bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of Viscous Fingering in Microchannels With Hybrid-Patterned Surface Using Lattice Boltzmann Method
Authors: Tursynkhan Margulan , Dauyeshova Bagdagul , Adair Desmond , Monaco Ernesto , Rojas-Solórzano Luis
Published: January 2020

In recent years, a large effort has been devoted to the study of the viscous fingering phenomenon in microchannel flows. This phenomenon plays a crucial role in many fields of industry and occurs in geological sequestration of carbon dioxide (CO2), in the secondary and tertiary oil recovery stages. Viscous fingering, also known as the Saffman-Taylor instability, occurs at the unstable interface between two fluids when the less viscous fluid displaces the more viscous fluid which is originally residing in a porous medium. This paper studies viscous fingering occurring between two segregated immiscible fluids, such that the less viscous one is forced into a microchannel where the more viscous fluid initially resides. The 2D microchannel walls are present with a hybrid-patterned configuration such that the top wall is smooth, and the bottom wall is ribbed. The multiphase Shan-Chen Lattice Boltzmann Method (SC LBM) is implemented to capture the complex interfacial phenomenon since this method has proven to accurately describe multiphase interfacial entangling. The LBM is based on the discretization of micro- and mesoscopic kinetic equations and the SC LBM simulation allows us to study the viscous fingering phenomenon in terms of non-dimensional quantities, including capillary number and viscosity ratio. The effect of hybrid-patterned rough walls on fingering formation in a 2D microchannel is investigated and compared to the phenomenon when plain smooth walls are in place. The numerical results show that the SC Lattice Boltzmann multicomponent model provides insightful characteristics associated to the physical nature of the fingering phenomenon in microchannels and the role of adjacent walls.
A Novel Framework of Lightweight Optimization Design of a Prototype Wafer Stage With Control Verification
Authors: Li Yujie , Zhang Ming , Zhu Yu , Li Xin , Wang Leijie
Published: January 2020

Performance requirements of a higher throughput and accuracy in precision motion systems, such as wafer stage used in integrated circuit manufacturing, are ever increasing. The lightweight design, as one of the design methods, can results in less power consumption and less negative environmental impacts for the required high levels of acceleration. The aim of this research is to investigate the advantage of the lightweight design and to mitigate the negative effect caused by the flexible characteristics using an appropriate control method. In this paper, a prototype wafer stage is the analysis object. Since the mass of the horizontal drive motors accounts for a large proportion of the total mass of the wafer stage, a novel lightweight optimization frame based on the minimum motor mass is presented, while a Lorenz motor model based on finite element method (FEM) and artificial neural network (ANN) is firstly constructed. Then the controller adopting the PID with the maximum control bandwidth and pole placement method are designed. Through numerical analysis, the mass of the mover of the mover of this stage is reduced from 10.28 Kg to 6.078 Kg after lightweight optimization. Taking the Moving Average (MA) and Moving Standard Deviation (MSD) of the servo error in Z-direction as the control index, a closed-loop simulation result shows that the lightweight wafer stage can separately fulfil the requirement of the MA and MSD of the servo error in z-direction within 20nm and 30nm just as the current rigid-body wafer stage without the lightweight optimization.
Shape Memory Metamaterials With Adaptive Bandgaps for Ultra-Wide Frequency Spectrum Vibration Control
Authors: Song Yihao , Shen Yanfeng
Published: January 2020

This paper presents a novel shape memory metamaterial, which can achieve adaptively tunable bandgaps for ultra-wide frequency spectrum vibration control. The microstructure is composed of a Shape Memory Alloy (SMA) wire and a metallic spring combined together with bakelite blocks, loaded by a lumped mass made of lead. The adaptive bandgap mechanism is achieved via the large deformation of the metamaterial unit cell structure during the heating and cooling cycle. By applying different heating temperature on the SMA wire, morphing microstructural shapes can be achieved. Parametric design is conducted by adjusting the lead block mass. Finally, an optimized microstructural design rendering a large deformation is chosen. Finite element models (FEMs) are constructed to analyze the dynamic behavior of the metamaterial system. Effective mass density of the unit cell is calculated to investigate and demonstrate the bandgap tuning phenomenon. In the simulation, two extreme shapes are simulated adhering to the experimental observations. The effective negative mass density and the moving trends are obtained, representing the development and shifting of the bandgaps. The width of the bandgap region covers about 50 Hz from the room-temperature state to the heating state. This enables the vibration suppression within this wide frequency region. Subsequently, a metamaterial chain containing ten unit cells is modeled, aligned on an aluminum cantilever beam. An external normal force with a sweeping frequency is applied on the beam near the fixed end. Harmonic analysis is performed to further explore the frequency response of the mechanical system. The modeling results from modal analysis, effective mass density extraction, and harmonic analysis agree well with each other, demonstrating the prowess of the proposed shape memory metamaterial for ultra-wide frequency spectrum control.
Computational Analysis of Combat Helmet Protection Against Blunt Impact to Head
Authors: Tan X. Gary , Bagchi Amit
Published: January 2020

Computational modeling provides significant benefits in assessing the helmet performance and identifying promising helmet designs. We develop multi-fidelity computational tools, representative virtual human head and helmet system models to help the design of next generation combat helmet with improved protection against blunt impact. By integrating the fast-running articulated human with personal protective equipment (PPE) biodynamics model with the high-fidelity human head with combat helmet finite element (FE) model, the multi-fidelity approach can be used to efficiently investigate impact-related traumatic brain injury (TBI) in the real-world scenario. The FE model is used to capture the dynamics of the composite helmet shell, foam pad suspension, retention strap and head while the biodynamics model provides the proper kinematics and boundary conditions for the FE model. An orthotropic elasto-plastic material with damage model is employed for the helmet shell. Enhanced tetrahedral elements are used to model the nearly-incompressible tissues. The head with helmet and without helmet under a severe impact due to a fall caused by blast loading are simulated and compared. The resulting biomechanical responses of head acceleration, shear stresses and strains in brain and mechanical injury criterion as well as helmet energy absorption are used to characterize the performance of helmet system.
Dynamic Parameters and Friction Model Identification of an Industrial Hybrid Robot
Authors: Zhang Binbin , Wang Liping , Wu Jun
Published: January 2020

To obtain higher performance for an industrial hybrid robot, the dynamic control method is utilized to control the robot. For dynamic control, the control performance is directly affected by the accuracy of the dynamic model. This paper investigated a method to establish and identify an accurate dynamic model. First, based on the Lagrangian dynamic equation and the Stribeck friction model, the unidentified dynamic model of the five-DOF hybrid robot is established. Second, identification experiments are carried out. Each of the driving joints performs frequent reciprocating motions individually. In the meantime, the moving speed is gradually increased to obtain driving torques of the respective joint at different moving speeds. Then the dynamic parameters with lower coupling are identified by using the standard deviation index and the least squares methods until all parameters are gradually determined. Finally, the hybrid robot moves a typical trajectory, while the currents of each joint are collected to obtain the driving forces. The actual driving forces, the identified dynamic model, and the unidentified dynamic model are compared. The results show that the identified method could significantly improve the accuracy of the dynamic model. The method proposed in this paper is general and can be applied to the other robots without adding any sensors.
Experimental Investigation of Combustion Behavior of Biodiesel-Water Emulsion
Authors: Singh Gurjap , Hentges Nicholas , Johnson Damion , Ratner Albert
Published: January 2020

Biodiesel has proved to be an attractive alternative fuel for the compression-ignition engine, with its blends of regular petrodiesel being sold at virtually every gas station in the United States. Researchers have explored many of its combustion properties and sought to modify them in the interest of better fuel economy, specific fuel combustion, and lower emissions. The emulsification of biodiesel with water in order to promote microexplosions during the combustion process is one such fuel modification method. Microexplosions fragment the fuel droplet into many smaller droplets, which promote homogeneous combustion, and can result in smoother power output and better fuel economy. Present research analyzes the droplet combustion properties of soy biodiesel with 10% water and 0.1% POLYOX™ polymer. A sub-millimeter droplet is suspended on three 16μm silicon carbide wires and ignited using hot wire loops. The combustion process is recorded at 1000 frames/second by a high-speed CCD camera. Combustion behavior of the emulsified fuel is then analyzed by post-processing the resulting high-speed images. Results show several microexplosion events. Combustion trends are plotted, and combustion rates are determined. Burning rate for the emulsion was found to be very close to that of base fuel, with 2.1% decrease noted. It is hoped that present research will spark further interest in the fuel behavior modification of biodiesel.
An Analytical Study of BMI Effects on Obese Senior Females in Vehicle Frontal Impact
Authors: Xu Huijie , Zhan Zhenfei , Yin Yunlei , Dong Wenxiang , Wang Qingmiao , Chen Ruyi , Jin Xin
Published: January 2020

Prior works showed that elderly females are a vulnerable segment of the population that needs special attention for their safety in traffic accidents. To study the injury performance of this vulnerable group in motor vehicle crashes (MVCs), a finite element model was developed to represent the full body of 70-year-old regular sized female. However, this model did not take the variations in size and shape among this group of people into account. In this study, an adaptive radial basis functions (RBF) methodology is developed to rapidly morph the baseline model to the target models defined by the statistical models of external body surface and the exterior ribcage. High speed frontal crash simulations are subsequently performed to investigate the effects of BMI on impact injuries. The results show that obese senior female occupants sustained higher risks of thorax, femur and head injuries than that of regular sized occupants. While BMI has no linear effect on head and thorax injury.
Design and Evaluation of a Blood-Contacting Medical Device for Improving Functionality and Durability of Vascular Anastomosis
Authors: Singh Gurjap , Esmaeilpour Mehdi , Bhama Jay K. , Ratner Albert
Published: January 2020

An example of vascular anastomosis is coronary artery bypass grafting (or CABG), which is the most common open-heart surgery in the United States today. It is used to treat people with coronary heart disease. Although it generally produces good outcomes, it is not without risk of failure. Due to rotation-related fluid stress on the graft at the point of attachment, possibility of clots forming at extraction and perfusion sites is high. The possibility of endothelialization at the suture joints carries a further risk of flow obstruction. Present research proposes a new blood contacting medical device that is attached to both ends of a vascular graft, and aids in flow rotation at the points of blood extraction and perfusion, thereby alleviating the possibility of clotting at those sites. It also shifts the suture lines such that the endothelialization causes minimal flow obstruction compared to current techniques. Simplified 3D models of both the current grafting technique and the proposed device are evaluated with periodic rectified sine pulse acting as a surrogate for human blood pulse. For both perfusion and extraction, better outcomes were observed for vascular anastomosis with the proposed blood contacting medical device.
MoVE: A Mobility Virtual Environment for Autonomous Vehicle Testing
Authors: Compere Marc , Holden Garrett , Legon Otto , Martinez Cruz Roberto
Published: January 2020

Autonomous vehicle researchers need a common framework in which to test autonomous vehicles and algorithms along a realism spectrum from simulation-only to real vehicles and real people. The community needs an open-source, publicly available framework, with source code, in which to develop, simulate, execute, and post-process multi-vehicle tests. This paper presents a Mobility Virtual Environment (MoVE) for testing autonomous system algorithms, vehicles, and their interactions with real and simulated vehicles and pedestrians. The result is a network-centric framework designed to represent multiple real and multiple virtual vehicles interacting and possibly communicating with each other in a common coordinate frame with a common timestamp.

This paper presents a literature review of comparable autonomous vehicle softwares, presents MoVE concepts and architecture, and presents three experimental tests with multiple virtual and real vehicles, with real pedestrians. The first scenario is a traffic wave simulation using a real lead vehicle and 3 real follower vehicles. The second scenario is a medical evacuation scenario with 2 real pedestrians and 1 real vehicles. Real pedestrians are represented using live-GPS-followers streaming GPS position from mobile phones over the cellular network. Time-history and spatial plots of real and virtual vehicles are presented with vehicle-to-vehicle distance calculations indicating where and when potential collisions were detected and avoided. The third scenario highlights the avoid() behavior successfully avoiding other virtual vehicles and 1 real pedestrian in a small outdoor area. The MoVE set of concepts and interfaces are implemented as open-source software available for use and customization within the autonomous vehicle community. MoVE is freely available under the GPLv3 open-source license at gitlab.com/comperem/move.
An Improved Predictive Model for Effective Thermal Conductivity of Polymer Composites With Non-Dilute Filler Concentrations
Authors: Raza Kabeer , Akhtar Syed Sohail , Arif Abul Fazal M. , Hakeem Abbas Saeed
Published: January 2020

Most of the predictive models for thermal conductivity of composites are derived based on the assumption that the filler concentration in the matrix is dilute. This assumption leads to inaccurate predictions when filler concentration is essentially non-dilute and hence there is a need to propose a model that could handle a non-dilute filler concentration. In this work an improved and realistic model for effective thermal conductivity of polymer matrix composites with non-dilute filler’s concentrations is derived and validated by experiments. The proposed model can handle fillers with variable size and shapes. The derivation is based on the Bruggeman’s differential effective medium theory where the high volume fractions can be obtained by incrementally adding ‘small volume fractions’ into the ‘existing composite’ at each stage. The proposed model is validated by experimentally produced different series of ceramic particles-polymer composites. Differently sized and shaped alumina (Al2O3) & aluminum nitride (AlN) particulate fillers, and high density polyethylene (HDPE) & polypropylene (PP) matrices were used as the variable ingredients. Using different combinations of filler, matrix and particle size six different series of composites were produced with variable filler concentrations up to 50% by volume. The microstructure of the produced samples was studied by field emission scanning electron microscope to relate the morphology with the predictions. The predictions of proposed model are found in close agreement with the measured thermal conductivities. To understand the detailed effects of different parameters, parametric studies are presented and discussed. It is found that aspect ratio of particulate fillers is the most sensitive parameter to enhance effective thermal conductivity. Overall, the proposed model is proven to be useful in composite material design for heat transfer applications. It is expected that the proposed model will open new doors for the researchers and polymer composite industry to develop new composite designs for achieving ultrahigh thermal conductivities.
Reviewing Machinability of Fibre-Reinforced Polymer (FRP)/Metallic Stacks Using MQL
Authors: Ghoshal Abhishek , Khan Adnan , Zahid Moosa , Pervaiz Salman , Kannan Sathish
Published: January 2020

Minimum quantity lubrication (MQL) assisted techniques are gaining popularity because of their lower environmental impact and cost effectiveness. Fibre reinforced polymers (FRP) are mainly utilized in the aerospace and automotive sectors, because of their high strength-to-weight ratio, low coefficient of thermal expansion, high corrosion resistance, high modulus to weight ratio and improved tensile strength. Besides that, they are extremely light weight and suitable for structural applications. For fibre reinforced polymers (FRP) composites, all of these properties in combination provide superior functional performance. In a wide range of applications dissimilar material stack-ups of composites and aluminum and/or titanium are used for wing or tail plane structures. Mostly these fibre reinforced polymers (FRP) composites are drilled to provide options for their assembly with other components. However, machining of these fibre reinforced polymers (FRP) composites is very hectic task. It is due to their high abrasive nature and high heat resistance. In this paper, the machinability of fibre reinforced polymers (FRP) composites was explored and reviewed when machined using minimum quantity lubrication (MQL). The study was conducted by systematic selection of experimental and numerical studies from the latest published literature in state of the art. The study reviewed the effects of different parameters on the tool wear, thrust force, work-piece hole diameter, burr height and chip formation. The study provides critical insights about the potential and understanding of machining fibre reinforced polymers (FRP) composites under minimum quantity lubrication (MQL) assisted methods.
Estimates of Area, Output and Levelized Energy Cost of Solar Energy Schemes in Saudi Arabia
Authors: Alabdulkarem Abdullah , Abdulghani Mohannad
Published: January 2020

Saudi Arabia consumes a significant amount of oil domestically for transportation and energy generation purposes. The booming population and high power consumption contribute to a sharp increase in power demands. The Saudi electric utility is investing heavily in upgrading the power grid and generation infrastructure to keep up with surging consumption. The desert belt in Saudi Arabia is exposed to substantial levels of solar irradiance, which renders Saudi Arabia a good candidate for large scale solar energy schemes. Upper and lower limits of cost and energy output are to be estimated for such ambitious endeavors to enter the national and international conversations. In this work, an attempt was made to estimate the area of photovoltaic panels and levelized energy cost required for generating the peak load and baseload power demands of the entire country and contrast them against the subsidized and unsubsidized cost of electricity in the kingdom. The levelized energy cost was found to be higher than the unsubsidized cost of electricity in the kingdom. The area required for both schemes was not found to be a limiting factor when compared to the available land area.
Effect of Motion Type on Joint Contact Forces
Authors: Schmitz Anne , Norberg Jaclyn
Published: January 2020

Race walking has grown over the past decade because it provides exercise without the high impact loads of running. In fact, race walking has been shown to result in decreased ground reaction forces. We predict these lower ground reaction forces will extend to knee joint loading as well, thus explaining the decrease rate of knee osteoarthritis in race walkers compared to runners. This is a secondary analysis of instrumented motion capture data collected from fifteen competitive race walkers as they ran and race walked over a force plate. A Visual3D to OpenSim pipeline was used to create muscle actuated forward dynamics simulations of race walking and running. The resulting muscle forces were subsequently used to actuate a discrete element knee model to calculate joint forces. The peak tibiofemoral joint contact load during race walking was 18% lower than the load during running. This load was distributed between the medial and lateral compartments such that the medial load was 27% lower and the lateral load 35% lower in race walking. This suggests race walking is a lower impact exercise safer for the joints. This may be advantageous for people who would like to exercise at a higher intensity that walking provides but have joint problems, e.g. those with osteoarthritis.
Univariate and Multivariate Gauge Repeatability and Reproducibility Analysis on the High Frequency Dynamic Mechanical Analysis (DMA) Measurement System
Authors: Esmaeeli Roja , Aliniagerdroudbari Haniph , Hashemi Seyed Reza , Al-Shammari Hammad , Alhadri Muapper , Farhad Siamak
Published: January 2020

The quality of the collected data from a measurement system affects eventual decision making process. Therefore, the reliability of any measurement system is an important factor to be studied. Gauge repeatability and reproducibility (Gauge R&R) is the standard method to evaluate the measurement system and assess the adequacy of variation in the measurement data. Gauge R&R is a statistical tool which evaluates two main characteristics of the measurement system: repeatability and reproducibility. The Dynamic Mechanical Analysis (DMA) is a common measurement system for studying the dynamic mechanical properties of viscoelastic materials such as polymers. The newly developed High Frequency Dynamic Mechanical Analysis (HFDMA) is able to directly run the simple shear test at high frequencies without changing the specimen temperature. The complex shear modulus and damping factor of the viscoelastic materials are reported by the HFDMA system. In this study the uni-variable Gauge R&R study based on Analysis of Variance (ANOVA) is done on each measured characteristic of the HFDMA measurement system. The source of variations for each characteristic is distinguished. Then the multivariate Gauge R&R based on the Multivariate Analysis of Variance (MANOVA) is done and the percentage of multivariate Gauge R&R for the measurement with the multiple variables is reported. The results indicate that the HFDMA measurements are both repeatable and reproducible. Thus, the new HFDMA can be used as a measurement system to measure the mechanical properties of viscoelastic materials at high frequencies.
Flame Stability in Inverse Coaxial Injector Using Repetitive Nanosecond Pulsed Plasma
Authors: Zare Saeid , Lo Hao Wei , Roy Shrabanti , Askari Omid
Published: January 2020

There has been recently a growing interest in the use of methane as a strong candidate for both interplanetary and descent/ascent propulsion solutions. The higher boiling point and higher density of methane compared with hydrogen, makes its storage tank lighter, cheaper and smaller to launch. Methane is abundant in the outer solar system and can be harvested on Mars, Titan, Jupiter, and many other planets and therefore, it can be used in reusable rocket engines. However, there are still some technological challenges in methane engines development path. Among those challenges, ignition reliability and flame stability are of great importance. These challenges can be addressed by integrating low-temperature plasma (LTP) through repetitive nanosecond pulsed (RNP) discharge to the injector design. This research work focuses on Air/CH4 jet flames in a single-element coaxial shear injector coupled with RNP plasma discharge to study the influence of LTP on ignition characteristics and flame stability using advanced diagnostic techniques. The experiments have been performed for different fuel composition, jet velocities, discharge voltages and frequencies at atmospheric conditions. The transient flame behavior including flame oscillation is studied using direct photography by CMOS high-speed camera. The effect of plasma discharge location on flame stability is also investigated. To demonstrate the effectiveness of RNP discharge on liftoff and blowout/blowoff velocities, the jet velocity at the critical conditions is measured in terms of discharge frequencies and the enhancement of flame stability is then evaluated. The collected experimental data have shown that the RNP discharge can significantly extend the flame stability by reducing the liftoff height and increasing the velocity at which blowout/blowoff occurs.
Detailed Chemical Mechanism Generation for Combustion of Ethanol-Air Mixture
Authors: Roy Shrabanti , Hadi Fatemeh , Askari Omid
Published: January 2020

Significance of ethanol as an alternative source of renewable energy is increasing every day. In this study a chemical mechanism has been developed to predict the characteristic of ethanol oxidation in a wide range of temperature and pressure of 300–2500 K and 1–50 atm, respectively. The mechanism is generated using reaction mechanism generator (RMG). Sensitivity analysis on the mechanism is done to find the reactions responsible in the deviation of numerical results with experimental data. Rate coefficient of important reactions is corrected with well-accepted data from literature which helps to improve the mechanism against experiment. The validation is done with laminar burning speed and ignition delay time results at various operating conditions. The results show a reasonable agreement in both high pressure and low temperature cases. A good prediction of major species concentration is found in flame structure measurement. A comparison of the current mechanism with other available chemical mechanisms is also presented at different operating conditions. Compared to other mechanisms, this improved mechanism has an advantage of handling the high pressure and low temperature operating conditions within a reasonable time and accuracy.
Leidenfrost Phenomenon and its Impact on Sessile Drop Evaporation for Different Liquids and Surfaces
Authors: Ahmed Pranzal , Amin M. Ruhul , Ali Mohammad
Published: January 2020

Recent study of the applications of the Leidenfrost effect has sparked renewed interest in this phenomenon. Due to Leidenfrost effect, a droplet can be levitated by its own vapor layer on a sufficiently heated surface. In this work an experimental investigation has been performed to determine the Leidenfrost point (LFP) of different liquids on different surfaces. Copper, aluminum and brass plates were used with water, methanol, and ethanol as different liquids to study the variation of LFP. The experiment was conducted with incident droplets of water, methanol, and ethanol on the three different metal blocks which were heated by cartridge heaters. The input powers in the heaters were varied by a voltage variac. At each temperature, droplet evaporation time was recorded where the highest evaporation time corresponded with the LFP. For the ranges of parameters considered in this study, the Leidenfrost temperature for water varied from 180°C to 200°C. For organic fluids like methanol it varied from 160°C to 200°C while for ethanol it varied from 160°C to 200°C. These findings are important because accurate modeling of Leidenfrost phenomenon is crucial for the design of many cooling devices. If a vapor layer is present between the liquid and the surface to be cooled, then the cooling becomes inefficient. This is especially important for the rapid cooling of overheated components in high power density systems, such as nuclear reactors and other devices.
Design of Metacarpophalangeal Single-Piece Joint Prosthesis to Increase Motion in Abduction/Adduction
Authors: Millard Nathan , Yee Raymond K.
Published: January 2020

One of the leading causes of disability is rheumatoid arthritis (RA), especially that of the hand, the metacarpophalangeal (MCP) joint being affected the most. Current single piece prostheses are designed to allow for motion in flexion and extension, but little effort is put towards motion in abduction and adduction. The objective of this study is to determine the effects of web (hinge) joint cross-sectional geometry on stress, strain, shear strain, strain energy, and reaction moment magnitude for an MCP joint that is subject to not only flexion and extension but also abduction and adduction. Using finger bone dimensions from the literature, geometry was produced in ANSYS finite element software. The geometry was assigned a hyperelastic material constitutive model, making the analysis nonlinear. The cross-sectional shape of the hinge was controlled by ellipse dimensions, one for thickness and one for width. Motion boundary conditions were applied to the distal portion of the model resulting in bending at the hinge. The study showed that for flexion/extension motion the von Mises (equivalent) stress, shear strain, and equivalent strain are linearly proportional to the thickness but inversely proportional to the width. The reaction moment and strain energy are linearly proportional to the thickness but exponentially proportional to the width. For motion in abduction and adduction the behavior is opposite; the width acting as the thickness does in flexion/extension motion and the thickness acting as the width does in flexion/extension motion. It was also seen that high levels of shear strain develop on the palmer side of the model, indicating that failure has the most potential to occur in that area.
The Mechanical Response of a Cantilever Beam With an Embedded Crack With Non-Linear Crack Surface Closure Effects
Authors: Fang Xiaomin , Charalambides Panos G.
Published: January 2020

This study addresses the crack surfaces closure effects of a cracked cantilever beam subjected to transverse force applied at its free end under static loading. A crack closure method is developed as needed to account for crack surface contact in regions wherein the linear solutions predict physically inadmissible crack surface inter penetration. An efficient finite element algorithm is developed accordingly to solve the static problem of the beam containing a fully embedded sharp crack in a linear, elastic, homogeneous and isotropic system. Emphasis is placed on the comparison between the near-tip fracture characteristics estimates, e.g. the normalized energy release rate, Mode I and Mode II stress intensity factors (SIF), and mode mixity, with closure effects and those without closure effects reported elsewhere. The crack length, orientation, and crack center location appear as the studied model parameters of a beam of fixed beam aspect ratio. In addition, based on the study observations of pure Mode II crack, a case study on the beam with an embedded vertical crack in the compressive regime is reported to show the deformed profiles due to full crack surfaces closure during loading. The curvature profile of the cracked beam with and without closure effects are compared to those of the healthy beam for the application of closure effects in improving the results accuracy.
Thermal Transport in Actinide Oxide Fuels With Interstitial Defects
Authors: Mitchell Katherine , Horner Hunter , Resnick Alex , Park Jungkyu , Farfán Eduardo B. , Yee Tien , Hummel Andrew
Published: January 2020

Molecular displacement occurs in the oxide fuels of nuclear reactors during operation. This causes several types of point defects to be generated inside the oxide nuclear fuels. To improve the safety and efficiency of nuclear reactor operation, it is necessary to better understand the effects of point defects on the properties of the oxide fuels. In this study, we examine the effects of interstitial defects on thermal transport in two representative actinide oxides used in modern reactors (UO2, and PuO2). Reverse non-equilibrium molecular dynamics (RNEMD) is employed to approximate the thermal conductivities for the aforementioned fuels at several sample lengths and at defect concentrations of 0.1%, 1%, and 5%. The results show that alterations to the lattice structures of these fuels reduce their thermal conductivities significantly. For example, oxygen interstitial defects at concentrations even as low as 0.1% decreased thermal conductivity by 20% at 100 units for each fuel.
Investigation of Surface Characteristics and Chip Morphology in High Speed Cutting of Inconel718 Based on SHPB System
Authors: Wang Zengqiang , Zhang Zhanfei , Wang Wenhu , Jiang Ruisong , Lin Kunyang , Xue Hongliang , Guo Biao
Published: January 2020

High speed cutting (HSC) technology has the characteristics of high material removal rates and high machining precision. In order to study the relationships between chip morphology and machining surface characteristic in high speed cutting of superalloy Inconel718. High-speed orthogonal cutting experiment are carried out by used a high speed cutting device based on split Hopkinson pressure bar (SHPB). The specimen surfaces and collected chips were then detected with optical microscope, scanning electron microscope and three-dimensional surface profile measuring instrument. The results show that within the experimental parameters (cutting speed from 8–16m/s, depth of cut 0.1–0.5mm), the obtained chips are sawtooth chips and periodic micro-ripple appear on the machined surface. With the cutting speed increases, machining surface roughness is decreases from 1.4 to 0.99μm, and the amplitude of periodic ripples also decreases. With the cutting depth increases, the machining surface roughness increases from 0.96 to 5.12μm and surface topography becomes worse. With the increase of cutting speed and depth of cut, the chips are transform from continues sawtooth to sawtooth fragment. By comparing the frequency of surface ripples and sawtooth chips, it is found that they are highly consistent.
Characterization of GRE Pipes Fatigue Failure Subjected to HTHP Loading Conditions
Authors: Abdo Jamil , Hassan Edris , Kwak Jan
Published: January 2020

GRE composite pipes are a great substitute for Carbon steel, however, obstacles of introducing GRE composite pipes into oil and gas transmission lines have been primarily related to inadequate testing data to maintain materials’ extended performance and pipes fatigue failure characterization. Customized testing facility has been designed and fabricated to substantiate design of GRE pipes under controlled service conditions. The testing procedure was conducted based on ASTM and ISO Standards. Pipes filled with crude oil were placed in a thermal and pressure enclosure at a temperature of 65°C and an internal pressure of 130 bars for 1000 hours and fatigue failure behavior of the GRE pipes were investigated. Pipes with a surface crack a/t = 0.5 and 0.3 were exposed to alternating internal pressure of 25 cycles/min and a load ratio of R = 0.05. Fatigue tests were performed at two load levels: 50%, and 30% of the pipes strength under static internal pressure.

Results show that the GRE pipes burst suddenly without any leakage when the internal pressure was high, however, the pipe exhibit leakage first and then fails when the internal pressure was low. The maximum fatigue life obtain for GRE reference and HTHP specimen pipes in the crack region were 72,237 cycles and 73,107 cycles, respectively, with applied 0.5 static internal pressure (102 MPa) and a/t = 0.3 ratio. The minimum fatigue life obtained in the crack region are 14,105 cycles and 13,627 cycles for GRE reference and HTHP specimen pipes, respectively, with applied 0.5 static internal pressure (170 MPa) for a/t = 0.3 ratio.
Research on Flywheel Battery With Flux Switching Permanent Magnet Motor and its Application on Servo Press
Authors: Liu Chen , Zhao Shengdun , Dong Peng , Zhang Peng
Published: January 2020

Servo press is a manufacturing machine that usually works under impact loads. Flywheel battery is an energy storage device that has been widely studied in recent years. In this paper, a flywheel battery system for servo press energy compensation was put forward. In considering the efficiency and structure robustness, the flux switching permanent magnet (FSPM) motor is appropriate for flywheel battery as energy conversion device. In this study, the flywheel battery structure and working principle were first described. Then the motor characters were analyzed by FEM. After that, a simply initiative power control strategy was introduced for the flywheel battery. Finally, the prototype of flywheel battery with FSPM motor was made and connected to a servo press’s motor driver. The experiments were taken with and without the flywheel battery respectively. The experiment results proved that the flywheel battery could compensate a certain of DC link voltage loss during the press stamping process. That makes the servo press’s driven motor has a more stable power source and reduces the electrical shock to other equipment. In conclusion, the flywheel battery with FSPM motor is an effective energy storage system for servo press. It is believed that with the miniaturization and simplification of flywheel battery, the flywheel battery will be more general in impact load devices.
Effects of Gravity Level on Morphology of Laminar Double Flames
Authors: Chen Tao , Liu Yu Cheng
Published: January 2020

Laminar double flames exist in many combustion configurations involving non-premixed or partially-premixed combustion processes. These flames can exhibit a “double-branched” structure due to local mixing in a non-premixed fuel and oxidizer flows. The dynamics and morphology of double flames in a convective flow could be significantly influenced by buoyancy driven convection such that various strengths of gravitational field may lead to complete different flame behaviors.

In this work, double flames generated at the flow nozzle of a slot burner were investigated using the open source software, OpenFOAM®. A two-dimensional simulation was used to replicate the geometric feature of a slot-burner flame. Conditions of interests include five different gravity levels with and without radiative heat transfer. Through analyzing the spatial distribution of velocity, temperature, heat release rate and species, the difference of double flames at different gravity levels were studied. The results show that higher gravity levels appear to entrain the cool surrounding fluid through buoyancy effects, which is indicated through obvious negative x-velocity region. The heat release rate and OH radical information are used to explain intrinsic behaviors of diffusion flame and premixed fuel-rich branches.
Design of a Composite Mountain Bike Hydraulic Disc Brake
Authors: Rahman AHM E. , Pugh David
Published: January 2020

The primary goal of the project is to design a hydraulic disk brake system for mountain bikes made from reinforced plastics. Hydraulic brakes offer significantly better performance for a mountain bike over traditional cable rim break or cable disk break. Nevertheless, people are unable to appreciate advantage because of the price. The traditional hydraulic disk brake systems are made of aluminum alloy. With a proper design, it may be possible to create a lever assembly and a caliper that would be competitive on price and weight. Often bike parts are judged by how much they weight, the less they weight, the more they are desirable. This is only true to a certain extent because lighter parts come with a premium price tag. The current project proposed that the injection molded brakes would be lighter because of the material being used and cost-effective because the manufacturing process can be utilized. Commercial reinforced plastic composites have been identified as lighter materials compared to aluminum alloy. Through an iterative design process, the final designs of lever assembly and caliper have been achieved. The stopping force has been determined considering the abrupt stoppage with a standard weight person riding the bike. Based on the stopping force the stress analyses were obtained using FEA simulation for master cylinder, slave cylinder, and lever. At the end, the final designs were chosen based on the stress analyses and manufacturability.
Variation Analysis for Composite Parts With Considering Local Delamination Defects
Authors: Liu Jinyu , Li Zhimin , Liu Tao , Li Xinxin
Published: January 2020

Laminate composite components have been widely used in engineering fields, such as aerospace and aircraft fields, automotive industries, marine and civil engineering. Due to inherent properties of laminated composites, the effects of local delamination defects will result in a decrease of assembly dimensional precision and mechanical property, and a variation analysis considering the effect of delamination defects become increasingly indispensable. In order to understand the influence relationship between delamination defects and manufacturing deviations, a methodology based on the method of influence coefficients is proposed to analyze the influence relationship between delamination defects and manufacturing deviations. Then, local delamination modes are developed based on the interface deformable bi-layer beam model with consideration of transverse shear and delamination tip deformations. This model provides an accurate solution with the delaminated composite structures. Finally, the effect of local delamination length ratio (a/h) has been further studied for the assembly precision analysis based on the flexible joint model, and the comparison of simulation result shows that the delamination has a signification influence on the structural performance and the quality of the product.
Strain and Photovoltaic Sensitivities of Dumbbell-Shape GNR-Base Sensors
Authors: Goundar Jowesh Avisheik , Kudo Takuya , Zhang Qinqiang , Suzuki Ken , Miura Hideo
Published: January 2020

The area-arrayed dumbbell-shape Graphene Nano-Ribbons (GNRs) were fabricated by using chemical vapor deposition and photolithography technologies. The electronic behavior of the fabricated GNR-FET structure was evaluated for its photonic properties with an incident light intensity of 1-mW. The 200-nm wide GNRs structure showed metallic properties, while those with the width of 40 nm showed semiconductive properties as was expected. The light-induced photocurrent was observed in all the fabricated GNRs structures. The average photocurrent observed in the 2-mm wide graphene structure was 3.3 A/m2 and that observed in the 40-nm wide area-arrayed GNRs structure was 261 A/m2, respectively. Based on this photocurrent, the external photosensitivity of the 40-nm wide GNRs structure was about 2.6 × 105 A/W.m2 and this value was much larger than that of conventional Si-base solar cells. In addition, the effect of strain on the resistivity of GNRs was measured. Uniaxial tensile strain was applied to the area-arrayed GNRs structures with the width from 200 nm to 40 nm. The gauge factor obtained from the GNRs with the width wider than 100 nm was about 3, and that with the width of 40 nm was about 160. Therefore, highly-sensitive strain sensors can be realized by using GNRs thinner than 70 nm.
Dynamic and Static Fracture Toughness of Al/Epoxy Resin Interface
Authors: Saito Yusaku , Sudo Kosuke , Kanamori Kohei , Yonezu Akio
Published: January 2020

This study evaluates the interfacial fracture strength and toughness of an epoxy resin/aluminum alloy based on two different tests of impact loading and quasi-static loading. In the impact test, we carried out the Laser Shock Adhesion Test (LaSAT). This method uses a strong ultrasonic wave induced by pulsed laser irradiation to induce interfacial fracture. Due to the grease layer ablation caused by laser irradiation, strong elastic wave generates and propagates. The tensile stress acts on the Al/epoxy resin interface, inducing an interfacial delamination. This delamination is further extended by an additional laser irradiation in order to evaluate the interfacial fracture toughness. By simulating the experimental delamination progression in FEM (Finite Element Method), we evaluated the dynamic fracture toughness of the Al alloy/epoxy resin interface. On the other hand, a quasi-static test for the toughness evaluation was conducted using a uniaxial tensile test. Before the tensile test, we produced an initial crack (initial delamination) at the interface by using laser ablation. Subsequently, this sample having initial crack is loaded by uniaxial tension. It is found that the interfacial crack progresses, resulting in unstable interfacial fracture. Furthermore, we conducted FEM simulation, in order to estimate the stress distribution near the delamination. By deriving a stress intensity factor from the stress distribution, we evaluated the quasi-static fracture toughness. To compare the dynamic and quasi-static fracture toughness of Al alloy/epoxy resin interface, we clarified the loading rate dependency of interfacial fracture toughness.
Self-Synchronization in a Class of Motor Driven Reciprocating Mechanisms
Authors: Sinha Anubhab , Bharti Saurabh Kumar , Samantaray Arun Kumar , Bhattacharyya Ranjan
Published: January 2020

The phenomena of ‘self-synchronization’ is investigated in Reciprocating Mechanisms, namely — crank slider mechanisms. A typical crank-slider mechanism comprises a rotating crank, a sliding piston and a connecting rod in between them. A series of such mechanisms are installed inside a common vibrating base structure. Each of these mechanisms are independently powered by a DC motor. So, for ‘n’ number of mechanisms, there are also ‘n’ number of motors driving them. The assembly is then set up an SDoF vibrating system. A multi-body simulation model is developed on MSC Adams. The numerical study shows that even with different voltage inputs for each motor, the individual mechanisms ‘self-synchronize’ by attaining a single common driving speed. The synchronization is self-induced due to energy interactions between the non-ideal drives and the common vibrating base. Moreover, the tendency to synchronize is so strong that once synchronized, the mechanisms continue to do so even when one or more motors are switched off. The study demonstrates how synchronization can assist in driving multiple mechanisms simultaneously, possibly with minimal power requirements as well as reduced vibrations.