bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Nanoscale Rheological and Mechanical Properties of Thin Film Asphalt Binder
Authors: Faisal Hasan M. , Khan Zafrul Hakim , Tarefder Rafiqul
Published: February 2017

Traditionally, mechanical properties of asphalt concrete (AC) is evaluated through macro-scale testing. However, when aggregates are mixed with asphalt binder, it creates a thin film of 20μm to 40μm around the aggregate particles and the primary strength of AC is derived from the interaction between the binder and aggregates. Therefore, to understand the behavior of asphalt concrete it is necessary to study the binder properties in a nanoscale. Nanoindentation test has been adopted to examine the thin film material property. In a nanoindentation test, a loaded nanoindenter is used to indent the sample surface and measure the indenter displacement as a function of load. To this day, most researchers have used the Oliver-Pharr method to analyze the indentation test data and obtain Elastic modulus (E) and hardness (H) of the material. Generally, in a nanoindentation test, there is a loading and unloading phase. In an elasto-plastic material, loading phase has elastic and plastic response and unloading phase has only elastic response. In Oliver-Pharr method, elastic modulus is obtained through the slope of the unloading curve. Therefore, Oliver-Pharr method mostly applicable for the elasto-plastic metals because it does not incorporate any viscous effect. However, in case of visco-elastic material like asphalt, during the unloading phase, the slope of the unloading curve becomes negative due to the viscous flow. Therefore, using Oliver-Pharr (OP) method in this circumstances will yield an inaccurate value of modulus of elasticity. In the current study, the test data was modeled and analyzed using a well-established spring-dashpot-rigid (SDR) model for viscoelastic material to determine the elastic, plastic and viscous properties. The model assumes the indenter displacement is a function of a quadratic spring, a quadratic dashpot and a plastic rigid body. The loading phase of the nanoindentation test has three contributing parameters: elasticity (E), indentation viscosity (η) and hardness (H). During creep, only contributing parameter is indentation viscosity (η) and while unloading the contributing factors are found to be E and η. Nonlinear least square curve fitting technique was employed to model the nanoindentation test data to the SDR model to find out the contributing parameters E, η and H. In addition, the extended dwell time on the asphalt binder samples produced positive load displacement curves, which were further analyzed with Oliver-Pharr method. Comparison between two models results show traditional Oliver-Pharr model predicts the material properties 5 to 10 times lower than SDR model, as Oliver-Pharr does not consider the viscous behavior in the material.
Performance Summary of Continuous Mining Machine Proximity Detection Systems
Authors: Bissert Peter T. , DuCarme Joseph P. , Carr Jacob L. , Jobes Christopher C. , Yonkey Jeffrey A.
Published: February 2017

Since 1984, remote controlled continuous mining machines (CMM) have caused 40 crushing and pinning fatalities in the United States. Due to limited space in the underground environment and visibility needs, CMM operators typically work close to the machine which exposes them to the danger of being struck or pinned by it. Because of these fatalities, the Mine Safety and Health Administration (MSHA) has published a rule requiring proximity detection systems (PDSs) on all CMMs except for full-face machines. To test PDS performance, researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a series of field tests in underground coal mines throughout the United States on CMMs equipped with PDSs. The field tests collected data under a variety of conditions to evaluate the warning and shutdown zone performance of these systems. A baseline test condition was measured when the machine was operating in non-mining mode. Three additional conditions discussed in this paper include testing of the PDS while the machine was operating in mining mode, examining the possibility of parasitic coupling to the trailing cable, and examining the effects of the presence of a shuttle car. The results of this study indicate that the average warning and stop zones vary minimally between non-mining mode and trailing cable influence measurements, as well as between the mining mode and shuttle car presence tests. A majority of the measurements for warning and stop zones showed repeatability within +/− 5 inches (12.7 cm). Additionally, parasitic coupling to the trailing cable was not experienced during this field testing. However, these results show that the range of stop zone measurements varied by 4.7 ft on average and as much as 11.7 ft in different field sites. This is most likely due to individual preferences by operators during installation when the warning and stop zone distances are set. While a PDS should effectively stop a CMM when an operator gets too close to the machine, the large variations between field test measurements indicate that there is a wide variation of performance established during system installation.
Integrating First-Principle Calculation and Phase-Field Simulation for Lithium Dendritic Growth on the Anode of a Lithium-Ion Battery
Authors: Chen Lei
Published: February 2017

Lithium (Li) dendrite formation compromises the reliability of Li-ion batteries, either because dendrite pieces lose electrical contractor or growing dendrite penetrates the separator and leads to internal short-circuiting. In this paper, a multi-scale computational approach integrating phase-field model and first-principles calculation is proposed to predict the Li dendrite formation at the anode/electrolyte interface of Li-ion batteries. The first-principles calculation is employed to atomically determine the interfacial energy, which is subsequently fed into the phase-field model at the micro-scale. 1D distribution of fields is first analyzed to validate the proposed model. An apparent 2D tree-type Li dendrite, widely observed in experiments during electrodeposition, is produced using the model. Finally, the 2D dendritic evolution under different electrochemical conditions specified by the applied current densities is discussed.
Active Torque Vectoring in High Speed Lane Change Maneuvers
Authors: Steinbock Nathaniel , Prange Laura , Fabien Brian C.
Published: February 2017

Emergency lane changes are often the best course of action when avoiding obstacles on the road, but this maneuver has the possibility of sending the vehicle out of control. The University of Washington EcoCAR team has a hybrid-electric vehicle outfitted with an electric drivetrain and variable torque control to each of the rear wheels. Each rear wheel has an electric motor that is independently controlled to provide torque to the wheel. A lateral vehicle dynamics model is used to develop a torque control strategy to improve the safety and maneuverability of a modified hybrid-electric 2016 Camaro as part of the EcoCAR 3 competition.

The specific scenario simulated is a two-lane lane change at a speed of 55 mph. We would like to increase the yaw and lateral accelerations that the vehicle can perform safely by controlling differing torques out of the two motors. Regulating these accelerations requires a control strategy over the left and right motor torques. Equal-torque control of the electric motors will be used as a baseline.
Experimental Measurement of Inter-Die Thermal Resistance in a Two Die 3D IC
Authors: Choobineh Leila , Jain Ankur , Jones Jared
Published: February 2017

Thermal modeling and temperature prediction in 3D ICs are important for improving performance and reliability. A number of numerical and analytical models have been developed for thermal analysis of 3D ICs. However, there is a relative lack of experimental work to determine key physical parameters in 3D IC thermal design. One such important key parameter is the inter-die thermal resistance between adjacent die bonded together. This paper describes a novel experimental method to measure the value of inter-die thermal resistance between two die in a 3D IC. The effect of heating one die on the temperature of the other die in a two-die stack is measured over a short time period using high speed data acquisition to negate the effect of boundary conditions. Numerical simulation is performed and based on a comparison between experimental data and the numerical model, the inter-die thermal resistance between two die is determined. There is good agreement between experimental measurement and theoretically estimated value of the inter-die thermal resistance. Results from this paper are expected to assist in thermal design and management of 3D ICs.
Dynamic Characterization and Modeling of Carbon Composite Ballistic Behavior
Authors: Yen Chian-Fong , Kaste Robert , Yu Jian , Chen Charles Chih-Tsai , Carey Nelson
Published: February 2017

Design of the new generation of aircraft is driven by the vastly increased cost of fuel and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aircraft structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic impact conditions. Using a meso-mechanics approach, a laminated composite is represented by a collection of selected numbers of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by the strain-rate dependent layer progressive failure model using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA as a user-defined material subroutine. In this paper, the ballistic limit velocity (V50) was established for a series of laminates by ballistic impact testing. Correlation of the predicted and measured V50 values has been conducted to validate the accuracy of the ballistic modeling approach for the selected carbon composite material. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic and blast survivability.
Analysis of a Multi-Cascade Methyl Linoleate / SCO2 / Transcritical CO2 / R-410A Refrigeration Cycle for Use in High Temperature High Pressure Environments
Authors: Anderson Kevin R. , McNamara Christopher , Gatti Ariel
Published: February 2017

This paper presents the results of an analysis of a hybrid cascaded Methyl Linoleate / Supercritical (SCO2) / Transcritical CO2 / R-410A cycle for extreme environment refrigeration applications. The particular application of this cascaded CO2 refrigeration cycle stems from a space exploration application of a Venus lander mission. The payload of the Venus lander is subject an extremely harsh environment, i.e. the objective is to maintain a 1 cubic meter payload cavity at 35 °C, with dissipation of 500 W to an environmental temperature of 465 °C. Complicating the situation is the Venus local atmosphere is 9 MPa, and the atmosphere is mainly comprised of CO2 (95.5% by volume, 3.5% N2 by volume). Because this temperature is so high, to stay under the saturation dome we need some fairly exotic fluids to do a normal vapor compression system. Some of the only fluids with critical points allowing for this particular application are sulfuric acid and Fatty Acid Methyl Ester (FAME) type bio-diesels such as Methyl Linoleate (MLL). The actual heat rejection process and throttling processes are the primary challenges of this research topic. Results of a COP comparison and a lift curve are carried out in order to determine efficiency and guide feasibility of realizing the actual hardware to be used in the cycle.
Development of Active Mechanical Models for Flexible Robots to Duplicate the Motion of Inch Worms and Snakes
Authors: Rios Oscar , Ono Takeyuki , Murakami Hidenori
Published: February 2017

Due to the advent of pneumatic actuators, tendon-actuation mechanisms, and artificial muscles, an increasing number of robot engineers are developing flexible and soft robots. The emergence of soft and flexible robotics has offered new methods of locomotion that have applications in a wide variety of sectors. The research presented here focuses on developing mechanical models for such flexible robots. Two models are developed that will aid the modeling of soft robotics: (i) a discrete multi-body model consisting of jointed cylindrical segments and (ii) a thorough continuous beam model with internal actuation. The mechanical models serve as indicators of the necessary internal actuation for soft robots to reproduce or mimic the observed or necessary motion.
A MOOSE-Based Implicit Peridynamic Thermomechanical Model
Authors: Chen Hailong , Hu Yile , Spencer Benjamin W.
Published: February 2017

In this paper, we present an implicit formulation of peridynamic theory for coupled thermomechanical problem based on the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework, with special application to the simulation of fracture behavior of nuclear fuels at high temperature. First, the coupled peridynamic thermomechanical model is briefly reviewed. Next, an implicit formulation for the solution of static or quasi-static problems is proposed. Finally, the formulation is verified against benchmark solutions for both elasticity and heat conduction problems. The nuclear fuel fracture problems is modeled using the proposed implicit scheme. The mesh dependencies of crack initiation are also investigated.
Conceptual Design of an Energy Harvesting Accessory for Road Vehicles
Authors: Hurtado Hurtado Gerardo , Romero Navarrete José Antonio
Published: February 2017

The use of transportation residual energy can represent an alternative energy source to reduce the consumption of fossil fuels. In specific economic environments, in which the road conditions are not good, the vibration of the vehicles’ masses, represent a potential enormous source for such alternative energy source. In this paper, the conceptual design of an energy-harvesting accessory to be installed in existing suspensions of vehicles, is presented. The principles of operation include an electromagnetic generator, a rectifier and a battery. Validation of the proposed accessory is made through simulation that indicates the feasibility of this device.
A Novel 3D Printing Technique to Synthesise Gas Diffusion Layer for PEM Fuel Cell Application
Authors: Jayakumar Arunkumar , Ramos Maximiano , Al-Jumaily Ahmed
Published: February 2017

Gas Diffusion Layer (GDL) is a versatile component of the PEM fuel cell stack and the well-known gas diffusion substrates used in the PEM fuel cell stack incorporates the carbon fiber based GDLs which suffers from limitations due to degradation and carbon oxidation. The present paper describes the novel integrated approach using 3D printed microfabrication technology to develop a durable, cheap and conductive gas diffusion material. Mechanical and Electrical characterization of the proposed material is performed which evidently indicates that the proposed material can be a promising candidate for gas diffusion layer in future.
A Nonlocal Lattice Particle Framework for Modeling of Solids
Authors: Chen Hailong , Liu Yongming
Published: February 2017

In this paper, we present a nonlocal lattice particle framework for modeling the brittle behaviors of both isotropic and anisotropic solid materials. Different from other continuum based models, the formulation of this lattice particle model is discrete and there is no spatial derivative involved. This avoids the singularity issues of discontinuous problems, which commonly exists in continuum based models. The model is also nonlocal that a discrete element can interacts with its neighbors up to certain distance. This nonlocality better solves some issues in other discrete models, such as fixed range of Poisson’s ratio. The modeling capability and accuracy are demonstrated using numerical examples.
Application to the Reciprocating Compressor Condition Monitoring Using Vibration Models
Authors: Mori Yoshifumi , Saito Takashi , Nakamura Takenori , Fujita Katsuhide
Published: February 2017

The purpose of this study is to establish a new monitoring technique to detect the state of sliding portion and connecting portion, where it is known that some failure often occurs.

In this paper, we examined the feasibility of estimation for the state in which the support rigidity of the sliding portion using the vibration characteristics in the experiment for a small experimental equipment and in the eigenvalue analysis based on the mathematical model. To simulate the change of the rigidity for the sliding portion, we employ two kinds of material, carbon and molybdenum steel as the ring bush of the ground support. To obtain the natural frequencies and modes for both the case, the impact tests are carried out for several crank angles in the small experimental apparatus as the vibration characteristics is depend upon the crank angle. Based on the obtained natural frequencies, the parameter identification was carried out. As a result, it showed the possibility of estimating the characteristics of the sliding portion by focusing on the natural vibration characteristics.
Entropy for Strongly Coupled Oscillators
Authors: Tufano Dante A. , Sotoudeh Zahra
Published: February 2017

This paper examines an approach to determining the entropy of coupled oscillators that does not rely on the assumption of weak coupling. The results of this approach are compared to the results for a weakly coupled system. It is shown that the results from each methodology agree in the case of weak coupling, and that a correction term is required for moderate to strong coupling. The correction term is shown to be related to the mixed energy term from the coupling spring as well as the geometry and stiffness of the system. Numerical simulations are performed for a symmetric system of identical coupled oscillators and an asymmetric system of nonidentical oscillators to demonstrate these findings.
An Analytical and Geometrical Study of the Dzhanibekov and Tennis Racket Phenomena
Authors: Rios Oscar , Ono Takeyuki , Murakami Hidenori , Impelluso Thomas J.
Published: February 2017

We consider the torque-free rotation of a rigid body with three distinct moment of inertia values and angular velocity components. As can be seen in the Dzhanibekov and tennis racket phenomena, rotations about the largest and smallest principal moments of inertia create stable rotations. However, when rotating about the principal intermediate moment of inertia, an unstable rotation is produced that leads to the basis of this phenomena. In this publication, the above phenomena are examined and explained analytically and applied to a satellite system to observe the change in trajectory as the solar panels and reflectors are deployed. To begin the derivation, the Euler torque-free equations for a rotating rigid body are formulated using the moving frame method. The derived equations are then non-dimensionalized and a complete analytical solution, including an expression for the non-dimensional period, is presented. Second, we further look at the limiting axisymmetric cases and examine the effect as the intermediate moment of inertia is varied. Lastly, the analytical expressions are compared with the numerical simulation to validate the results. The complete solution is then summarized and shown to clearly prove that the conservation of angular momentum is indeed preserved in the phenomena.
Optimization on Layout and Processing Route of Dual-Robot Machining Center for Large Car Dashboard
Authors: Cao Chunping , Wu Kai , Wang Jun , Sun Yu
Published: February 2017

The manufacturing of the large car dashboard is different from other manufacturing process for its special structure in the automotive interior field. Hole position, shape, size and distribution of the different types of large car dashboard are not in same, which make the manufacturing process more difficult and result in poor efficiency. Multi-robot machining units are introduced by enterprise to improve working efficiency and shorten the working time. In this paper, taking a typical automobile car dashboard as the processing object, the layout optimization problem of dual robot machining center for large car dashboard is studied to obtain the largest space coincidence rate of two robots and the shortest processing time. First, a dual-robot machining center for large dashboard is established. Then a genetic algorithm and an improved ant colony algorithm are used to obtain the largest space coincidence rate and the shortest cycle time. At last, the coincidence of the robot working space and the processing cycle are compared in this paper. Compared with the company’s existing working state, the coincidence working space rate has being increased by 14.6 percent, and the cycle time has being reducing by 1.2min, which demonstrates the effectiveness and feasibility of the method.
Numerical Modeling for the Energy Conversion and Thermal Transmission Accompanying the Process of Oily Cuttings Agitation
Authors: Sun Zhipeng , Zhu Hongwu , Hua Jian
Published: February 2017

As a kind of unconventional gas reservoirs, shale gas reservoirs are full of potential to develop and have attracted global attention. Accompanying the exploiting of shale gas, a large amount of drilling cuttings contaminated by the oil-based drilling fluid are generated inevitably. How to deal with the drilling cuttings in a environmental-friendly way is tough especially for offshore oilfield. So it is important to investigate this aspect deeply and develop methods to clean the contaminated drilling cuttings. As is known to all, the thermal desorption technology has outstanding performance in oily cuttings cleaning. This paper bases on a kind of mechanical-thermal cuttings cleaning apparatus where the contaminated drilling cuttings are heated up by friction heat produced by the friction between the cuttings and the agitating vanes. And the harmful substance is separated from the cuttings in the agitated and high temperature flow field. This thesis investigates the fundamental of the energy conversion in the frictional process, infer formulas analyzing the thermo-physical phenomena and quantitatively model the energy conversion and thermal transmission accompanying the friction.

Firstly, the principle of heat transfer and the law of conservation of energy are employed to investigate the natural law of the energy conversion in the frictional process. Based on the investigation, taking the liquid bridge between the oily cuttings and the agitating vane into account, this paper deduces the physical equations and the frictional energy model to calculate the total frictional heat, heat density and temperature distribution.

Following up the frictional model, in the Eulerian-Lagrangian coupling framework, this paper develops a parallel numerical platform of computational fluid dynamics combined with discrete element method (CFD-DEM). In the coupling approach, the gas motion is solved at the computational grid level while the solid motion is resolved at the particle-scale level. Furthermore, the coupling approach is extended with the frictional energy model. The numerical platform can calculate the dense gas-solid motion in the fluidizing apparatus, the convective heat transfer between gas and solid phase, and the conductive heat transfer between particles. Based on the platform, the mechanical-thermal energy conversion and the convective heat transfer between gas and oily cuttings, and the conductive heat transfer between cuttings and the agitating vanes are investigated. Meanwhile an experiment is conducted. By comparing the numerical results with the experiment data, the paper can come to the conclusion that how to dispose the nonlinear parameters such as the friction contact area, the friction coefficient and the normal pressure is the key to accurately model the energy conversion and the heat transmission. What’s more, it can be understood that the convective heat transfer between gas and solid phase play an important role in the heat transmission.
Fast Multidisciplinary Design Optimization in the Development of Mechatronic Systems
Authors: Reul Andreas , Schwerdt Lukas , Rinderknecht Stephan
Published: February 2017

Multiobjective multidisciplinary optimization supports the development of mechatronic systems. A suitable approach is required for a short calculation time and sufficient results. All aspects of the system model (mechatronic system, cost model and time optimal control problem) are incorporated into one nonlinear optimization model, following the all-at-once approach. The dynamic simulation is discretized in time and optimization variables are introduced for the state at each time step. Formulating the problem in an algebraic modeling language and solving it by the interior point method allows very fast solution times. This enables a fast turnaround time during the preliminary design phase in the product development. Sensitivities of the objective with respect to model parameters and design constraints are generated by the solver and used to guide the modeling and development process. Using these sensitivities, the model can be improved where necessary while keeping the model complexity low by simplifying less important parts. As example an electromechanical actuating system is considered, in which the rotary motion of a motor is converted to a translational movement with a gate-tape gear.
Thermal Enhancement of an LED Light Engine for Automotive Exterior Lighting With Advanced Heat Spreader Technology
Authors: Uras Umut Zeynep , Tamdoğan Enes , Arık Mehmet
Published: February 2017

In recent years, light emitting diodes (LEDs) have become an attractive technology for general and automotive illumination systems. LEDs have been preferable for automobile lighting due to its numerous advantages such as long life, low power consumption, optical control and light quality as well as robustness for high vibration. Thermal management is one of the main issues due to severe ambient conditions and compact volume. Conventionally, tightly packaged double sided FR4 based printed circuit boards are utilized for both driver electronics components and LEDs. In fact, this approach will be a leading trend for advanced Internet of Things (IOT) applications in near future.

A series of numerical models are developed to determine the local temperature distribution on both sides of a light engine. Results showed that FR4 PCB has a temperature gradient of over 63°C while the maximum temperature is 105°C. This causes a significant degradation of lifetime and lumen extraction as many LEDs are recommended to be operated below 100°C. In addition to FR4, Aluminum metal core and vapor chamber based advanced heat spreader substrates are developed to obtain thermal impact on the substrate due to a wide range of thermal conductivity of three boards. To mimic real application, two special flex circuits are developed for LEDs and driver circuit. 10 red and 6 amber LEDs at one flex-PCB, and driver components are populated on the other flex-PCB are mounted. Both flex circuits are attached each side of the substrate. Experimental results showed that the local hotspots occurred at FR4 PCB due to low thermal conductivity. Later, a metal core printed circuit board is investigated to minimalize local hot spots. High conductivity metal core PCB showed a 19.9% improvement over FR4 based board. A further study has been performed with an advanced heat spreader based on vapor chamber technology. Results showed that a thermal enhancement of 7.4% and 25.8% over Al metal core and FR4 based boards with an advanced vapor chamber substrate.
Kinematic Calibration of a 2-DOF Parallel Orientation Manipulator: Theory and Simulation Results
Authors: Gabrielli Andrea , Borboni Alberto , Carbonari Luca , Palpacelli Matteo-Claudio
Published: February 2017

The objective of this work is the calibration analysis of a 2-DOF orientation manipulator, conceived for micro-orientation tasks inside a microassembly workcell. The proposed device is an overconstrained spherical five-bar mechanism, already widely studied in the scientific literature and known for being a simple but robust solution for the realization of robot wrists; its 5R parallel kinematics architecture allows a wide orientation workspace and good accuracy performances. The present paper sets the theoretical bases for the “geometrical calibration” of the PKM (Parallel Kinematics Machine) and discusses the first simulation results: the meaning of “geometrical calibration” is intended as the identification of the construction and assembly errors that affect the manipulator static accuracy.
Fabrication of Tunable Silk Materials Through Microfluidic Mixers
Authors: Nalbach Joseph R. , Jao Dave , Petro Douglas G. , Raudenbush Kyle M. , Ahmad Shibbir , Xue Ye , Hu Xiao , Xue Wei
Published: February 2017

A common method to precisely control the material properties is to evenly distribute functional nanomaterials within the substrate. For example, it is possible to mix a silk solution and nanomaterials together to form one tuned silk sample. However, the nanomaterials are likely to aggregate in the traditional manual mixing processes. Here we report a pilot study of utilizing specific microfluidic mixing designs to achieve a uniform nanomaterial distribution with minimal aggregation. Mixing patterns are created based on classic designs and then validated by experimental results. The devices are fabricated on polydimethylsiloxane (PDMS) using 3D printed molds and soft lithography for rapid replication. The initial mixing performance is validated through the mixing of two solutions with colored dyes. The microfluidic mixer designs are further analyzed by creating silk-based film samples. The cured film is inspected with scanning electron microscopy (SEM) to reveal the distribution uniformity of the dye particles within the silk material matrix. Our preliminary results show that the microfluidic mixing produces uniform distribution of dye particles. Because the microfluidic device can be used as a continuous mixing tool, we believe it will provide a powerful platform for better preparation of silk materials. By using different types of nanomaterials such as graphite (demonstrated in this study), graphene, carbon nanotubes, and magnetic nanoparticles, the resulting silk samples can be fine-tuned with desired electrical, mechanical, and magnetic properties.
3D Dynamic Simulation of a Flow Force Compensated Pressure Relief Valve
Authors: Altare Giorgio , Rundo Massimo , Olivetti Micaela
Published: February 2017

The paper deals with the 3D and 0D simulation of a conical popped pressure relief valve with flow force compensation. The commercial CFD code PumpLinx® was used to create a dynamic model of the valve and the interaction between the poppet dynamics and pressure field was taken into account. The model is able to determine the equilibrium position of the poppet in order to estimate the regulated pressure as function of the flow rate. A good agreement with the experimental data was found in the evaluation of the effect of the flow force compensation. Once validated, the CFD code was used to study the influence of the deflector geometry on the opening force. Moreover it was also used for determining some proper data to be supplied as input to a lumped parameters model of the valve. The tuning of the 0D model involved the discharge coefficient and the flow force. For the evaluation of the flow force compensation, a lookup table was calculated by the CFD code and then interpolated in the 0D model as function of the poppet displacement and of the flow rate.
Impact of Different Operating Conditions on the Dynamic Excitation of a High Head Francis Turbine
Authors: Eichhorn Markus , Doujak Eduard
Published: February 2017

Fatigue analysis becomes more important in the design phase of Francis turbine runners due to the changing requirements on hydropower plants, affected by the increasing amount of volatile energy sources. Francis turbines are operated more often and over longer periods of time at off-design conditions to provide regulating power to the electric grid. The lifetime of a Francis runner depends mainly on the dynamic excitation induced by unsteady pressure pulsations like the rotor-stator interaction or draft tube vortex ropes. An approach using one-way coupled fluid-structure interactions has been developed and is now extended using unsteady CFD simulations as well as harmonic and transient FEM computations. The results are compared to strain gauge measurements on the according high head Francis turbine to validate the overall procedure. The investigations should be further used to perform a fatigue analysis and to examine the applicability for lifetime investigations on Francis machines with different specific speeds.
Experimental Research on Deflection Control of Cantilever Beam Based on Hybrid Photovoltaic/Piezoelectric Actuation Mechanism
Authors: Lu F. , Wang X. J. , Liu Y. F.
Published: February 2017

When ultraviolet light illuminates on polarized PLZT ceramic, a large voltage can be generated between the electrodes due to the anomalous photovoltaic effect. The shape control of flexible shell can be realized by using hybrid photovoltaic/piezoelectric actuation. In this paper, a novel non-contact deflection closed-loop control model of cantilever beam based on hybrid photovoltaic/piezoelectric actuation can be proposed. The photovoltage of PLZT ceramic irradiated by ultraviolet light is applied to drive PVDF actuator. The closed-loop control equations of deflection of cantilever beam is derived based on the mathematical model of PLZT ceramic with coupled multi-physics fields and the constitutive model of cantilever beam. Then, parameters of deflection control equations of cantilever beam during illumination phase and light off phase are identified through the deflection static experiment. After that, the deflection closed-loop control experiment of cantilever beam based on hybrid photovoltaic/piezoelectric actuation mechanism is carried out to verify the control model. The experimental results show that the deflection of cantilever beam with a simple on-off control method can achieve the target value by applying UV light to PLZT ceramic. It also should be noted that, the deflection curve of cantilever beam illuminated by strong UV light has an undesirable fluctuation.
CFD Simulation of Jet Mixing With Asymmetric Co-Flows in a Down-Scaled Rotary Kiln Model
Authors: Teng Ziyan , Johansson Simon P. A. , Larsson I. A. Sofia , Lundström T. Staffan , Marjavaara B. Daniel
Published: February 2017

Rotary kilns used in the iron pellet production in the grate-kiln pelletizing process normally have two asymmetric secondary air channels. The primary jet is ejected from a burner located in the middle of a back plate. As a consequence of the high flow rates and irregular-shaped secondary air channels, the aerodynamics in the kiln is strongly connected to the combustion and sintering performance. In this work a Computational Fluid Dynamics study is performed on a downscaled, simplified kiln model established in earlier numerical and experimental work. Comparisons are made with the experiment and among three turbulence models, the standard k-ε model, a k-ε model modified for turbulent axisymmetric round jets and Speziale-Sarkar-Garski Reynolds Stress Model (SSG-RSM hereafter). Recirculation regions with negative axial velocity are found at the upper side of the kiln and behind the back plate. Results from the standard k-ε model have the best fit to the experimental data regarding the centerline decay and the jet spreading of the velocity. The spreading rate of the scalar concentration calculated from the results with the modified k-ε model and the SSG-RSM fit better with the experiment, but they both underestimate the centerline decay and the spreading of the velocity. The modified k-ε model yields a more physical and realistic flow field compared to the standard k-ε model, and the results are close to those obtained with the SSG-RSM. Unlike the isotropic development of the jet predicted with the standard k-ε model, the modified k-ε model and the SSG-RSM show different development of the jet in the horizontal and vertical directions.
Effects of Crimped Fiber Paths on Mixed Mode Delamination Behaviors in Woven Fabric Composites
Authors: Cavallaro Paul V. , Hulton Andrew , Salama Mahmoud , Jee Melvin W.
Published: February 2017

This research investigated the fracture toughness and crack propagation behaviors of woven fabric reinforced polymer (WFRP) composite laminates subjected to single and mixed mode loadings using numerical models. The objectives were to characterize the fracture behaviors and toughness properties at the fiber/matrix interfaces and to identify mechanisms that can be exploited for increasing delamination resistance. The mode-I and mode-II strain energy release rates GI and GII, the effective critical strain energy release rate, Gc_eff, (also known as the mixed mode fracture toughness) and crack growth stabilities were determined as functions of crimped fiber paths using meso-scale, 2D multi-continuum finite element models. Three variations of a plain-woven fabric architecture were considered; each having different crimped fiber paths. The presence of mixed-mode strain energy release rates at the meso-scale due to the curvilinear fiber paths was shown to influence the interlaminar fracture toughness and was explored for pure single-mode and mixed-mode global loadings. It was concluded that woven fabric composites provided a Fracture Toughness Conversion Mechanism (FTCM) and their toughness properties were dependent upon and varied with positon along the crimped fiber paths. The FTCM was identified as an advanced tailoring mechanism that can be further utilized to improve toughness and damage tolerance thresholds especially when the mode-II fracture toughness GIIc is greater than the mode-I fracture toughness GIc.
Lateral Stability Analysis for Car-Trailer Combinations
Authors: Lee Eungkil , Sun Tao , He Yuping
Published: February 2017

This paper presents a parametric study of linear lateral stability of a car-trailer (CT) combination in order to examine the fidelity, complexity, and applicability for control algorithm development for CT systems. Using MATLAB software, a linear yaw-roll model with 5 degrees of freedom (DOF) is developed to represent the CT combination. In the case of linear stability analysis, a parametric study was carried out using eigenvalue analysis based on a linear yaw-roll CT model with varying parameters. Built upon the linear stability analysis, an active trailer differential braking (ATDB) controller was designed for the CT system using the linear quadratic regulator (LQR) technique. The simulation study presented in this paper shows the effectiveness of the proposed LQR control design and the influence of different trailer parameters.
Integrated Computational Approach for Heat Exchangers Design
Authors: Goh Chung-Hyun , Fumo Nelson , Ming Zhenjun
Published: February 2017

Heat exchangers are present in a variety of processes and industries. Increasing system efficiency is the most effective method and one of the greatest concerns in reducing energy consumption. In this paper we applied an integrated design approach to heat exchangers design, which combines the Integrated Multi-Scale Robust Design (IMRD) with the Grey Relational Analysis (GRA). As a case study, a double-pipe heat exchanger was used.

The IMRD performs the horizontal integration in the Process-Structure-Property-Performance (P-S-P-P) relationship through forward modeling and inductive exploration processes, while the vertical integration in the P-S-P-P relationship is accomplished by adopting localization and homogenization concepts.

For the proposed application into heat exchangers, the IMRD explores solution spaces and suggests feasible solution ranges for improving the thermal-hydraulic performance, while the GRA evaluates the relative importance of design variables in the heat exchanger.

In the preliminary study, it is found that the feasible solution range is significantly reduced for maximizing the heat transfer rate, compared to the equally balanced function, while the feasible solution range is less sensitive in minimizing annular pump power. To validate the IMRD simulation results from a CFD model are used.
Assessment of Water Droplet Evaporation Path in a Full Separation MED Desalination System
Authors: Guo Penghua , Li Peiwen , Li Jingyin
Published: February 2017

An innovative concept of full separation multi effect distillation (FSMED) desalination system has been proposed in the present study. A full separation tank (FST) is integrated to a conventional multi effect distillation (MED) water treatment system to enhance the water productivity and thermal efficiency. The concentrated brine from the MED is atomized into tiny droplets and fully evaporated in the FST due to the effective convective heat transfer between water droplets and hot air-steam flow. A simplified non-equilibrium vaporization model is developed to describe the movement and evaporation behavior of a single water droplet in FST. Simulations are conducted to investigate the effect of the radiation heat transfer and droplet gravity on the droplet evaporation and movement behavior. The relationship of the water droplet size and falling distance with the hot air-steam temperature, and initial injection/spray parameters is investigated and presented. Results from the study provide important guidance to the design of such a water treatment system.
Multi-Mode Vibration Control of Plates Using a Single Actuator and a Single Sensor
Authors: Majeed Majed A. , Alhazza Khaled , AlSnafi Altaf
Published: February 2017

Multi-mode vibration control using single actuator and single sensor is considered as a difficult control scheme. Most researchers use multi actuators and multi controllers to control multimode structural vibrations. In the present work, a multi-mode control model consists of a single actuator and single sensor, both attached at the top of simply supported thin plate, is developed. A piezoelectric actuator is used and it is assumed to be perfectly bonded to the plate, which means the bonding thickness is neglected. The sensed accelerometer signal is integrated and then filtered to include only the first and the second vibration modes. The linear equations of motion of the plate are derived and discretized using Galerkin’s Method. The resulting coupled equations are combined with velocity delay feedback controller to reduce the structure vibration. Genetic Algorithm is then used to optimize controller parameters using the root mean square of the input signal as an objective function. The results showed that the use of single-input single-output (SISO) delay feedback multimode controller can efficiently be used on any structure to control multimode systems.
A Methodological Approach to Support the Design of Induction Hobs
Authors: Landi Daniele , Cicconi Paolo , Germani Michele , Russo Anna Costanza
Published: February 2017

Nowadays in many industrial applications, i.e. electrical household appliances, it is necessary to have a robust and safe control for some variables involved in the analysis of the performances of different products. In addition, the recent eco-design directives require products increasingly eco-friendly and eco-efficient, preserving high-performance but a low power consumption. For these reasons, the physical prototypes of products require many expensive and complex tests in term of time, resources and qualified personnel involved. To overcome these limitations, the proposed approach is focused on the use of virtual prototyping tools, which support and reduce the expensive physical experiments.

The main objective of this paper is the development, implementation and testing of an innovative methodology, which could be an improvement for the sustainable design of induction hobs.

Induction heating applied to the domestic cooking has significantly evolved since the first cooking hobs appeared. Different issues such as maximum power available for heating a pot, dimensional compactness of the hobs, or inverter electronics efficiency have achieved a great development.

The proposed methodology provides the development of a multi-physic model which is able to estimate the efficiency of the induction hobs starting from the design data of the project. In particular, the multi-physic model is composed by an electromagnetic simulation and a thermal simulation. The electromagnetic simulation, starting from electrical values such as voltage, current and frequency, is able to simulate the eddy current induced in the bottom of the pot, and resistance leads to the Joulean heating of the material. The thermal simulation is able to measure the energy consumption during the operational phase and the temperature reached by the materials. Therefore, the thermal power obtained by the Joulean heating is, at the same time, the output of the electromagnetic simulation and the input of the thermal one.

The proposed model can be applied to design product and simulate the performance considering different operating conditions such as different types of cookers, different coils and different materials. Through the use of virtual prototyping tools is possible to control the heat flux on the whole system (stove, pot, water), and to evaluate the energy efficiency during the operational phase. The proposed tool makes the product-engineer more aware about decision-making strategies in order to achieve an energy saving, calculated over the whole life cycle.
Experimental Study of Hot Surface Ignition of Prevaporized Jet-A and Canola Methyl Ester
Authors: Spens Alex , Harter Jesse , Parthasarathy Ramkumar N. , Gollahalli Subramanya R.
Published: February 2017

In order to understand the ignition characteristics of liquid biofels such as canola methyl ester (CME), a set-up was built and tested. The rectangular combustion chamber (7 cm by 7 cm by 33cm high) had a viewing window in the front. Liquid fuel was injected into a stream of hot air, vaporized and mixed and the fuel/air mixture was passed through the combustion chamber vertically upward. The combustion chamber was filled with mixtures of various equivalence ratios. A 120V dryer heating element was mounted horizontally at the center of the chamber and served as the hot surface. The power input to the hot surface, the temperatures at different locations inside the chamber and images obtained from a high speed camera were recorded simultaneously. The ignition delay, ignition energy and flame velocities were documented over a range of equivalence ratios with Jet-A and CME as fuels. The ignition delay and ignition energy reached minimum values around equivalence ratios of 1.1–1.3. The ignition delay and ignition energy values for CME were comparable to those of Jet A and the flame velocities were 30% lower. This set-up can be used to measure relative ignition characteristics of liquid biofuels and blends of biofuels and petroleum fuels.