home tasks involving senior citizens. One of these robots is Finley, a 4.5kg and 92 cm tall robot that is completely 3D printed with 27 degrees of freedom. To handle various tasks and complexities, grippers with many actuators cannot be installed as Finley’s end-effector due to the robot’s weight restrictions and 3D printed nature. One possibility is to use function-specific end-effectors that can be swapped based on the need. But swapping each gripper requires assembly of various components and electronics apart from the downtime during such events. To make it easier to swap these end-effector grippers, a magnetic modular wrist system has been developed and integrated into Finley. It employs a purely magnetic connection and provides electrical continuity to the gripper from the forearm so that all included actuators can function. This would allow Finley to handle diverse activities using simpler end-effectors, thereby reducing difficulties related to installation and use of such devices. The paper will discuss the detailed design, testing, implementation, and future work.
Thermal Performance Analysis of an Air Source Heat Pump Coupled With a Solar Air Collector for Domestic Water Heating in a Cold Climate
Authors: Bhadra Sheel , Mwesigye Aggrey
Published: January 2025

Reducing building-related CO2 emissions requires decreasing energy consumption and/or adopting cleaner, more efficient technologies. Air source heat pumps (ASHPs) are increasingly favored for building heating, especially in mild climates. When powered by clean and renewable energy sources, they offer significant potential for emission reduction. However, cold climates present unique challenges for these conventional heating systems, prompting interest in integrating renewable energy sources such as solar energy and energy storage with ASHPs to maintain consistent performance and lower their energy use during the coldest days. This study investigates the performance of an air source heat pump integrated with a solar air collector for domestic water heating in a cold climate. The study aims to quantitatively evaluate the contribution of the solar air collector to the overall reduction in energy consumption, enabling a thorough assessment of the integrated system’s efficiency and operational performance. The coupled air collector – ASHP – TES tank model was developed using a transient system simulation tool (TRNSYS). The impact of collector orientation, with tilt angles between 30 and 70°, collector surface areas between 8 and 16 m2 and mass flow rates ranging from 0.25 to 1 kg/s, which are considered suitable for a 2-ton heat pump, were systematically examined. Results show that the optimal tilt angle for maximizing useful annual energy gain is 51°, aligned with Calgary’s latitude, surpassing alternative tilt angles (30, 40, 60, and 70°). Furthermore, the integration of the solar air collector improves the annual average coefficient of performance (COP) by 16 % and reduces the annual average compressor work by 8%. This comprehensive analysis highlights the potential of integrating solar energy with ASHPs to enhance hot water efficiency and reduce energy consumption in cold climates.
Multi-Objective Optimization for Performance Enhancement of a Toroidal Propeller Using CFD and FSI
Authors: Ciftci Omer , Cadirci Sertac
Published: January 2025

This study aims to optimize the toroidal propeller design to be used for commercial mini-drones. Preliminary CFD simulations were carried out for validation purposes using APC11x5e propeller available in open-source database. In order to validate the numerical results, thrust coefficient, power coefficient, and aerodynamic efficiency obtained from quiescent air and cross-flow-conditions were compared with experimental data. The verified CFD approach showed good agreement with the experimental data for all conditions in obtaining propeller thrust, power, and efficiency values. The same numerical approach was later adopted for the optimization analyses. Optimization was applied to the in-house designed toroidal propeller and was conducted using NSGA-II and Sobol method for DoE combined with FSI. The design variables for multi-objective optimization are the vertical angle, camber angle, and side inclination angle. The aerodynamic objective functions are the thrust and efficiency coefficient and the structural objective function is the strength (von-Mises stress) of the propeller. Ultimately, Pareto optimal designs indicating increased aerodynamic efficiency, higher thrust, and a safer structure are obtained in the defined range of the design variables suggesting that higher thrust, efficiency and strength shall be regarded in the design process of a toroidal propeller for enhanced performance.
Reduced Order Modeling of Thermal Runaway Propagation in Li-Ion Battery Packs With Comprehensive Treatment of Heat Source Terms
Authors: Parhizi Mohammad , Ostanek Jason , Premnath Vinay , Jeevarajan Judith
Published: January 2025

This work aims to develop a novel framework for thermal runaway and propagation modeling, focusing on balancing between computational efficiency and accuracy. The proposed framework leverages a zero-dimensional (0D) modeling approach for heat transfer, facilitating ease of extension to battery pack-level simulations. The model integrates multiphysics phenomena such as decomposition reactions, internal heat generation, gas generation, electrolyte evaporation, and a simplified model for burning the vent gas to enhance accuracy without sacrificing computational efficiency. The thermal node model is also integrated with an electrochemical model, i.e., the pseudo-two-dimensional (P2D) model. These additions enable the framework to capture key physical processes contributing to thermal runaway while maintaining computational feasibility. The thermal node representing the Li-ion cell in this study can be replaced by a thermal mass and finite element component to improve the spatial resolution of the thermal model. The developed model was used to simulate the thermal runaway of a single 18650 Li-ion cell triggered using external heating and was calibrated against experimental data. The computational efficiency of the model enabled its integration with optimization tools for parameter estimation and model calibration. The model was then extended to a battery pack containing 25 Li-ion cells to investigate the likelihood of propagation under varying conditions.
Nonlinear Dynamics Simulation of a Shoulder Link of KINOVA GEN3 Robotic Arm Over a Range of Frequencies
Authors: Yousuf Louay S.
Published: January 2025

A robotic arm of KINOVA GEN3 with a shoulder link is considered in this paper over a range of frequencies. Robotic arms perform precise manipulations in a wide variety of applications from factory automation to medical surgery. Chaos motion is happened due to the impact between the actuator and its base frame due to the tension and compression pressure at the shoulder link. In industry when the robot is working, the stress is concentrated around the shoulder link and might cause failure and fracture the mentioned part due to the chaotic motion. The level of chaos is investigated using sample entropy, an approximate entropy, permutation entropy, and fuzzy entropy. A fast and slow algorithm in MatLab software is prepared to solve for the entropy values. Range-A and Range-B algorithm of entropy is added to check the results of entropy. The higher value of entropy, the more chaos motion. The KINOVA GEN3 robotic arm is moved with seven degrees of freedom. The chaos level is discussed at different frequencies ranges of shoulder links such as 250000, 500000, 750000, and 1000000 Hz are used. The frequency and mode shape have been calculated using Finite Element Method of partial differential equation toolbox in MatLab software. It can be noticed that the motion of shoulder link is chaotic at frequency range 1000000 Hz.