bluuebunny/crossref_metadata_2025_split huggingface dataset:
Guided Wave Damage Imaging of Composite Laminates With Least-Squares Reverse-Time Migration (LSRTM)
Authors: He Jiaze , Schwarberg Anthony 
Published: February 2023

Abstract
A method for adapting least-squares reverse time migration (LSRTM) for ultrasonic guided wave imaging of composite laminates is proposed in this paper. As composites become more widely used in fields such as the aerospace industry, the need for high resolution imaging in structural health monitoring (SHM) and nondestructive evaluation (NDE) is also growing. For instance, delamination is a common problem in composite laminates, which has led to a certain degree of apprehension in the use of composite materials for load-bearing structures. Although the solver-based imaging techniques using conventional reverse time migration (RTM) methods illuminate damage with a wide range of damage-scattering effects, the resulted images do not fully define the damage regions due to the limited data acquisition aperture, sensor density, frequencies/wavelengths, and incompleteness of adjoint reconstruction. Previously, we have derived the LSRTM theory and benchmarked its high-resolution damage imaging performance for isotropic plates. To improve damage imaging in composite laminates, this paper proposes to create an ultrasonic guided wave-based LSRTM method for anisotropic materials. The derivation of the forward modeling operator and the adjoint operator is presented. Numerical case studies were conducted to show the improvement of LSRTM over RTM in mapping damage in composite plates. Multiple damage sites or damage with a complex shape were created in the numerical studies based on Born approximation-based modeling.
Implementation of ANN Modeling Techniques and Genetic Algorithm in the Diameter Prediction of MWCNTs/Epoxy Nanofibers for CFRP Structures
Authors: Biswas Pias Kumar , Zende Pradnya , Dalir Hamid , Agarwal Mangilal 
Published: February 2023

Abstract
Electrospun multiwalled carbon nanotubes (MWCNTs)/epoxy nanofibers are placed between the layers of standard carbon fiber-reinforced polymer (CFRP) prepreg composites to improve their physical and mechanical properties. As epoxy resin is a thermosetting material, it must be electrospun carefully maintaining a specific viscosity of the epoxy, and optimizing all electrospinning parameters is both costly and time-intensive. Thus, prior to implementing the different experimental techniques, a modeling methodology is an effective tool for regulating the electrospinning process’s contributing factors. In this case, it is observed that having a smaller diameter of MWCNT/epoxy is very critical because MWCNTs stay aligned inside epoxy nanofibers with a smaller diameter than nanofibers with a bigger diameter. Those aligned MWCNTs can lead up to a 29% increase in the flexural strength of a CFRP structure. different Employing artificial neural networks (ANN) models, the present study investigates the effect of key parameters on the fiber diameter and uniformity of electrospun MWCNT/epoxy nanofibers. The goal of this work is to implement and differentiate the multilayer perceptron (MLP) feedforward backpropagation ANN, radial basis function neural network (RBFNN), and very commonly used support vector machine (SVM) methods in order to construct computational models for predicting diameter of MWCNT/epoxy nanofiber with high accuracy.
Acoustic Emission Measurement and Location Analysis of Acoustic Emission Source for Superconducting Coil Quench During Training
Authors: Hirokawa Junko , Nishimura Osamu , Hisakuni Yousuke , Kano Akira , Uehara Hideaki , Monda Tomoko , Hirohata Kenji , Ito Toshinobu , Takami Shohei , Orikasa Tomofumi , Sato Kiyokazu 
Published: February 2023

Abstract
Acoustic emission (AE) measurement is a non-destructive testing method that can detect high-frequency elastic waves generated by mechanical events inside an object, and is able to localize the wave source by using multiple sensors. In order to determine the mechanism causing the quench phenomenon in superconducting coil, we applied the AE method to a small ellipse-shaped coil in a training experiment. Six AE sensors were installed on the coil surface before the coil was cooled to 4 K in a vacuum vessel and excited. The current to the coil was controlled to produce a gradual increase until the quench occurred. The entire training experiment ended after over 10 quenches and all AE events that occurred in each training cycle were measured. The location of the AE source inside the coil was calculated from the difference in arrival time between sensors, and the results were plotted on an expansion plan of the coil. High-amplitude AE events appeared in areas assumed to have sufficiently high internal stress to cause concentration of strain energy.
Characterizing the Training and Evaluation of Graduate Teaching Assistants (GTAs) at Research-Intensive Universities: Highlighting Best Practices and Opportunities for Reform
Authors: Saxena Ankit , Hood Larkin , Manogharan Guha , Berdanier Catherine 
Published: February 2023

Abstract
Graduate Teaching Assistants (GTAs) play a crucial role in undergraduate and graduate education in Mechanical Engineering (ME). Depending on the course and course instructor, GTAs hold a variety of responsibilities such as grading homework and exams, interacting with students in labs and during office hours, proctoring exams, and administrative and technical assistance to faculty. In less frequent cases, GTAs create course content or take the lead in the classroom. In many engineering departments, especially at research-intensive universities, GTA appointments are reserved for first-year students who have not yet found research funding, or to cover a lapse in research funding. This structure reflects a prioritization of research over teaching, compounded by a documented lack of formal pedagogical training for GTAs. GTAs may receive training in the form of short workshops with information pertaining only to their duties as GTAs and are rarely provided with formal evaluations from students and faculty. As each university, department, and even individual supervising faculty have differing expectations, training, and evaluations of GTAs, the levels at which graduate students as future faculty are trained for pedagogical roles are, at best, inconsistent. To propose opportunities for best practices in the training and evaluation of GTAs in Mechanical Engineering, however, it is necessary to characterize different existing paradigms of GTA support across mechanical engineering departments. This paper seeks to answer the following questions:
1. What are the existing patterns in how ME departments manage and support their graduate teaching assistants
2. How do multiple stakeholders associated with GTAs characterize the expectations, training, and evaluation of teaching assistants?
To answer these research questions, we employ a content analysis of publicly available resources for Graduate TAs in Mechanical Engineering programs departments within the 14 universities in the Big 10+ academic alliance. Assuming the amount and the digital location/affiliation of digital resources corresponds with the integration of GTAs into departmental teaching priorities, our findings indicate a wide variety of different models through which GTAs are supported and evaluated. However, most Mechanical Engineering programs in the United States rely heavily on resources located outside of their respective Colleges of Engineering, leaning on the Graduate schools and universities more centrally, indicating only peripheral prioritization of the training and evaluation of GTAs. The patterns within these data lead to implications in terms of gaps in resources and summative assessment to better educate and evaluate GTAs to help them develop into the Mechanical Engineering faculty of the future.
Effects of Infill on the Additive Manufacturing of Piezoresistive Pressure Sensors
Authors: Banks James D. , Khaleghian Meysam , Emami Anahita 
Published: February 2023

Abstract
The surge of growth in additive manufacturing (AM) has brought about increased interest in smart devices and advanced manufacturing. Fused Filament Fabrication (FFF) often presents itself as the starting equipment for industrial applications and hobby enthusiasts. The introduction of conductive polymer composites into FFF has brought about widespread capabilities, particularly in the areas of flexible sensors, printed electronics, and other multi-functional materials. Piezoresistive sensors have especially been of interest due to their use in wearable electronics and structural health monitoring coupled with the increasing commercial availability of conductive thermoplastic filaments. However, while much research has been devoted to the geometrical parameters in piezoresistive sensors in conventional manufacturing, little has been investigated with respect to additive manufacturing. Here, we present a unique method for tailoring the sensitivity of FFF produced flexible pressure sensors by altering the infill printing settings, therefore affecting the electromechanical response. Sensors were printed using common infill patterns (Concentric, Grid, Gyroid, Honeycomb, Lines, and Cubic) and low infill percentages (5–15%) capable of sensitivities of 2,010 kPa−1 under an applied pressure of up to 60 kPa and 530 kPa−1 under an applied pressure of up to 950 kPa. This work demonstrates the ease-of-fabrication and performance of flexible pressure sensors using an inexpensive and simple fabrication method.
Utilizing Stent Wall Shear Stress to Assess Stent and Flow Diverter Performance for Treating Intracranial Aneurysms
Authors: Suess Taylor N. , Gent Stephen P. 
Published: February 2023

Abstract
Analysis of flow diverting intracranial aneurysm repair devices has traditionally focused on reducing intrasaccular blood flow velocity and aneurysm wall shear stress (WSS) as the primary metrics for improved perceived device performance. However, the interpretation of this data has been debated, particularly with regards to the specific biological benefits of high or low aneurysm WSS. Therefore, this research proposes an additional parameter of WSS at the stent struts that could provide valuable insight regarding the device’s potential to promote occlusion at the aneurysm neck by indicating potential locations of increased platelet activation and microparticle shedding. Fluid flow effects were evaluated for two flow diverters (Pipeline™ and FRED™) and three stents (Enterprise, Atlas™, and LVIS™) using computational fluid dynamics (CFD) models developed from two patient-derived CTA datasets with aneurysms in the middle cerebral artery (MCA) and basilar artery (BA), respectively. The device WSS data provides an additional metric for evaluating the ability of the device to constrain the blood flow within the main vessel, as well as determining the point at which the blood flow is released into the aneurysm, indicating the potential locations of the initiation of aneurysm occlusion. It is hypothesized that high device WSS close to the aneurysm neck creates a higher likelihood of aneurysm occlusion due to platelet activation and microparticle shedding, while high device WSS proximal on the device would indicate higher likelihood of undesirable daughter vessel occlusion. Conversely, low-to-moderate device WSS throughout the device length could be interpreted as less flow diversion and more consistent blood flow allowed into the aneurysm, resulting in lesser device performance.
Crystalline Phase Changes due to High-Speed Projectiles Impact on 304L Steel
Authors: Slewa Muna 
Published: February 2023

Abstract
The physical characteristics and molecular structure of 304L steel are well known; however, little is known about the high-velocity impact on this metal. The effects of high-speed velocity impact on the crystalline structure and material phase changes are studied experimentally. The effects of an impact on the crystalline structure are assessed by impacting 304L steel plates with Lexan projectiles. A two-stage light gas gun accelerates projectiles to a velocity of 6.58 km/s at the point of the impact. The impacted plates’ surfaces are inspected using the Electron Back Scatter Diffraction (EBSD). Nine regions are examined and analyzed. These regions are selected from the area immediately under the impact crater to locations not physically affected by the impact.
Observations of collected EBSD images show that the predominant phases are Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC). A Hexagonal-Close-Packed (HCP) phase is also indexed. Since these crystalline structures are the most expected lattice formations, the samples are post-impact examined for molecular structure allocation changes. In this study, traces of HCP were found at some locations in all post-impact stages. This study also indicates that the FCC crystalline structure remained the dominant phase after impact. 304L steel iron alloys show resistance to phase changes behavior under high pressure shocks even close to the crater and impact holes.
A Physics-Based Computational Model for the Cold Spray Deposition of Composite Coatings
Authors: Abubakar Abba A. , Arif Abul Fazal M. , Akhtar Syed S. , Al-Athel Khaled S. 
Published: February 2023

Abstract
Composite coatings with tailored properties can be effectively deposited with the cold spray process via careful control of deposition parameters. To avoid repetitive experiments, numerical models are commonly used to optimize the cold spray deposition process parameters. The present study proposes using a physics-based hybrid computational approach to model the cold spray deposition of Ni-Ti/Al2O3 composite coating used for wear applications. The method involves using point cloud (for the impacting particles) and finite elements (for the deformed splats structures and substrate) to simulate dissimilar particles impact and interactions, plastic deformation, and temperature rise. The approach is computationally efficient and adequately captures the thermo-mechanical deformation resulting from the interactions among dissimilar particles. The simulations are carried out for various combinations of material types, particles sizes and shapes, and impacting velocities. The results from the simulations are analyzed and validated by comparing them with that of previous works. The plastic deformation and temperature rise within the mating bodies increase with increasing particles’ kinetic energies. The Ni-Ti-Al2O3 powder particles lead to higher plastic deformation, temperature rise, and inter-particle bonding due to the presence of the hard Al2O3 particles. The temperature does not rise above melting; however, recrystallization of coating microstructure becomes possible even at a low deposition rate.
Data Augmentation Using Spectral Failure Deltas to Diagnose Bearing Failure
Authors: Wescoat Ethan , Krugh Matthew , Mears Laine 
Published: February 2023

Abstract
Labeled training data are challenging to obtain in a manufacturing environment during production due to the time and cost constraints of the labelling process. Of the labeled training data that is collected, failure data comprises a small proportion or is non-existent in production datasets for condition monitoring. The small proportion can be related to failures occuring uxpectedly and parts are replaced quickly, meaning the failure state is rare and makes up a small portion of the run life and number of samples collected. The lack of labeled data and failure data leads to challenges in creating effective predictive systems, such as Digital Twins, to accurately determine equipment health state and remaining useful life. This work investigates training predictive algorithms using an augmented failure data set derived from laboratory systems with knowledge of real-world failures. Data are collected under different failure progressions and operating conditions to create variability for the variety of different production applications to apply these data augmentation methodologies. These same data are transformed by adding the variability measured through purposefully damaging the mechanical system to create the degraded and failed state data. This variability is extracted using a spectral augmentation technique on the surrogate system’s failure data under an artificial fatigue case. The fatigue case is created by incrementally damaging the bearing raceway and measuring the damaged surface area with respect to the total bearing raceway. The measured difference between these pre- and post-lab damage states is used as the damage state data set transformation function. The augmented and “true” data are then compared using class probability analysis and diagnosing particular failure instances. For future research, relatability analysis will be investigated to see how the effects change between bearings of different sizes.
Comparison of Residual Stresses in Cold Spray Coatings: Lagrangian vs. Eulerian Finite Element Methods
Authors: O’Donnell Jacob , Smith Michael , Cavallaro Paul 
Published: February 2023

Abstract
Cold spray is a novel thermal spray process in which a gas at high temperature and pressure deposits solid particles onto a substrate material. Current research utilizes a variety of methods of modeling techniques in order to capture the physics and dynamics of a cold spray particle impact, incorporating elements of the Lagrangian and Eulerian modeling methods. This research modeled the cold spray event of single and multi-particle impacts using Lagrangian and Eulerian methods. The material of both the particle and substrate are a standard Aluminum 6061-T6 alloy. The objectives of the models are to: (1) obtain particle and substrate deformations and residual stresses as functions of particle velocity, particle temperature, and substrate temperature; (2) establish the minimum number of successive particle layers such that the substrate residual stresses reach steady state; and (3) identify numerical limitations in the Lagrangian and Eulerian modeling methods using ABAQUS/Explicit.
The Lagrangian method predicted a maximum von Mises stress 23.72% lower than that of the Eulerian. The Lagrangian models allowed for discrete node tracking, however, thus allowing for improved surface definitions and transient material point tracking. The Eulerian models also better handled the plastic deformation and resultant temperature generation within the model, and thus were able to handle multiple particle impacts while the Lagrangian could not. The multi-particle models using the Eulerian method reported that seven particles were required for the substrate steady-state stress to remain independent of subsequent particle impacts. Concentric initial position multi-particle models saw a maximum 42.00% reduction in von Mises stress compared to the single-particle models and a maximum 53.18% reduction compared to multi-particle modes with randomized initial particle positions. Multi-particle impacts demonstrated a reduction in stress when compared to the single particle impact due to the increased thermal softening present.
Prototype Design and Manufacture of a Deployable Tensegrity Microrobot
Authors: Kazoleas Christian , Mehta Kaushik , Yuan Sichen 
Published: February 2023

Abstract
Micro-, and milli-scale robots have been of great R&D interest, due to their ability to accomplish difficult tasks such as minimally invasive diagnosis and treatment for human bodies, and underground or deep-sea tests for environment monitoring. A good solution to this design need is a multi-unit deployable tensegrity microrobot. The microrobot can be folded to only 15% of its deployed length, so as to easily enter a desired working area with a small entrance. When deployed, the tensegrity body of the robot displays lightweight and high stiffness to sustain loads and prevent damage when burrowing through tightly packed tissues or high-pressure environments. In this work, topology, initial configuration and locomotion of a deployable tensegrity microrobot are determined optimally. Based on the design, a centimeter-scale prototype is manufactured by using a fused deposition modelling advanced additive manufacturing or 3-D printing system for proof of concept. As shown in experimental results, the deployable tensegrity microrobot prototype designed and manufactured can achieve an extremely high folding ratio, while be lightweight and rigid. The locomotion design, that mimics a crawling motion of an earthworm, is proved to be efficient by the prototype equipped with stepper motors, actuation cables, control boards and a braking system.
Comparative Analysis of Coefficient of Performance (COP) Correlations of Single-Effect Vapor Absorption Refrigeration (VAR) Cycle
Authors: Khan Muhammad Saad , Kadam Sambhaji T. , Kyriakides Alexios-Spyridon , Hassan Ibrahim , Papadopoulos Athanasios I. , Rahman Mohammad Azizur , Seferlis Panos 
Published: February 2023

Abstract
Most of the absorbent-refrigerant pairings are evaluated considering single-effect vapour absorption refrigeration (VAR) cycle. The coefficient of performance (COP) based modelling of VAR enables its quick performance evaluation. The development of efficient and environmentally benign fluid pairing is required to replace conventional refrigerants. Operating parameters-based COP models are scarce for single-effect VAR systems, and fewer correlations are available for the COP estimation. The paper compares five performance-based models reported in the literature for operating absorption cooling systems with various refrigerant and absorbent pairing. The comprehensive mean absolute percentage error (MAPE) analysis was performed for five reported correlations for more than 1601 data points of different fluid pairings. Results revealed that RMSD and MAPE values seem significantly higher for the reported correlations apart from the recently developed COP correlation accounted for fluid parameters in prediction. This indicates that the earlier reported correlations only accounted for the specific fluid pairing and could not incorporate different fluid pairing, which has been considered a recently reported correlation that resulted in the significantly improved prediction ability for COP. The finding from this study highlighted that the newly registered COP prediction correlation could be beneficial for developing new single-effect VAR cycles as it accounted for both the operating parameters and fluid parameters.
Effect of Process Parameters on Wall Thickness Uniformity of Integrated Forming of Hollow Axle
Authors: Ye Caoqi , Shu Xuedao , Li Yiman , Xu Haijie , Wang Jitai , Xia Yingxiang 
Published: February 2023

Abstract
This paper innovatively puts forward the integrated forming of shape and hole of hollow axle. For verifying the feasibility of this method, the integrated forming of hollow axle is simulated by finite element method, and the hollow axle with good forming quality is obtained. On this basis, the effects of feed angle of the disc roll on the wall thickness uniformity of the middle long shaft section are explored. In order to characterize the wall thickness uniformity of each shaft, eight longitudinal sections are taken on each long shaft section, the wall thickness variance of the longitudinal section is calculated, and then the average value of the wall thickness variance of the eight longitudinal sections is used to represent the uniformity of the long shaft section wall thickness. The simulation results show that with the increase of the feed angle of the disc roll, the wall thickness of the long shaft section becomes more uneven, but the increase of the feed angle of the disc roll will improve the rolling efficiency; This paper expounds the influence law of feed angle on the wall thickness uniformity of hollow axle with integrated forming, which provides a theoretical basis for realizing the short and accurate forming of hollow axle.