bluuebunny/crossref_metadata_2025 huggingface dataset:
The Development of a Friction Stir Extrusion Machine for Producing Multiscale Extruded Cylinders and Hollow Tubes
Authors: Emblom William J. , Foreman Christopher , Kreamer Charles , Frazier Sydney , Doiga Seth , Leaumont Michael , Olayinka Ayotunde , Darby Paul , Wagner Scott W.
Published: February 2023

Friction stir processing is being used to improve characteristics of advanced manufactured process by improving the strength and ductility of material, joining, surface characteristics, and alloying. In addition, friction stir processing may be used as a first step for recycling metallic waste.

The authors are interested in the friction stir processing because they see that friction stir extrusion may be used for producing unique components that could be useful for the development of fuel cells, micromanufacturing, heat exchangers, biomedical applications, and MEMS.

The goal of the current project is to develop a custom built friction stir machine in order to investigate multi-scale friction stir extrusion processes. The machine will be used to characterize various friction stir extrusion processes such as forward and backwards extrusion to produce solid cylinders and tubes with outside diameters up to 37-mm down to 3-mm and for tubes with internal diameters down to 2-mm. In addition, various materials will be evaluated for friction stir extrusion processes and the process parameters will be used.

The machine described is being implemented in 3 phases. The first phase was the building of the basic machine and perform open-loop tests. The second phase was the implementation of process monitoring and begin to implement closed-loop control. The third phase of building the friction stir machine is to fully implement closed-loop control and begin charactering specific processes.

This paper describes the current state of the project (Phase 2). A force transducer, thermocouple, and a displacement transducer are used to monitor the process parameters. A PLC is used to record the process parameters as well as control the 10HP 3-phase 240v ac electric motor that powers the rotating probe.

Open-loop tests where the extrusion process was performed manually by the equipment operator were performed where the operators attempted to control forces during the tests and to perform component and system integration tests.

A-1100-o aluminum solid billets 12.7mm in diameter were used to produce tubes (OD: 12.7-mm, ID: 6.35-mm). Observations, temperatures, and forces were recorded and are presented. Because this machine was a proof-of-concept machine that is being converted to a production machine, observations made will be used to improve the machine for Phase 3.
Viable and Sustainable Measures of Meeting Student Outcomes Related to Communication in Graduate Capstone Projects and Specialty Papers
Authors: Shimek Gary , Kumpaty Subha
Published: February 2023

The Master of Science in Engineering program at Milwaukee School of Engineering has had its share of curriculum changes based on feedback from various stakeholders and annual assessment of the program leading to continuous improvement. One of the student outcomes is to have demonstrated an ability to integrate and analyze information in a chosen specialty in the form of scholarly work, either as an independent specialty paper or as an independent engineering project. And another outcome that follows is to have the ability to effectively present and communicate technical concepts, both orally and in writing. Even with all the engineering skills developed through discipline-specific coursework, these two outcomes were still quite a challenge to numerous students. While the program director takes measures to connect students with the appropriate advisor and even assists in technical content, the program needed and implemented the constant presence of a non-technical person as a member of the committee to improve communication of students through all stages of proposal writing, progress report and final report. We had tried one class of technical writing as a separate entity for students to take before they embarked on a capstone project, but the effectiveness varied as the principles had to be personally applied by the graduate student for the individual project. With the new approach, the student’s resources have grown, the project path has been made seamless, the effectiveness of working on the technical content and report writing in tandem right from the literature search and proposal development has resulted. The historic development of the current approach, including an overview of program educational objectives and student outcomes, is presented. The paper also showcases the results in terms of publications by the students who have grown in confidence in writing skills. This paper aims at enabling informed discussion for engineering graduate programs across the United States seeking to aid their students in this critical area of communication.
2D Numerical Ultrasound Computed Tomography for Elastic Material Properties in Metals
Authors: Aktharuzzaman Md , Anwar Shoaib , Borisov Dmitry , Rao Jing , He Jiaze
Published: February 2023

Adequate knowledge of the materials through characterization during the development, production, and processing of the material is required for quality assurance and in-service safety. Material characterization involves the evaluation of properties such as elastic coefficients, material microstructures, morphological features, and associated mechanical properties. Ultrasonic signals are sensitive to useful acoustic properties, including wave speeds, attenuation, diffusion backscattering, variations in microstructure, and elastic properties (e.g., elastic modulus, hardness, etc.). To obtain a quantitative estimation of the material properties, an emerging imaging technique known as ultrasound computed tomography (USCT) can be utilized. This paper proposes to map the wave speeds (i.e., longitudinal and shear) inside elastic parts employing a wave-based methodology (known as full waveform inversion (FWI)) for USCT. FWI is a partial differential equation-constraint, nonlinear optimization technique. It is based on full wavefield modeling and inversion to extract material parameter distribution using wave equations. FWI consequently produces high-resolution images by iteratively determining and minimizing a waveform residual, which is the difference between the modeled and the observed signals. The performance of FWI based ultrasound tomography in material property reconstruction in numerical studies has been presented. The results show its application potential in nondestructive material characterization.
Effect of SF6 and C4F8 Flow Rate on Etched Surface Profile and Grass Formation in Deep Reactive Ion Etching Process
Authors: Sharma Pallavi , Pleil Matthias , Jackson Nathan
Published: February 2023

Deep reactive ion etching (DRIE) is one of the most important methods of etching silicon and involves numerous interdependent parameters that affect the resulting etching quality and device functionality. Some of the issues in the etching process include bottom grass formation, notching effects, and isotropic etching. The influence of SF6 and C4F8 flow rates, as well as etching and passivation cycle duration, on the etched sidewall profile and grass growth is discussed in this paper. The combination of a 300 sccm SF6 flow rate and a 100 sccm C4F8 flow rate produces a flat bottom surface with no grass formation. The creation of grass begins in the corners of the structures as the SF6 flow rate increases while the C4F8 flow rate remains constant (100 sccm). The flow rate of C4F8 was varied from 50 to 200 sccm (with SF6 at 300 sccm), with lower flow rates affecting the profile of the etched sidewalls and higher flow rates causing grass development. The etch/passivation cycle ratio was also discovered to be important in preventing grass growth. The clamping or loading of the 4-inch wafer had cooling issues that affected the surface profile of the structures and demonstrated that insufficient cooling of the substrate during etching led to the production of isotropic etching of structures and resolved using lubricant media for proper heat dissipation. The process recipes were optimized to achieve flat smooth bottom surface and straight vertical sidewalls with no defects.
Effect of Metallic Insert Design Parameters on the Load-Carrying Capacity of GFRP Bolted Connection
Authors: Elbshbeshy Amr , Ali Mahmoud , Shazly Mostafa , Bahei-El-Din Yehia
Published: February 2023

Threaded metallic inserts can be embedded between laminates to avoid drilling and prevent the bearing stresses on the hole boundaries. In the present work single lap joint configuration was used to evaluate the joint strength using embedded metallic inserts. The parameters were selected using the Design of Experiment (DOE) to facilitate and control the variables that will be tested. Parameters such as the tightening torque, the specimen length (L), fiber orientation, and loading rate were kept fixed for all tests. Other design parameters such as edge distance to hole diameter (E/D) using 3 levels and the thickness of the specimen (t) were evaluated using 2 levels, 3 replicates for each. Finite element analysis using ABAQUS was conducted to simulate the experiment, and the results of the experimental work were used to validate the FEA model. The failure was initiated in the matrix at the composite-insert contact surfaces. The fiber failure begins in the laminate which is in contact with the metallic insert surface. Progressive delamination and fiber failures led to several peaks in the load-displacement curve before total failure by shear-out. It was found that the joint strength tends to increase with a lower E/D ratio in both single and double layers of fabrics.
Autonomous Aerial Supply Delivery: Parachute Release and Impact Study
Authors: Hughes Kristina , King Katherine , Hickman Shane , Rannow August , Freisinger Gregory , Huntoon Stewart , Kuhlwein Ekaterina , Rooney Benjamin
Published: February 2023

Military missions are often limited by the quantity of supplies that soldiers can carry with them. The purpose of this research was to develop an autonomous aerial cargo delivery device capable of resupplying soldiers in contested and remote locations. Specifically focusing on the final leg of delivery, this device aims to transport cargo from existing long-range Unmanned Aerial Systems (UAS) to soldiers on the ground in a controlled and safe manner.

The solution developed through this research included low altitude drops of small, palletized, parachute-suspended loads from assorted UAS in flight. The device developed to accomplish this would be responsible for safely holding a variety of cargo, releasing from the UAS, decelerating in flight on its descent, and absorbing shocks on impact with the ground. By receiving signals from the UAS, this device would operate autonomously as no human interaction is required for its operation. Engineering analysis was conducted on these areas and an initial prototype was constructed based on relevant findings. Although intended for use with multiple UAS platforms, the Squad Operations Advanced Resupply (SOAR) UAS, currently in development at the US Army DEVCOM Soldier Center, was selected specifically as the basis for prototype modeling and design.

Through pilot testing, evaluation, and analysis it was determined that this method of inserting supplies into remote and contested environments is a viable and novel solution to small unit resupply. The device’s reliability was confirmed in its operation and data showed that the device increased survivability of cargo. This method of airdrop has great potential for future military and humanitarian applications and is worthy of further development.
The Influence of Magnetic Vector Potential in Electroplasticity
Authors: Grimm Tyler J. , Mears Laine
Published: February 2023

The application of an electric current in situ with plastic deformation has been shown to produce non-thermal effects, which often present as a reduction in flow stress. This phenomenon is known as electroplasticity. Despite over 60 years of research, the mechanism(s) responsible for this behavior remains unknown.

The magnetic vector potential is explored herein as a possible mechanism that may contribute towards electroplasticity. This effect is explored experimentally by isolating the potentials experienced during a common electrically-assisted tension/compression test through use of a solenoid. It was discovered that the vector potential does not affect the flow stress or elongation in several materials that were tested. This conclusions eliminates one possible mechanism of the electroplastic effect.
Acoustically Induced Vibration Mitigation
Authors: Arjunan Raj , Swindell Rob , Ghosh Arindam , Karczub Denis , Horder Nick , Mann J. Adin
Published: February 2023

Reduction of the fatigue risk presented by acoustically induced vibration in flare header systems using mitigations that either reduce dynamic stress concentration effects or the level of vibration are of considerable interest to designers and plant operators. Assessments of the relative performance of different types of pipe fittings in reducing dynamic stress levels are presented based on the evaluation of data from full-scale laboratory tests of a pressure-relief system. A modal-analysis based finite-element methodology is also developed so that predictions may be extended to other piping arrangements that vary in thickness, size or connection type. The pipe fittings considered in the test are Pipet®, fabricated tee (Stub-on arrangement), sockolet (small-bore branch connections only), full-wrap reinforced fabricated Tee and Sweepolet®. For the finite-element method reducing tee connection is considered in addition. The test system produced significant levels of both turbulent-induced vibration (FIV) and acoustically induced vibration (AIV), which required differentiation of stress evaluations for the low-frequency FIV region and the mid-to-high frequency AIV region. The relative performance of mitigations (through selection of the type of pipe fitting) was found to be particularly relevant in the low-frequency FIV region. The reductions in dynamic stress and vibration of small-bore branch connections from installation of clamped bracing are also presented. The results show that the use of reducing Tees and full-wrap reinforcements for Stub-on connections for tailpipe and sub-header branch connections provide significant mitigation of dynamic stress and improvement of fatigue life over the use of Pipet® and Stub-on fittings. However, for the Sweepolet® connection which was expected to provide similar improvement the benefits are not fully realized in the 10S configuration.
Recovering From Cyber-Manufacturing Attacks by Reinforcement Learning
Authors: Prasad Romesh , Swanson Matthew K. , Moon Young
Published: February 2023

A Cyber-Manufacturing systems (CMS) is an integration of informational and operational entities that are synchronized with manufacturing processes to increase productivity. However, this integration enlarges the scope for cyber attackers to intrude manufacturing processes, which are called cyber-manufacturing attacks. They can have significant impacts on physical operations within a CMS, such as shutting down plants, production interruption, premature failure of products, and fatal accidents. Although research activities in this emerging problem have been increased recently, existing research has been limited to detection and prevention solutions. However, these strategies cannot ensure a continuous function of an attacked CMS. To ensure continuous functioning of a CMS, a robust recovery strategy must be developed and employed. Current research in recovery has been limited to feedback controllers with an assumption of a complete knowledge of a system model. To overcome this limitation, a recovery agent augmented by reinforcement learning was developed. This is to utilize the ability of reinforcement learning to handle sequential decisions and to proceed even without a complete knowledge of a system model. A virtual environment for recovery agents has been developed to assist efforts needed to obtain sample data, experiment various scenarios, and explore with reinforcement learning. Two cyber-manufacturing attack scenarios have been developed: (i) spoofing a stepper motor controlling additive manufacturing processes, (ii) disrupting the sequence of the pick and place robot. The recovery agent takes random actions by exploring its environment and receives rewards from the actions. After many iterations, it learns proper actions to take.
Model Predictive Control of the Transparent Omnidirectional Locomotion Compensator With a Simple Prediction of a Walking Fire Ant
Authors: Le Kevin , Morgan Todd , Plank Riley , Penick Clint , Kim Dal Hyung
Published: February 2023

Automation in studying the behavior of small animals or insects is a key to finding behavior stereotypes. In this paper, we have demonstrated the Model Predictive Control (MPC) for locomotion compensator for a walking fire ant to reduce error based on the prediction of an ant’s movement. We have implemented the MPC with the simple trajectory prediction of a walking ant, which generates optimal control input to minimize the error on current and future positions. In our Transparent Omnidirectional Locomotion Compensator (TOLC), the ant freely walks without tethering atop a transparent acrylic sphere. Using the near-infrared (NIR) camera underneath the transparent sphere and a motorized omnidirectional wheel system, we can reorient the sphere to maintain the ant’s position on top of the sphere. The adaptive MPC method was implemented in the TOLC, while the reference trajectory is predicted using the moving average of the past history movement. The results show significantly reduced error with the predicted ant positions, and compared to the method without prediction of future positions of the walking ant. The average position error using the MPC methods with prediction is 0.413 mm, improved 48.0% from that without prediction (0.794 mm). Furthermore, the average position while tracking moves toward the target center using the MPC control with prediction.
Development of an Artificial Neural Network (ANN) Constitutive Model for Mechanical Metamaterials
Authors: Hussain Arif , Sakhaei Amir Hosein , Shafiee Mahmood
Published: February 2023

Metamaterials are a group of materials with artificial engineered structures that exhibits customized properties which are not naturally available in other materials. To accelerate the computational analysis of components made from metamaterials that helps novel engineering product design process, it is crucial to develop an accurate and robust model for these materials in macroscale. The classical approach to drive a material model in continuum level is based on development of a phenomenological model to represent the physical behaviour of the material. However, this approach has specific limitations in including the effect of tailoring design parameters in the model which is a key element for metamaterials. In this study, we have proposed an artificial neural network (ANN) constitutive model to represent the macroscale mechanical behaviour of metamaterials in three-dimensional domain. Because of its extraordinary capabilities to stimulate computational performance in identifying and constructing prospective microstructure model for mechanical metamaterials, the proposed ANN constitutive model provides intriguing advantages over conventional models. The ANN constitutive model has been trained based on strain-stress data which is obtained from microscale simulation of 3D cubic lattice structure under various loading conditions. The trained material model is then validated by measuring the accuracy of material behaviour prediction.
Selective Patterns for Circular Dimples Distribution As a Means to Enhance Structural Mechanical Response of Tubular Components
Authors: Sakonder Cuneyt , Paredes Marcelo
Published: February 2023

Bioinspired materials and structures subjected to external loads tend to exhibit unprecedented mechanical behavior, especially impact loads and extreme quasi-static forces. It has been observed that certain bioinspired structures may withstand excessive compressive loads with little or moderately inelastic response due to their complex materials’ architecture that extends at various length scales. On the other hand, nature inspired patterns may be an alternative to improve mechanical response, especially in the form of selective notches/dimples distribution over the surface of tubular members. The main goal behind this idea seeks to overturn the deleterious effects of circular notches or dimples on tubular components’ strength due to interaction of stress concentration fields generated at the hole’edges. By selecting an optimized pattern of dimples distribution along the tubular component, an interesting behavior can be observed, as the interaction of stress concentrations tend to cancel out each other rather than add them up and bring the structural component to premature failure. In this exploratory study, a numerical investigation is carried out on notched tubular members models with surface circular dimples, strategically distributed following bioinspired patterns typically observed in nature such as hexagonal, honeycomb and net patterns. Additionally, this study pursues to gain understanding on the possible beneficial effects that this type of selective dimples distribution might bring in stressed components not only made of metallic alloys, but also biological materials such as blood vessels replacement nonsynthetic, decellularized graft whose mechanical response can be greatly enhanced.
Performance of Flat-Tube Louvered-Fin Automotive Evaporator With R1234yf
Authors: Gurudatt H. M. , Narasimham G. S. V. L. , Sadashive Gowda B.
Published: February 2023

Following the Kyoto Protocol and the more recent Kigali agreement, Hydrofluoroolefins (HFOs) are considered as the low global warming drop-in or substitute refrigerants for hydrofluorocarbons (HFCs) which have high global warming potential. The HFO R1234yf gained significant importance as a replacement for R134a in automobile air conditioning. In this context, the performance of a two-slab automotive evaporator with R1234yf numerical simulation is reported in this paper. The simulation is conducted by considering the heat transfer from air to the outside wetted surface consisting of louvered fins and tube wall, from there to the inside tube wall, and from there to the bulk of the boiling refrigerant inside the tube. The combined effect of heat and mass transfer from air to the wetted surface is described by the enthalpy potential method. For the two-phase and superheating regions suitable heat transfer correlations are employed. The results show that the refrigerant side heat transfer coefficient increases with increase in vapour quality up to around 80% and then decreases with further increase in the vapour quality. The major contribution to the cooling capacity is the latent heat abstraction during the flow boiling process occurring inside the tube. The temperatures of the condensate water film surface and the inner and outer tube wall surfaces are nearer to the bulk temperature of the refrigerant because of the high heat transfer coefficient on the refrigerant side. Results are also presented for the refrigerant side pressure drop and the evaporator exit air temperature and humidity ratio.
Estimating Combined Impact of Urban Heat Island Effect and Climate Change on Cooling Requirements of Tall Residential Buildings in Hot-Humid Locations
Authors: Kamal Athar , Hassan Ibrahim , Wang Liangzhou (Leon) , Rahman Mohammad Azizur
Published: February 2023

Climate change estimates are critical in developing long-term solutions to the dwelling problems that we currently face. This study combines the impact of climate change and the urban heat island effect to study the outcomes of future weather conditions on the cooling of tall residential buildings in hot and humid climates. For the year 2050, we calculate the impact of urban characteristics through the urban weather generator and climate change through the world weather gen tool on the micro-climatic condition of a district in a newly constructed city near Doha, Qatar, the Lusail City. A total of four weather files are compared to the weather data gathered from the established weather station in the city (two for the year 2020 and three for the year 2050). Results reveal that once the open weather map file has been processed through the urban weather generator (UWG) first and then the climate change model, the MAE increases to 3.30, and the RMSE goes to 3.8 with a maximum deviation of 11.4°c occurring. If the process is done the other way around, the climate change model is applied first, and then the UWG file is applied, the MAE of 3.46 is with RMSE of 3.94 with a maximum deviation of 11.3°c occurring. The impact of these weather files is then assessed on a tall residential building in Lusail. A significant increase of 777197 kwh or 20% is seen in the openweather map file that has been processed first through the climate change model and then through the urban weather generator (as compared to the rural weather file); an increase of 739983 kwh or 19% is seen in the openweather map file that has been processed first through the UWG and then through the climate change model; finally close to 22.6 percent increase or 874088 kwh is seen in the openweather map file that has been processed first through the climate change model and then through the climate change model.
Variable Kinematic Shell Finite Elements for Dynamic Analyses of Rotating Structures
Authors: Filippi Matteo , Azzara Rodolfo , Carrera Erasmo
Published: February 2023

This paper makes use of low- and high-fidelity finite plate and shell elements for vibrational analyses of various rotating structures. The two-dimensional models, developed with the Carrera Unified Formulation (CUF), are obtained by adopting two different kinematics expansions, namely the Lagrange-like (LE) and Taylor-like (TE) polynomials. The possibility of selecting different kinematic expansions enables various configurations such as composite, reinforced and sandwich structures to be considered. The equations of motion of rotors with arbitrarily shaped cross-sections are derived with respect to a co-rotating reference system. All contributions induced by the rotational speed (the Coriolis force, the spin-softening and the stress-stiffening terms) for both spinning and blade-like configurations are included in the equations of motion. Furthermore, the linearized and geometrically nonlinear approaches are presented to compute the speed-induced stiffening effect. Numerical simulations are performed on a swept-tip blade and a shallow shell to validate the formulation. Comparisons with solutions available in the literature demonstrated the accuracy of the approach.
Video Verification of an Instrumented Mouthguard in American Collegiate Men’s Rugby
Authors: Fetchko Travis , Boudreau Grace , Roach Megan , Cameron Kenneth , Rooks Tyler
Published: February 2023

There are few published studies investigating wearable head impact sensors which focus on rugby. Devices mounted externally on the head can shift or be fully removed during normal play. Investigation into the use of instrumented mouthguards in rugby has recently begun. However, different devices and their associated software have varying reliability in helmeted vs. non-helmeted sports which must be verified. This study implemented the Impact Monitor Mouthguard device in male American collegiate rugby players, and used video-verification to assess the reliability of the device’s validity software. We found a Positive Predictive Value of 97.0%, which compares favorably to previously published values for this device. We believe this is the first study to analyze the accuracy of sensor events rejected by the software, which resulted in a Negative Predictive Value of 97.0%.
An Investigation on the Aerodynamics, Vibrations, and Control of an Electroactive Membrane
Authors: Ojo Oluwatosin , Pulok Mohammed Khairul Habib , Su Ji , Chakravarty Uttam K.
Published: February 2023

Dielectric elastomer membrane(s) are smart material(s) that produce large actuation strains. They are also a class of electroactive polymers that function as actuators and sensors to convert and sense electrical signals to mechanical deformation and vice versa. Unique properties, such as flexibility, lightweight, and the ability to have an electrical field-induced deformation, make the dielectric elastomer membrane an ideal solution to the challenges faced by many applications, including the wings of unmanned aerial vehicles. This study aims to analyze the modal characteristics and aerodynamics of the dielectric elastomer membrane both computationally and experimentally. An electroactive membrane, VHB 4910, is considered the specimen, and the conductive material of carbon grease is used as an insulator on both surfaces of the membrane. Finite element models are developed to compute the resonance frequencies and mode shapes. The computational results of the modal analysis are validated using a closed-loop vibration testing experimental arrangement and digital image correlation system. Aerodynamic analyses are conducted using a wind-tunnel setup with a data acquisition system. A shape sensitivity study is also performed to see how five different shapes of a constant area affect the aerodynamics and vibrations of the membrane. The modal characteristics are controlled by adjusting the prestretch, true stress, and applied voltages. The natural frequencies decrease as the applied voltage increases. The aerodynamic coefficients increase with the angle of attack up to a particular range.
Books Trimmer Industrial Machine Knives Diagnosis: A Condition-Based Maintenance Strategy Through Vibration Monitoring via Novelty Detection
Authors: Viale Luca , Daga Alessandro Paolo , Garibaldi Luigi , Caronia Salvatore , Ronchi Ilaria
Published: February 2023

In recent years, Artificial Intelligence (AI) is ever more exploited in all the scientific and industrial fields and is allowing significant developments in mechanical engineering too. An emblematic contribution was given in terms of safety and reliability since Machine Learning (ML) techniques permitted the monitoring and the prediction of the state of health of machinery, allowing the adoption of predictive maintenance strategies. In fact, data-driven models — based on acquisitions — attract considerable interest both thanks to its theoretical and application development. The evolution of diagnostic techniques is oriented towards Condition-Based Maintenance (CBM) strategies, thus allowing improvements in terms of safety enhancement, cost reduction and increased performances. This paper proposes the development and implementation of a diagnostic/prognostic tool applied to an automated books trimmer industrial machine, implementing condition monitoring by means of accelerometers which can be integrated into a Supervisory Control And Data Acquisition (SCADA) system. Given its use, the core components of this production line are three knives, subjected to significant impulsive forces. Therefore, the target of the work is to infer the wear of these three knives, as they are critical elements of the machinery and have a high impact on the quality of the final product. The project was carried out in collaboration with Tecnau — an industry-leading company — which made it possible to conduct experimentation and data acquisition on their machinery. An appropriate Design Of Experiments (DOE) and the use of inferential statistical techniques — such as the ANalysis Of VAriance (ANOVA) and the identification of significant effects — applied to the multivariate dataset allowed recognizing the most relevant features for Novelty Detection (ND). Both the Linear Discriminant Analysis (LDA) and the k-Nearest Neighbors (kNN) method permitted to correctly distinguish the patterns representing the health conditions of the machinery, classifying the data in the reduced multidimensional space according to the final product quality. The results obtained in terms of accuracy are very positive and promising. This means that the developed method is able to successfully identify the state of health of the blade in spite of varying functioning parameters (book thickness and size, paper type and characteristics) and operating conditions. The algorithm speed and its integration into the industrial line make a real-time condition-based maintenance strategy possible. This diagnostic method is suitable for applications oriented to the paradigm of Industry 4.0 and the digitalization of the industrial sector, which can be integrated with the Internet of Things (IoT) and cloud systems.
Hybrid Solver for the Radiative Transport Equation in Nongray Combustion Gases
Authors: Jajal Nehal , Mazumder Sandip
Published: February 2023

The absorption coefficient of molecular gases exhibits strong oscillations with wavelength. Thus, solution of the Radiative Transfer Equation (RTE) in a medium comprised of combustion gases require repeated solution of the gray RTE, rendering such calculations computationally very expensive. Popular methods to solve the RTE include the Finite Angle Method (FAM) and the Spherical Harmonics Method (PN). FAM, the finite-angle variant of the discrete ordinates method, produces accurate solutions when used with sufficient angular resolution. However, it has high computational cost. The lowest order Spherical Harmonics Method (P1) requires solution of a single elliptic partial differential equation and is very efficient in comparison to FAM. It yields accurate solutions for fairly isotropic intensity fields. In this study, a Hybrid solver for the nongray RTE is proposed that capitalizes upon the efficiency of the P1 method and the accuracy of the FAM. Depending on the spectral (or band) optical thickness, an appropriate solution method is chosen. The objective is to determine optimal parameters for selecting the solution method that can provide the best compromise between accuracy and computational cost. Using the statistical narrow band (SNB) model for carbon dioxide and water vapor, the nongray radiative transfer equation is solved in inhomogeneous media enclosed in multidimensional enclosures. Two different approaches — cut-off and filter optical thickness — are investigated for selecting the solution method. Several problems, both two-dimensional and three-dimensional, and with and without coupling to other modes of heat transfer are considered. The filter approach was found to be the best choice for prediction of the radiative source, while the cut-off approach was found to be the best for prediction of wall radiative heat fluxes.
An Undergraduate Research Study: Effect of Welding Methods and Weld Puddle Manipulation on the Tensile Strength of Welded Joints
Authors: Kopac Jordan , Mahinfalah Mohammad , Schaefer Mathew
Published: February 2023

Benefits of undergraduate research have been documented by many researchers [1, 2]. This paper presents the results of an undergraduate research project conducted over two terms. An experimental study was conducted to determine the effect of specific MIG welding methods and manipulation of the weld puddle on tensile strength of welded joints. The two investigated methods were, “stringer” which is straight and consistent speed weld that has no manipulation of the puddle and “weaving” where the welder is weaving his or her puddle in a variety of different motions, most commonly a cursive ‘e’ or a back-and-forth motion.

Statistical data analysis was performed on the results from the tensile testing to confirm that the variation between the samples is significant enough to conclude that there is a difference between the groups’ means. Additionally, analysis and observations of the samples after polishing and acid etching was completed to see how well each welding method penetrated and fused during the welding process.
Five Key Attitudes for a Successful Co-Op: the Value of Cooperative Education Within an Undergraduate Program
Authors: Schneider Anakin , Iglesias Patricia
Published: February 2023

Cooperative education programs (Co-ops) and internships are becoming increasingly popular within undergraduate engineering curriculums and with students who participate in them. These programs provide real-world experience and practical applications of key concepts that students learn in the classroom.

In a recent internship, both the academic knowledge of basic engineering principles and preconceived knowledge of workplace attitudes were challenged and evaluated. The internship involved facilitating numerous projects focused on streamlining production and working with various levels of management to complete them. In reflecting on the overall internship experience, five key attitudes were realized as being important to both personal and professional successes as an engineering intern. The attitudes are “Respect the Workday,” “Be Confident, Be Humble,” “Respect the Work Environment,” “Let Go of Things You Cannot Control,” and “Make the Experience Your Own!”

This paper will act as a friendly guide to any undergraduate engineering student as they proceed with their first co-op experience and provide important key takeaways and pragmatic examples from this experience that either exemplify or misrepresent the attitudes. The paper will also outline a framework for engineering industry leaders on how to standardize and promote positive work environments that will realize success for students willing to learn fundamental engineering competencies. It will also call for the creation of more undergraduate engineering programs to require cooperative education experiences, which are key to a student’s application of classroom knowledge. The conclusion of this paper is simple — follow the advice, put it into practical use, and enjoy the experience.
Conveyer-Less Matrix Assembly Layout Design to Maximize Labor Productivity and Footprint Usage
Authors: Verma Ankur , Oh Seog-Chan , Wells James W. , Arinez Jorge , Kumara Soundar
Published: February 2023

The automotive industry has used in-line conveyor systems to move vehicles through the general assembly process since the early days of vehicle manufacturing in the 20th century. With products shifting to EVs (Electric Vehicle) and the emergence of AMRs (Autonomous Mobile Robot), there is an opportunity to transform the assembly process into a more flexible conveyor-less matrix-based system. One key development need is how to structure and optimize such an asynchronous system. This paper presents a new methodology for designing a conveyor-less matrix assembly layout to maximize labor productivity, workstation utilization, and footprint usage, while minimizing the system costs, and cycle times. Specifically, we develop an asynchronous assembly system for the automotive trim area. We aim to answer the question: How do we decide on an optimum number of workstations for the asynchronous assembly system, such that productivity and ROI are maximized? For this, we use cycle times, the number of operations per workstation, reference heights, and precedence graphs as input variables. Similarity matrices are used to quantify the similarity of tools, ergonomics, and human operations between workstations. Workstation utilization percentage and makespan are the metrics used to compare between alternative layouts. Finally, we perform a cost and makespan analysis to evaluate the ratio of trim area costs to total revenue, calculate makespan, and report the best layout found in the study. Quantifying subjective data, repeatability, less setup, and simulation time are the attributes that make this methodology valuable to any virtual commissioning software, an integral part of the smart manufacturing ecosystem.
On the Micromechanical Properties of Conventional and 3D-Printed Rebar
Authors: Allameh Seyed M. , Eckart Alexis , Fonseca Lopez Jose , Miller Roger , Lenihan Avery , Allameh Hadi
Published: February 2023

This study is focused on the micromechanical properties of conventional rebar and how they could be used for comparison with the 3D printed rebar tensile and fatigue properties. Current trends in additive manufacturing hint at the eventual use of 3D printing in the construction of homes and office buildings. Nowadays, 3D printing of homes is being achieved on an experimental basis by depositing extruded concrete in layers up to the ceiling to make walls, and then building a roof on top of the walls by conventional methods. This practice is not suitable to make bridges, multistory office buildings or structures that substantially experience tensile stresses. It is necessary to incorporate steel rebar in otherwise easily printed concrete structures. One way to achieve this is direct welding of steel into concrete by mounting a welder gun on to the 3D printing head and conducting 3D welding of the rebar. This has been accomplished and mild steel weldments have been 3D welded onto concrete. To make it acceptable for construction, the reliability of such printed rebar must be investigated. Early results of microscale tensile and fatigue testing on steel weldments made by additive manufacturing show desirable mechanical properties. However, the comparison has been made with macroscale tensile and fatigue properties of conventional rebar. To ascertain the reliability of 3D printed rebar welded onto concrete, it is essential to conduct a comparison with the micromechanical properties of conventional mild steel rebar. To achieve this, micro-specimens were machined off thick and thin conventional rebar in various orientations including along and across the longitudinal axis of the rebar and at different depths from the surface to investigate their micromechanical properties. Dog-bone shaped specimens 1000-micron in gage length with square gage cross sections measuring 200-micron × 200-micron were extracted from the surface as well as from the center of thick and thin rebar rods using a HAAS CNC. Samples were polished to a mirror finish and then tested in an Instron Electropulse E1000 load frame equipped with microgrippers that allowed monotonic and cyclic loading of the samples at a frequency of 50Hz. The results of micromechanical testing obtained from conventional rebar are compared with the those obtained from testing micro-specimens machined from mild steel weldments deposited by 3D welding on ceramics. The results demonstrate the reliability of mild streel rebar printed by 3D welding onto concrete. The implications of the findings on the use of additive manufacturing in 3D printing reinforced concrete and how it will impact the construction industry are discussed.
A Digital Twin Framework for Mechanical Testing Powered by Machine Learning
Authors: Kahya Müge , Söyleyici Cem , Bakır Mete , Ünver Hakkı Özgür
Published: February 2023

The aviation industry demands innovation in new materials and processes which can demonstrate high performance with minimum weight. Strength-to-weight ratio (STR) is the key metric that drives the value justification in this demand stream. However, aviation’s test and certification procedures are time-consuming, expensive, and heavily regulated. This study proposes a Digital Twin (DT) framework to address the time and high costs of mechanical testing procedures in the aviation industry. The proposed DT utilizes new Machine Learning (ML) techniques such as Transfer Learning (TL). Hence, a proof-of-concept study using TL in the Aluminum material group has been demonstrated. The promising results revealed that it was possible to reduce the test load of new material to 40% without any significant error.
Molecular Dynamics Simulation of the Effect of Hydrogen on the Interaction Between Dislocations in Alpha-Iron
Authors: Oyinbo Sunday Temitope , Jen Tien-Chien
Published: February 2023

In this study, we use extensive molecular dynamics (MD) calculations based on a highly-accurate interatomic potential to examine how hydrogen atoms impact the mechanisms behind the mobilities of edge and screw dislocations in alpha-iron (α-Fe) at a temperature ranging from 300 K to 500 K. The dislocation mobility in α-Fe is shown to be temperature and hydrogen concentration-dependent in this MD investigation. It is demonstrated from the results that hydrogen impurities that are efficient in locking dislocations exist in the form of complexes that are scattered discretely along the dislocation line and that these complexes operate as extremely effective impediments to the mobility of dislocations. The hydrogen impact on the edge dislocation motion from the dislocation velocities versus shear stress reveals that the movement of edge dislocations in α-Fe with hydrogen is much damped as the hydrogen concentration increases. Furthermore, the motion of screw dislocations in the α-Fe is by the process of kink-pair nucleation and migration. according to the simulation results, the locking mechanism of the cross-slip seen along the dislocation path is due to the strong-feature energy landscape and inherent energy fluctuation in the system, resulting in jogs formation.
A New Approach to Nonlinear Dynamic Modeling and Vibration Analysis of Tensegrity Structures
Authors: Yuan Sichen , Zhu Weidong
Published: February 2023

Tensegrity structures have experienced continued research and development interests in the past several decades. Revealing dynamic characteristics of a tensegrity structure, for example: vibration analysis, is an important objective in structural design and analysis. Traditional dynamic modeling methods are inaccurate in predicting dynamic responding of a tensegrity structure, due to their neglection of internal displacements of structure members. To solve this issue, a new nonlinear dynamic modeling method for tensegrity structures is proposed in this paper. This method defines position of a structure member as a summation of boundary-induced terms and internal terms in a global coordinate system. A nonlinear dynamic model of a tensegrity structure is derived from Lagrange equation, as a system of ordinary differential equations. This dynamic model can be linearized at an equilibrium configuration for vibration analysis. As shown in simulation results, the proposed method can predict natural frequencies of a tensegrity structure with a better accuracy than the traditional methods. Unlike the traditional methods that can only predict dynamic responses in a low frequency domain, the proposed method can also reveal dynamic responses of a tensegrity structure in a higher frequency domain by only using a small number of internal terms.
Bolt Loosening Detection for a Steel Frame Multi-Story Structure Based on Deep Learning and Digital Image Processing
Authors: Zhao Yadian , Yang Zhenglin , Xu Chao
Published: February 2023

Bolted joints are widely used in the field of aerospace, civil and mechanical engineering. During their service life, extreme loading or environmental factors can cause the loosening of bolts. In this paper, a bolt loosening detection method based on computer vision and image processing is developed to identify bolt rotation angle in a steel multi-story frame structure. The experimental results show that the bolt target detection accuracy can reach 100% by using the Yolo-V5s deep learning model trained with a self-developed bolt object dataset. The dataset consists of 337 bolt images captured in nature scenes. For the angle calculation, the final result shows that the identification error is less than 5.8°, and at a slight camera angle (0∼20°), the maximum error even does not exceed 2.8°. Thus, the effectiveness of this method for detecting rotary loosening of bolts is well validated.