bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Functionally Gradient Materials Under International Research Experiences for Undergraduates Program: US - South Africa Collaboration
Authors: Kumpaty Subha , Akinlabi Esther , Gray Andrew , Sivak Kevin , Erinosho Mutiu , Pityana Sisa
Published: January 2019

This paper details the ongoing research conducted by Milwaukee School of Engineering senior undergraduate students in South Africa under the third year of the Research Experiences for Undergraduates grant EEC-1460183 sponsored by the National Science Foundation (Principal Investigator Dr. Kumpaty). Andrew Gray and Kevin Sivak conducted research in summer of 2017 under advisement of Dr. Kumpaty and his South African collaborators, Dr. Esther Akinlabi, Dr. Mutiu Erinosho and Dr. Sisa Pityana. They extended the work of Paoli (reported in IMECE2017-71037), with varying percent of Mo (0–15%) in the combination of Ti64-Mo deposited on Ti64 substrate at laser powers of 1500 and 1700 W for a select scan speed. Laser metal deposition was completed at the CSIR – National Laser Center, in Pretoria, South Africa and the material characterization was performed at the University of Johannesburg as in the previous year. Hardness decreased with addition of Mo. Lowest hardness was observed in 10% Mo layers, and greater percent of Mo led some agglomeration issues due to its melting temperature being much higher than that of Ti64. Corrosion tests were also attempted. Etching challenges were present as percent of Mo varied in the same sample. Results are directly applicable to biomedical industry in evaluating functionally graded materials. An alumnus of MSOE, Peter Spyres served as a liaison for our international REU participants as he engaged them during the weekends in a cultural immersion which otherwise would not have been possible. Gray and Sivak were able to spend July 4th at the U.S. Consulate in Pretoria. While the research collaborators have generously provided support, it is the care taken by Peter’s remarkable household, which enhanced the beneficial value of this international research enterprise.
Transition From Planar Stratified Flow in Converging Microchannels
Authors: Lamberty Zachary , Park Minseo , Macken Nelson , Melvin Adam T.
Published: January 2019

Microfluidic applications may involve the control of flows through a series of junctions. For example, flow branching is typically used to deliver specific quantities of fluid to various locations and converging flows are associated with mixing processes. The shape of the fluid interface of the converging flows at and downstream of the flow junction is the focus of this study. In particular, we investigate the transition from planar stratified flow to annular flow. We report results for microchannel configurations which have a main channel and an intersecting (at 90 or 45 degrees) daughter channel. Two 90 degree channels are investigated, one with cross sectional dimensions 129 × 100 um and the other 200 × 100 um. The 45 degree channel dimensions are 161 × 100 um. We compare flows of water over various Reynolds numbers (based on total flow) of 5–400. Flow visualization is achieved using confocal fluorescence microscopy. Flow modules are fabricated using soft lithography techniques and are enclosed by bonding plasma cleaned glass slides to the PDMS module. At lower Reynolds numbers, e.g., < 20, stratified flow is achieved with some curvature at the interface. As the Reynolds number increases, the flow transitions to have large degrees of curvature and eventually into annular flow. This transition is influenced by Reynolds number, flow ratio (daughter/total flow), channel geometry (cross section) and configuration (45 vs. 90 degrees). Flow regime plots are produced for all microchannel configurations. This study should provide insight into intersecting microfluidic flows when the Reynolds number is high enough to produce a non-planar fluid interface at the junction.
Structural Optimization of Truck Front-Frame Under Multiple Load Cases
Authors: De Shuvodeep , Singh Karanpreet , Alanbay Berkan , Kapania Rakesh K. , Aguero Raymond
Published: January 2019

An optimization framework is developed to minimize structural weight of the front-frame of heavy-duty trucks while satisfying stress constraint. The shape of the frame is defined by a number of design parameters (which define the shape of the side-rail, position and width of the internal brackets, and width of the flanges). In addition, the thickness of the engine-mount, the side-rails, inner-brackets, radiator mount, shock absorber and cab-mount connector are also considered as design variables. Aluminum Alloy, 6013-T6 is chosen as the material and the maximum allowable stress is the yield stress (320 MPa). A quantity known as ‘Violation’ is defined as the ratio of area in the front-end module where stress constraint is violated to the total area of the frame is introduced to implement stress constraints. For optimization, the penalty method is used where the objective is to minimize the total weight while keeping the value of the ‘Violation’ parameter less than 0.1 %. The Particle Swarm Optimization Algorithm is implemented using parallel computation for optimizing the structure. Commercial FEA software MSC.PATRAN is used for creating the geometry and the mesh whereas MSC.NASTRAN is used to perform static analysis. Six design load conditions, each corresponding to a road condition are used for the problem.
Quadruple Flow and Acoustic Coincident Resonance of Rotating Bladed Disks Interacting With Stationary Elements
Authors: Kushner Frank
Published: January 2019

In recent years it has been discovered that besides non-uniform flow excitation such as from stator wakes; acoustic pressure pulsation can be a concern, especially for high pressure centrifugal compressor impellers. This has been termed “triple coincidence” and explains rare failures and likely a reason, at least partially, for some previous undocumented failures. Bladed disk interaction resonance discovered by the author in the mid 1970’s can be avoided such as for centrifugal impellers as needed, depending on vibratory mode involved, available damping, and potential excitation level. Especially for stages having vanes in the diffuser near impeller tips, concern for high cycle fatigue is very high as certain numbers of vanes combined with number of rotating blades can give correct phase to excite a highly responding mode. Intentional mistuning of disk-dominated modes has potential for reducing response. A similar but more complex interaction is with transverse acoustic modes having a specific number of nodal diameters. In this case acoustic gas modes in cavities at sides of impellers can match rotating acoustic pulsations at BPF (blade passing frequency) and/or harmonics, termed Tyler-Sofrin modes with increased noise. Also acoustic mode matching impeller structural mode can give the triple coincidence causing resonant response of the impeller. The concern for this coincidence is often difficult to evaluate. For some cases, calculations give enough evidence to modify number of vanes or blades to correct a possible cause of a fatigue failure. This coincidence can add to the direct response, e.g. from either upstream wakes or downstream diffuser vane interacting “potential flow” excitation, herein termed “quadruple coincidence resonance”. Dimensions of impeller side cavities are axisymmetric and are set by aerodynamics, so that outer and inner radii define transverse modes with small radial dimensional changes available. Often a minor aerodynamic performance compromise can be used to change designs to avoid serious resonances, e.g. revise numbers of vanes and/or blades, avoid the response of a matching diameter mode or have a different less responsive mode to alleviate concern. Besides turbomachinery e.g. compressors and pumps, some other methods as described could be utilized for any cavity that has diametrical mode shapes, or possibly other patterns for pressure pulsation frequencies. These modification(s), including patent-pending method, PCT/US2018/020880 described herein can alleviate if not eliminate concern for any mechanism having structural vibration excitation and/or environmental noise issues.
Mechanical Properties of 3D Printed Biomimicked Composites
Authors: Allameh Seyed M. , Miller Roger , Allameh Hadi
Published: January 2019

Additive manufacturing technology has significantly matured over the last two decades. Recent progress in 3D printing has made it an attractive choice for fabricating complex shapes out of select materials possessing desirable properties at small and large scales. The application of biomimetics to the fabrication of structural composites has been shown to enhance their toughness and dynamic shear resistance. Building homes from bioinspired composites is possible if the process is automated. This can be achieved through additive manufacturing where layers of hard and soft materials can be deposited by 3D printing. This study examines mechanical properties of reinforced concrete fabricated by 3D printing. Preliminary results of 4-point bend tests are presented and the implications of 3D-printed home building on current conventional construction practices are discussed.
Thermal-Mechanical Study of 3D Printing Technology for Rail Repair
Authors: Mortazavian Ershad , Wang Zhiyong , Teng Hualiang
Published: January 2019

The complicated steel wheel and rail interaction on curve causes side wear on rail head. Thus, the cost of maintenance for the track on curve is significantly higher than that for track on a tangent. The objective of this research is to develop 3D printing technology for repairing the side wear. In this paper, the study examines induced residual thermal stresses on a rail during the cooling down process after 3D printing procedure using the coupled finite volume and finite element method for thermal and mechanical analysis respectively. The interface of the railhead and additive materials should conserve high stresses to prevent any crack initiation. Otherwise, the additive layer would likely shear off the rail due to crack propagation at the rail/additive interface. In the numerical analysis, a cut of 75-lb ASCE (American Society of Civil Engineers) worn rail is used as a specimen, for which a three-dimensional model is developed. The applied residual stresses, as a result of temperature gradient and thermal expansion coefficient mismatch between additive and rail materials, are investigated. At the beginning, the worn rail is at room temperature while the additive part is at a high initial temperature. Then, additive materials start to flow thermal energy into the worn rail and the ambient. The thermal distribution results from thermal analysis are then employed as thermal loads in the mechanical analysis to determine the von-Mises stress distribution as the decisive component. Then, the effect of preheating on residual stress distribution is studied. In this way, the thermo-mechanical analysis is repeated with an increase in railhead’s initial temperature. In thermal analysis, the temperature contours at different time steps for both the non-preheated and preheated cases indicate that preheating presents remarkably lower temperature gradient between rail and additive part and also represents a more gradual cooling down process to allow enough time for thermal expansion mismatch alignment. In mechanical analysis, the transversal von-Mises stress distribution at rail/additive interface is developed for all cases for comparison purposes. It is shown that preheating is a key factor to significantly reduce residual stresses by about 40% at all points along transversal direction of interface.
Investigation of Three-Dimensional Lagrangian Coherent Structures in Flow Past Single and Arrays of Plate: Linear Energy Harvesting Applications
Authors: Attiya Bashar , Liu I-Han , Altimemy Muhannad , Daskiran Cosan , Oztekin Alparslan
Published: January 2019

Large Eddy Simulations (LES) are performed to investigate the coherent structures in flows past a single and an array of tandem plates. Lagrangian coherent structures (LCS) are used to investigate the nonlinear vortex dynamics of flow past a single plate. The Finite-Time Lyapunov Exponent (FTLE) is calculated using the velocity data obtained from Large Eddy Simulations (LES). All simulations are conducted at Reynolds number of 50,000. LCS for a single plate is presented in this study to elucidate and comprehend highly turbulent flow interactions in these flows. The LCS is compared against most commonly used Eulerian structures which are contours of the vorticity and the Q-criterion. The FTLE fields reveal much clearer turbulent structures compared to the Eulerian structures. FTLE better describes the evolution of larger scale eddies. The Q-criterion of flows past an array of plates is also presented.
Development of a Single Walled Tank Under Cryogenic Conditions Made of Composite
Authors: Kutz Philipp W. , Otremba Frank , Werner Jan , Sklorz Christian
Published: January 2019

The use of glass-fiber reinforced plastic (GRP) can reduce the weight of tanks significantly. By replacing steel with GRP in tanks for gases (propane, etc.) a weight reduction of up to 50 % was reached. In this project not only the material should be optimized, but also the design. Previous tanks consist of a double-walled structure with an insulation layer between the two shells (e.g. vacuum). Goal of this project is to realize a single-walled construction of GRP with an insulation layer on the outside.

To determine the temperature dependent material values, two different experiments are performed: In the first experiment, temperature dependent material properties of liquid nitrogen found in literature research are validated in a simple setup. The level of liquid nitrogen in a small jar is measured over the experiment time. Numerical simulation shows the change of nitrogen level with sufficient precision. In the second experiment, a liquid nitrogen is applied on one side of a GRP plate. Temperature is measured with thermocouples on top and bottom of the GRP plate, as well as in the middle of the plate. By use of numerical simulation, temperature dependent thermal conductivity is determined.

In the third experiment, a test stand is designed to examine different insulation materials. In this test stand, the insulation material can easily be changed. A numerical simulation, in which the determined material data is used, is performed as well for this test stand.

The experiments show, that GRP can be used in cryogenic environments. Multiphase simulations are a suitable tool to describe the energy absorption of thermal energy due to thermal phase change. Results on different insulation materials will follow.
Non-Gray Radiation Exchange: The Internal Fractional Function Reconsidered
Authors: Lienhard John H.
Published: January 2019

The radiation fractional function is the fraction of black body radiation below a given value of λT. Edwards and others have distinguished between the traditional, or “external”, radiation fractional function and an “internal” radiation fractional function. The latter is used for simplified calculation of net radiation from a non-gray surface when the temperature of an effectively black source is not far from the surface’s temperature, without calculating a separate total absorptivity. This paper examines the analytical approximation involved in the internal fractional function, with results given in terms of the incomplete zeta function. A rigorous upper bound on the difference between the external and internal emissivity is obtained. Calculations using the internal emissivity are compared to exact calculations for several models and materials. A new approach to calculating the internal emissivity is developed, yielding vastly improved accuracy over a wide range of temperature differences. The internal fractional function can be useful for certain simplified calculations.
Energy Demand, Efficiency Measures and Embodied Energy in the Italian Residential Sector
Authors: Abd Alla Sara , Bianco Vincenzo , Scarpa Federico , Tagliafico Luca A.
Published: January 2019

This paper investigates a strategy for energy saving in the Italian residential sector that includes in the assessment the embodied energy related to the efficiency measures. Simulations are run in three main cities (Milan, Rome and Naples) covering different climate zones. The purpose is, firstly, to estimate the baseline of the buildings energy consumption, secondly, to simulate the implementation of realistic retrofit solutions and, finally, to assess the retrofitting’ embodied energy and its energy payback time.

The energy payback is based on the comparison between the net saved operational site energy and the embodied energy of the selected measures.

By running the simulations, it is possible to estimate the maximum potential for energy savings and realistic estimation of achievable results in short-medium period.

Results show the energy efficiency measures more convenient in terms of energy payback depending on the climate zone.

For Naples, a focus on façade insulation has been held and the results defined the optimal material thickness in terms of embodied energy and net saved operational site energy in a life cycle of 15 years.
Performance and Emissions Analysis of Partially Pre-Mixed Charge Compression Ignition Combustion
Authors: Srivatsa Charu Vikram , Mattson Jonathan , Depcik Christopher
Published: January 2019

In order to investigate the performance and emissions behavior of a high compression ratio Compression Ignition (CI) engine operating in Partially Premixed Charge Compression Ignition (PPCI) mode, a series of experiments were conducted using a single cylinder naturally aspirated engine with a high-pressure rail fuel injection system. This included a moderately advanced direct injection strategy to attempt PPCI combustion under low load conditions by varying the injection timing between 25° and 35° Before Top Dead Center (BTDC) in steps of 2.5°. Furthermore, during experimentation the fuel injection pressure, engine speed, and engine torque (through variance of the fuel injection quantity) were kept constant. In-cylinder pressure, emissions, and performance parameters were measured and analyzed using a zero-dimensional heat release model. Compared to the baseline conventional 12.5° BTDC injection, in-cylinder pressure and temperature was higher at advanced timings for all load conditions considered. Additionally, NOx, PM, CO, and THC were higher than conventional results at the 0.5 N-m load condition. While PM emissions were lower, and CO and THC emissions were comparable to conventional injection results at the 1.5 N-m load condition between 25° and 30° BTDC, NOx emissions were relatively high. Hence, there was limited success in beating the NOx-PM tradeoff. In addition, since Start of Combustion (SOC) occurred BTDC, the resulting higher peak combustion pressures restricted the operating condition to lower loads to ensure engine safety. As a result, further investigation including Exhaust Gas Recirculation (EGR) and/or variance in fuel Cetane Number (CN) is required to achieve PPCI in a high compression ratio CI engine.
Experimental Study of Hygroscopy of Single and Different Mixtures of MgCl2, KCl, NaCl, ZnCl2 for Application As Heat Transfer Fluids in CSP
Authors: Wang Xiaoxin , Hu Qichao , Kim Gil-Pyo , Xu Xiankun , Li Peiwen , Gervasio Dominic
Published: January 2019

Eutectic molten chloride salts by MgCl2, ZnCl2, KCl, and NaCl are considered as promising high temperature heat transfer and thermal storage fluid in concentrated solar power (CSP) systems. However, chloride salts MgCl2 and ZnCl2 are water affinity, so they can absorb water from surroundings easily. This will increase the corrosion of metals when the molten salts stay with metals at high temperatures. Our study also found that the presence of trace water in the solid salt caused vapor pressure of the molten salts increase. The current work presents studies about the kinetic processes of water absorption and removal from single and different mixture of NaCl, KCl, MgCl2 and ZnCl2 salts. The process of water uptake from ambient air and removal through heating are measured quantitatively. Water removal from molten salts through sparging with argon gas was employed as a further treatment method.
Experimental Investigation of Heat Transfer Enhancement Through Array Jet Impingement on Various Configurations of High Porosity Thin Metal Foams
Authors: Madhavan Srivatsan , Singh Prashant , Ekkad Srinath V.
Published: January 2019

High porosity metal foams are known for providing high heat transfer rates, as they provide significant increase in wetted surface area as well as highly tortuous flow paths to coolant flowing over fibers. Further, jet impingement is also known to offer high convective cooling, particularly on the footprints of the jets on the target to be cooled. Jet impingement, however, leads to large special gradients in heat transfer coefficient, leading to increased thermal stresses. In this study, we have tried to use high porosity thin metal foams subjected to array jet impingement, for a special crossflow scheme. One aim of using metal foams is to achieve cooling uniformity also, which is tough to achieve for impingement cooling. High porosity (92.65%) and high pore density (40 pores per inch, 3 mm thick) foams have been used as heat transfer enhancement agents. In order to reduce the pumping power requirements imposed by full metal foam design, we developed two striped metal foam configurations. For that, the jets were arranged in 3 × 6 array (x/d = 3.42, y/d = 2), such that the crossflow is dominantly sideways. This crossflow scheme allowed usage of thin stripes, where in one configuration we studied direct impingement onto stripes of metal foam and in the other, we studied impingement onto metal and crossflow interacted with metal foams. Steady state heat transfer experiments have been conducted for a jet plate configuration with varying jet-to-target plate distance z/d = 0.75, 2 and 4. The baseline case was jet impingement onto a smooth target surface. Jet diameter-based Reynolds number was varied between 3000 to 11000. Enhancement in heat transfer due to impingement onto thin metal foams has been evaluated against the enhancement in pumping power requirements. For a specific case of z/d = 0.75 with the base surface fully covered with metal foam, metal foams have enhanced heat transfer by 2.42 times for a concomitant pressure drop penalty of 1.67 times over the flow range tested.
Flexible Fiber Motion in Fiber-Reinforced Composite Material Processing
Authors: Zhang Diwei , Peng Xiaobo , Zhang Dongdong
Published: January 2019

Simulation of a single flexible fiber suspension solved using partitioned fluid structure interaction (FSI) strategy is presented in this paper. The study of fiber motion during injection modeling process in composite material manufacturing is the motivation of this research. Fluid field is solved by mixed finite element method (FEM). Stokes equation is used as governing equation due to low Reynolds number characteristics. Total Lagrangian (TL) incremental FEM is used for calculating flexible fiber translation, rotation and deformation. Bathe time integration method is used for solving fiber dynamics. The interaction between the fiber (solid) and fluid results from forces on the surface of fiber, which are extracted from fluid solver and are exerted on fiber, solved as the natural boundary condition. After solid solver running forward a certain time step, new positions and velocities of each node on fiber surface are obtained which can be used for updating fluid mesh domain and served as essential boundary condition of fluid field. The process continues until the motion and deformation of fiber are obtained. Example of rigid and flexible fiber motion in a simple shear flow and a Poiseuille flow are presented in this paper. The simulation of rigid fiber are very close to the result of Jeffery’s theory. Snake rotation can be observed when the flexible fiber was tested in Poiseuille flow.
Springback Analysis in Hybrid Material Deformation
Authors: Mamros Elizabeth M. , Nikhare Chetan P.
Published: January 2019

In the automotive and aerospace industries, cost and overall weight are major opponents that are affecting design opportunities. Research to investigate possible cost and weight reduction methods is continuously being performed focusing especially on the hybrid materials being used to manufacture parts. Currently, different types of metals with polymers are being chosen to make punched parts, but the deformation of the materials has not been fully investigated. The way that the material deforms will dictate the material properties held by the subsequent parts. Without knowing these material properties, it is difficult to prevent manufacturing problems during various processes. One major problem encountered when forming solid metal parts is that when the die is removed, the deformed parts change shape due to the elastic properties of the material. This shape change is called springback. This undesirable result causes the parts to be the incorrect shape and to not align correctly during assembly. One possible solution would be to investigate the material properties of trilayer hybrid materials consisting of metal and composite layers adjoined by adhesive. Trilayer channels will be tested by punching and measuring the resulting springback. Two different trilayer design setups will be tested, composite metal composite sandwich and metal composite metal sandwich, and will be compared with the deformation in a single layer metal channel. The outcome of these tests will determine which trilayer design will have the greatest success in reducing the undesirable springback effects.
Synthesizing Bidirectional Constant Torque Compliant Mechanisms Using Precompressed Beams
Authors: Thanaki Monik , Zhou Hong
Published: January 2019

A constant torque compliant mechanism has its output torque invariant in a large scope of input rotation. Different from conventional constant torque compliant mechanisms in which the input shaft can only rotate in one direction, the input shaft of a bidirectional constant torque compliant mechanism can rotate either clockwise or counter-clockwise. The direction of the output or resisting torque changes with the input rotation direction. A common problem in the current bidirectional constant torque compliant mechanisms is that they require a preloading range that is a certain starting range of the input rotation. Within the preloading range, the output torque does not have the desired torque, and it increases from zero to a value. The preloading range weakens the performance of bidirectional constant torque compliant mechanisms. In this paper, precompressed beams are used as building blocks for bidirectional constant torque compliant mechanisms to surmount the preloading problem. Bidirectional constant torque compliant mechanisms are synthesized through optimizing the design parameters of the composed precompressed beams. The introduced synthesis approach is demonstrated by synthesizing bidirectional constant torque compliant mechanisms that have different numbers of precompressed beams.
Linkage Synthesis for Solar Tracking
Authors: Jani Kavan , Zhou Hong , Leung Chung
Published: January 2019

Solar trackers orient solar panels toward the Sun to increase solar energy harvesting. To enhance solar energy capture, solar trackers change solar panels’ orientation throughout the day to follow the Sun’s path and make solar panels normal to the solar ray. The current solar trackers make solar panels perpendicular to the solar ray because of the active motion control of the solar panels. However, they also consume considerable power since the motion of solar panels is usually generated by two motors simultaneously and continuously. The merits of the existing sensor-based dual-axis solar trackers are compromised by their motor power consumption. In this research, the Sun’s location relative to an arbitrary point on Earth is determined at any time on any day in any year. Because of the determined solar location and path, only one axis is needed for the proposed solar tracker since it does not rely on any sensor to determine the Sun’s location. The current single-axis solar trackers face challenges on the limited oscillation range of the solar panels and the potential interference between an oscillating solar panel and its corresponding ground. In this paper, a sensor-free single-axis solar tracking linkage is designed to surmount these challenges. The solar tracking motion of the designed linkage is simulated. The designed linkage is fabricated and tested. The motion of the fabricated linkage is controlled by a microcontroller to generate the desired intermittent solar tracking motion.
Stochastic Modeling of a High Speed Composite Flywheel for Energy Storage
Authors: Riley Matthew E. , Pettingill Justin
Published: January 2019

This work will demonstrate the development and experimental validation of the stochastic models to predict the composite material’s mechanical and electromagnetic response as a function of the constituent reinforcing materials. First, stochastic micromechanics models will be developed for the case of multiple disparate supporting materials. These micromechanics models will then be validated against traditional finite element models and experimental results over the feasible parameter space. The developed models will then be utilized to define the optimal geometry of the composite flywheel including constraints such as displacement, stress, flux, magnetic field density, and manufacturability.
Dielectrophoretic Control of a Droplet at the Interface of Two Liquids in a Three Liquid System
Authors: Lokanathan Manoj , Wikramanayake Enakshi , Bahadur Vaibhav , Bonnecaze Roger
Published: January 2019

The influence of an electric field on a water droplet resting at the interface of two immiscible liquids is studied experimentally and theoretically. The droplet is initially in a state of equilibrium due to the balance between gravitational, buoyancy and capillary forces. Application of an electric field across the droplet-interface system disturbs the equilibrium. The electrical force increases the immersion angle of the droplet and eventually causes it to ‘sink’ when a critical immersion angle is reached.

Experiments are conducted with a deionized water droplet, resting at the interface of silicone oil and sunflower oil. Experiments involve the application of an electric field and image analysis to track the voltage dependent immersion angle. The objective is to determine the threshold voltage at which the droplet sinks. Experiments are complemented by an analytical model that balances gravity, buoyancy, capillary, and dielectrophoretic forces to predict the change in the position of the droplet and the immersion angle. Experiments and analysis were conducted for Bond numbers ranging from 0.1 to 1.7, the latter being the critical size at which a droplet will ‘sink’ due to its weight. The predicted immersion angles and threshold voltage show a good match to the experimental measurements. Overall, this work highlights the utility of electric fields to control interfacial phenomena at the interface of two immiscible liquids.
Understanding the Effect of Oxygenated Biofuels Addition on Combustion Characteristics of Gasoline
Authors: Roy Shrabanti , Zare Saeid , Askari Omid
Published: January 2019

The change in laminar burning speed and ignition delay time of iso-octane with the addition of oxygenated fuels are investigated. As oxygenated fuels, ethanol and 2,5 dimethyle furan (DMF) are used. To confirm the process and mechanism a detailed validation is done on laminar burning speed and ignition delay time. Further, three different blending ratios of 5%, 25% and 50% for both ethanol/iso-octane and DMF/iso-octane are investigated separately. Wide range of equivalence ratio from 0.6–1.4 is considered in calculating laminar burning speed. Ignition delay time is measured under various temperatures from 650 K to 1100 K. Results of each blending are compared with the pure fuels. A comparison is also done between the effects of these two oxygenates. It has found that for each blending case presence of DMF brings larger change in the behavior of iso-octane than ethanol. This observation refers to further study on comparison of these two oxygenates.
Heat Transfer Across Crystalline and Amorphous Silicon Surfaces in Contact With Water and the Effects of the Interfacial Liquid Structuring
Authors: Paniagua-Guerra Luis E. , Gonzalez-Valle C. Ulises , Ramos-Alvarado Bladimir
Published: January 2019

The understanding of nanoscale heat transfer across solid-liquid interfaces poses similar challenges as solid-solid interfaces; however, the higher mobility of liquid particles increases the complexity of this problem. It has been observed that liquid particles tend to form organized structures in the vicinity of solid surfaces; additionally, the formation of such structures has been reported to correlate with heat transfer across interfaces. Classical molecular dynamics simulations were used to investigate the behavior of liquid water in contact with crystalline and amorphous silicon. The in-plane and out-of-plane structure of interfacial water was characterized under different artificial wettability conditions, i.e., the silicon-water interaction potentials were calibrated to reproduce a wide range of wettability conditions. The change in the vibrational density of states was analyzed in order to quantify the mismatch between modes on both sides of the solid-liquid interfaces. Linear response theory was used to calculate the thermal boundary conductance at the different interfaces and a correlation was found between surface chemistry and heat transfer.
Anti-Corrosive Coating Using Recycled High Density Polyethylene for Automotive Chassis
Authors: Bachert Joshua , Rahman A. H. M. E. , Abu-Ayyad Ma'moun
Published: January 2019

Both high corrosion costs and an over-abundance of plastic waste have significant global impacts. This research seeks to help in both areas by utilizing recycled plastic as an anticorrosive coating. Many plastic-based coatings, especially those developed in more recent years, already contain recycled content. This research, which utilizes 100% recycled high density polyethylene (HDPE) as a powder coat, will add to the increasingly sustainable catalog of anti-corrosive coatings. The HDPE was applied to mild steel samples with traditional electrostatic powder coating equipment. The coating thickness was measured using scanning electron microscope (SEM) characterized and was found to be roughly 116 μm. The SEM analysis did not reveal any porosity in the coating. The immersion corrosion test in 5% H2SO4 for 2–3 days showed corrosion products at the bottom of the beaker. The maximum corrosion obtained was 424.4 mills/year (mpy) after 70.45 hours of immersion and the minimum corrosion obtained was 0.0 mpy after 5.58 hours of immersion. The acid immersion tests indicated that the corrosion started from the edges and advanced towards the inner surfaces. The coating on the edges was not uniform and may be porous. The salt immersion test in 5% NaCl solution by mass showed the sign of corrosion products after 5.5 hours and increased with time. A few samples showed corrosion over 25% of the surface after 70.5 hours of immersion. This is again attributed to the fact that the edges were not coated completely. The corrosion resistance can be improved by avoiding the sharp edges on the part.
An Easier Approach to Introduce Entropy in Undergraduate Thermodynamics Classes
Authors: Haseli Yousef
Published: January 2019

The common tutorial method of teaching entropy is far twisted and complicated. The convention is to first present Carnot corollaries followed by a “rational argument” to justify the corollaries. In the next step, the efficiency of Carnot engine is argued to be solely dependent on the thermal reservoirs temperatures. Then, thermodynamic temperature scale is introduced to show QL/QH equals TL/TH followed by the Clausius inequality, and finally introducing entropy S. It is not surprising why entropy has been one of the most difficult concepts to teach or learn. The way it is taught in textbooks is not straight unlike many other properties and concepts that are comparably much less cumbersome to understand. Interesting to note is that the inventor of entropy; Clausius, derived the famous Carnot efficiency by simply using the p-V diagram of a Carnot cycle operating with an ideal gas. The objective of this article is to shed light to the original method of Clausius and to present a simple and easy-to-digest approach, so students can better understand where entropy is originated from. Furthermore, we will show that the proof of Carnot corollaries is not concrete and certain objections can be raised.
Generation Mechanism of Interfacial Residual Stress and its Effect on Mechanical Properties of Hybrid Fiber-Reinforced Thermoplastic Polymer (HFRTP)
Authors: Cao Wan , Kang Ning , Sun Lingyu , Xiang Shanshu , Yang Xudong , Zhang Yiben
Published: January 2019

For automotive weight reduction, fiber-reinforced thermoplastic polymer (FRTP) is preferred due to its short curing time, good recycling and easy formability of complex parts. Hybrid fiber-reinforced thermoplastic polymer (HFRTP) can take the advantage of two processes (thermo-stamping and injection) and two materials (continuous FRTP and discontinuous FRTP) to form an integrated structure with both complex shape and excellent performance simultaneously. However, the unmatched thermodynamic properties between different materials would produce interfacial residual stress (IRS) as the temperature variation, which will cause the structure separate at the interface and structural warping. This paper would explain the generation mechanism of IRS between thermo-stamping zone of continuous FRTP and injection zone of discontinuous FRTP and investigate the effect of IRS generated during the process on the subsequent load-bearing capacity. The simulation results found that the generation mechanism is that the residual stress of over-molded injection is the superposition of shrinkage stress and thermal stress, which has a negative effect on the mechanical properties.
Brownian Dynamics Simulations of Aggregation Phenomena in a Magnetic Particle Suspension With an Alternating Magnetic Field (Relationship Between the Aggregate Structure and the Heat Production)
Authors: Suzuki Seiya , Satoh Akira , Futamura Muneo
Published: January 2019

The present study addresses physical phenomena of a suspension composed of magnetic spherical particles in an alternating magnetic field in order to elucidate particle aggregation phenomena and their influence on heat production. For this objective, we have performed Brownian dynamics simulations in a variety of circumstances of the magnetic field strength and frequency of an alternating magnetic field, and the magnetic dipole-dipole interaction strength. As in a time-independent uniform external magnetic field, large aggregates are formed in the case of strong magnetic particle-particle interactions. However, these clusters exhibit completely different behaviors that are dependent on the frequency of an alternating magnetic field. If the frequency is significantly high, then the viscous torque is the dominant factor, so that the formation of the clusters is not significantly influenced by the time-dependent magnetic field. If the frequency is significantly low, the magnetic field have a significant effect on the rotational motion of the particles, so that the formation of the cluster is dependent on which factor dominates the particle motion between the applied magnetic field and the magnetic particle-particle interaction. If the magnetic interaction is more dominant than the external field, stable chain-like clusters are formed in the field direction, and the magnetic particle-particle interaction induces a significant delay for the moments inclining in the alternating magnetic field direction. This behavior gives rise to a hysteresis loop with a larger area and therefore a large heating effect is obtained.
Monte Carlo Simulation of the Laser-Induced Temperature Dynamics in Very Thin Scattering and Absorbing Biological Layer Piles
Authors: Eze Reginald C.
Published: January 2019

Radiative-thermal models of light transport in tissue are presented that stimulates the thermal effects of pulsed laser radiation on very thin scattering and absorbing biological layers. Thermal therapies require a firm understanding of temperature-depth relationship for tissue modification or destruction, especially through very thin layers that are characterized by contrasting opto-thermal properties. Temperature distribution in biological layers of thicknesses in the order of their mean free path or less are evaluated before the onset of thermal diffusion for both the traditional model of Monte Carlo simulation and that with new features tailored for very thin layers. Temperature dynamics in very thin layers such as skin in dermatology is a typical example. For instance, during the heating of small volumes of tissue as in fractional photothermolysis, nonablative dermal remodeling and ablative skin resurfacing, short pulse lasers are used by choosing pulse length sufficiently short that will not damage the surrounding healthy tissue, but sufficiently long enough to allow damage, necrosis or coagulation over the entire target area. This is in contrast to the situation where thermal dissipation due to heat conduction is the principal determinant of tissue damage. Numerical results obtained from both models differ significantly. While the model designed specifically for very thin scattering layers tends to confine temperature rise to specific layers, the traditional model have a tendency to misjudge the layers of interest thereby giving rise to temperature increase in undesired locations. These results will advance our understanding of radiation transport in layers that are extremely very thin, and help develop better treatment modules for laser therapeutic treatment regimes in surgery and dermatology.
Thermohydraulic Effect of Aspect Ratio on Combination Angled Dimpled in a Rectangular Channel
Authors: Aasa Samson Abiodun , Jen Tien-Chien
Published: January 2019

Solar thermal panels’ heat enhancement through cooling techniques is important for the effective use of the panels. This study is performed on a simulated internal cooling channel of a solar thermal cell with an artificial technique using angled dimpled rough end-wall and exploring the combination of the different geometrical surface to enhance the heat transfer from the wall. Circular and oval shape dimples combination arranged in staggered form are tested. However, the oval geometrics are varied typical to flow direction. The following combinations of circular and oval dimpled are therefore examined (1) 90° circular by 90° oval dimples to the mainstream (2) 90° circular by 60° oval dimples to the mainstream (3), 90° oval by 90° circular dimples to the mainstream and (4) 60° oval by 90° circular to the mainstream. All of which are having pitch/depth ratio, P/δ of 6, dimple centre to centre, P, of 30 mm, and print diameter, D, of 20 mm (for both circular and oval shape), oval small diameter of 10 mm. These combinations are tested for three aspect ratios of 0.049, 0.035 and 0.0249. This study is conducted for a Reynolds number range of 1,000–11,000, and local and averaged heat transfer coefficient values are presented for all the geometries. Pressure drops are measured along the mainstream of the smooth and dimpled channel end-wall and friction factors are calculated. The combination of the 60° oval and 90° circular dimple surface exhibits the best performance of all the cases considered, a moderate pressure drop was also observed compared with others like a combination of pin fins, ribs-protrusions, grooves etc. These values were higher or comparable to the best-performing dimple geometries commonly used for the internal cooling process.
A Global-Local Strategy for the Elastoplastic Analysis of Complex Metallic Structures via Component-Wise Approach
Authors: Carrera Erasmo , Kaleel Ibrahim , Nagaraj Manish , Petrolo Marco
Published: January 2019

A global-local approach has been developed for the elasto-plastic analysis of thin-walled metal structures, which interfaces between commercial finite element software and advanced structural theories based on the Carrera Unified Formulation (CUF). The structure is modeled in CUF using the Component-Wise approach where Lagrange polynomials enhance the cross-section kinematics of the beam element. The von Mises constitutive model with isotropic work hardening is used to describe the material nonlinearity. Two types of the global-local approach have been discussed: (1) elastoplasticity is considered in both global and local analyses, and (2) a linear global analysis is followed by a nonlinear local analysis. It is shown that the second version maintains the accuracy of the solution for cases where the plastic zone is localized within the structure. The described approach results in a significant reduction in the computational size of the problem, compared to standard 3D finite element analysis.
Impact of the Chamber Shape on a Soft Actuator Mechanism to Mimic the Esophageal Swallowing Process
Authors: Caballero-Ruiz Alberto , Hernández-Angulo Juan A. , Ascanio Gasca Gabriel , Vega-Alvarado Leticia , Ruiz-Huerta Leopoldo , Brito-de la Fuente Edmundo
Published: January 2019

A physical prototype of a human esophagus has been developed for reproducing the human swallowing process with the aim of studying various disorders that impair its function as well as for the development of new foods and technologies for their treatment. Several studies related to the peristalsis phenomena have been conducted in recent years by studying the effect of different parameters defining the peristaltic wave. Mathematical models have been developed to investigate the impact of an integral and a non-integral number of waves during the swallowing of food stuff such as jelly, tomato puree, among others. Swallowing through the esophagus has not only been studied numerically but also reported by using a pneumatic soft actuators. In the present work, the development of a soft actuator mechanism to reproduce the peristaltic wave as the one reported by F.J. Chen et. al. 2014 is described. Such a mechanism consists of a rubber structure that contains an array of chambers actuated by pressurized air to generate the peristaltic wave. The final chamber shape was determined after an iterative process, which involves the elastomer properties, different chamber shapes, finite element analysis and image processing. The characterization of the developed peristaltic mechanism was made by correlating a theoretical study of swallowing peristaltic model and the waveform obtained from the X-ray radiography analysis as the mechanism is actuated. As result, the soft actuator mechanism can reproduce a peristaltic waveform with a correlation coefficient near to 0.9 with respect to the mathematical model reported in literature. In addition, the manufacturing process based on additive manufacturing technologies is also presented.
Development of a Passive Prosthetic Ankle With Slope Adapting Capabilities
Authors: Bhat Sandesh G. , Redkar Sangram , Sugar Thomas G.
Published: January 2019

In this work, the authors first study different designs of prosthetic ankles. Then, a new design is proposed, and its dynamics are discussed. Various experiments are conducted to verify the concept. The results of the experiments are discussed, and a conclusion is drawn based on the discussion. An OpenSim simulation is run to emulate the effects of the prosthesis on an amputee’s residual leg. Further iterations of the same design are then discussed and presented. Finally, a conclusion is drawn on the usability of the ankle along with some suggestions for future research.