bluuebunny/crossref_metadata_2025 huggingface dataset:
Cancelling Gyroscopic Effects in AMB Systems With Flexible Rotors via Modal Feedback
Authors: Sahinkaya Alican , Sawicki Jerzy T.
Published: January 2020

For active magnetic bearing (AMB) systems with rotors having significant polar to transverse moments of inertia ratio, the influence of gyroscopic effects needs to be considered in controller design procedures to prevent excessive vibrations and potential instability during operation. This consideration leads to conservative controllers due to large uncertainties caused by the rotational speed range of the rotor, or gain-scheduled controllers that require larger computational power, both of which are not desirable. A cross-feedback control has been applied in the literature to compensate for the gyroscopic effects of AMB systems with rigid rotors. However, the method is not applicable to AMB systems with flexible rotors due to lack of full-state sensory information and under actuation. This paper proposes a novel modal state feedback control as an addon controller for AMB systems with flexible rotors to compensate for the gyroscopic effects of selected modes. The aim of the add-on controller is to alter the open loop AMB system such that the open loop dynamics presents reduced gyroscopic effects of the selected modes from a controller point of view, reducing the uncertainties in the model for robust controller design. The proposed approach is demonstrated on an AMB rotor test rig with a rotor configuration featuring noticeable gyroscopic effects. The comparison of the frequency response data of the open loop AMB system with and without the proposed add-on controller shows the feasibility of the approach.
Calibration Strategies and Modeling Approaches for Predicting Load-Displacement Behavior and Failure for Multiaxial Loadings in Threaded Fasteners
Authors: Mersch John P. , Smith Jeffrey A. , Orient George E. , Grimmer Peter W. , Gearhart Jhana
Published: January 2020

Multiple fastener reduced-order models and fitting strategies are used on a multiaxial dataset and these models are further evaluated using a high-fidelity analysis model to demonstrate how well these strategies predict load-displacement behavior and failure. Two common reduced-order modeling approaches, the plug and spot weld, are calibrated, assessed, and compared to a more intensive approach — a “two-block” plug calibrated to multiple datasets. An optimization analysis workflow leveraging a genetic algorithm was exercised on a set of quasistatic test data where fasteners were pulled at angles from 0° to 90° in 15° increments to obtain material parameters for a fastener model that best capture the load-displacement behavior of the chosen datasets. The one-block plug is calibrated just to the tension data, the spot weld is calibrated to the tension (0°) and shear (90°), and the two-block plug is calibrated to all data available (0°–90°). These calibrations are further assessed by incorporating these models and modeling approaches into a high-fidelity analysis model of the test setup and comparing the load-displacement predictions to the raw test data.
Development of a Virtual Lab in Assistance of a Fluid Mechanics Laboratory Instruction
Authors: Zhao Yitong , Flanagan Elbon , Abbasi Hamza , Black Kayla , Wang Xin , Cardona Andres
Published: January 2020

Physical laboratory experiments are built to provide students with hands-on opportunities and have long been crucial for engineering training. However, due to the rapid growth in number of enrollments, limited and shared space, undergraduate students have experienced an increasing difficulty gaining valuable hands on experience in the lab. While traditional lab should never be abandoned, adding virtual labs to assist with it could benefit students without the limitation of enrollment capacity or lab availability. In this paper, we discussed a pilot study of developing a virtual fluid mechanics laboratory to supplement existing physical lab exercises.

The virtual lab was designed to enrich students’ lab experience, stimulate interests, and bring more individual exercise time. It was developed to contain two components: a virtual lab tour and a virtual reality (VR) simulated pump experiment. The virtual tours served as a pre-lab instruction tool that provided students with an overview of the fluid mechanics lab. The VR pump experiment replicated the physical experience of performing the physical lab.

Preliminary feedbacks were positive for both components of the virtual lab. Students considered that the virtual tours were very informative and useful, while that the VR pump lab was intuitive and time-saving. This proved that with realistic lab simulations, the virtual lab had great potential to provide students more flexibility to perform hands-on experiment and to develop technical acumen outside of the physical classroom. Further improvement was discussed to implement in the next stage to create more immersive experience in assistance of the lab instruction.
Analysis of a Stokes Flow Past a Cube (Friction and Diffusion Coefficients for Brownian Dynamics Simulations)
Authors: Okada Kazuya , Satoh Akira
Published: January 2020

Magnetorheological properties significantly depend on the regime of aggregate structures. In the case of cubic particles, closely-packed clusters that are significantly different from those for the case of spherical or rod-like particles are formed in the system since magnetic cube-like particles prefer a face-to-face contact with the neighboring particles. Therefore, a cubic particle suspension is expected to exhibit a sufficiently strong magnetorheological effect, which may be investigated by means of Brownian dynamics simulations. However, the translational and rotational diffusion (or friction) coefficients of a cube are not known and indispensable in order to develop this simulation technique. From this background, in the present study, we have analyzed the flow field around a cube in a Stokes flow regime in order to estimate the diffusion (or friction) coefficients of cube-like particles that are required for performing Brownian dynamics simulations of a cubic particle suspension. In the situation of a uniform flow field with a Reynolds number sufficiently smaller than unity, the force acts on the cube only in the flow field direction, and the torque acting on the cube may be regarded as negligible. In the situation of a rotational flow field with a sufficiently low Reynolds number, the torque acts on the cube only in the direction of angular velocity of the rotational flow field, and the force negligibly act on the cube. These characteristics are in significantly similar to those for the case of spheres in a Stokes flow situation. From these results, we may conclude that the diffusion coefficients of cube-like particles can be expressed by introducing a correction factor to those of the spherical particles.
Simulation of MoS2 Nanolayer Membrane Performance for Water Desalination Using ReaxFF
Authors: Oviroh Peter Ozaveshe , Han Jitian , Jen Tien-Chien
Published: January 2020

The use of nanolayer membrane for desalination is an emerging new technology for water purification. Improvements in nanotechnology have led to the development of a variety of nanolayer membranes such as MoS2 and Graphene for water purification that could replace current materials used for reverse osmosis. The reaction of water on 2D monolayer of Molybdenum disulphide (MoS2) was studied using the ReaxFF. Different vacant sites were created such as Mo- and S-vacancy, MoS and S2-divacancy, MoS2 and MoS2-triple for the minimization. The H-O-H and O-H-H molecule demonstrated a stable negative adsorption energy on the different vacancies created, while both the Mo vacancy+H-O-H and the Mo+S2 triple vacancy+O-H-H produced positive binding energies which are unfavourable to adsorption. The molecular dynamics simulation was done to study the factors which could influence membrane performance thereby guide to physical tests. Pore chemistry play a significant role in modulating the water flux and this is explained through the energy barriers.
Monocular Visual Inertial Odometry (VIO) Dataset Collection With a Self-Calibrating Platform for Inertial Measurement Unit (IMU)
Authors: Tian Yuan , Compere Marc
Published: January 2020

In this study, we built a monocular visual inertial odometry (VIO) dataset with a proposed self-calibrating platform for an inertial measurement unit (IMU). For a learning-based method, lack of database is the biggest limitation. One goal of this study is to generate a high-quality VIO database. Meanwhile, a properly calibrated inertial measurement unit (IMU) is critical for improving VIO system accuracy and precision. However, a professional IMU calibration tool is usually expensive and large. The proposed self-calibrating platform shows its benefits in eliminating the manual work in calibration and reducing the cost of the expensive platform, which brings more opportunities to students and researchers. This self-calibrating system was useful for collecting monocular visual inertial odometry datasets while driving. . The calibrated IMU generates 14 numbers at 100Hz: time, 3-axis accelerometer measurements, 3-axis gyroscope measurements, 3 Euler angles, and 4 quaternions. This VIO system is composed of a monocular camera, GoPro Hero 3, an IMU, BNO055, and a GPS, ANT-555. The sensors are mounted on a John Deere Gator™ Full-Size Crossover Utility Vehicle and are operated on an Intel NUC, a mini-size computer. The final dataset contains monocular images, IMU measurements, and GPS outputs.
Design of a Turbopiston Pump Guided by Computational Analysis
Authors: Wang Ting , Rousset Patrick W.
Published: January 2020

An innovative pump, TurboPiston Pump (TPP), has been invented to incorporate the merits of centrifugal, axial, and positive displacement pumps. The TPP is designed to deliver large flow rates with a potential at high pressure of up to 1000 psia with one stage. To improve the original design, an understanding of the flow behavior inside the pump is needed. The objective of this study is to simulate the flow field inside the pump and study its performance to guide the design process. This study includes modeling the pump with the transient sliding mesh scheme using a commercial computational fluid dynamics solver, ANSYS/FLUENT. The flow pattern, static pressure distribution, and total pressure losses are calculated and analyzed. The regions of high total pressure losses and potential creation of cavitation are identified. A plastic demonstration model and a metal prototype have been fabricated based on the result of the CFD analyis.
A Hypothesized Mechanistic Model of Longitudinal Wall Motion at the Common Carotid Artery
Authors: Hao Zhili , Reynolds Leryn , Herre John M.
Published: January 2020

In light of recently recognized independent clinical values of longitudinal wall motion ux(t) at the common carotid artery (CCA) and the struggle on appropriate arterial indices for interpreting ux(t), this paper hypothesizes a mechanistic model of ux(t) and explores clear implications of the antegrade amplitude ux0-ante and retrograde amplitude ux0-retro of ux(t) in systole to the cardiovascular (CV) system. By examining findings on ux(t) and other relevant findings through the lens of the engineering essence of ux(t), a mechanistic model of ux(t) is hypothesized: the left ventricle (LV) base rotation is the excitation source for initiating the longitudinal elastic wave propagating along the arterial tree; wall shear stress at an artery serves as a local external source for supplying energy to the longitudinal elastic wave; and longitudinal elasticity at the arterial wall dictates the wave propagation velocity. Integrating the mechanistic model with findings on ux(t) gives rise to interpretation of ux0-ante and ux0-retro for their clear implications: longitudinal elasticity Exx at the common carotid artery (CCA) is estimated from ux0-ante, and ux0-retro is an inverse indicator of the maximum base rotation of the LV and a positive indicator of longitudinal elasticity at the ascending aorta (AA). For the first time, this model reveals the mechanisms underlying those statistical-based findings on ux(t).
Finite Element Analysis of the Effect of Porosity on the Plasticity and Damage Behavior of Mg AZ31 and Al 6061 T651 Alloys
Authors: Perkins Allen , Yang Wenhua , Liu Yucheng , Chen Lei , Yenusah Caleb
Published: January 2020

Porosity has been known to have a profound effect on a material’s mechanical properties, often weakening the material. Highly porous metallic materials prove troublesome for supporting a load-based structure due to the voids that are present throughout the microstructure of the material. In this study, the previously developed ISV damage plasticity model is used to investigate the effect of the porosity on aluminum alloy 6061-T651 and magnesium alloy AZ31 through finite element analysis (FEA). It is determined that porosity has a profound impact on the strength of the aluminum alloy and much lesser effect on the magnesium alloy. Porosity is also shown to affect other properties of the materials, such as the hardness and pore growth.
Designing a Better Virtual Reality (VR) Experience
Authors: Asencio Armand J. , Graham Ian C. , Korsen Ryan , Ma Guohua , McCusker James
Published: January 2020

Virtual reality (VR) is a great new technology which has extensive applications, and it is imperative that there is a way to use VR comfortably. This will allow VR to become an everyday tool, creating a more interactive world. With more VR integration new technologies can be created and allow VR to expand further into fields like therapy or military training. However, VR comes with some unfortunate side effects. The cybersickness that many people experience when using a VR system has been shown to trigger a thermoregulatory response that causes sweating, the sensation of being excessively hot, as well as nausea. These symptoms of cybersickness make it uncomfortable to use a VR system for any long period of time. In order to combat this, the authors present a device which can effectively cool the user to extend the time duration a user can comfortably use a VR system.
Estimating Pacejka (PAC2002) Tire Coefficients for Pneumatic Tires on Soft Soils With Application to BAJA SAE Vehicles
Authors: Saunders Amanda , White Darris , Compere Marc
Published: January 2020

BAJA SAE is an engineering competition that challenges teams to design single-seat all-terrain vehicles that participate in a vast number of events, predominately on soft soils. Efficient performance in the events depends on the traction forces, which are dependent on the mechanical properties of the soil. To accurately model vehicle performance for each event, a model of the tire traction performance is required, and the tire model must be incorporated with a vehicle dynamics simulation. The traction forces at the soil-tire interface can be estimated using the Bekker-Wong stress integration method. However, commercially available vehicle dynamics simulation software, with a focus on on-road vehicles, does not utilize Bekker-Wong parameters. The Pacejka Magic Tire (MT) Formula is a common method for characterizing tire behavior for on-road vehicles. The parameters for the Pacejka MT Formula are usually produced by curve fitting measured tire data. The lack of available measured off-road tire data, as well as the additional variables for off-road tire performance (e.g. soil mechanics), make it difficult for BAJA SAE teams to simulate vehicle performance using commercial vehicle simulation tools. This paper discusses the process and results for estimating traction performance using the Bekker-Wong stress integration method for soft soils and then deriving the Pacejka coefficients based on the Bekker-Wong method. The process will enable teams to use the Pacejka Magic Tire Formula coefficients for simulating vehicle performance for BAJA SAE events, such as the hill climb, (off-road) land maneuverability, tractor pull, etc.
A First Principle Study on the Adhesion and Stability of Al203 (0001)/Pt (111) Film Interface
Authors: Mohlala Lesego M. , Coetzee Rigardt A. M. , Jen Tien-Chien , Olubambi Peter A.
Published: January 2020

The first-principles calculation with density functional theory (DFT) is a powerful tool for studying solid-solid interfacial behaviour at the atomic scale. In this study, the interfacial properties of Al2O3 (0001)/Pt (111) atomic layer deposited film, such as adhesion strength, fracture toughness; interfacial energy and stability are investigated using the Cambridge Serial Total Energy Package (CASTEP) code in Material Studio. Two interface models with different Pt (111) configurations are investigated to elucidate their influence on the adhesion strength and interfacial stability. Moreover, the density of states plots (PDCS) is presented to further comprehend the electronic structures and bonding nature of interface. The work of adhesion obtained from the calculations is 2.836 J/m2 and 2.694 J/m2 for model 1 and 2 respectively. In addition, the interfacial energy for model 1 (−6.429J/m2) is smaller than that of model 2 (−5.881J/m2). The calculated results indicate that model 1 possesses high interface strength and thermodynamic stability. The lattice mismatch was calculated to be 10.46%, suggesting the formation of semi-coherent interface formation with coherent structural interface structures and misfit dislocation networks (MDN). The results obtained from the density functional theory simulations were compared and correlated with available literature.
Research on the Diagnosis Method of Reciprocating Compressor Valve Leakage Fault With Vibration Signal
Authors: Zhang Zetian , Hou Chenggang , Li Xueying , Zhang Zhaoning
Published: January 2020

Reciprocating compressor is one of the key machines in chemical and petrochemical industries. The most common failure mode in the compressor is valve leakage. Generally, leakage fault is considered to be of little harm to machines. However, it was found that the serious leakage of the valve would cause abnormal bending vibration of the piston rod and accelerate the formation of fatigue cracks. Most researchers utilized the signal of cylinder dynamic pressure, valve temperature or acoustic emission to diagnose valve leakage fault. However, each of these methods has disadvantages.

In this paper, a new method is proposed to diagnose valve leakage fault using vibration signal. The main idea is that the severity of valve leakage can be assessed by analyzing energy of the main frequency band during compression process and the delay of discharge valve opening. Firstly, the vibration signal in the time domain is segmented into several angle-domain signals according to the keyphasor signal. Each of the angle-domain signals corresponds to one cylinder working cycle. Then, the time-frequency analysis is conducted with the Gaussian window, and the main energy frequency band and the compression process are determined. Filtering the signal with a bandpass filter based on the main energy frequency band, and the root-mean-square (RMS) of the filtered signal during compression process is calculated in a crank revolution. Besides, the angle of discharge valve opening is detected. Based on the two indicators, the severity of valve leakage can be estimated.

To verify the effectiveness of the method, keyphasor of the flywheel, cylinder dynamic pressure and vibration acceleration of valve are acquired on a double-acting oil-free air compressor under different degrees of suction valve leakage. The experimental results and analysis show that the proposed method can well identify the valve leakage fault, even in the case of weak leakage, and is very effective in quantifying the severity of leakage.
Robust Design of a Test Bench for PHM Study of Ball Screw Drives
Authors: Bertolino A. C. , De Martin A. , Jacazio G. , Mauro S. , Sorli M.
Published: January 2020

Over the last two decades, one of the most prominent research themes in the aerospace community involved the definition of “more electric aircrafts”. For flight control systems the trend is to replace the traditional electro-hydraulic solution with electro-mechanical actuators. However, safety issues severely hinder the diffusion of this technology. A possible breakthrough in this field can be the development of robust PHM techniques to anticipate the occurrence of failures.

Ball screws feature one of the highest failure rate within EMAs’ mechanical components. Since their accurate modeling is fairly complex, experimental results are needed to support simulation outcomes to help in the definition of reliable health monitoring schemes.

This paper presents the model-based design of a novel test bench intended for PHM analyses of ball screw drives. At first the test bench layout is introduced and compared to the state of the art. A high-fidelity model of the test bench is presented and exploited to perform a Monte Carlo simulation campaign with the goal to characterize its behavior versus measure and process noise in presence of varying size backlash. Finally, a test procedure for backlash identification is defined.
Cure Monitoring of Adhesive for Composite/Metal Bonded Structure Based on Highly Nonlinear Solitary Waves
Authors: Bin Wu , Mingzhi Li , Xiucheng Liu , Heying Wang , Cunfu He , Zongfa Liu
Published: January 2020

In this paper, a nondestructive evaluation technique based on highly nonlinear solitary waves (HNSWs) is proposed to monitor the curing process of adhesive for composite/metal bonded structure. HNSWs are mechanical waves with high energy intensity and non-distortive nature which can form and propagate in a nonlinear system, such as a one-dimensional granular chain. In the present study, a finite element model of the one-dimensional granular chain is established with the commercial software Abaqus, to study the reflection behavior of HNSWs at the interface between the particle at the end of chain and the sample. The simulation results show that the time of flight (TOF) of the primary reflected solitary wave decreases with the stiffness of the sample increases, and the amplitude ratio (AR) between the primary reflected solitary wave and the incident solitary wave increases. An HNSWs transducer based on the one-dimensional granular chain is designed and fabricated. The relationship between the characteristic parameters of the primary reflected solitary wave (TOF and AR) and the curing time of adhesive for a composite/metal bonded structure is experimentally investigated. The experiment results suggest that the TOF decreases and the AR increases as the epoxy cures. The experimental results are in good agreement with the simulation results. This study provides a new characterization method for monitoring the curing process of adhesive for composite/metal bonded structure.
Structural and Mechanical Analysis of Silane Compounds Coatings on AISI 304
Authors: Baruwa Akinsanya Damilare , Akinlabi Esther Titilayo , Oladijo O. P. , Mwema Frederick
Published: January 2020

The structures and mechanical strength existing in three different hydrophobic silane compounds, Henicosyl-1,1,2,2-tetrahydrododecyltrichlorosilane (FDDTS), Tridecafloro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and [Tris(trimethylsiloxy)silyethyl]dimethylchlorosilane (Alkyl) under same deposition conditions were studied and presented in this paper. The effect of the chemical composition on the mechanical strength and the structural evolutions as related to chlorosilane was inquired. The structures were investigated by using field emission scanning electron microscope (FESEM), atomic force microscope (AFM) and surface profiler while the nature of the mechanical strength was determined from nanoindentation and nano scratch. From the data obtained, the FDDTS showed to be denser in structures than both Alkyl and FOTS. The root-mean-square (RMS) roughness exhibited by FDDTS was larger when compared to the other two silanes. The mechanical ability shows that the FDDTS has the largest maximum penetration load as well as highest scratch resistance. Overall, the FDDTS would perform excellently in the applications where combine hard and wear resistance organic coating is required.
Conversion of a Heavy-Duty Diesel Engine to Natural-Gas Spark-Ignition Operation: Test Bench Development
Authors: Liu Jinlong , Dumitrescu Cosmin E. , Bommisetty Hemanth , Ulishney Christopher
Published: January 2020

Partial conversion of the large inventory of diesel engines to natural gas (NG) spark-ignition (SI) will reduce U.S. dependence on imported petroleum and enhance national energy security. This paper describes the methodology used to retrofit such an engine as well as the experimental setup used to investigate and optimize the conversion, including engine modifications, coupled dynamometer, engine control, and data acquisition system. Low-pressure gas injectors placed upstream of the intake valve produced a homogeneous combustible mixture inside the cylinder. The final setup was verified via experiments that changed the equivalence ratio from 0.7 to 1.0 at 900 rpm, using methane as a natural gas surrogate. The results showed that despite the higher compression ratio (which increased in-cylinder pressure and temperature at spark timing compared to conventional SI engines), a high-energy spark plug was necessary to produce robust and repeatable ignition. In addition, the moderate compression ratio of the converted engine (13.3) resulted in knock-free operation at all equivalence ratios. Finally, the reliable and stable operation at the investigated conditions (COVIMEP < 1.5%) and low rate of pressure rise (< 3 bar/deg CA) support this solution for converting diesel engines to NG SI operation, at least for the conditions investigated here. The trend of engine-out emissions agreed well with existing studies, which also validated the design of the test cell for optimizing engine efficiency and sampling emissions.
Integration of Digital Equipment Based on General Information Model and Model Mapping to MTConnect
Authors: Zhang Zhaokun , Shao Zhufeng , Wang Liping , Luo Yong
Published: January 2020

Integration of various kinds of digital equipment in manufacturing systems is the foundation and premise of cyber-physical systems and intelligent manufacturing. However, interfaces and datatypes of digital equipment from different vendors often differ from each other, which leads to system heterogeneity and information island problems. Heterogeneity becomes an obstacle for information integration. The key to solving this problem is the information model and the communication protocol. To solve the information integration problems among heterogeneous digital equipment, an implementation scheme based on the information model and its mapping to MTConnect is proposed and verified in this paper. First, the architecture and functions of integration of digital equipment are analyzed. Then, a general information model structure of digital equipment and the corresponding modeling rules are established, which can be used to guide the information modeling of various types of equipment. Next, the mapping rules that transform the information model to the MTConnect information model are defined. Based on the information model and model mapping to MTConnect, the digital equipment is able to integrate with other equipment or system via the mapping interface with the aid of the MTConnect protocol. Finally, the implementation of vertical integration based on the information model and its mapping to MTConnect is verified experimentally.
Study of Heating and Cooling Rate of Cobalt Oxide-Based TCES System Using Experimental Redox Kinetics Analysis
Authors: Vahedi Nasser , Romero Carlos E. , Snyder Mark A. , Oztekin Alparslan
Published: January 2020

Cost-effective solar power generation in CSP plants requires the challenging integration of high energy density and high-temperature thermal energy storage with the solar collection equipment and the power plant. Thermochemical energy storage (TCES) is currently a very good option for thermal energy storage, which can meet the industry requirement of large energy density and high storage temperature. TCES specifically exploits reversible chemical reactions wherein heat is absorbed during the forward endothermic reaction and released during the reverse exothermic reaction. The associated enthalpic storage of energy (i.e., the heat of reaction) offers higher density and enhanced stability compared to sensible and latent heat storage. Metal oxide redox reactions are particularly well-suited for TCES given their characteristically high enthalpy of reaction and high reaction temperature. In addition, the air is suitable as both a heat transfer fluid (HTF) and reactant; thus, simplifying process design and eliminating the need for indirect HTF storage and any intermediate heat exchanger. Among the palette of available metal oxides, cobalt oxide is one of the most promising candidates for TCES given its high enthalpy of reaction with high reaction temperature.

One of the critical design parameters for TCES reactors is the optimal heating and cooling rates during respective charging and discharging modes of operation. In order to study the effect of heating/cooling rate on cobalt oxide TCES performance, a constant 10°C/min rate was selected for both storage cycle heating and cooling. Considering the intrinsic redox kinetics of cobalt oxide at considered constant heating/cooling rate, we studied milligram scale quantities of cobalt oxide (99.9% purity, 40 μm average particle size) using a dual-mode thermogravimetric (TGA)/differential scanning calorimetry (DSC) system, which simultaneously measures weight change (TGA) and differential heat flow (DSC) as a function of TCES cycling under continuous air purge. In addition, we investigated the cyclic stability of cobalt oxide in the context of the redox kinetics and particle coarsening behavior, employing scanning electron microscopy (SEM).

TGA/DSC tests were conducted for 30 successive cycles using pure cobalt oxide. It was shown that pure cobalt oxide in powder form (38μ particle size) could complete both forward and reverse reaction at the selected heating rate with little degradation between cycles. In parallel, SEM was used to examine morphology and particle size changes before and after heating cycles. SEM results proved grain growth occurs even after only five initial cycles.
Experimental Setup of Combustion Visualization Inside a Heavy-Duty Diesel Engine Converted to Natural-Gas Spark-Ignition Operation
Authors: Padmanaban Vishnu , Liu Jinlong , Dumitrescu Cosmin E.
Published: January 2020

The conversion of existing diesel engines to natural-gas (NG) spark-ignition (SI) operation would reduce U.S. dependence on oil imports and curtail greenhouse gas emissions. As the literature shows that the combustion process in such converted engines is different compared to that in conventional SI engines, understanding the effects of the diesel geometry and fuel effects on the in-cylinder flame propagation is important for optimizing engine operation. This paper describes the experimental setup that allowed the visualization of combustion phenomena inside a single-cylinder diesel engine converted to single-fuel NG spark-ignition operation through the addition of a spark plug and a low-pressure gas injector. The synchronization between the piston position and image acquisition was done using over-the-counter electronic components. While the setup could not visualize flame propagation inside the squish region, the combustion images, together with the pressure-based analysis, help understand the characteristics of lean NG flame propagation inside a diesel geometry, which is an important for designing a highly-efficient combustion process.
Parametric Study of Metal 3D Printing Process Using Finite Element Simulation
Authors: Khanna Kshitiz , Yee Raymond K.
Published: January 2020

Metal additive manufacturing (AM), also known as metal 3D printing, is a challenging process to be controlled for desirable outcome due to its many process parameters. Residual stresses or deformations may occur in an AM manufactured part because of rapid heating and cooling cycles in the layers. The effect of process-controlled parameters in laser powder bed fusion (L-PBF) on deformations of a manufactured part has not been well examined and reported only sparely in literature. The objectives of this paper are: to study deformation behavior of a L-PBF printed part using finite element method, to perform parametric study of process input variables by changing few selected process parameters in the simulations, and to attempt identifying optimal values within the studied range of selected parameters to minimize part distortion. In this study, the material used for the heat sink finite element model was Inconel 718 which is commonly found in AM manufactured parts. ANSYS finite element program was employed to simulate a heat sink fabrication. The finished dimensions of the heat sink model were 12 mm in height, 26 mm in width, and 26 mm in depth. Thermal-mechanical sequential coupling approach was employed to simulate layer-by-layer built up process. The resulting deformations was evaluated by varying laser travel speed, base plate temperature, and initial layer angle. The maximum deformation (distortion) was observed at the corners of the heat sink model upon release from the base plate and found to be approximately 0.115 mm. Based on this study, the relative optimal simulation results for minimum distortion for selected parameters were 600 °K base plate temperature, 600 mm/sec speed of laser, and 0° initial layer angle. These results can be served as foundation for further study of varying other L-PBF process parameters.
Implementation of Multi-Scale Characterization and Visualization on Enhancement of Solid Mechanics Education
Authors: Wang Jingyu , Mason Nyree , Akasheh Firas , Kremer Gul , Siddique Zahed , Liu Yingtao
Published: January 2020

This paper presents the implementation and preliminary analysis of a multi-scale material and mechanics education module for the improvement of undergraduate solid mechanics education. 3D printed and conventional wrought aluminum samples were experimentally characterized at both the micro- and macro-scales. At the micro-scale, we focus on the visualization of material’s grain structure. At the macro-scale, standard material characterization following ASTM standards is conducted to obtain the macroscopic behavior. Digital image correlation technology is employed to obtain the two-dimensional strain field during the macro-scale testing. An evaluation of students understanding of solid mechanics and materials behavior concepts is carried out in this study to obtain the student data and use it as baseline for further evaluation of study outcomes. We plan to use the established multi-scale mechanics and materials testing dataset in a broad range of undergraduate courses, such as Solid Mechanics, Design of Mechanical Components, and Manufacturing Processes. Our current effort is expected to demonstrate the real materials’ multi-scale nature and their mechanical performance to undergraduate engineering students. The successful implementation of this multi-scale approach for education enhances students’ understanding of abstract solid mechanics theories and establishing the concepts between mechanics and materials. In addition, this approach will assist advanced solid mechanics education, such as the concept of fracture, in undergraduate level education throughout the country.
Designing and Analyzing Savonius Wind Turbines
Authors: Manne Varun Kumar Reddy , Zhou Hong
Published: January 2020

Savonius wind turbines are drag-type vertical axis wind turbines. Their blades experience less drag while moving against the wind flow and more drag while moving in the wind direction. The drag difference rotates Savonius wind turbines and produces electrical power. Savonius wind turbines can catch wind from any direction. No yaw motion mechanism is needed for them to be pointed in the wind direction. Savonius wind turbines have simple structures and are convenient to install and maintain. They can operate on low wind speed and have good starting characteristics. Compared with horizontal axis wind turbines and lift-type vertical axis wind turbines such as Darrieus and Giromill wind turbines, Savonius wind turbines have relatively low power conversion efficiency. This is because of their drag-type nature which generates positive and negative torque on their advancing and returning blades, respectively. Savonius wind turbines are suitable for locations where power conversion efficiency can be compromised for the sake of low cost and high reliability. One major drawback from Savonius wind turbines is the negative static torque which lowers their self-starting ability. Although the negative static torque of Savonius wind turbines can be mitigated by adding additional components such as curtains, nozzles and ducts to them, these additional components make them complex and lose omnidirectional performance. In this paper, Savonius wind turbines are designed based on their geometric parameters to remove their negative static torque and improve their performance. Savonius wind turbines with different numbers of blades and other geometric parameters are designed, analyzed and simulated.
Aero-Engine Vibration Propagation Analysis Using Bond Graph Transfer Path Analysis and Transmissibility Theory
Authors: Mir-Haidari Seyed-Ehsan , Behdinan Kamran
Published: January 2020

In recent times, due to the increase in global energy commodities prices, aero-engine manufacturers are investing in advanced aero-engine technologies to reduce the operating costs. These innovative technologies include overall weight reductions to develop efficient aero-engines. Due to these circumstances, the overall exposure of the aero-engine to vibration transfer due to various loading conditions such as the rotor loading forces has significantly increased. Due to advancement in technologies and demand for greater passenger comfort, vibration transfer reduction to the aircraft fuselage has received prominent attention. In this paper, an analytical transmissibility study called the bond graph Transfer Path Analysis (TPA) has been extensively studied and its applications are explored. Bond Graph TPA is a reliable and feasible theoretical methodology that can be implemented on various large mechanical systems in the design stages to tackle noise and vibration problems before prototyping to significantly reduce the development costs. Bond graph transfer path analysis (TPA) is an advantageous method compared to the existing empirical TPA methodologies such as the Operational Path Analysis due to its efficient analytical nature. In this paper, bond graph TPA has been implemented on a reduced aero-engine model to determine vibration contribution at various aero-engine locations to propose structural design guidelines to minimize the vibration transfer.
Dynamic Modeling and Analysis for a Planar Three Degrees-of-Freedom Manipulator Under Prescribed Mount Motion
Authors: Ono Takeyuki , Eto Ryosuke , Yamakawa Junya , Murakami Hidenori
Published: January 2020

This paper presents dynamic modeling of a planar, three degrees-of-freedom manipulator consisting of two parallel plates, referred to as top and base plates, which are connected by three actuated legs. When a sensitive equipment is carried by a moving robot or vehicle, it becomes necessary to mount the equipment on a platform which achieves precise positioning for stabilization. The objectives of this paper are to derive analytical equations of motion and apply them to control simulations on the stabilizing planar manipulator.

In the derivation of analytical equations of motion, the moving frame method is utilized to describe the kinematics of the two-dimensional multibody system. For the manipulator system comprised of jointed bodies, a graph tree is utilized, which visually illustrates how the constituent bodies are connected to each other. For kinetics, the principle of virtual work is employed to derive the analytical equations of motion for the manipulator system.

The resulting equations of motion are used to numerically assess the performance of a sliding mode controller (SMC) to stabilize the top plate from the motion of the translating and rotating base plate. In the numerical simulation, the SMC is compared with a simple PID controller to evaluate both the tracking performance and robustness.
Electro-Mechanical Behavior of Smart Sandwich Plates With Porous Core and Graphene-Reinforced Nanocomposite Layers
Authors: Behdinan Kamran , Moradi-Dastjerdi Rasool
Published: January 2020

The use of piezoelectric sensor and/or actuator layers in engineering structures provides smart sandwich structures with adaptive responses. Moreover, due to the brittle behavior of piezoceramic materials, inserting nanocomposite and porous layers between piezoelectric layers offers more flexible and lighter structures along with maintaining the advantages of nanocomposite materials. Therefore, in this paper, we have proposed smart sandwich plates consisting of a porous polymeric core and two graphene-reinforced composite (GRC) layers integrated with two piezoceramic layers. The distributions of porosities and randomly oriented graphene particles are assumed to be functionally graded (FG) along the thickness of core and nanocomposite layers, respectively. For the static behavior of the proposed sandwich plates, the coupled electro-mechanical governing equation has been extracted by minimizing potential energy equation with respect to displacement and electrical potential. The governing equation has been discretized by adopting a higher order shear deformation theory (HSDT) of plates and a developed mesh-free method. Using the developed solution framework, the effects of porosity and graphene characteristics, electromechanical loads, and layer thicknesses on the deflection behavior of the proposed FG piezoelectric porous nanocomposite sandwich plates (FG-PPNSPs) have been studied.
An Adaptive Integral Sliding Mode Control for the Sleeve Angle of a Novel Rotary Valve and its Experimental Study
Authors: Zhu Muzhi , Zhao Shengdun , Bao Dafei
Published: January 2020

In this paper, an adptive integral sliding mode control (AISMC) based on extended state observer (ESO) is proposed for the valve sleeve angle posotion control of a novel rotary valve for the first time. The novel rotary valve is designed for the electro-hydraulic transmission system with high frequency and flow especially adopted in the fatigue testing machine, and the unique valve structure and working principle is presented firstly to achieve the sleeve angle control model for the design of tracking controller. In order to obtain continuous reference trajectory and ensure control performance for integrel sliding mode, a third-order differentiator is designed and verified by matlab/Simulink simulation shows accurately tracking performance. To validate the excellence of the AISMC based on ESO, The spool position tracking experiment is also carried out on the test bench and the results show higher position tracking effectiveness and disturbance robustness compared with the PID controller.
Theoretical Model for Piezoelectric Energy Harvesting Device Based on Composite Granular Chain of Spheres
Authors: Bin Wu , Shuo Yang , Xiucheng Liu , Heying Wang , Ting Xiao , Cunfu He
Published: January 2020

In this study, a simple and high-performance piezoelectric energy harvesting devices (PEHD) based on composite granular chain of spheres (CGCS) is investigated. The CGCS is constructed by inserting a light granular chain into the middle of a heavy granular chain. When an impact imposed to the CGCS, the energy of the impact will be carried by solitary wave propagating in the chain. The existence of the heavy-light interface and light-heavy interface makes the middle section of chain a container to trap the energy of the solitary wave. Therefore, the solitary wave will reflect back and forth in the container and experience slow energy attenuation. Piezoelectric wafer is embedded into one of the spheres of the container to act as a PEHD.

Theoretical model of the proposed PEHD is given to explain the energy conversion process from external impact to the output voltage of the piezoelectric wafer. The bridge between the solitary wave-induced stress and the electric field is highlighted. Experiments are performed in CGCS to observe the solitary wave-induced voltage of the piezoelectric wafer and the measured waveform agree the theoretically prediction results. Finally, the effects of the differences in material properties of between the light and heavy spheres and the segment number of composite chain on the collected energy are investigated for improving the efficiency of capture energy. It is suggested that increasing the numbers of composite segments and enlarging the differences between the light and heavy sphere is helpful to improve the performance of CGCS-based PEHD.
A Novel Design of a Large-Stroke Shape Memory Alloy Linear Actuator
Authors: Yang Fei , Wang Jian , Han Miaoling , Lu Yifan , Yue Honghao , Wu Miao
Published: January 2020

The traditional actuation systems such as combustion engines, electro motors, hydraulic and pneumatic machines, have several drawbacks: large volume and weight, huge energy consumption and high cost. To overcome these problems, this paper presents a novel large-stroke linear actuator actuated by shape memory alloy (SMA) wires. Multiple SMA wires are distributed in the space three-dimensionally and connected in series to achieve a larger stroke of the actuator. The tandem structure makes the SMA actuator easy to integrate into a narrow available space with dimension constraints. A theoretical model for bias element selection is developed through analysis of the driving paths. A prototype of the proposed SMA actuator is fabricated and corresponding experiments are conducted to verify the functions and performances. The critical working performances of the SMA actuator such as the output displacement, heating electric current, actuation time and reset time are obtained and investigated. The results prove that the proposed SMA actuator can output an ideal driving stroke and enough actuation force in confined space. This research provides design ideas for the large-stroke SMA actuator in more application fields.
Study on Surface Roughness of Milling In-Situ TiB2 Particle Reinforced Al Matrix Composites
Authors: Liu Xiao-fen , Wang Wen-hu , Jiang Rui-song , Xiong Yi-feng , Lin Kun-yang , Zhang Zhan-fei
Published: January 2020

The current state of surface roughness focuses on the 2D roughness. However, there are shortcomings in evaluating surface quality of particle reinforced metal matrix composites using 2D roughness due to the fact that the measuring direction has a vital impact on the 2D roughness value. It is therefore of great importance and significance to develop a proper criterion for measuring and evaluating the surface roughness of cutting particle reinforced metal matrix composites. In this paper, an experimental investigation was performed on the effect of cutting parameters on the surface roughness in cutting in-situ TiB2/7050Al MMCs. The 2D roughness Ra, 3D roughness Sa and Sq were comparatively studied for evaluating the machined surface quality of in-situ TiB2/7050Al MMCs. The influence of cutting parameters on the surface roughness was also analyzed. The big difference between roughness Ra measured along cutting and feed directions showed the great impact of measuring direction. Besides, surface defects such as pits, grooves, protuberances and voids were observed, which would influence 2D roughness value greatly, indicating that 3D roughness was more suitable for evaluating surface quality of cutting in-situ TiB2/7050Al MMCs. The cutting depth and feed rate were found to have the highest influence on 3D roughness while the effect of cutting speed was minimal. With increasing feed rate, cutting depth or width, the 3D roughness increased accordingly. But it decreased as cutting speed increased.