bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Imaging of Elongated Thickness Defects in Pipelines Using Ultrasonic Guided Wave Tomography
Authors: Rasgado Moreno Carlos Omar , Ratassepp Madis 
Published: February 2024

Abstract
Monitoring the wall thinning in pipelines is crucial in the energy industry to guaranty its proper operation. Typically, in pipelines where fluids with particles or solid particles are transported, larger erosion is encountered which is usually the same along the length of the pipe. Conventionally, Non-Destructive testing techniques for wall thinning are based on a local point-by-point ultrasonic measurements, which is slow and costly. In contrast, Guided Wave Tomography (GWT) based on Full Waveform Inversion (FWI) is an accurate and high-resolution reconstruction method, that enables the monitoring of the whole pipe area by processing the waves excited and received by transducer arrays. Although FWI have been used successfully to reconstruct small localized defects in the past, the reconstruction of the elongated defects remains a challenge as the waves propagating through the defect may undergo cycle-skipping effect which breaks down the inversion algorithm. In this study, the limits of FWI are explored when reconstructing elongated defects on a steel pipe with 6.5 mm in thickness, 230.2 mm in diameter and 720 mm in length. Four elongated Hann-shaped defects were modeled in a three-dimensional (3-D) finite element model, and reconstructed using FWI based on an acoustic two-dimensional (2-D) forward model. The defects have a 70 mm width, 1.5 mm in depth, and longitudes of 25%, 50%, 75% and 95% each of the pipe length. Two initial velocity-thickness models were considered, one homogeneous along the reconstructed domain and the other one with a velocity variation. The velocity-thickness variation model was based on the time of flight (TOF) of the transmitted signal of the aligned transducers. For 25% and 50% defects’ longitudes good agreement was found between 3-D finite element model and the 2-D reconstructed model, when the background initial velocity model was constant. In contrast, for defects with a longitude larger than 75% of the pipe’s distance, good agreement was found between 3-D finite element model and the 2-D reconstructed model when selecting a suitable initial velocity-thickness model.
Investigation of NH3/Air Laminar Burning Speed and Flame Structure at High Pressures
Authors: Alvarez Luis F. , Shaffer James , Dumitrescu Cosmin , Askari Omid 
Published: February 2024

Abstract
Understanding the effect of fuel properties on ammonia (NH3) flame characteristics is important for practical applications. This study investigated NH3/air mixture ignitability, flame morphology, and propagation rate in a constant volume combustion chamber (CVCC) at high-pressure conditions using high-speed schlieren imaging. Experiments were performed at an equivalence ratio, ϕ, from 0.7 to 1.3, initial pressures from 1 atm to 10 atm, and an initial temperature of 298 K. The study also used a novel filling method that accounts for the NH3 adsorption on the stainless steel CVCC surfaces. While the data analysis suggested that the NH3 adsorption was negligible, the CVCC passivation before the start of the experiments (i.e., allowing enough time for NH3 to adsorb on the chamber walls) reduced the experimental uncertainty with respect to the actual NH3/air (ϕ) inside the CVCC. More, the low speed of NH3/air flames can negatively affect flame stretch and laminar burning speed (LBS) calculations for mixtures at high initial pressures due to the significant buoyancy effects. Hence, a special method accounting for buoyancy was implemented to calculate the volume of the combustion products and, subsequently, to compute the LBS of the non-spherical NH3/air flames. The high-speed schlieren imaging showed that, as the pressure increased, the flames got smaller, indicating a decrease in speed and therefore an increase in buoyancy. Cellular structures were absent during the period of flame propagation inside the chamber. The conventional constant pressure methodology was used for the LBS calculations. Results indicated that for the evaluated conditions, the LBS increased with ϕ until reaching a maximum value for ϕ = 1.1. In addition, it was shown that as the initial pressure increased, the LBS value decreased, similar to the conventional trend seen for hydrocarbons LBSs.
An Experimental and Computational Study of Mechanically and Dynamically High Loaded Separators for Lithium-Ion Batteries
Authors: Bulla Marian , Sahraei Elham , Kolling Stefan 
Published: February 2024

Abstract
In recent years, the automotive market has been pushed to significantly reduce CO2 emissions and increase the development and production of electrically powered powertrains. Currently, the best industrial storage method for electric energy is the lithium-ion battery, which is already used in the automotive industry and in consumer electronics (e.g., cell phones and laptops). The Li-ion cell is considered the most promising energy storage source currently available on the market. Motor vehicles are exposed to various crash and abuse scenarios under different load conditions. With the increasing use of these batteries in vehicles, safety has become a concern due to unintended failures and accidents. For this purpose, a detailed study of the separator in terms of mechanical stiffness as a function of fabrication direction and loading rate was carried out. Based on the results a new material model was developed in which the orthotropic-visco-elastic and orthotropic-visco-plastic mechanical behavior of a polymeric material can be considered. In addition, based on uniaxial tensile tests with local strain measurement, a novel failure criterion for finite element analysis was developed to predict the effects of high mechanical loads in terms of triaxiality, large plastic strains, orthotropy and viscosity. Finally, a simulation model for a PE separator was developed combining the new failure with a G’Sell and Swift-Voce strengthening rule. This model was able to predict the anisotropic behavior of the PE separator during deformation and failure. The modeling method presented in this work allowed accurate prediction of the strength of the tested PE separator. The proposed new failure criterion predicted the failure strain for all three directions within a range of 3% and agreed very well with the tests performed. Some small deviations occurred due to the simplified boundary conditions as well as the influence of the element length. However, it should be noted that the real tests showed scatter in a much larger range. The quantitative comparison was made based on the elongation response at fracture of the three differently oriented specimens (MD, DD, TD). The present failure criterion and detailed calculation method should be useful in the development of batteries and be used as an important new computational tool for the for evaluating the safety of lithium-ion batteries under high mechanical load and crashworthiness. The proposed failure criterion can also be combined with other constitutive material laws. The results of these investigations are implemented in the failure model based on Elham Sahraei’s model (/FAIL/SAHRAEI) in the explicit crash solver OpenRadioss™.
Finite Element Analysis of 3D Printed Stand-Alone Transforaminal Lumbar Interbody Fusion Cages Under Various Loadings
Authors: Zhang Yufei , Kang Minjae , Su Siheng 
Published: February 2024

Abstract
With the development of 3D printing technology in the biomedical field, orthopedic implant designs such as transformational lumbar interbody fusion (TLIF) cage that were challenging to realize in the past have become a reality. The traditional metal lumbar interbody fusion cage would cause stress shielding and bone remodeling because of their relatively high Young’s modulus compared to natural bone. This study investigated the mechanical properties of TLIF cages produced by traditional method and 3D printing technology using finite element analysis (FEA) under five different body motions, including standing, lifting objects, lifting objects & forward bending, lateral bending, and forward bending. Stress analysis of traditional titanium alloy Ti-6Al-4V cage, 3D printed Polyetheretherketone (PEEK) TLIF cage, and 3D printed porous carbon fiber reinforced Polyetheretherketone (CFR-PEEK) with various infill densities by FEA showed the mechanical properties of 3D printed CFR-PEEK solid cage is comparable to Ti-6Al-4V cage with maximum Von-Mises stress of 12.391 MPa, total deformation of 0.0029257 mm under the ‘standing’ condition with a 1000N axial compressive force. The minimum factor of safety (SF) for Ti-6Al-4V cages are above 15 under all postures, while 3D printed PEEK solid cages under some postures are not reliable with a SF smaller than the recommended value of 2.0. On the other hand, SF for 3D printed CFR-PEEK porous cages was above 2.0 with an infill density 50% and above, demonstrating that 3D printed CFR-PEEK would be an excellent candidate for the lumbar cages.
Improving Efficiency of Automotive Coating and Curing Processes Through Deep Learning Algorithms and High-Fidelity CFD Modeling
Authors: Candido Sílvio , Pendar Mohammad-Reza , Páscoa José Carlos 
Published: February 2024

Abstract
The automobile industry has relied on computational fluid dynamics (CFD) simulations to analyze and optimize the coating and curing processes, speed up product development, and lower the cost of product development. However, CFD modelings of these processes are computationally expensive due to the complexity of the models and the large number of simulations needed, especially when its used complex sprays such as the nithrothermal electrospray. As a result, more efficient methods must be developed to reduce computing time without compromising accuracy. In this article, we analyze how deep learning techniques can be used to predict coating and curing processes using electrospray CFD simulation. A dataset of 3D Eulerian-Lagrangian CFD simulations of coating and curing processes employing electro-spray for the automotive industry has been used to train different deep-learning models. We investigated how hyperparameters such as batch size and layer count affected deep learning model performance compared to conventional CFD simulations. For this, we evaluated the deep learning models’ efficiency and accuracy in terms of computing time. We also investigated how hyperparameters such as batch size and layer count affected deep learning model performance. Also, we’ve looked at the target’s final droplet deposition, and distribution that is required to accurately estimate the distribution. Furthermore, we studied the percentage of snapshots of the droplet distribution electrospray necessary to predict the target’s final deposition from the Lagrangian distribution. According to our findings, deep learning models can drastically reduce the amount of time needed to run CFD simulations. Depending on the model and hyperparameters applied, we can forecast the whole CFD simulation by utilizing somewhere between 10% and 15% of the initial spray development. Also, we discovered that the use of recurrent cells as an LSTM model outperformed the other models in terms of accuracy and computational efficiency, where the LSTM layers can extract better the features of the input snapshots. Overall, our research demonstrates the potential of deep learning techniques to significantly shorten the computing time of CFD simulations of coating and curing processes for the automotive sector. The results of this study have significant implications for coating and curing process design and optimization in the automobile industry as well as in other industries where CFD simulations are frequently employed.
Simulating Soft Robotic Finger Joint Using Simplified Model Free Adaptive Control and Finite Element Analysis for Transmission Line Maintenance
Authors: Narayan Meenakshi , Yu Zhiyuan 
Published: February 2024

Abstract
The article describes a simulation model of a soft robot finger joint that can be used in robots mounted on unmanned autonomous drones for the inspection and repair of high voltage transmission lines. The model uses finite element analysis (FEA) to analyze the torque load on a spherical robot finger joint with a defined payload at variant joint roll-yaw-pitch angle under gravity using design of experiment (DOE). The data obtained from FEA is further analyzed in Matlab using curve fitting methods to obtain a model of the finger joint. A simplified version of Model Free Adaptive Control (SMFAC) algorithm is proposed to control the desired torque and orientation of the finger joint using FEA data. The simulation results show a faster convergence rate of 99.9% and lower settling times in milliseconds compared to PID, indicating that real-time control of robot fingers can be achieved using this control algorithm. The soft robot hands can also be used for a wide range of grasping tasks beyond powerline maintenance. The article suggests that future work will involve expanding the one-joint FEA model into a multibody dynamics model to simulate the mechanical behavior of the soft robot hand and designing and controlling soft finger prototypes attached to drones for power line inspection and repair.
In-Situ Damage Progression Observations in Cross-Ply CFRP Composite Beams Under Low-Velocity Impact and Quasi-Static Indentation Loading
Authors: Batmaz Onur Ali , Coker Demirkan 
Published: February 2024

Abstract
In this work, we conducted in-situ low-velocity impact (LVI) and quasi-static indentation (QSI) experiments on CFRP composite beams with two different layup configurations, [04/904/02]s and [02/902/02/902/02]s, to investigate the ply clustering effects on the LVI-induced damage mechanisms. The LVI experiments were conducted utilizing high-speed photography to observe the complete sequence of damage progression. We performed QSI experiments to qualitatively identify the damage mechanisms observed during LVI events since it reduces the complications in monitoring the damage progression in the short period of impact loading. QSI experiments allowed us to obtain magnified in-situ observations on one edge of the beam with a traveling digital microscope, while a high-resolution camera was employed on the opposite edge to measure full-field strain distributions using the digital image correlation (DIC) method. We observed nearly identical damages in terms of form, location, and sequence on the specimens with identical layup configurations in both LVI and QSI experiments. However, damage mechanisms differed in the [04/904/02]s and [02/902/02/902/02]s configurations, with the latter experiencing fiber breakage in addition to matrix cracking and delamination as observed in the former configuration. The magnified in-situ observations allowed us to detect macroscopically undetectable matrix cracks that did not significantly affect the global response of the beam. The continuous monitoring of the micro-scale damages in conjunction with the DIC analyses illuminated the details of damage mechanisms observed in cross-ply laminates under LVI loading.
Hydrodynamics of Metachronal Rowing at Intermediate Reynolds Numbers
Authors: Lei Menglong , Lou Zhipeng , Wang Junshi , Dong Haibo , Li Chengyu 
Published: February 2024

Abstract
Metachronous rowing is a swimming mechanism widely adopted by small marine invertebrate like comb jellies, in which rows of appendages perform propulsive strokes sequentially in a coordinated manner with a fixed phase difference. To simulate metachronous rowing at intermediate Reynolds number, in this paper, a row of flexible cilia models was placed inside the flow field, with their roots stroke at a sinusoidal function of time and a fixed phase difference. A fully coupled two-way numerical solver was developed, which solves the Navier-Stokes equations for the fluid field coupled with the differential equation for the flexible cilia model. This numerical solver is applied to investigate how the row of cilia models are deformed by the hydrodynamic forces (pressure and shear) and momentum and thus impact hydrodynamic performance. Results show that the passive deformation of cilia potentially improve the hydrodynamic performance compared to the rigid cilia. With the metachronous rowing mechanism, the cilia generate the thrust to move forward. The approach used in this study presents a general way to explore the fluid dynamics of complex fluid-structure interaction problems.
Theoretical Study of Counter-Current Liquid-Vapor Flow Under Condensation Conditions Over Non-Isothermal Vertical Wall of Two-Phase Closed Thermosyphon
Authors: Zolfagharroshan Mohammad , Xu Minghan , Zueter Ahmad , Sasmito Agus 
Published: February 2024

Abstract
This paper proposes a new mathematical formulation describing the relationship between shear stress and film thickness to model condensing falling film of liquid in vertical thermosyphons. The mathematical model incorporates various factors, encompassing the contribution of shear stress resulting from friction force and phase change at the liquid-vapor interface, the impact of subcooling, and the influence of the convective boundary on film heat transfer. Vapor phase condensation in thermosyphons with relatively longer condenser lengths, where temperature variation is inevitable, is an area of interest for using the proposed model. The novel formulation is solved iteratively with the analytical solution of conservation equations, thermal equilibrium, and thermal resistance analogy. Optimized relaxation factors are used, and when the convergence criteria are met, the model marches over the condenser wall. The high accuracy of the model in regenerating literature data allowed the implementation of parametric study analyses on the variation of ambient air temperature, heat transfer coefficient, and wind velocity. The results are verified with a numerical model based on the modified Nusselt theory, and the underestimation of the latter approach in film thickness prediction and, consequently, heat flux has been discussed. The introduced model indicated the promising potential for laminar to wavy-laminar film regimes and could be applied to similar cases, such as co-current flows and evaporating thin films by minor revision.
Self-Sensing Piezoelectric Composite Structures via Generation and Reception of Ultrasonic Guided Waves
Authors: Zhou Shulong , Shen Yanfeng 
Published: February 2024

Abstract
This paper proposes a novel family of intelligent piezoelectric composite structures for the purpose of establishing structural self-awareness via integrating the function of load bearing with the capability of transmitting and receiving high frequency mechanical waves. To develop a deep insight into the mechanism of the intelligent structure, coupled-field Finite Element Models (FEM) are constructed to conduct the transient dynamic analysis for understanding the wave propagation characteristics in piezoelectric composite beams. In particular, the model employs the Equivalent Average Parameter (EAP) method, utilizing overall and nominal quantities, in order to simulate the self-sensing composites. The guided wave generation and tuning characteristics are investigated utilizing the harmonic analysis model with absorbing boundary conditions. Furthermore, meticulously crafted through a continuous process of material ratio optimization and process step refinement, sample piezoelectric composite plates are fabricated to ensure the highest degree of sensitivity and reliability during experimental demonstration. A pitch-catch active sensing setup is utilized to verify the capability of the piezoelectric composites for generating and receiving ultrasonic guided wave. Moreover, a Scanning Laser Doppler Vibrometer (SLDV) is applied to visualize the waves generated in the structure for analyzing the propagation modes of ultrasonic guided waves in the piezoelectric composite material. The numerical simulations and experimental demonstrations showcase that the proposed piezoelectric composite system possesses great potential for realizing self-awareness for future intelligent structures. The paper finished with summary, concluding remarks, and suggestions for future work.
Heat Transfer Enhancement for Circular Cylinders Undergoing Flow-Induced Vibrations: Effect of Spacing Ratio and Stagger Angle
Authors: Ali Ussama , Islam Md. , Janajreh Isam 
Published: February 2024

Abstract
Effective heat transfer is of utmost importance in the design and operation of industrial components, such as heat exchanger tube bundles, as it directly dictates their efficiency and durability. These components often encounter flow-induced vibrations, which subsequently influence the heat transfer characteristics. This study focuses on investigating heat transfer and flow-induced vibrations in two circular cylinders. The Reynolds number (Re) is set at 100, and the reduced velocity (Ur) is increased from 2 to 14. The cylinders’ dimensionless spacing (L/D), arranged in tandem, is changed from 1.5 to 6, and the stagger angle (α) between the cylinders is varied from tandem (0°) to staggered (45°) and side-by-side arrangement (90°). The lift (CL) and drag (CD) coefficients, streamwise and transverse vibrational amplitudes (Ax/D and Ay/D), average Nusselt number (Nuavg), Strouhal number (St), vortex shedding patterns, and temperature distribution are analyzed. Results reveal that the lock-in occurs at Ur = 8 for all arrangements. The results demonstrate that the Nuavg for the downstream cylinder is consistently lower than the upstream cylinder in the tandem arrangement due to the upstream cylinder providing a shielding effect. Rising L/D to 6 from 1.5 increases the Nuavg by 8.6% and 9.8% for downstream and upstream cylinders, respectively. As the L/D increases, the Nuavg for both cylinders increases, implying a reduction in the effect of each cylinder on the other. However, in the staggered and side-by-side arrangement, the Nuavg for both cylinders are similar, indicating that the cylinders have little to no influence on each other. The highest Nuavg is observed at the lock-in condition for all L/D and α values. The temperature contours mirror the vorticity contours, suggesting that vortex shedding has a positive effect on heat transfer.