bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastohydrodynamic Analysis of the Conrod Small-End of a High Performance Motorbike Engine via a Mass Conserving Cavitation Algorithm
Authors: Mastrandrea Luca Nicolò , Giacopini Matteo , Dini Daniele , Bertocchi Enrico
Published: March 2016

In this contribution a complementarity formulation for the solution of EHL problem in presence of cavitation is employed in order to investigate the tribological behavior of the conrod small-end of a high performance motorbike engine. The influence of different physical and geometrical parameters is discussed. In particular, the clearance between the conrod small-end and the piston pin, the lubricant physical properties, the surface roughness and the stiffness of the piston pin are investigated, thus providing preliminary guidelines for the correct design of the coupling. Due to the negligible influence of the transversal forces acting on the conrod small-end and of the relative sliding speed between the mating surfaces, a two symmetrical model of the assembly is prepared and results are compared with those obtained adopting a simply symmetrical model.
Effect of Cold Storage on Mechanical Properties of Aorta
Authors: Zhao Shijia , Lof John , Kutty Shelby , Gu Linxia
Published: March 2016

Aortic allografts have been widely used in treatments of congenital heart diseases with satisfactory clinical outcomes. They were usually cryopreserved and stored for surgical use. The objective of this work was to investigate the effect of cold storage on mechanical properties of aorta, since the compliance mismatch was one important factor associated with the complication after graft surgery. The segments of porcine descending aorta were divided into two groups: the fresh samples which were tested within 24 hours after harvesting served as control group, and frozen samples which were stored in −20°C for 7 days and then thawed. The uniaxial tension tests along circumferential direction and indentation tests were conducted. The average incremental elastic moduli within each stretch range were obtained from the experimental data obtained during tension tests, and the elastic moduli were also calculated by fitting the force-indentation depth data to Hertz model when the tissue was stretched at 1.0, 1.2, 1.4 and 1.6. In addition, the average incremental elastic moduli of both fresh and frozen aortic tissue along axial direction were also obtained by using uniaxial tension tests. The comparison showed that cold storage definitely increased the average incremental elastic modulus of the aortic tissue along circumferential direction; however, the difference is not significant for the elastic moduli along axial direction.
A Method to Determinate the Energy Potential Generation From Biomass Gasification
Authors: Arango Meneses Juan Fernando , Palacio Vega Mario Andrés , Mendoza Fandiño Jorge Mario , Gómez Vásquez Rafael David , Arrieta Almario Álvaro Ángel
Published: March 2016

This paper is about the development of a computational method to determinate the energy generation potential from residual biomass gasification, in function of the variables and working conditions as the equivalence ratio (ER), and the elemental composition of the biomass, using air as gasifying agent; and by this way promote the generation of low cost energy, whether it be electrical or mechanical energy in order to take advantage of products which normally have no value added. This method was developed using the simulation software of chemical and thermodynamic processes Aspen HYSYS®, this software has a large number of components and the possibility of evaluating their physicochemical properties, along with the equations of state of Peng-Robinson which allow you to define the properties of different fluids with a low error range.

The energy generation potential was evaluated with 5 different biomasses commonly generated by agroindustry in Córdoba-Colombia (Rice husk, sesame stalks, cotton waste, corncobs and coconut fiber) by a modeling of the kinetics of the reactions, where a combination between the reaction mechanisms in function of the Gibbs free energy and reactors, whose yields have been programmed from statistical regressions obtained from other reference, was carried out, and thus simulate the gasification process at 1000 ° C and an ER between 0.21–0.3, getting in this way a synthesis gas with heating values of around 6 (MJ /Nm3) and efficiencies of around 60%.
Energy Harvesting Using Small Renewable Energy Sources: UAV Application
Authors: Zafar Sayem , Gadalla Mohamed
Published: March 2016

A renewable energy harvesting system is designed and tested for micro power generation. Such systems have applications ranging from mobile use to off-grid remote applications. This study analyzed the use of micro power generation for small unmanned aerial vehicle (UAV) flight operations. The renewable energy harvesting system consisted of a small wind turbine, flexible type PV panels and a small fuel cell. Fuel cell is considered the stable source while PV and wind turbine produced varying power output. The load of around 250 W is simulated by a small motor. The micro wind turbine with the total length of 4.5 m and the disk diameter of 1.8 m is tested. The micro wind turbine dimensions make it big enough to be used to charge batteries yet small enough to be installed on rooftops or easily transportable. The wind turbine blades are installed at an angle of 22°, with respect to the disk plane, as it gives the highest rotation. The voltage and current output for the corresponding RPM and wind speeds are recorded for the wind turbine. Two 2 m and a single 1 m long WaveSol Light PV panels are tested. The PV tests are conducted to get the current and voltage output with respect to the solar flux. The variation in solar flux represented the time of day and seasons. A 250 W PEM fuel cell is tested to run the desired load. Fuel cell’s hydrogen pressure drop is recorded against the output electrical power and the run time is recorded. System performance is evaluated under different operating and environmental conditions. Data is collected for a wide range of conditions to analyze the usability of renewable energy harvesting system. This energy harvesting method significantly improves the usability and output of the renewable energy sources. It also shows that small renewable energy systems have existing applications.
Analysis of Turbulence Induced Thermal Mixing Effects on T-Junction Fluid-Structure Degradation
Authors: Hasan Mohammed , Basu Debashis , Das Kaushik
Published: March 2016

Thermal striping generally is recognized as a significant long-term degradation mechanism in the primary cooling water circuit of nuclear power plants (NPPs). This phenomenon occurs by mixing of hot and cold water streams in the primary coolant loop. Depending on the flow configuration, the turbulent mixing process can lead to thermal striping, temperature fluctuations in the T-junction region, thermal fatigue, and crack generation in the associated structure. The objective of this study is to provide an in-depth look into the underlying physics for thermal fatigue to determine appropriate screening criteria and risk significance for the regulatory safety evaluation process. In addition, the structure of turbulence in the T-junction also is investigated. The computational method comprised of Large Eddy Simulation (LES) modeling to simulate turbulence and Proper Orthogonal Decomposition (POD) analysis to capture the coherent structures and turbulence scales. In addition, Conjugate Heat Transfer (CHT) analyses have been performed to predict the thermal field and temperature distribution in the solid piping material of the T-junction. Finally, the corresponding thermal stress in the solid pipe is estimated based on a simplified one-dimensional model to assess the thermal-structure degradation.
Motorcycle Swing Arm Development and Refinement Using Response Optimization
Authors: Sapanaro Michael , Ghosh Suhash , Sahay Chittaranjan
Published: March 2016

The purpose of this project is to develop a motorcycle rear swing arm using finite element analysis and response optimization. This paper aims to discuss the specific features, benefits, and precautions when using design optimization to develop a specific project. Design Optimization has been an evolving process for many years. The latest versions of finite element software allow users to develop, analyze, and optimize structural designs within one program quickly and efficiently. A single shock absorber mounted close to the chassis and centrally located was the design selected to be analyzed. The design was selected for use in a variety of motorcycle types. This project consisted of a unique set of design attributes that were ideal to exemplify design optimization techniques. Static structural models were created to refine the design before using response optimization. These models finalized the material selection and initial sizes. A central composite design type was generated with selected boundary conditions for four parametric dimensions of the model. The ideal design of this component would include the resulting stress below a safe allowable value, minimal deflection, and the least amount of weight. It is evident that these three parameters will oppose one another as geometry is changed. Conceptually, an ideal candidate can be created that is a balance of the three parameters. Using the parameters of the selected candidate, a new model was generated for analysis. The final model was further refined by removing unnecessary material that was identified in the structural models.

The first step in a thorough optimization is generating an appropriate amount of design parameter values that are an acceptable representation of all the possible outcomes, or design of experiments (DOE). The DOE tool used to generate the parameters in this project was central composite design (CCD), since it is the most appropriate for second order response models [1]. The second order relationship was confirmed using a trade-off plot. The two level, four input parameter DOE produces twenty five potential candidates that were refined using response surface. The response surface method used in this design process [2,3] to make judgement calls on the final design is examined during this development, and proves useful. Initial static structural models are created and used to set up the model for optimization. Material selection was also accomplished in this phase of development. This process aides in the overall design process by identifying areas of concern as well as the range of parameters that will be analyzed. Multiple acceptable candidates were selected through the use of the optimization tools and a final candidate was selected based on the output of the design attributes and the values of the corresponding parametric geometry. The final selection was also made with the consideration for cost, ease of fabrication, and standardization.
On the Implementation of Producer Gases as Alternative Fuels in Steel Reheating Furnaces
Authors: Saffaripour M. , Ersson M. , Jonsson L. T. I. , Andersson N. , Saffaripour M. H. , Jönsson P. G.
Published: March 2016

During the past decades, combustion of producer gases from other facilities has been introduced as one of the promising techniques in steel furnaces. The impurities inside producer gases are responsible for a low quality steel production due to formation of the molten ash that forms sticky layers of solutions on steel surfaces. Therefore, a comprehensive investigation is needed before a full implementation of producer gases inside the industrial furnaces. In this paper, the effects of impurities inside the gasified biomass flue gases are thermodynamically investigated regarding temperature zones inside a reheating furnace. After that, the high temperature agent combustion (HiTAC) is investigated as a solution for a steel batch reheating furnace to reduce the side effects of using the producer gases. Finally, computational fluid dynamics (CFD) is used as a numerical technique to compare four different producer gases in the studied furnace. The temperature distribution is validated with existing literature data. It shows a good agreement with a 5% error in the heating and a 10% error in the soaking zones of the reheating furnace. The comparison of simulation results assists in the understanding of the chemical and thermal behavior of different gases and provides useful data for the furnace fuel optimization.
The Effect of Raised Benches Containing Crops on the Indoor Environment in Greenhouses
Authors: Kruger Sunita , Pretorius Leon
Published: March 2016

The purpose of this paper is to investigate the influence of peninsular arranged perforated benches containing plants on the indoor environment of a naturally ventilated greenhouse. The results are compared to a greenhouse containing peninsular arranged solid benches with no plants. The investigation will be conducted numerically using three-dimensional Computational Fluid Dynamics (CFD) models. The overall temperature and velocity distribution were investigated at different sections of the greenhouse. The temperature and velocity distributions at plant level were of particular interest. Results indicated that the greenhouse containing the perforated benches were in general cooler, but also exhibited higher velocities throughout. The velocities observed were higher than those recommended by ASHRAE [1]. It was concluded that care should be taken when placing plants on the perforated benches especially in the regions adjacent to the walls, as this can lead to non-uniform crop production.
Modeling of Welding Joint Using Effective Notch Stress Approach for Misalignment Analysis
Authors: Nuruzzaman Md , Wu Christine Q. , Ojo Olanrewaju
Published: March 2016

This research represents the methodology to develop a weld model to assess the structural integrity of welded joints based on stress analysis by finite element method (FEM) and experimental validation. The stress distribution in the welded joints mainly depends on geometry, loading type and material properties. So, it is a great challenge to develop a weld model to predict the behavior of stress distribution and weld stiffness in the joints. In this study, the effective notch stress approach has been used for weld joint modeling. Parameter tuning has been done for the lowest experimental validation error. The effective notch radius is the only tuning parameter in this weld model. The weld model with effective notch radius in between 0.1 to 0.2 mm has shown a good agreement with the experimental results. Through this study, the weld model based on effect notch stress has been validated experimentally for the first time. The validated weld model was then used for misalignment analysis. Both experimental and FE results confirmed that axial misalignment of 20% of specimen’s thickness would have increased maximum principle stresses more than 25–30%.
Effect of Prestress on Bridge–Vehicle Interactions
Authors: Zhong Hai , Yang Mijia
Published: March 2016

Prestress applied on bridges affects the dynamic interaction between bridges and vehicles traveling over them. In this paper, the prestressed bridge is modeled as a beam subjected to eccentric prestress force at the two ends, and a half-vehicle model with 4 degrees of freedom is used to represent the vehicle passing the bridge. A new bridge–vehicle interaction model considering the effect of prestress with eccentricity is developed through the principle of virtual work. The correctness and accuracy of the model are validated with literature results. Based on the developed model, numerical simulations have been conducted using the Newmark’s β method to study the effects of vehicle speed, eccentricity and amplitude of the prestress, and presence of multiple vehicles. It is shown that prestress has an important effect on the maximum vertical acceleration of vehicles, which may provide a good index for detecting the change of prestress. It is also interesting to find that the later-entering vehicle on the prestressed bridge will largely reduce the maximum vertical acceleration of the vehicle ahead of it.
The Effect of Closure Laws on the Simulation Results of Two-Fluid Model of Gas-Solid Flows
Authors: Duan Yifei , Feng Zhi-Gang
Published: March 2016

There are two primary approaches in modeling fluid-solid flows based on the method of treating particles suspended in flows. The first approach is the Eulerian-Lagrangian or Discrete Element Method (DEM) approach that tracks individual particles by solving the equations of motion of these particles. The second approach is the Eulerian-Eulerian approach or two-fluid model (TFM) that considers particles as another continuum phase or fluid. The TFM is preferred in modeling and predicting gas-solid flow behaviors in many engineering applications because of its efficiency in handling large-scale complex systems with large number of particles. However, one of the challenges in TFM is the uncertainty related to the selection of closure laws and transport properties of solid phases. In this study we employ the MFIX code, a general-purpose TFM computer code developed at the National Energy Technology Laboratory, to investigate the effect of different drag models and heat transfer models on the simulation results on the flow hydrodynamics and heat transfer of gas-solid fluidized beds. Three drag models (Gidspow model, Syamlal-O’Brien model, and Koch-Hill model) and two heat transfer model (Gunn model and a recently developed model by Sun et al., 2015) are tested. Simulation results from these models are compared with experimental measurements. The accuracy and applicability of these models are assessed and discussed.
Evaluation of Mechanical Properties of Plasma Sprayed Mixture of Partially Stabilized Zirconia and Tungsten Carbide on Low Carbon Steel
Authors: Salimi Jazi M. , Abuali Galedari S. , Azarmi F. , Tangpong X. , Huang Y. , Lin Z.
Published: March 2016

Industries such as aerospace, automotive, oil and gas utilize various chemical, thermal, and mechanical techniques to improve the surface properties of engineering components. Deposition of metallic or nonmetallic materials on the surface of engineering components using different thermal spraying techniques is a common method to improve the mechanical properties of the surface of the components working at severe conditions. Thermal spraying techniques are capable of deposition of a coating layer with high corrosion, wear, erosion, and high temperature resistance. This technology can also be used for surface repair and treatment. Zirconia (ZrO2) based coatings are excellent candidates to serve at high temperature due to their tribological and insulation properties, and also high stiffness. ZrO2-based coatings are usually used in aircraft and gas-turbine engines as thermal barrier coatings. However, the relatively low wear and erosion resistance of Zirconia-based coatings limits their application. Among all coating materials, Tungsten Carbide (WC) based materials are commonly used to improve wear and corrosion resistance of the surface. It is speculated that combination of ZrO2 and WC follows by generating a coating with desirable thermal and mechanical properties, particularly at high temperature conditions. In the presented work, an innovative thermally sprayed coating material was proposed by depositing mixture of ZrO2-Y2O3 and WC-Ni (YPSZ/WC-Ni) powders on a low carbon steel substrate using Atmospheric Plasma Spraying (APS). As thermomechanical properties of coatings are under the influence of the microstructural features such as porosity, micro cracks, voids, and possible oxides, in this study microstructure and phase consistency of the resultant coating was briefly evaluated. To this end, Optical Microscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) were used. The results indicated that deposited coating was well-bonded to the substrate with minimum observed separation line. Porosity amount of APS deposited YPSZ/WC-Ni measured by image analysis of the cross-sectional area Moreover, mechanical properties including hardness and elastic modulus of the coating were evaluated. Since thermally sprayed coatings exhibit anisotropic behavior, the Knoop hardness in the longitudinal and transverse directions were analyzed in this study. Elastic modulus of the coating was also evaluated, based on the measurement of elastic recovery of Knoop indentation in both directions using Marshal analytical model. Wear resistance of the coating was also investigated by pin-on-disk method, at room temperature. The friction coefficient of the consecutive coating was calculated and had a value lower than that of reported for APS deposited YPSZ.
Feature Model Approach for Managing Variablility of Dynamic Behavior Models in Mechatronic Systems
Authors: Abrishamchian Farisoroosh , Oestersötebier Felix , Trächtler Ansgar
Published: March 2016

The design of mechatronic products requires cooperation and coordination of the involved disciplines. To analyze the dynamic behavior of the product’s subsystems and their components, multiple dynamic behavior models (DBM) are developed in different levels of detail (modeling depths) and domains. However, in order to simulate the complex interactions and dependencies between them, models of the whole system are needed, which fit the varying modeling objectives and analysis goals. These comprehensive models are often extensive and the manual construction presupposes deep insight in the specific model approaches and modeling tools. Furthermore, consistency needs to be ensured. The paper describes a way to automatically configure simulation models of the system adopting a Software Product Line (SPL) approach. With the use of feature models, SPL approach provides a structured method for managing variability. The particular focus of this paper is on handling of components in different tools with more than one level of detail through deployment of feature modeling. Also, it presents the concept of a multifunctional model client (MMC), which facilitates integration of solution and system knowledge.
Vehicle Evaluation During Sustained Solid Axle Tramp: Part 2 — Application of Methodology to Shock Absorber Design Strategies
Authors: Semones Paul T. , Roberts H. Alex , Renfroe David A.
Published: March 2016

EI Consultants (formerly The Engineering Institute) has, for over a decade, researched and tested methods of mitigating the controllability effects of solid rear axle tramp by optimizing rear axle rotational damping. This optimization has explored the balance between increasing the damping forces of the shock absorbers and increasing the distance between the shock absorbers positioned along the axle. Axle tramp is detrimental to vehicle handling and stability, since the reduction in normal force at the rear tires can lead to a total loss of control situation. On solid rear axles such as those common on SUVs and light trucks, underdamped tramp motion will result in an oversteer characteristic of the vehicle as the rear lateral capacity is compromised due to the tires alternately bouncing out of firm contact with the road surface. In severe cases of axle tramp, the alternating normal forces at both the input tire and the opposite tire will go to zero when each tire fully leaves contact with the ground.

EI Consultants has tested numerous SUVs and light trucks and their responses to axle tramp. In order to excite the tramp mode in a sustained fashion for close study of suspension design alternatives, the test methodology utilizes one rear tire with three vulcanized rubber lumps, placed equidistant about the circumference of the tire. Throughout this research, increased effective rotational damping has been repeatedly demonstrated to have a direct relationship to increased controllability.

The most recent testing included maneuvers modeled after those recommended in test standard SAE J266: Steady-State Directional Control Characteristics for Passenger Cars and Light Trucks. This testing included multiple shock absorber configurations, and the data was analyzed in multiple domains to provide insight on the effectiveness of various shock absorber design strategies.

Several shock absorber design variables were evaluated, with the most significant of these being the lateral distance between the shock mounts along the axle. Other variables that were able to be observed and evaluated in the latest testing included the balance between shock absorber rebound and compression forces, and the relative effect of “staggered” shocks in side-view angle, where one shock is positioned with a rearward angle, and the other shock is positioned with a forward angle. The effectiveness of placing shocks further apart along the length of the axle was unmatched.

This paper is the second of two companion papers presenting theory and results on EI Consultants’ most recent axle tramp testing. Where the first paper focused on new understandings of test data analysis theory, this paper will summarize the results of numerous tests and their application to various design strategies for improving solid rear axle tramp damping, with a motivation for enhancing vehicle controllability and highway safety.
Aeroacoustics of Open Cavities With Modified Geometry for Low Mach Number Flow
Authors: Yenigelen Evren , Zafer Baha
Published: March 2016

A numerical study using our source code to acquire the acoustic properties of subsonic flow past an open cavity with different modified geometries will be presented in this paper. A Modified Curle’s analogy will be applied to solve the far field acoustics of the flow. Several cases with different leading edge of cavity fillet radii will be analysed and the effects will be investigated. It is important to find a way to attenuate the sound generation by the cavity, as it is an undesired situation for most applications. In this work a passive system, fillet modification to the leading edge of the cavity, is suggested and the effects of it on the sound generation is investigated.
Assessment of the Pitting Corrosion Degradation Lifetime: Case Study of Boiler Tubes
Authors: Naseh Moghanlou Lida , Pourgol-Mohammad Mohammad
Published: March 2016

In this research, degradation of the metal corrosion for a combined-cycle power plant boiler is investigated. By application of the developed methodology, the corrosion lifetime is estimated for the boiler tubes. At first, with special focus on the corrosion failures, the important failure modes and mechanisms are evaluated for the metallic boiler tubes via FMEA method. It was found that pitting corrosion is one of the most common modes of corrosion. So far, most studies have estimated the lifetime of pitting corrosion using the deterministic data, in which the results are valid only for certain limited conditions. Also, majority of the previous works on the corrosion were conducted experimentally and lesser efforts have been made in the field of the corrosion modeling. The proposed models are based on deterministic approach, however corrosion has a stochastic nature, and it is affected by many stochastic factors. In order to improve deficiencies of available deterministic models, in the present paper, stochastic and uncertainty methods are employed to study the corrosion. The temporal process of metal degradation is analyzed in different conditions through the stochastic approach. A proper degradation model is selected for providing the best estimation of pitting corrosion life. Uncertainty intervals/distributions are determined for some of the model parameters and the parameter intervals are specified. The deterministic model is converted to a probabilistic model by taking to account the variability of the uncertainty input parameters. The model is simulated using Monte Carlo method via simple sampling from the uncertainty distribution of the sources. In order to have better estimation of the parameters and also considering the experimental data in the modeling, the result of the life estimation is updated by the Bayesian method. Finally for the element that is subjected to the pitting corrosion degradation, the distribution of the life estimation is obtained. The uncertainty associated with the result is estimated as the probability of occurrence of each event. Modelling results shows that pitting corrosion has stochastic behavior and the lognormal distribution is the most appropriate option for the pitting corrosion modeling. In order to validate the results, the estimations were compared with the power plant field failure data.
Aero-Thermal Shape Optimization for the Discrete Film Cooling of a Turbine Airfoil
Authors: El Ayoubi Carole , Ghaly Wahid , Hassan Ibrahim
Published: March 2016

A multiple-objective shape optimization is implemented for two staggered rows of discrete film cooling holes on the suction surface of a turbine vane. The optimization aims to maximize the film cooling performance while minimizing the corresponding aerodynamic penalty. The cooling performance is assessed using the adiabatic film cooling effectiveness, while the aerodynamic penalty is measured with a mass-averaged total pressure loss coefficient. The conical expansion angle, the compound angle, and the length to diameter ratio of the non-expanded portion of the hole are selected as geometric design variables. The effect of varying the geometric variables on the adiabatic film cooling effectiveness and the aerodynamic penalty is analyzed using the optimization method and three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations. A non-dominated sorting genetic algorithm (NSGA-II) is coupled with an artificial neural network (ANN) to perform the multiple-objective optimization. RANS simulations are employed to construct the ANN network which produces low-fidelity predictions of the objective functions during the optimization. The Pareto front of optimum solutions is generated. Two optimum designs, denoted as the aerodynamic, and thermal optimums are chosen from the Pareto front and evaluated through RANS simulations. The optimum designs present improved performance in comparison to the reference design, which consists of cylindrical holes.
An Experimental and Numerical Study of Shape Memory Alloy-Based Tensegrity/Origami Structures
Authors: Rohmer John L. , Peraza Hernandez Edwin A. , Skelton Robert E. , Hartl Darren J. , Lagoudas Dimitris C.
Published: March 2016

This paper presents an initial experimental and numerical study on a novel concept of integrated tensegrity/origami morphing structures. Both tensegrity and origami are known for their potential transformative roles in applications in fields which exist at the interplay of shape, size, and function. Their integration, proposed here for the first time, is based on the interest in uniting the strengths of origami (membrane integration and folding capabilities) with the strengths of tensegrity (minimal mass and controllable rigidity). In order to achieve morphing capabilities while retaining low mass, the considered structures possess intrinsic material actuation provided by shape memory alloy (SMA) members. Two different representative structures of the proposed concept are studied. The first corresponds to a tensegrity/origami cylinder based on the double-helix tensegrity topology. Shape memory alloy wires play the role of the tensile members of the tensegrity structure while foldable surface components play the role of compressive members. The second structure corresponds to a tensegrity plate, which although not having a continuous dense surface, can be morphed in novel ways using origami principles. Fabrication of experimental prototypes and evaluation of the observed structural transformation are presented. Finite element analysis is performed to numerically evaluate the characteristics of the novel proposed structures. This initial study shows that the integration of tensegrity and origami results in a powerful combination that provides structural stability, flexibility in design and lightweight actuation mechanisms while allowing for significant deflections during morphing.
Implementation and Verification of RKPM in the Sierra/SolidMechanics Analysis Code
Authors: Littlewood David , Hillman Mike , Yreux Edouard , Bishop Joseph , Beckwith Frank , Chen Jiun-Shyan
Published: March 2016

The reproducing kernel particle method (RKPM) is a meshfree method for computational solid mechanics that can be tailored for an arbitrary order of completeness and smoothness. The primary advantage of RKPM relative to standard finite-element (FE) approaches is its capacity to model large deformations, material damage, and fracture. Additionally, the use of a meshfree approach offers great flexibility in the domain discretization process and reduces the complexity of mesh modifications such as adaptive refinement.

We present an overview of the RKPM implementation in the Sierra/SolidMechanics analysis code, with a focus on verification, validation, and software engineering for massively parallel computation. Key details include the processing of meshfree discretizations within a FE code, RKPM solution approximation and domain integration, stress update and calculation of internal force, and contact modeling. The accuracy and performance of RKPM are evaluated using a set of benchmark problems. Solution verification, mesh convergence, and parallel scalability are demonstrated using a simulation of wave propagation along the length of a bar. Initial model validation is achieved through simulation of a Taylor bar impact test. The RKPM approach is shown to be a viable alternative to standard FE techniques that provides additional flexibility to the analyst community.
Parametric Studies of Coal Gasification in an Entrained-Flow Gasifier
Authors: Zhang Cheng , Schultheiss Kiel , Mitra Aniruddha , Rahman Mosfequr
Published: March 2016

Although alternative energy sources, such as nuclear, wind, and solar, are showing great potential, hydrocarbon fuels are expected to continue to play an important role in the near future. There is an increasing interest in developing technologies to use hydrocarbon fuels cleanly and efficiently. The gasification technology that converts hydrocarbon fuels into syngas is one of these promising technologies. Entrained-flow gasifiers are the preferred gasifier design for future deployment due to their high carbon conversion, high efficiency and high syngas purity. Current designs of entrained-flow gasifiers still have serious problems such as injector failure, refractory failure, slag blockages, downstream fouling and poisoning, poor space efficiency, and lack of dynamic feedstock flexibility. To better understand the entrained-flow gasification process, we performed parametric studies of coal gasification in the laboratory-scale gasifier developed at Brigham Young University (BYU) using ANSYS FLUENT. An Eulerian approach was used to describe the gas phase, and a Lagrangian approach was used to describe the particle phase. The interactions between the gas phase and particle phase was modeled using the particle-source-in-cell approach. Turbulence was modeled using the standard k-ε model. Turbulent particle dispersion was taken into account by using the discrete random walk model. Devolatilization was modeled using a version of the chemical percolation devolatilization (CPD) model, and char consumption was described with a shrinking core model. Turbulent combustion in the gas phase was modeled using a finite-rate/eddy-dissipation model. Radiation was considered by solving the radiative transport equation with the discrete ordinates model. Second-order upwind scheme was used to solve all gas phase equations. First, the numerical model was validated by using experimental data for the mole fractions of the major species (CO, CO2, H2, and H2O) along the gasifier centerline. Then, the effects of concentrations of steam and oxygen at the inlets, and steam preheat temperature were studied. Model predictions found that increasing the steam concentration or steam preheat temperature in the secondary inlet generally decreases CO concentration, while increasing CO2 and H2 concentrations. Increasing the steam concentration in the secondary inlet showed no significant effects on predicted gas temperature in the gasifier. Increasing the oxygen concentration in the primary inlet generally increases gas temperature, CO and CO2 concentrations, while decreasing H2 concentration.
Method for Computational Implementation of Components Selection System
Authors: Weber Claudio J. , de Souza Gilberto F. M. , Hidalgo Erick M. P. , Mayer Mateus
Published: March 2016

The tools used to select mechanical components in a design process work separately, do not communicate with each other, and do not focus the selection process of all the components in a product as one, with all its interrelationships and the effects that one choice have over other to which it is connected, the effect over the production chain, and the supply logistic. To assist in this process a method for component selection is being proposed to be implemented in an expert system (ES) that can select all the components in one integrated form without requiring the use of other tools. The method is organized in two stages, the first one defines the classification and organization of components based on ontology. The second step, the information is organized as a matrix of decision for each component group. In order to allow the information use by the ES, they need to be expressed in a metric way. The influence information of a component over another one, which the first is connected to is empirical, undocumented, and is related to the application mode. These influences generate technical requirements on the borderer components, so they are connected and structured by a dependency matrix. The information of decision matrix and influences are used for creating a knowledge base, based on rules to select the components. As a result the selected components are shown in a structure as a tree, where all selected components for the project are seen, how they connect, the influence that one causes over the other, the justification of selection, what criteria and emphasis are used in the selection, which requirements is necessary in the parts to be manufactured, and which components may not be used and why. In order to show how the method works, it will be used the design of a machine’s transmission.
Convective Heat Transfer and Pumping Power Requirement Using Nanofluid for the Flow Through Corrugated Channel
Authors: Noor Shafi , Ehsan M. Monjurul , Mayeed M. S. , Islam A. K. M. Sadrul
Published: March 2016

Convective heat transfer rate for turbulent flow using nanofluid through both plain and corrugated channel has been investigated numerically in the present study. Three different types of nanofluids namely Al2O3-water, TiO2-water and CuO-water of different volume fractions (1%, 2%, 3%, 4% and 5%), are used as the working fluid flowing through the channel. The corrugated channels have wall geometries of trapezoidal shape of different amplitude-wavelength ratios. Grid independence study was carried out for all the geometries. The obtained results in case of base fluid-water flowing through parallel plate channel have been validated with well-established correlations. The study has been conducted by finite volume method to solve the transport equation for the momentum, energy and turbulence quantities using single phase model of the nanofluids where the thermophysical properties of the nanofluids are calculated by using different correlations from the literature. In this study, the heat transfer enhancement using nanofluids compared to that using base fluid-water is presented for a range of Reynolds number- 15000 to 40000. The pumping power required for the flow through the channels increases with the increase in the viscosity of the fluid which justifies the increase in pumping power requirement in case of nanofluids compared to that with water. While using corrugation at the wall of the channels, in addition to the enhancement in the convective heat transfer rate, there is an increase in the pumping power requirement for the same Reynolds number. However, for a given requirement of heat transfer rate, the required pumping power can be reduced by using nanofluids. This study includes the trend and limit of volume fraction of nanofluid during this pumping power reduction phenomenon. The results show that with the increase in the volume fraction of the nanofluids, the convective heat transfer rate increases which is same for all the geometries of the fluid domain. Addition of nanofluid reduces the pumping power requirement for a constant heat transfer rate. The volume fraction of the nanofluids with which the maximum reduction of pumping power takes place at the optimum working condition is also found in the present study. This study draws a comparison among three different nanofluids in terms of the enhancement in the convective heat transfer rate and corresponding pumping power requirement for the flow through the trapezoidal shaped corrugated channel of various amplitude-wavelength ratios in order to find out the best nanofluids for its optimum results within a specified range of working conditions.
Creation of Statistically Equivalent Periodic Unit Cells for Protein-Bound Soils
Authors: Rosa Isamar , Roedel Henning , Lepech Michael D. , Loftus David J.
Published: March 2016

In 2010, NASA was directed to develop technologies to reduce the cost and risk of space exploration and send humans beyond the International Space Station. A central challenge to long-duration space missions is a lack of available construction materials in situ. This work focuses on a novel class of composites that can be produced extraterrestrially in situ by desiccating a mixture of soil, water, and protein binder to create a strong, versatile material. To date, experimental tests of mechanical properties have shown significant variability among samples.

This paper focuses on the creation of Statistically Equivalent Periodic Unit Cells (SEPUC) to stochastically model protein-bound composites for the purpose of creating FE models that provide insights into experimental results. Model inputs include the soil granulometry and volume fractions of the phases. Ellipsoidal particles are placed, and protein coatings and bridges are created, using a Level Set based Random Sequential Addition algorithm. Each image is assigned a statistical descriptor and a simple genetic algorithm is used to optimize for a statistical descriptor close to that of experimental specimens.

The framework is validated by comparing experimental images of protein-bound soils obtained by micro-CT scanning with those obtained through the SEPUC framework.
Numerical Simulation of Filtration of Charged Oil Particles in Stationary and Rotating Tubular Membranes
Authors: Jahangiri Mamouri Sina , Tarabara Volodymyr V. , Bénard André
Published: March 2016

Cross flow filtration (CFF) is a common membrane separation process with applications in food, biochemical and petroleum industries. In particular, membranes can be used for liquid-liquid separation processes such as needed in oil-water separation. A major challenge in cross flow filtration is membrane fouling. It can decrease significantly the permeate flux and a membrane’s efficiency. Membrane fouling can be mitigated by inducing shear on the membrane’s surface and this can be enhanced by inducing a swirl in the flow. In addition, a possible approach to improve membrane efficiency consists of repelling droplets/particles from the porous surface toward the centerline using a repulsive electric force. For this purpose, the surface of the membrane can be exposed to electric potential and droplets/particles are also induced to have the same electric charge.

In this work, numerical simulations of charged non-deformable droplets moving within an axially rotating charged tubular membrane are performed. The results show that by increasing the electric potential on the membrane surface, the repelling force increases which obviously improves the grade efficiency of the membrane. However, the electric field gradients found in the flow field require large potentials on the membrane surface to observe a noticeable effect. Hence, a smaller solid cylinder is located in the centerline of the flow channel with zero potential. This solid cylinder enhances the electric field gradient in the domain which results in higher repelling forces and larger grade efficiency of the membrane at small potentials. The addition of a small cylinder in the flow field also improves the grade efficiency increases due to the higher shear stress near the membrane surface.
Using LES to Understand Wake Evolution During the Diurnal Cycle
Authors: Nielson Jordan , Bhaganagar Kiran
Published: March 2016

Numerical study using actuator-line method based Large Eddy Simulation (LES) has been performed to understand the role of atmospheric stability on the wake effects of horizontal-axis full-scale 5-MW wind turbine (WT). The paper will specifically focus on using specific instances in the diurnal cycle corresponding to stable, neutral and unstable ABL state to gain understanding on the transient aerodynamics of a wind turbine throughout the diurnal cycle. Capturing accurate Atmospheric Boundary Layer (ABL) characteristics is key factor in improving the accuracy of WT model predictions as turbulence developed in the ABL has potential to adversely affect the fatigue lifetime and performance of wind turbines. ABL simulations for the diurnal cycle are performed to isolate the key ABL metrics such as surface momentum flux, boundary layer height, surface temperature flux, wind shear, and temperature gradient that influence the wake evolution of WT. Precursor ABL inflow is generated for the WT simulations. The positive heat flux on the surface causes high vertical velocity fluctuations described with streaks and updraft motions during the day while surface cooling rates result in increased shear and strong temperature gradients during the night. The surface temperature, geostrophic wind velocity, heating/cooling rates, and period of the diurnal cycle are varied in different simulations to compare turbulent statistics and the helical vortices of the wind turbine wake. The results have revealed surface temperature and surface flux are the important ABL metrics that have a strong effect on altering the turbulence in the WT wake. In addition, instabilities related to WT blade rotation exhibit sensitivity to ABL metrics. The positive heat flux shows higher mixing and causes large wake movement in the day-time conditions. The results aid in quantifying the movement of the wake at different times of the diurnal cycle. During night-time conditions mixing is low, causing slower wake recovery times. This is the first study to clearly isolate the key ABL metrics that influence the full-scale WT near-wake effects The study has implications in improving the predictions of WT power loss due to wake deficits. Further, this study sets an important direction on future modeling studies in identifying the ABL conditions in a diurnal cycle that influence the WT wake evolution.