bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &gt; 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.