bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Selective Laser Sintering of High-Density Polyethylene Using Optimized 3D Printing Parameters
Authors: Hoelzel Benjamin , Herren Blake , Saha Mrinal C. , Liu Yingtao
Published: January 2022

In this paper the processing parameters for 3D printing of HDPE via SLS technology is explored. Five different print types are developed by varying the output power of laser, chamber temperature, and scanning speeds between 10 mm/s and 80 mm/s in order to determine the optimal printing parameters that are needed for the manufacturing of consistent porous HDPE parts. The porosity of each print type is investigated via scanning electron microscopy (SEM). Experimental results demonstrates that Print Types I – IV have significant melted regions on the top layers of the print likely due to the absorption of heat overtime. Therefore, Print Type V is developed to eliminate curling by progressively increasing the scanning speed at increments of 1 mm/s between each layer, which can result in the desired HDPE prints with consistent porosity and drastically increased printability of complex geometries. Print Type V printing parameters are used to produce various HDPE prints with high quality and complex geometries.
Design and Testing of a Low-Cost Ventilator to Battle the Global Pandemic
Authors: Near Eric , Ihsan Mustafa , Chan Waylon , Viswanathan Vimal
Published: January 2022

COVID-19 is an infectious disease that has dramatically affected the world, causing a pandemic and changing many aspects of people’s lives and how they interact. The condition is highly contagious and aims at a person’s respiratory system. A ventilator, a medical device that helps patients breathe when they are unable to do it independently, is needed because COVID-19 inflames the airways in the lungs, making it difficult to breathe normally. Ventilators are not the cure for COVID-19 but are a piece of equipment to help people breathe until that body function can be done independently. Such equipment can be expensive to acquire and cumbersome to operate. The Spartan Ventilator uses off-the-shelf equipment, economic controls, and robust techniques to supply a patient’s lungs with oxygen. The system is designed for oxygen tanks that are commonly found within hospitals. However, a mechanical pump will be used as a substitute. All processes are controlled and monitored by an LCD touchscreen attached to an Arduino. The user interface is presented with simple buttons and menus to maximize screen space, provide quick readings of pressure, and control breaths per minute (BPM). PVC pipes, a cheap and durable material suitable for the non-volatile transportation of gas, were used. The valves we use are not definitive; they can be replaced with any 12V valve. The significant differences with the Spartan Ventilator are the price and the simplicity that the new technology has. The Spartan Ventilator can be very cheap compared to other professional ventilators that can be found in hospitals. The ventilator can be ten times less expensive than different professional ventilators while having the same efficiency and power.
First-Ply Failure Pressure of Symmetric Laminated Hybrid Composite CNG Tank
Authors: Shrigandhi Ganesh , Shah Mihil , Kothavale Basavaraj S.
Published: January 2022

In recent years, compressed natural gas (CNG) as a fuel for the automobile is overgrowing, as it is cheap and environmental friendly compared to gasoline and diesel fuel. To improve fuel efficiency, lightweight composite pressure vessel tanks are used for the storage of CNG. Due to high specific strength, fiber-reinforced composites are most widely used. Synthetic fibers like carbon, glass fiber are used for the fabrication of these pressure vessels.

In the last few decades, due to environmental concerns, the hybridization of synthetic fiber with natural fiber has gained the attention of researchers. This paper focuses study on the effect of adding natural fiber on first ply failure (FPF) pressure based on the Tsai-Wu failure criterion. The laminate stacking sequence on first ply failure pressure for carbon/epoxy, E-glass/epoxy, and hybridization of these fibers with abaca fiber is studied. Abaca is strongest among other natural fibers as it contains high cellulose which is responsible for strength of the fiber. CNG tank with a 30-liter capacity, inside diameter 261mm, thickness 12 mm, applied pressure of 25 MPa with both ends closed is considered. Stacking sequence of symmetric laminate [(90)2/∓θ/(90)2]S, for different orientation of helical winding i.e. θ = 15°, 25°, 35°, 45°, 55°, 60°, 75° is analysed for these composite materials. A hybrid tube made of synthetic and natural fiber with uniform thickness is considered. The simulation results of the first ply failure pressure are compared with theoretical results. Autodesk Helius Composite software is used for calculating material properties and, first, ply failure analysis.

It is observed that burst pressure decreases as helical angle θ increases, and for the stacking sequence of [(90)2/∓15°/(90)2]S burst pressure is maximum for all tubes. The Burst pressure of the hybrid carbon/Abaca tube reduces by 69.5% to 42% for winding angle between 15° to 45° compared to standard carbon tube. For hybrid E-Glass/Abaca tube, burst pressure reduction was 21% to 4.7% for winding angle between 15° to 45° compared to standard E-Glass tube. For hybrid Carbon/Abaca tube, the drop in burst pressure is less 23.7% to 1.74%, respectively, compared to carbon tube for helical angle in the range 55° to 75°. Slight improvement in burst pressure (1.14% to 7.5%) is observed for the helical angle between 55° to 75° in the case of a hybrid E-Glass/Abaca tube compared to the E-Glass tube only. For the E-Glass tube, intermediate lamina can be replaced by Abaca fiber.
Experimental and Analytical Analysis of a Hindmarsh-Rose Neuron Model in a Nonlinear Circuit System
Authors: Liu Yan , Zhang He , Li Yuchen
Published: January 2022

In this paper, nonlinear dynamic behaviors of a Hindmarsh-Rose (HR) neuron model are investigated through discrete mapping method. Periodic and chaotic firing motions are observed of the system with different external excitation. Stability boundaries in terms of the external excitation are predicted by the eigenvalues of the global mappings. A nonlinear analog circuit is developed on circuit simulations for the verification of the various firing patterns of the HR neuron model. A route from periodic firing activity to chaotic firing are observed in simulation and confirmed by the theoretical research. Time series for the potential of numerical model and circuit model are presented. The evolution processes of the routes into and out of chaotic firing activities are revealed.
Verification Study of CFD Prediction Accuracy of Liquid Droplet Impingement Erosion Rate for Engineering Applications
Authors: Qian Shaoxiang , Hu Xidong , Kanamaru Shinichiro
Published: January 2022

Multi-phase flows containing liquid droplets widely exist in piping system of process plants. Sudden geometry change like elbow causes the flow turbulence, which leads to droplet impingement against the piping wall. As a result, erosion can be induced, and hence, may cause leak of piping. Therefore, it is essential to evaluate erosion rate for determining design margin and finding countermeasures for erosion-related trouble. Some models have been proposed for predicting droplet-induced erosion rate, but there is large difference in their prediction accuracy. The present study aims at verifying prediction accuracy of some major erosion models for engineering applications.

CFD simulations of water jets are conducted to verify the prediction accuracy of erosion induced by liquid droplets, using the published experimental data. In the present simulations, a two-way approach is applied for solving the air-water two-phase flow. An original algorithm is used to calculate the droplet-induced erosion rate using the obtained two-phase flow fields. The investigated erosion models include the models of Haugen, DNV and Isomoto. CFD results show that almost all the investigated erosion models for various simulation conditions provide the conservative evaluation of erosion rates, compared with the experimental results. Among them, the erosion rates predicted by Haugen model are closest to the experimental results with acceptable prediction accuracy for engineering applications.
Sound Radiation of Locally Resonant Unidirectionally Ribbed Plates
Authors: Fossat Pascal , Ichchou Mohamed
Published: January 2022

This paper suggests a comprehensive case study of acoustic radiation from ribbed plate with inner resonance. Based on explicit design rules and homogenized model for flexural waves, it shows that bending waves propagation significantly differs from classical models in terms of wavenumber features in the neighborhood of local resonances, and comments on the influence of the atypical structural response on the radiated pressure field. The investigation of the acoustic radiation from an infinite and finite ribbed plate is proposed. The trend of the resulting radiated pressure fields from the homogenized model matches with classical models outside frequency bands associated with local resonance, however inner resonance yields additional frequency ranges in which acoustic radiation is either strongly reduced or enhanced. For both mechanical and acoustic responses, theoretical results are successfully compared with finite element method. Further consideration may focus on the radiation mechanisms with coupled bending and torsion in the stiffner.
Development of a Pellet and Filament Form Integrated Multi-Material Additive Manufacturing Co-Extruder
Authors: Krishnanand  , Taufik Mohammad
Published: January 2022

There are two methods to 3D print a part using extrusion-based additive manufacturing technology namely filament-based and pellets/granules-based. Filament-based extrusion needed a wire form material called a filament, which is pushed by a motor and gear mechanism, into a heating zone. In the heating zone, it converts in semi-solid form and is extruded out of the nozzle to deposit in a layer-over-layer manner. This extrusion strategy needed a non-flexible filament, so it limits the variety of materials. Converting material into wire form also increases the cost of 3D printing. Pellet-based extrusion accepts the material in granules form. It is fed into the heating zone using an extrusion screw. This technology can accept a wide range of materials and eliminate the cost of producing filament. But pellet-based technology is still not being used on 3D printers, on the other hand, filament-based technology in the form of 3D printers is very popular in the market. So, in this study development of noble pellet and filament form integrated multi-material additive manufacturing co-extruder has been presented. The developed co-extruder is capable to accept material in filament form as well as pellet/granules form. This will help to 3D print a particular part with several materials. This hybrid form of the extruder is accommodating the features of both types of extrusion-based additive manufacturing. As per need, one can easily shift from filament extrusion to pellet/granules extrusion using this co-extruder.
Comparative Energy and Exergy Analysis of Large Capacity Ammonia-Water and Water-Lithium Bromide Vapor Absorption Refrigeration (VAR) Cycles
Authors: Khan Muhammad Saad , Kadam Sambhaji T. , Kyriakides Alexios-Spyridon , Hassan Ibrahim , Papadopoulos Athanasios I. , Rahman Mohammad Azizur , Seferlis Panos
Published: January 2022

District Cooling Plants (DCP) is the sustainable way of energy consumption, refrigeration, and supply of chilled water to end-users via chillers and distribution networks. Thermodynamic assessment of the vapor absorption refrigeration (VAR) in the open literature has been performed for cooling capacity well below the actual requirement (less than 300 kW) of DCP. Therefore, this work aims to investigate energy and exergy analysis of large-scale single effect VAR cycles operated on NH3-water and water-LiBr systems for a cooling capacity of 4000 kW and assess several operating parameters’ influence on cycle performance. Different parameters such as evaporator operating pressure (water-LiBR = 0.010–0.020 atm, NH3-water = 5.39–6.20 atm), chilled water outlet temperature (288–297 K), absorber temperature (300–305 K), condenser temperature (310–315 K), cooling output (2900–4000 kW) and heat input (4300–5500 kW) to the generator are varied during the parametric analysis. The exergy destruction analysis of the cycle’s components is also included in the study. Overall, the COP (0.89) and Exergy efficiency (89%) of water-LiBr were found to be higher than that of an equivalent NH3-water system which is 0.697 and 81%, respectively. The maximum exergy destruction was found at the absorber unit (24%), followed by the generator (23%). Furthermore, the NH3-water and water-LiBr simulations were optimized for different parametric conditions, and optimal operating conditions were identified for large-capacity district cooling systems. Therefore, the findings will provide the roadmap for designing and optimizing large-scale DCP operated on VAR cycles.
Strategic Management and Operational Energetic Education, Opportunity for Future Small Developers and Entrepreneurs
Authors: Radulescu Bogdan Alexandru , Radulescu Victorita
Published: January 2022

Romania, as part of the EU has adopted new legislation concerning international energetic exchanges, based on the rules of cooperation. This paper illustrates some new concepts and essential steps in engineering education and beyond. International rules and their implementation at national level need to be adapted to the new financial and economic realities, quite important, especially in the actual economic pandemic context. All rules and regulations are based on the market economy interconnected to the international grids, necessary in the development of business opportunities. The second part presents the analysis of the target market segmentation, based on possible new criteria. Given the objectives of analyzing attractiveness and competitiveness, the advantages of being an educated engineer based on the selection of the strategy choice are determined. Success depends on the ability to understand and generate customers. The analysis of the strategic role of small developer management to ensure competitiveness and economic efficiency is also mentioned. All new graduates, master or doctoral students specialists in power engineering will have to deal with the new strategic objectives of investments, new legislation and trends as solutions to minimize global warming, increase energy efficiency, utilization of renewable resources, and environmental protection.
Multibody Dynamic Adams Model of a Ball Screw Mechanism With Recirculation Channel
Authors: Bertolino Antonio C. , De Martin Andrea , Mauro Stefano , Sorli Massimo
Published: January 2022

The presence of the recirculation channel of ball screws is often ignored in literature mathematical models since steady state analyses are usually performed. However, high-fidelity dynamic models of these components should include it to correctly represent the motion of the spheres. This would allow to enhance the model realism and to use it as a virtual test bench, also for PHM purposes. This paper presents a detailed three-dimensional multibody model developed in the MSC ADAMS environment in order to exploit its capabilities to represent a contact between generic arbitrary shaped bodies, such as the recirculating channel and deflector. Consequently, no ideal constraints are arbitrarily imposed and the full dynamics of every component is fully described. A first model validation is performed extracting the ball passing frequency from the nut axial acceleration signal. Furthermore, the dependence of the load distribution on geometric errors and external force application point eccentricity is investigated.
Evaluation of Dimensional Accuracy of Additively Manufactured Metal Parts in Fused Filament Fabrication Process
Authors: Alyammahi Mozah Saeed , Atatreh Saleh , Susantyoko Rahmat Agung , Alkindi Tawaddod
Published: January 2022

Additive Manufacturing (AM) technologies have been recently adopted to produce functional spare parts in advanced applications. High dimensional accuracy is essential in these applications, where it is expected for the dimensions of manufactured parts to meet the design specifications and tolerances. Different additive manufacturing processes exhibit different dimensional accuracies. This paper investigated the dimensional accuracy of additively manufactured metal parts produced by Fused Filament Fabrication (FFF). We designed a new testing structure (Test-Part) incorporating multiple features in a single build. Two different metal materials, 17-4 PH stainless steel, and copper were used to manufacture the test parts. We also compared the dimensional accuracy of metal parts against a composite polymeric material, Onyx, fabricated using the FFF process. The manufactured Test-Parts were scanned using an advanced laser scanning technology to precisely measure the dimensions and capture the geometry’s details. A detailed three-dimensional analysis was conducted to evaluate the extent of resemblance between the manufactured parts and the CAD model. Results showed that the copper Test-Part exhibited the highest dimensional accuracy (lowest dimensional deviation compared to the CAD model) among the three materials. Overall, metal 3D printed parts exhibited better dimensional accuracy compared to composite polymeric parts.
A Systematic Study of Pedestrian Contrast and Detection From Vehicle Headlights
Authors: Bayan Fawzi P. , Timbario Thomas A. , Nelson Jonathan D. , Sheldon Stuart , Wahba Ronny E. , Keys Brandon
Published: January 2022

An important factor in evaluating the visibility of pedestrians at night is the contrast they offer an observer. This paper investigates and quantifies the influence of various parameters on contrast. An experiment was conducted using pedestrians and surrogate human models positioned along a grid in relation to the illuminated headlights of vehicles positioned on a dry asphalt roadway with no additional overhead lighting. As part of this experiment, headlight illuminance was mapped, and pedestrian luminance data were comprehensively collected to provide parametric data necessary to evaluate patterns affecting contrast. Luminance and illuminance data are presented in the form of three-dimensional plots and further related to visibility levels using the Adrian model. The results of this study highlight and quantify important factors present in night visibility of pedestrians. These include position of the pedestrian both longitudinally and laterally, reflectivity of the clothing, vertical variations in luminance and illuminance, the background, and headlamp characteristics. They emphasize that three-dimensional modeling of headlight illuminance and pedestrian luminance enhances the understanding of pedestrian contrast and visibility.
Effect of Leg Topologies on Thermal Reliability of Thermoelectric Generators Systems
Authors: Aljaghtham Mutabe , Celik Emrah
Published: January 2022

Increasing the temperature gradient across thermoelectric (TE) devices improves the TE power output significantly. However, enhanced thermal gradients lead to high thermal stresses and these stresses must be taken into consideration in the design process to develop TE systems with enhanced thermal reliability. The shape of TE leg plays a major role on the performance of these systems. Conventional prismatic TE leg structure has been the preferred leg topology commonly utilized in TE devices due to its simplicity and high thermoelectric performance. Other leg topologies have also been considered in the literature to quantify their effects on TE performance. This current study investigates the thermal reliability of a several TE leg topologies such as trapezoidal leg, butterfly leg, vertical and horizontal cross-shaped leg, X-leg, Y-leg, I-leg according to the construction of each shape. 3D numerical model is presented to quantify the Von Mises stresses of these configurations and compared to conventional rectangular TE leg shape. The vertical cross-shaped and butterfly configurations generate 36% and 27% TE power higher than the conventional rectangular TE leg, respectively. On the other hand, the conventional TE leg has the lowest thermal stress compared to other TE leg topologies.
Prediction of a Blast Induced Peak Particle Velocity in Mining Operations: A Fuzzy Mamdani and ANFIS-Based Evaluating Methodology
Authors: Machesa Mosa , Tartibu Lagouge K. , Okwu Modestus O.
Published: January 2022

Activities in the mining industries as a result of rock blasting is the cause of extreme rock vibration which is considered a serious environmental hazard. In most cases, explosives are often used for the disintegration of rocks in opencast mine. One of the major challenges often experienced in mining industries is the case of ineffective use of explosive energy while performing such opencast operation, this could lead to disproportionate ground vibration, often measured by peak particle velocity (PPV). To reduce such ground vibration and environmental impediments, it is important to adopt creative models for the effective prediction of PPV. Considering the inevitable impact on rock mass, neighbouring structures and sometimes on human beings, an accurate prediction of ground vibrations and the evaluation of the aftereffects must be carried out prior to the actual blasting event. This research is an exposition of the prediction performance of a blast-induced PPV using a creative model -Fuzzy Mamdani Model (FMM) and a hybrid algorithm -Adaptive Neuro-Fuzzy Inference System (ANFIS), in mining operation. These models are employed to predict the blast-induced PPV, which is a measurement of the movement or vibration of a single earth particle as the shock waves from a particular location or blasting event moves through the system. Experimental dataset used in this research consists of three (3) input variables (change weight per delay, distance and scaled distance) and forty-four (44) record samples; the peak particle velocity represents the experimental result. The dataset is fed into MATLAB 2020 platform as input parameters. Results obtained using the creative and hybrid algorithms were compared based on root mean squared error (RMSE) and correlation coefficient between the experimental and predicted values of the PPV. The regression values obtained are 0.8487 and 0.97729 for the Fuzzy Mamdani model and ANFIS model respectively. From the result obtained, the best vibration prediction was achieved using the ANFIS model. It can be concluded that the ANFIS model gave a better prediction in terms of speed of computation and prediction accuracy. It is recommended that other hybrid algorithms and metaheuristic techniques be introduced and compared with the existing solution models for effective prediction of PPV in mining operations.
Detection of Jamming and Filament Breakage in FDM Using Vibration of Feeder Stepper
Authors: Rooney Sean P. , Pitz Emil , Pochiraju Kishore
Published: January 2022

In the field of additive manufacturing (AM), mid-print failure is exceedingly common due to user error, bad design, or environmental factors that cannot be readily prepared for. This holds for most if not all types of AM, but perhaps none more so than the popular Filament Deposition Modeling (FDM) method machines. Absent total power failure, the bulk of the common modes of failure in FDM can be expressed as having an immediate impact on the mechanical system, whether that be a head collision due to warping, increased pressure on the stepper as it tries to push jammed filament, etc. The open loop nature of FDM machines does nothing to help the high rate of failure that FDM printers are known for compared to traditional methods of manufacturing. In this paper, a method for predicting failure due to mechanical malfunction of an FDM 3D printer is presented. The method proposed seeks to close the loop on FDM machines by characterizing the vibrations of the stepper motors which comprise an FDM machine. Using the acoustic emissions, a classifier is trained in order to assess the state of a print based off of supervised learning of known modes of failure. The resulting model is able to successfully predict jamming or air printing during a print with 90% training accuracy.
Effect of Stenosis Location on the Flow Distribution in Coronary Branches: Experimental and Numerical Study
Authors: Abuouf Yasser , Albadawi Muhamed , Ahmed Mahmoud
Published: January 2022

Coronary artery disease is the abnormal contraction of heart supply blood vessel. This contraction in the blood vessels limits the flow of oxygenated blood to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. fractional flow reserve is the most accurate diagnostic method because it estimates the reduction in blood flow. The flow is distributed between coronary branches. However, the stenosis could change the blood distribution percentage. Accordingly, some branches could have further reduction in blood flow. The aim of this study is measuring the blood distribution percentage and reduction in each branch in patient-specific right coronary artery experimentally and numerically. Moderate stenoses with 60% area ratio are added in three locations. The flow in each branch is measured. On the other hand, A comprehensive three-dimensional computational flow model is developed. The model is validated using the experimental results. The validated model is used to predict the results in case of non-Newtonian blood flow. Based on the predicted results, when the stenosis is far from the bifurcation, the reduction in the inlet and the branches is between 38.5% and 41% for all flowrates. However, the closer the stenosis to the bifurcation, the larger the reduction in the side branch compared to the inlet. It shows 100% reduction when the stenosis is 10mm away from the bifurcation and 66.5% when it is 25mm from the bifurcation compared to 64.3% and 55.5% in the main branch, respectively. Accordingly, the physician should not rely only on the reduction of flow in the stenosed artery and investigate further into the branches.
Influence of Arterial Wall Elasticity on Blood Flow Dynamic Factors of Stenotic Carotid Artery
Authors: Albadawi Muhamed , Abuouf Yasser , Ahmed Mahmoud
Published: January 2022

Carotid artery is the major blood vessel which carries oxygenated blood to the brain and the face. Atherosclerosis is a major arterial disease characterized by a progressive contraction of the blood vessel. It occurs due to the deposition of cholesterol and lipids beneath the internal layer of the artery which is called stenosis. Carotid artery stenosis causes serious implications which considered one of the leading causes of morbidity and mortality in most countries. The existence of stenosis had a significant effect on the blood flow dynamic factors. Adding the arterial wall response through the wall elasticity will achieve more accurate and realistic flow characteristics. In this study, the arterial wall elasticity through two-way Fluid-Structure Interaction (FSI) was considered to the developed model to calculate the blood flow dynamics. Moreover, blood dynamic factors will be used to investigate the flow characteristics with rigid and elastic arterial wall and temporal blood responses. To estimate the blood dynamic factors, a three-dimensional reconstructed patient-specific carotid artery geometry with realistic boundary conditions is considered. Hence, a three-dimensional comprehensive model including the non-Newtonian Carreau blood flow viscosity model under pulsatile flow conditions is developed. The two-way FSI procedure was performed by applying an arbitrary Lagrangian-Eulerian (ALE) formulation to calculate the arterial response. Results indicated that using FSI has a crucial role in investigating the blood flow dynamic factors which resulted in low shear stress, pressure gradient, and velocity distribution comparing to the rigid arterial wall response. The efficient use of Computational Fluid Dynamics (CFD) has the potential to shed light on the assessment of the stenosis severity by adding the arterial wall and temporal blood response to the developed model.
A Parametric Study of Piezoelectric Energy Harvesting by Vortex Induced Vibration of a Pair of Cylinders
Authors: Cornett Thomas , Chattopadhyay Arka P. , Esmaeilpour Mehdi
Published: January 2022

The design of a piezoelectric based device that uses interference bluff body to harvest wind energy is presented. Different prototypes including cantilever beam, cylinder as oscillating body, and cylinder as interference body were used and tested to investigate the effects of interference bluff body’s properties such as the size and distance from fix oscillating body on the performance of energy harvesting system. To compare the frequency of oscillating beam and its natural frequency, a numerical simulation based on Finite Element Method was performed to obtain the natural frequency of cantilever beam. It was found that the energy harvester can be greatly improved by placing a fixed bluff body as interference bluff body in upstream of the oscillating bluff body. Through experimental tests, this study reveals that both diameter of interference cylinder and the distance between oscillating and interference cylinder play a key role in the energy harvester’s performance. Moreover, two different modes of oscillation were observed, depending on diameter of interference cylinder and its distance from bluff body. For all cases, the Fast Fourier Transform (FFT) analysis was used to monitor the frequency of oscillating cylinder and these values were compared with the natural frequencies obtained by Finite Element Method’s analysis. The results showed that the shorter beams oscillate with a frequency of about 5 Hz, close to the natural frequency of 6Hz, while the longer beams oscillate with a frequency of about 2.2 Hz, close to the natural frequency of 2.17Hz.
Velocity and Heat Transfer Studies of an Impinging Jet Using Magnetic Resonance Velocimetry and Infrared Thermometry
Authors: Humbert Nathan , Galante Jack , Davidson F. Todd , Helmer David B. , Elkins Christopher J. , Tamm Gunnar O. , Benson Michael J.
Published: January 2022

Heat transfer performance of a single cylindrical orthogonal jet impinging on a flat plate was obtained through steady-state infrared (IR) thermometry. One Reynolds (Re) number of 23,000 based on pipe exit diameter was considered. The distance of the jet exit plane from the shim varied from two to ten times the impingement jet diameter in increments of two diameters. The observed temperature and constant heat flux boundary condition allowed for the calculation of a Nusselt (Nu) number distribution to estimate the heat transfer performance of the impingement jet. At the smallest separation distance of two diameters, the relative maximum heat transfer performance is found at the stagnation point followed by a second peak occurring at a radial distance of approximately two diameters from the stagnation point. Compared to all jet exit separation distances studied, the distance of six diameters exhibited the greatest magnitude Nusselt number at the stagnation point. A paired fluids experiment using Magnetic Resonance Velocimetry (MRV) techniques collected hydrodynamic data of a single impinging jet at a matching Re number of 23,000 and jet exit plane distances. This work provides relevant data for correlation of impingement cooling design through unique analysis of the fluid mechanics and heat transfer characteristics of a single impinging jet. Measurement uncertainty was assessed to range from +/−1% to +/−10% for Nusselt number and +/−7% for velocity.
Generalized Study on Time-Dependent Creep Analysis of Functionally Graded Thick-Walled Cylinders Under Thermal and Mechanical Boundary Conditions
Authors: Ahmed Jasem A. , Wahab M. A.
Published: January 2022

A multiscale model has been developed to investigate the creep behavior of functionally graded thick-walled cylinders. Finite element (FE) simulations are employed to evaluate the position-dependent parameters associated with creep constitutive law at the microscale. A macroscopic FE model solves the non-linear boundary value problem to determine the time-varying creep stresses and strains. The framework proposed can predict the creep response of functionally graded pressure vessels based on the constitutive behavior of the creeping matrix, and volume fraction profile. Effective creep properties have been computed using three different micromechanical models and the homogenized creep response and its effect on the macroscopic behavior are compared. Considering the computational expenses associated with the large 3D-finite element models, investigations show that simple 2D-axisymmetric model can “closely capture” the creep behavior in such multiscale methods. Radial variations of constituent volume fractions have significant effects on stress distributions and creep strains histories. The models are beneficial to investigate the choice of material combinations and heterogeneity profiles, thereby reducing cost of materials, fabrication, and testing associated with experimental trials.
Friction Assessment in Hot Forging Operations Using Large-Scale Ring Compression Test
Authors: Gomez Diego , Ledesma Elias , Hino Ryutaro , Hamasaki Hiroshi , Aguilera Eduardo , Ruiz Ismael
Published: January 2022

The ring compression test is the most extended experiment for friction characterization in metal forming processes. However, these experiments are commonly carried out under laboratory environments with small specimens and highly controlled conditions, which may not accurately represent the industrial forging operations. For instance, a small size specimen does not provide enough surface area for the oxide scale formation and heat transfer, and these phenomena are critical in industrial processes. Then, friction characterization results are more accurate by using large-size specimens. In this paper, friction was determined by reverse engineering, using the commercial finite element (FE) code QForm, which is a commercial code for specific metal forming applications. Finite element models were adjusted considering both the final ring dimensions as well as the load-stroke during the entire experiment.

The design of experiments (DOE) matrix includes different factors and levels such as temperature, deformation speed, and high reduction. The temperatures were 900, 1100, and 1200 °C, the deformation speeds were 20, 80, and 150 mm/s, and the degree of deformations were 40, 60, and 80% in high reduction. The experiments were conducted to determine the friction in an actual crankshaft’s forging process. To determine that, ring specimens were done in a servo-hydraulic press, using compression plates made with the same material, thermal treatment, and surface coating as actual forging dies used in the crankshaft pre-forming operation. The temperature effect was higher than the deformation speed; however, these two factors have a strong interaction effect. On the other hand, from the FE models’ results, it was confirmed that the inner diameter reduction is highly sensitive to the coefficient of friction. However, the load-stroke behavior is less sensitive to friction changes, although it varies when different friction models are used.
Surface Finishing and Electroless Nickel Plating of Additively Manufactured (AM) Metal Components
Authors: Demisse Wondwosen , Mutunga Eva , Klein Kate , Rice Lucas , Tyagi Pawan
Published: January 2022

This study investigates the application of electroless nickel deposition on additively manufactured stainless steel samples. Current additive manufacturing (AM) technologies produce metal components with a rough surface. Rough surfaces generally exhibit fatigue characteristics, increasing the probability of initiating a crack or fracture to the printed part. For this reason, the direct use of as-produced parts in a finished product cannot be actualized, which presents a challenge. Post-processing of the AM parts is therefore required to smoothen the surface. This study analyzes chempolish (CP) and electropolish (EP) surface finishing techniques for post-processing AM stainless steel components CP has a great advantage in creating uniform, smooth surfaces regardless of size or part geometry EP creates an extremely smooth surface, which reduces the surface roughness to the sub-micrometer level.

In this study, we also investigate nickel deposition on EP, CP, and as-built AM components using electroless nickel solutions. Electroless nickel plating is a method of alloy treatment designed to increase manufactured component’s hardness and surface resistance to the unrelenting environment. The electroless nickel plating process is more straightforward than its counterpart electroplating. We use low-phosphorus (2–5% P), medium-phosphorus (6–9% P), and high-phosphorus (10–13% P). These Ni deposition experiments were optimized using the L9 Taguchi design of experiments (TDOE), which compromises the prosperous content in the solution, surface finish, plane of the geometry, and bath temperature. The pre- and post-processed surface of the AM parts was characterized by KEYENCE Digital MicroscopeVHX-7000 and Phenom XL Desktop SEM. The experimental results show that electroless nickel deposition produces uniform Ni coating on the additively manufactured components up to 20 μm per hour. Mechanical properties of as-built and Ni coated AM samples were analyzed by applying a standard 10 N scratch test. Nickel coated AM samples were up to two times scratch resistant compared to the as-built samples. This study suggests electroless nickel plating is a robust viable option for surface hardening and finishing AM components for various applications and operating conditions.
Image-Guided Multi-Response Modeling and Characterization of Design Defects in Metal Additive Manufacturing
Authors: Imani Farhad , Khanzadeh Mojtaba
Published: January 2022

The capability of metal additive manufacturing (AM) to produce parts with complex geometries manifests its potential to revolutionize manufacturing. However, the presence of heterogeneous defects even under optimized part design and processing conditions imposes critical barriers towards scaling metal AM to production environments. The recent advancement in imaging technology leads to a data-rich environment in AM and provides a unique opportunity to enhance understanding of design-quality interactions. However, the state-of-the-art image-guided methodologies focus on the characterization of the individual defect and are less concerned about transferring knowledge across heterogeneous defects to improve modeling and prediction ability. This study introduces a novel data-driven methodology to simultaneously quantify interactions between design parameters (e.g., orientation, thickness, and height) and heterogeneous defects (e.g., geometry distortion, discontinuity, and porosity) in the metallic AM build. A real-world case study on complex thin wall structures is evaluated with the single-response characterization models. Experimental results show average improvement of 64.8%, 70.4%, 73.3% in RMSE in comparison with single response model with inducing percentage u = 0.25, 0.5, and 0.75, respectively. The proposed model enables providing practitioners with a guideline to understand multimodal defects interrelation and fabrication of thin walls with minimal defects.
Numerical Simulation of Three-Dimensional Ocean Wave
Authors: Zhang Liting , Wang Xiuling
Published: January 2022

At present, caused by a large amount of wave energy resources and huge energy capacity, the development and utilization of wave energy have come to be an essential development focus of wave energy manufacturing. The purpose of this research is to simulate the ocean in an offshore environment. A three-dimensional Computational Fluid Dynamics (CFD) model was used to analyze the propagation of ocean waves. The Volume of Fluid (VOF) multiphase model and laminar model were used to analyze wave propagation in offshore conditions. Function Methodology and Mobile Methodology were implemented by applying User Defined Function (UDF) code which characterizes transient velocity profile. The parametric study was performed to analyze how velocity and amplitude change. The models were first validated by comparing them with previous analytical wave solutions. To prevent the reflection of the wave, a damping term was added by using User Define Function to define the viscosity of the water phase.
Controlling the Dynamics of a Quadratic Oscillator Using Infinite-Equilibrium
Authors: Xing Siyuan , Luo Albert C. J.
Published: January 2022

Dynamical systems with infinite-equilibria have been of great interest in recent years. The infinite-equilibrium can establish a flow barrier in phase space for control applications. For such a reason, a new method is proposed for controlling the dynamics of a quadratic oscillator by constructing an infinite-equilibrium through a feedback law. The local and global analysis of the unperturbed control system is presented, and the behaviors of the control system under disturbance is studied numerically. With the knowledge of disturbance, the control system can achieve bounded-input-bounded-output stability for any disturbance. Without the knowledge of disturbance, the control system can drive the flow to an equilibrium only for weak disturbance.
On the Vibration Transfer Characteristics From the Seat of the Vehicle to the Occupant
Authors: Morisaki Ryoma , Terashima Osamu , Kinoshita Fumiya , Touyama Hideaki
Published: January 2022

In this study, we aimed to achieve a human-adaptive vibration design in a vehicle cabin based on the sensory characteristics of the passengers. To this end, the psychological stress of the passengers as a result of the vibration of the seats in a commercial vehicle was studied. As an initial step, the vibrational acceleration of the seat was measured and its modal analysis was performed. We measured 22 points and 10 points of vibrational acceleration in three directions (vertical, longitudinal, and lateral) of the seat and its occupant, respectively, in a commercial vehicle. We then performed a modal analysis with the obtained data. The results show that the seat had four distinct vibrational modes in the idle state: vertical, horizontal, folding, and rising. The amplitude of the folding mode vibration was 24 Hz, which was consistent with the second-order vibration of the vehicle’s engine. This was the largest vibration of the seat. We also measured the brain and pulse waves of the seat’s occupant to estimate the psychological stress caused by the seat vibration. The results show that psychological stress can be estimated using brain waves. However, pulse waves were not suitable for estimating the psychological stress of the occupant owing to the negative influence of the noise caused by the engine on such waves. We also found that the sensitivity of the occupant to seat vibration can be estimated from the results of spectral analysis of the occupant’s gravity center.
Reinforcement Learning on Modular Robots Using Real-Time Decentralized Deconfliction in a Warehouse Environment
Authors: Sayed Andres , Scales Sara , Fox Austin , Stone Jafar , Crews Steven
Published: January 2022

This work seeks to incorporate existing methodologies for controlling and localizing robotic hardware of different capabilities in order to create an autonomous system of robots to move deliverables within an established environment. The system utilizes modular designs to employ rapid prototyping of different robotic capabilities highlighting the adaptability of this methodology. A high-level task manager centrally assigns priorities to each deliverable, and, through decentralized planning, the robots deconflict with one another during execution. Through the adoption of reinforcement learning techniques, our robots create individual path plans that adapt to both static and dynamic obstacles in real time. Contrasting other works that manage robotic systems in a predetermined and fixed environment, we demonstrate a single, simplified approach that can control and localize modular robots simultaneously in any given setting, to include warehouses and factories. This work utilizes the Robotic Operating System (ROS) to communicate between multiple robots of various capabilities and a single task manager, synchronizing autonomous movement and avoiding other tracked objects.
Crack Propagation and Fracture Toughness of Additively Manufactured Polymers
Authors: Pulok Mohammad Khairul Habib , Rahman M. Shafiqur , Chakravarty Uttam K.
Published: January 2022

Additive manufacturing (AM) technologies are catching the interest day by day due to their ability to produce very complex shapes or geometries. Investigating the fracture and fatigue behavior of additively manufactured parts are essential not only to understand their mechanical response but also to predict and prevent their failure. In this study, fracture and fatigue properties of additively manufactured polymers are investigated experimentally combining the servohydraulic material testing system (MTS 810) and the three-dimensional digital image correlation technology. The polymers used for the analysis are acrylonitrile styrene acrylate (ASA) and Onyx, which are readily available and more prevalent in AM applications. Both notched (i.e., pre-cracked) and unnotched specimens are printed in the edge and flat orientations by the fused deposition modeling printer in the shape of the standard ASTM sub-size flat dogbone structure. The tensile strain is studied ahead of the crack formation, and the crack propagation is observed in the photos obtained from the digital image correlation system. A finite element model of similar contemplation is generated for the validation and extended results. Results show that the orientation of manufacturing has a noticeable effect on the failure of the specimen. In the unnotched specimens, the crack occurs near the neck due to a high-stress concentration. Results for the high cycle fatigue test indicate that fatigue life decreases as the load increases for all types of specimens.
Acoustic Emission Detection and Signal Source Analysis of Boiler Water Wall Tube
Authors: Yuan Yilin , Shen Gongtian , Shen Yongna , Zhang Junjiao , Zhang Wenjun , Wan Qiang
Published: January 2022

This article introduces the entire process of acoustic emission detection of boiler water wall tubes. Due to the large curvature of the furnace tube surface, the sensor can only be installed in the area of the connecting plate between the furnace tubes, resulting in serious lateral attenuation. The distance between adjacent sensors in the lateral direction should be controlled within 40cm, but the longitudinal sensor can accept acoustic emission signals within the range of at least 80cm. Many acoustic emission positioning sources were found during the loading process. According to the standard of NB/T 47013.9-2012 “Nondestructive testing of pressure equipment Part 9: Acoustic emission testing”, the acoustic emission positioning sources were evaluated and classified. As a result, these signal sources are neither noise signals nor from crack propagation.