bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on Fatigue Damage Progression in Post-Impacted CFRP Composite Through Passive Thermography and Stiffness Measurement
Authors: Prakash Raghu V. 
Published: February 2023

Abstract
Reinforced polymer composite materials are widely used in several areas of aerospace, other civilian structures, in view of tailor-suiting to the design requirements. During service, barely visible damages are induced due to accidental tool drops, hail storms and bird strikes, and they can propagate due to fatigue cycles applied during a mission. The damage progression can result in loss of load carrying capacity and ultimate failure. Damage progression due to fatigue in composites has been an important aspect of study as it can result in loss of load carrying capacity and ultimate failure.
In this study, the stiffness degradation in a quasi-isotropic carbon fiber polymer composite specimen subjected to FALSTAFF (Fighter Aircraft Loading Standard for Fatigue) spectrum was assessed, after it has been subjected to a drop-impact. Fatigue test was carried out post-impact till specimen failure, which meant testing over several days. The unloading stiffness of the specimen was estimated from the load versus displacement data that was recorded after every block of FALSTAFF loading. It is observed that the stiffness of the specimen degrades with the progression of damage.
An Infrared thermal imaging camera (TIM 160 from MicroEpsilon, Germany) was used in passive mode to monitor the temperature changes in the specimen during fatigue cycling. In view of the long duration of fatigue test spanning several days and IR camera cooling requirements, the test was periodically interrupted after certain blocks of FALSTAFF loading. Temperature data during fatigue cycling was compared with stiffness degradation to understand the fatigue damage progression in specimens. The first derivative of temperature response data was found to have a reasonable correlation with the first derivative of stiffness.
Impact of Processing Parameters in Mechanical Properties of the Additively Manufactured Acrylonitrile Styrene Acrylate
Authors: Billah Kazi Md Masum , Sarker Md Rashedul , Gonzalez Mario Barron , Ramirez Jose Anibal , Hamidi Youssef K. 
Published: February 2023

Abstract
In this study, a relatively new and low-cost commodity-type 3D printing filament material, acrylonitrile styrene acrylate (ASA), was used as a feedstock to a commercially available, desktop fused filament fabrication 3D printer. The aim was to correlate the mechanical properties of the 3D printed specimen to the raster orientation and extrusion temperature. Although ASA bears multiple similarities to ABS (acrylonitrile butadiene styrene), its superior UV-resistant properties facilitate a wider adoption in various indoor and outdoor industrial applications. Following ASTM (American Society for Testing and Materials) D 638 standard, ASA specimens were 3D printed at raster orientation angles of 0°/90°, 30°/60°, and +45°/−45° at three different temperatures, namely: 230°C, 250°C, and 270°C. The fabricated specimens were then tensile tested and relevant mechanical properties characterized, including the modulus of elasticity, ultimate tensile stress (UTS), and tensile strain at failure. Overall, ASA material showed promising strength properties for various printing parameters. In addition, the 0°/90° raster orientation was observed to yield the highest mechanical properties, with an average UTS of 34 MPa. The +45°/−45° and 30°/60° specimens showed lower but quite comparable properties with an average UTS of 31 MPa. The results also indicated a strong relationship between the print orientations and the extrusion temperatures. Furthermore, fractured surfaces of the tested specimens were a brittle and craze type of failure on the bulk of the bead. The results of this research may not only aid consumer-level manufacturing endeavors, but also support the industrial-scale manufacturing as well as the numerical modeling community to accurately predict appropriate manufacturing conditions and materials performance.
Active Meta Materials and the Change of the Path of Elastic Waves and Blast Waves
Authors: Hanagud Sathyanara 
Published: February 2023

Abstract
The concept of a negative refractive index stimulated research activity in 1960s. One researcher showed that it is possible to realize negative refractive index if we have a material that can have simultaneous negative electric permeability and negative magnetic permittivity, at the same frequency. At that time, no such material was available.
After three decades, several physicists started to explore the possibility of using meta materials to achieve the objective. Meta materials are materials with specially designed internal structure. They extended the research further to design a coordinate transformation technique, with distributed permeability and permittivity to steer the optical wave in any desired path. It was difficult to achieve these objectives because the optical wave lengths are very small.
Then, the interest shifted to impacting elastic waves where the wave lengths are large. However, the goal of steering the wave required a new distribution of the elastic modulus and a new distribution of density, in the material after active meta material control. In this paper, a method of achieving such a distribution by using active meta materials and the associated control procedures is presented. Three basic structures are considered. They are the structures that resist flexural vibrations, longitudinal waves and torsional waves. All three cases result in identical active meta material control equations and control procedures with different natural frequencies that are functions of both the density and elastic constants.
Transformation Field Analysis in Clustering Discretization Method in Micromechanics of Random Structure Composites
Authors: Braginsky Michael , Buryachenko Valeriy 
Published: February 2023

Abstract
A linear composite medium consisting of a homogeneous matrix containing either the periodic or random set of heterogeneities is considered. One of the first reduced-order model (ROM) Transformation Field Analysis (TFA) by Dvorak for strains is modified in terms of eigenstresses for implementation to clustering-based ROMs (CROMs) initiated by the self-consistent clustering analysis (SCA) by WK Liu. A set of consistency conditions are obtained for both the effective properties and modified eigenstress concentration factors. One dissects that modified TFA represents a unified background of the central clustering-based ROMs comprising the self-consistent clustering analysis and FEM-clustering analysis. The other presents the scheme of estimation of inhomogeneous strain concentration factors in some prescribed clusters analyzed by the SCA. For statistically homogeneous CMs, a localized version of the modified TFA is proposed for clustering of the matrix (virtual coating) in the vicinity of inclusions. Only linear offline stage is considered whereas analysis of nonlinear online stage is beyond the scope of the current presentation.
Evaluation of Simulated Railhead Weld-Defect Repairs Using Ultrasound Techniques
Authors: Broderick Demario , Basit Munshi , Aglan Heshmat 
Published: February 2023

Abstract
In this study, the quality of simulated welded pearlitic railhead steel has been assessed using regular and phase array ultrasonic techniques. Three 136 RE premium, head hardened rail sections, 18 inch in length, were used. The rail sections were acquired from the Transportation Technology Center (TTCI), Pueblo Colorado. Slots of 1 inch (25.4 mm) in length and 0.75 inch (19 mm) in depth were machined into the center of the railheads. The welding process was optimized via preheating to promote weld flow, consequently yielding better fusion between the parent and the weld material. The rails were preheated using two electrical heating strips (6-inch length and 2.5-inch width) attached to the rail web below the slot. The rail section to be welded was held in a box filled with ceramic fiber to insulate the rail section from the surroundings. The maximum pre-heated temperature was 500 °C. The slots were then filled using POSTALLOY® 2892-SPL hard facing filler wire.
Nondestructive inspection for weld discontinuities and porosity was performed using the OLYMPUS EPOCH 1000i ultrasonic flaw detector. The transducer/probe detects a variety of defects, forms, and sizes caused by welding flaws and/or slag inclusions. The same probe was used in the calibration of the equipment so that multiple variables such as specimen thickness, intensity of the reflected beam off the rear wall, and frequency could be preset. The device was calibrated, and a grid was constructed to guide the probe’s movement during the phased array and ultrasonic tests, ensuring that a high level of accuracy was achieved. A coupling agent was applied to the surface (cross-section) of the railhead at the end of the rail section. The phase array probe was placed on that surface, pressed gently, and moved across the rail cross-section. The parameters utilized for conventional ultrasound techniques were a 5 MHz frequency, a velocity of 0.2320 in/μs and a gain of 30 dB. In phase angle mode, an angle of 45 was utilized. These parameters were optimized and chosen for the calibration of the device with a section of the parent rail having the same length as a welded rail. All three samples were evaluated; sample A had no defects, while samples B and C had defects with a diameter of 1/20 inch (1.25 mm) and 1/10 inch (2.5 mm), respectively.
According to the American Railway Engineering and Maintenance-of-Way Association (AREMA), standard, defects that are below a diameter of 1/16 inch (1.56 mm) within the sound path located on the railhead are acceptable. Thus, based on the AREMA standard, two of the rails passed the ultrasound inspection and one did not pass. Destructive testing is being performed to slice the welded rail sections to locate the defects in order to confirm the resolution of the ultrasound techniques used.
Dependency Evaluation of Defect Formation and Printing Location in Additive Manufacturing
Authors: Safari Kosar , Khalfalla Shihab , Imani Farhad 
Published: February 2023

Abstract
At present, components manufactured with laser powder bed fusion (LPBF) platforms face various quality and repeatability issues, restricting the use of this technology primarily to prototyping. While in-situ imaging offers a capability of deciphering complex LPBF process and characterizing influential parameters (e.g., design, machine parameters, and material) on part quality, the current analysis ignores the effect of the print location and scan strategy. This paper presents a systematic image-guided analysis to characterize the influence of the component location and scan pattern on final part quality. Specifically, a data-driven model is developed to extract the impact of these process parameters on melt pool signatures such as shape, size, and the number of spatters. Next, we perform the post-build analysis based on x-ray computed tomography (XCT) to quantify process parameters’ effect on trackwise part quality, according to the magnitude of distortion and porosity. Finally, hyperdimensional computing is established to take into account the part location and scan pattern impacts and connect in-situ melt pool signatures to the quality of each track. Experimental results on four identical components positioned in different locations on the build plate show that as the part location deviates from the midpoint, melt pool fluctuation increases, and the track quality deteriorates substantially. In addition, the scan patterns with a shorter length lead to more variations in melt pool length and poor trackwise quality.
Jet Formation After Droplet Impact on Microholed Hydrophilic Surfaces
Authors: Alam Md Nur E. , Tan Hua 
Published: February 2023

Abstract
Droplet impacts on solid surfaces produce a wide variety of phenomena such as spreading, splashing, jetting, receding, and rebounding. In microholed surfaces, downward jets through the hole can be caused by the high impact inertia during the spreading phase of the droplet over the substrate as well as the cavity collapse during recoil phase of the droplet. We investigate the dynamics of the jet formed through the single hole during the impacting phase of the droplet on a micro-holed hydrophilic substrate. The sub-millimeter circular holes are created on the 0.2 mm-thickness hydrophilic plastic films using a 0.5 mm punch. Great care has been taken to ensure that the millimeter-sized droplets of water dispensed by a syringe pump through a micropipette tip can impact directly over the microholes. A high-speed video photography camera is employed to capture the full event of impacting and jetting. A MATLAB code has been developed to process the captured videos for data analysis. We study the effect of impact velocity on the jet formation including jet velocity, ejected droplet volume, and breakup process. We find that the Weber number significantly affects outcomes of the drop impact and jetting mechanism. We also examine the dynamic contact angle of the contact line during the spreading and the receding phase.
Sagittal Plane Dynamic Model Using Tibiofemoral Articular Geometric Center and Experimental Tibiofemoral Center of Rotation to Predict Joint Forces During Knee Extension Exercise
Authors: Salinas Jose Mario , Caruntu Dumitru I. 
Published: February 2023

Abstract
A 2-dimensional anatomical dynamic model of the patellofemoral joint was developed for investigating the forces that contribute to patellar motion during the knee extension exercise. Sagittal bone profiles were aligned to kinematic experimental data to simulate bone motion. Kinematic experimental data was collected using VICON motion analysis system. Marker coordinate data was used to set body-fixed coordinate systems on femur and tibia. These body-fixed coordinate systems were used to drive the femur and tibia geometric profiles during the knee extension exercise. Kinematic experimental data was used to calculate the relative instant center of rotation of markers on tibia with respect to femur’s body-fixed coordinate system. The instant center was then used as an alignment point for the geometric center of femur’s posterior lateral condyle. A geometric approach was implemented to predict patellar motion. The position of patella’s center of mass was assumed to be a function of the position of the tibial tuberosity and the geometric center of the femoral condyle. Newton’s second law of motion was used to calculate the force exerted by the quadriceps muscle during the knee extension exercise. The patellofemoral contact was modeled as a deformable articular surface, which was represented mathematically as the overlapping area between bone profiles. Overall, the forces calculated for the quadriceps force were greater than those observed for the patellofemoral contact. The quadriceps force displayed an increasing trend as the flexion angle decreased until reaching its maximum value of 1,920 N at full extension. On the other hand, the patellofemoral contact force displayed an increasing trend as the flexion angle decreased until reaching its maximum value of 805 N at 37° of flexion.
Growth-Based Design of a Conducting Solid Cooled by Conjugate Gas Conduction and Surface Radiation
Authors: Sevart Chadwick D. , Bergman Theodore L. 
Published: February 2023

Abstract
A solid growth model (SGM) is developed to identify desirable configurations of a conducting solid that is cooled by conduction through a stagnant gas and surface radiation. Thermal performance is quantified by the overall thermal resistance, as well as a figure of merit that rewards both (i) low thermal resistance and (ii) use of a small amount of solid. The results show that radiation affects both the evolution of the solid shape and the thermal performance. Predictions of the novel SGM are compared to those of a formal topology optimization (TO) method, which incorporates the effects of radiation after the solid shape is determined by considering conduction only. While application of the TO method yields a lower overall thermal resistance when a high solid thermal conductivity is considered, the SGM leads to better thermal performance when a low solid thermal conductivity is involved.
Numerical Analysis of the Vibration of Slender Beams
Authors: Sarker Pratik , Chakravarty Uttam K. . 
Published: February 2023

Abstract
The use of rotating beam-like structures is very common in engineering systems including power generation machines, automotive systems, aircraft structures, energy harvesting systems, and many more. The dynamic response analysis of these systems is of utmost importance for proper prediction of their performance and life. Among different outcomes of the dynamic response analysis, one of the major parameters is the frequency of the free vibration. Because of realistic loads and couplings between different degrees-of-freedom of motion, for majority of the cases, there is no analytical solution available. Hence, the governing equations need to be solved numerically. There are several numerical approaches available to solve for the coupled frequency of free vibration of rotating beams. In this paper, an overview of the different numerical methods is presented for coupled, free vibration analysis of slender, rotating beam-like structures. Three different degrees-of-freedom including out-of-plane bending, in-plane bending, and torsional deformations are considered for the most general case. At first, the eigen value problem of the coupled, mathematical model of free vibration of the beam is presented analytically. Following that, the use of different numerical methods is presented with relevant examples and corresponding beam parameters. Finally, the implementation of the finite difference method is presented to compare the corresponding results with that obtained by other methods.
Nonlinear Stability Analysis of a Reconfigurable Origami-Inspired Structure
Authors: Moshtaghzadeh Mojtaba , Bakhtiari Ali , Mardanpour Pezhman 
Published: February 2023

Abstract
This study thoroughly investigates the stability of a reconfigurable origami-inspired structure using the Finite Element Method (FEM). We use the Kresling pattern to design this foldable origami structure. We evaluate how the design’s geometric parameters, such as length ratio, number of polygon sides, and circumscribed circle’s radius, change the origami structure’s stability. We discover that the buckling load drops by increasing the structure’s length ratio. Furthermore, the results illustrate that the structure with less polygon side can be folded under less force. The circumscribed circle’s radius plays a significant role in mechanical responses to a tip force applied to an origami structure. Based on the results, it appears that the crease lines carry the greatest amount of tip load. The results and conclusions are analyzed to provide a complete design guide that can be used to improve origami structure performance.
2-D Analytical Model of Heat and Moisture Diffusion in Bonded Single Lap Joints
Authors: Gerini-Romagnoli Marco , Nassar Sayed A. 
Published: February 2023

Abstract
A two-dimensional elastic analytical model for bonded single lap joints subjected to heat and moisture diffusion is presented. The distributions of peel and shear stress in the bond area are calculated. Local moisture concentration and bondline temperature determine the properties of the adhesive layer, which vary in the space and time coordinates. Adhesive diffusivity coefficient and absolute saturated concentration are affected by the material temperature, and scenarios of individual and combined heat and moisture diffusion are analyzed. The governing partial differential equations are solved numerically, and a simplified shear stress formulation is introduced for low-modulus adhesives.
Two-dimensional gradients in the adhesive properties affect the peel and shear stress in the bondline. Diffusive patterns in the direction of the loading axis of the joint can contribute to a positive stress redistribution along the overlap, while the results of this study show that softening patterns in the transverse direction may severely impact the joint performance. In the initial stages of environmental exposure, significant increases in peak shear stress are observed in the innermost portions of the bond area. Less significant gradients are observed for the peel stress distribution, under the same conditions. A 3-D Finite Elements Analysis is used to compute adhesive peel and shear stresses, and the results are in reasonable agreement with the proposed analytical model.
A Reduced Three-Phase Model for Solidification of Liquid in Large Tanks
Authors: Terala Shashank , Mazumder Sandip , Matharu Gurpreet , Vaishnav Dhaval , Ali Syed 
Published: February 2023

Abstract
A liquid water-urea mixture is stored onboard diesel vehicles and used for exhaust aftertreatment. In cold weather conditions, the mixture may freeze and the freezing process may span over a day. In the first part of our study (Journal of Thermal Science and Engineering Applications — Transactions of the ASME, Vol. 13, p. 011008, 2021) it was shown that traditional computational methods are impractical for modeling such large-duration freezing processes because of restrictions in the time-step size posed by numerical stability and physical time-scale considerations. A model, in which natural convection driven thermal transport is treated as a diffusive process, was developed and demonstrated. Since the flow field was not computed in this model, the computations were found to be orders of magnitude more efficient than traditional methods. This preliminary model did not account for the expansion of ice. Here, a new model that accounts for the expansion of ice and the consequent rise of the initial air-water/ice interface (ice dome formation) is presented. An additional conservation equation for excess volume fraction is introduced to this end and is solved using the unstructured finite-volume procedure and sub-time-stepping. Since the flow field is not computed, the air-water/ice interface is tracked using a new algorithm similar to the traditional volume-of-fluid method, but one that constructs fluxes using a diffusive formulation rather than an advective one. Validation studies in full-scale three-dimensional tanks show good agreement with measured temperature-time data. It is found that the air-water/ice interface first evolves to a concave shape before finally becoming a convex ice dome after full solidification.
Gearbox Vibration Analysis Using a Spectrogram and Power Spectrum Approach
Authors: Mohammed Sufyan A. , Ghazaly Nouby M. , Abdo Jamil 
Published: February 2023

Abstract
Vibration analysis is essential in rotating machinery fault diagnosis. As a vibration contains the dynamic information of a machine, improvement based on analysis has an effective role in predictive and preventive maintenance. In the present paper, the short Fourier transform is applied to determine the frequency variation of a gearbox signal with time due to different loads and driver speeds. In addition, the power spectral density (PSD) is used to represent the randomness of the signal since many frequencies occur simultaneously. The gearbox health condition is measured, and signal fault is simulated as tooth breakage for five cases: 0% (healthy), 25%, 50%, 75%, and 100% (complete tooth breakage). The obtained results proved that it is more powerful to use both spectrograms and PSD for gearbox fault diagnosis. This method is also improved with the ability to distinguish gearbox vibration signals for anomaly detection.