bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Dimensional Simulation of Ventilation Flow Through a Solar Windcatcher
Authors: Abdo Peter , Taghipour Rahil , Huynh B. P.
Published: November 2019

Natural ventilation is the process of supplying and removing air through an indoor space by natural means. There are two types of natural ventilation occurring in buildings: winddriven ventilation and buoyancy driven or stack ventilation. The most efficient design for natural ventilation in buildings should implement both types of natural ventilation. Stack ventilation which is temperature induced is driven by buoyancy making it less dependent on wind and its direction. Heat emitted causes a temperature difference between two adjoining volumes of air, the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. Combining the wind driven and the buoyancy driven ventilation will be investigated in this study through the use of a windcatcher natural ventilation system. Stack driven air rises as it leaves the windcatcher and it is replaced with fresh air from outside as it enters through the positively pressured windward side.

To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the winddriven ventilation alone, buoyancy driven ventilation alone, and combined buoyancy and winddriven ventilation. Different wind speeds between 0 up to 2.5 m/s are applied and the total air flow rate through the windcatcher is investigated with and without temperature of 350 K applied at the windcatcher’s outlet wall. As the wind speed increased the efficiency of the solar windcatcher decreased.
Effect of Pipe Inclination on Solids Distribution in Partially Stratified Slurry Flow
Authors: Matoušek Václav , Krupička Jan , Konfršt Jiří , Vlasák Pavel
Published: November 2019

Partially stratified flows like flows of sand-water slurries exhibit non-uniform distribution of solids (expressed as a vertical profile of local volumetric concentration) in a pipe cross section. The solids distribution in such flows is sensitive to pipe inclination. The more stratified the flow is the more sensitive its concentration profile is to the pipe slope. In general, the distribution tends to become more uniform (less stratified) if the inclination angle increases from zero (horizontal pipe) to positive values (ascending pipe) up to 90 degree (vertical pipe). In a pipe inclined to negative angles (descending pipe) the development is different. The flow tends to stratify more if it changes from horizontal flow to descending flow down to the angle of about −35 degree. If the angle further decreases towards −90 degree, then the flow becomes less stratified reaching uniform distribution at the vertical position.

This also means that the same flow exhibits a very different degree of stratification in ascending and descending pipes inclined to the same (mild) slope say between ±10 and ±40 degree. The rather complex development of the solids distribution with the variation of the inclination of pipe is insufficiently documented experimentally and described theoretically in predictive models for a concentration profile in partially stratified flow.

In order to extend the existing limited data set with experimental data for partially stratified flow of medium sand slurry, we have carried out a laboratory experiment with the slurry of narrow graded fraction of sand with the mean grain size of 0.55 mm in our test loop with an invert U-tube inclinable to arbitrary angle between 0 and 90 degree. A pipe of the loop has an internal diameter of 100 mm. Both legs of the U-tube have a measuring section over which differential pressures are measured. Radiometric devices mounted to both measuring sections sense concentration profiles across a pipe cross section. Furthermore, the discharge of slurry is measured in the test loop.

In the paper, experimental results are presented for various inclination angles with a small step between 0 and ±45 degree and a development in the shape of the concentration profiles with the changing inclination angle is analyzed. For the analysis, it is critical to distinguish between suspended load and contact load in the flow as the two loads tend to react differently to the flow inclination. The measured concentration profiles and pressure drops are compared with predictions by the layered model adapted for taking the flow inclination into account.
Characterization of Thermals in a Heated Turbulent Boundary Layer
Authors: Dennis Kadeem , Siddiqui Kamran
Published: November 2019

The hydrodynamic boundary layer encountered in many practical engineering systems is turbulent in nature and known to play a significant role in governing the induced friction drag and species transport. In turbulent boundary layer flows, heat transfer is often involved which increases flow complexity due to the influence of buoyancy. When the buoyant force is sufficiently large in magnitude, thermals carrying heated fluid are known to detach and rise from the wall. Literature review shows that in mixed convection, thermals have been primarily identified through qualitative flow visualizations and there is a scarcity of their quantitative assessment. Furthermore, the evolution of thermals in the boundary layer with respect to flow inertia and viscous shear is not well-understood. Hence, there is a need for a better understanding of the dynamics of thermals in mixed convection turbulent boundary layer flow.

The objective of this study is to experimentally investigate the three-dimensional nature of thermals rising from a turbulent boundary layer flow over a heated smooth horizontal flat plate. Experiments were performed in a closed loop low-disturbance wind tunnel with a test section featuring a 1 m long heated bottom wall. The multi-plane particle image velocimetry (PIV) technique was used to capture images in multiple planes with respect to the turbulent boundary layer mean flow direction for three-dimensional characterization. The measurements were conducted at Richardson numbers (Ri) of 0.3, 1.0, and 2.0. Flow visualization images are used to describe the nature of thermals and the dynamical processes involved during their interaction with bulk boundary layer flow. An image processing algorithm to detect thermals is then detailed and applied to experimental images. The performance of the new algorithm is then assessed in its ability to detect thermals.
Validation of a Developed Assessment Procedure for the Functional Performance of Wastewater Pumps
Authors: Pöhler Michael , Hasirci Ümit , Rese Tim , Thamsen Paul Uwe
Published: November 2019

To date, there is no standardised test available, which assesses the actual performance of a pump for wastewater (especially its clog-resistance) as well as providing references about its efficiency. The developed testing procedure presented in this paper can display the different levels of performance for different pumps. The functionality of the pump, together with its efficiency is aggregated to the Functional Efficiency Index (FEI). The developed testing procedure is validated with two pumps from the field. Both are considered to be very prone to clogging by their respective wastewater network operators.
Simulation of the Wake of the Flow Around Two Side-By-Side Circular Cylinders at Reynolds Number 5000
Authors: Jensen Anna Lyhne , Sørensen Henrik , Hærvig Jakob
Published: November 2019

Interaction between the wakes of two cylinders in side-by-side configuration creates interesting flow phenomena. The nature of the wake depends on the Reynolds number and the transverse pitch distance between the cylinders. The flow over two side-by-side cylinders of equal diameter is simulated in 3D at Reynolds number 5000 using Large Eddy Simulation (LES). The centre-to-centre transverse pitch ratio is varied and the flow behind the cylinders is classified into either a bi-stable flow regime with biased gap flow or a regime with parallel vortex streets. Furthermore, representative instantaneous flow fields, Strouhal number and the time varying drag coefficient C′D are presented.
Investigations Into Wet Wipe Related Clogging Phenomena of Wastewater Pumps
Authors: Mitchell Raja-Louisa , Busche Susanne , Thamsen Paul Uwe
Published: November 2019

To gain a better understanding of the operational problems confronting wastewater pumps due to nonwoven wet wipes, experimental data generated in a laboratory setting were compared with data collected in the field. Pump blockages from a wastewater pump operating in the field under normal conditions were collected and analysed. The types of wet wipes occurring in the blockages were identified and were categorised according to their (claimed) flushability. The clogging effect of comparable wet wipes was then investigated in the laboratory using a wastewater pump with a low resilience against clogging. Profound differences in the clogging effect of the nonwoven wet wipes could be observed. It could also be shown that wet wipes labelled as “flushable” have different clogging effects, depending on whether or not they comply with industry flushability guidelines.
DSMC Simulation of Rarefied Gas Flow Over a Wall Mounted Cube
Authors: Nabapure Deepak , Murthy Ram Chandra
Published: November 2019

The present study investigates the flow behavior of the rarefied gas over a wall-mounted cube. The problem is studied for different cube heights (h) of 9mm and 18mm in the slip and transition regimes. The Direct Simulation Monte Carlo (DSMC) method is employed to evaluate the properties such as velocity, pressure and temperature fields. The Reynolds number (Re) ranges from 403 to 807, and the Knudsen number (Kn) is in the range from 0.05 to 0.103. A typical shock wave is formed in front of the cube. The recirculation length of the vortices normalized with respect to the respective cube heights for Kn = 0.05 and Kn = 0.103 are about 1.11 and 1.95 respectively. Similarly, the center of the vortices is located at about 3.33 and 6.11 times the respective cube heights upstream, for Kn = 0.05 and Kn = 0.103. The local temperature and pressure variations observed upstream of the cube are two orders higher in magnitude and are primarily attributed to strong compressibility effects. The present study paves the way for benchmarking, and forms a basis for understanding the rarefied gas flows over complex geometries.
Predictive Model for Two-Phase Flow Performance of Mixed Flow Pumps
Authors: Patil Abhay , Ayyildiz Burak , Pirouzpanah Sahand , Delgado Adolfo , Morrison Gerald
Published: November 2019

Multiphase pumps are increasingly being used to transport gas-liquid multiphase flow in the oil and gas industry. Complexity of two-phase flow interaction and varying designs of multiphase pumps pose significant challenges to developing generalized performance prediction tool similar to the affinity laws. The goal of this study is to characterize the performance of two multiphase pumps with different specific speeds using experimental data to develop generalized prediction models. Initially, the performance is investigated in the terms of head, power input and efficiency for different Gas Volume Fractions (GVF). Dimensional analysis is performed to evaluate the effect of pump geometry and GVF. Head degradation due to the presence of gas is presented in the terms of dimensionless numbers. These numbers represent the systematic change in the energy loss due to two phase flow interaction and inherent characteristics of the pump design. This is utilized to develop a generalized model for two phase flow. The study is concluded by validating the model using experimental data.
Comparison of Field Measurements and Large Eddy Simulations of the Scaled Wind Farm Technology (SWiFT) Site
Authors: Blaylock Myra L. , Houchens Brent C. , Maniaci David C. , Herges Thomas , Hsieh Alan , Knaus Robert C. , Sakievich Philip
Published: November 2019

Power production of the turbines at the Department of Energy/Sandia National Laboratories Scaled Wind Farm Technology (SWiFT) facility located at the Texas Tech University’s National Wind Institute Research Center was measured experimentally and simulated for neutral atmospheric boundary layer operating conditions. Two V27 wind turbines were aligned in series with the dominant wind direction, and the upwind turbine was yawed to investigate the impact of wake steering on the downwind turbine. Two conditions were investigated, including that of the leading turbine operating alone and both turbines operating in series. The field measurements include meteorological evaluation tower (MET) data and light detection and ranging (lidar) data. Computations were performed by coupling large eddy simulations (LES) in the three-dimensional, transient code Nalu-Wind with engineering actuator line models of the turbines from OpenFAST. The simulations consist of a coarse precursor without the turbines to set up an atmospheric boundary layer inflow followed by a simulation with refinement near the turbines. Good agreement between simulations and field data are shown. These results demonstrate that Nalu-Wind holds the promise for the prediction of wind plant power and loads for a range of yaw conditions.
A Numerical Study of Sand Particle Erosion in a Series of Ball Seats in Gas-Particle Two-Phase Flow
Authors: Rasteh A. , Farokhipour A. , Rasoulian M. A. , Mansoori Z. , Saffar-Avval M. , Ahmadi G. , Mofakham A. A.
Published: November 2019

Fracking (fracturing) is of great importance for enhancing oil and gas production from low permeability reservoirs. Since in fracking fluid, suspension of sand particles are used, the erosion failure of fracturing equipment has become an increasing concern. Accordingly, investigation of erosion of commonly used fittings such as ball seats in order to decrease its adverse consequences has attracted considerable attentions. Although the erosion wear of gas-solid flows in the pipe sudden expansion was investigated in the literature, the effect of particle size, ball seat shape and the contraction configurations on the erosion-induced wear is not fully understood. This study is aimed to explore the most erosion-resistant configuration of a ball seat under various operational conditions. A CFD model is used and a wide range of geometries are investigated. The studied configurations are categorized in three main groups including single cone, double cone and curved cone. In each category, different cone angles and curve styles are considered.

The results showed that, among the single cone ball seats, the cone angle of 15° is the most erosion-resistant configuration. It was also shown that the third-order curve style cone has the best erosion performance.
Flow Characterization of Microfluidic Paper-Based Analytical Devices With Hollow Channels
Authors: Zhang Haipeng , Barmore Danielle , Ryu Sangjin
Published: November 2019

Microfluidic paper-based analytical devices (μPADs) are cost-effective point-of-care diagnostic devices. μPADs consist of porous filter paper patterned with hydrophobic solid ink barriers to create flow channels. Because a liquid sample flows through the paper channel driven by capillary force, the resultant flow is usually slow. To overcome this limitation, a hollow channel can be added to a μPAD to increase the flow speed significantly. The liquid flow through the hollow channel is known to be driven by a pressure difference between the inlet and outlet of the device. Accordingly, theoretical models have been proposed to understand and predict flow characteristics of μPADs with hollow channels. The goal of this study is to experimentally characterize liquid flow through μPADs having a hollow channel, by investigating relationships among the travel distance of the liquid front through the μPADs, the applied pressure difference, and the dimension of the hollow channel. Thus, the outcome of this study would contribute to validating the theoretical models and enable better control of liquid sample flow in μPADs with hollow channels.
Locomotive Capabilities of a Free-Swimming Robotic Tuna
Authors: Noviasky Nicholas , Matta Alexander , Bayandor Javid
Published: November 2019

As we try and understand more about the oceans and the creatures that inhabit them, the need for effective modes of aquatic transportation becomes abundantly clear. Taking a step back from traditional propeller-based systems, we look toward nature and the millions of years of natural selection to find inspiration. The successful designs that have prospered vary greatly from creature to creature depending on their lifestyle. From rays to jellyfish, the propulsion methods used are tailored for a specific purpose. Considering the vastness of the oceans and our desire to explore them, a quick and efficient mode of locomotion would be well suited for this task. A great example of this type of swimmer can be found within the genus Thunnus.

Tuna rely on a lift-based propulsion system classified as thunniform swimming. The majority of thrust from this propulsion method is derived from the caudal fin and part of the tail. As the tail sweeps through the water, interesting vortex structures are shed from the trailing edge of the lunate fin. Along with velocity components that travel parallel to the movement of the fish, two separate vortices are shed from the top and bottom inner surfaces of the caudal fin and meet at the lengthwise center axis of the fish. These can be best visualized from the flow velocity components analyzed within a plane just behind the caudal fin and perpendicular to the body length axis. Over time, a reverse Karman vortex street is formed from the combination of vortices from multiple tail beats. A robotic tuna and CFD model were created with the minimum number of joints to approximate thunniform swimming.

A modified scotch yoke mechanism was used to convert uniform rotation of a brushless DC motor to oscillatory motion that mimics the tail of a tuna. A servo is mounted on the tail to provide an adjustable angle of attack for the caudal fin. The dynamic CFD model of the tuna employs overset meshing techniques created in ICEM CFD 18.2 and is simulated within ANSYS Fluent 18.2. The model is actuated at the start of the tail and the base of the fin to represent thunniform swimming. The body of the tuna is held static as steady flow is passed around the model. The flow velocity was chosen as an approximation of the speed of a tuna of comparable size and tail-beat frequency.
Neutron Imaging of Capillary Effect Under High-Pressure and High Temperature Condition
Authors: Susanto Wilson , Ihara Tomonori , Hazuku Tatsuya , Morooka Shinichi , Ito Daisuke
Published: November 2019

The supercritical water reactor (SCWR), which is one of the generation IV reactor concepts, has particular thermal hydraulics features. If a severe accident happens and pressure and mass flux in a reactor core are rapidly decreased, a film boiling on a fuel cladding tube surface may occur at subcritical conditions. Once the film boiling happens, heat transfer on the cladding tube surface drastically deteriorated and may result in serious damage to the reactor core. The cooling capability during the film boiling depends on the wetting phenomenon, therefore, experiments to clarify wettability phenomenon in subcritical condition are required.

One of the experiments to clarify the wettability phenomenon is the capillary action experiment. In the closed system, the water level will elevate due to the injection of the water. The difference in water elevation is due to the capillary force in the different diameter of the pipes. Based on the different water levels with known surface tension, it is possible to quantify the contact angle. The challenge of the experiment is to measure the precise elevation of the water in small diameter metal pipes under high-temperature and high-pressure condition. Therefore, the neutron imaging was applied in this experiment. Neutron imaging is a structure visualization technique. The principle is the neutron flux captured after passing through the object for visualizing the structure of an object. Neutron flux which is captured using a scintillator plate thus can be seen as an image using CCD video camera.

Our research group focuses on the radiation induced surface activation (RISA) effect. Significant improvements of surface wettability and boiling heat transfer on oxide film coatedmaterials by the RISA were confirmed especially under room temperature conditions. In this present research, we evaluate the RISA effect on capillary action in a subcritical condition using the various diameter of the pipe. Neutron imaging was used to visualize the water-gas interface in small diameter stainless steel pipes. The capillary pipes with various inside diameters such as 0.5, 0.8, 1.2, 1.4, and 1.8 mm were used as a test section which was heated up to a temperature of 320° C under a pressure of 21 MPa. The pipes irradiated by γ-ray with an integrated irradiation dose of approximately 500 kGy and non-irradiated pipes with various diameters are installed in parallel and water levels in each pipe were compared to evaluate capillary action differences.
Design and Verification of Cooling Fans for Engine Rooms of Mobile Hydraulics Vehicles
Authors: Kim J.-H. , Lee G.-P. , Lim C.-H. , Lee S.
Published: November 2019

To provide an engine room of mobile hydraulic vehicle with an effective cooling for the combination set of a radiator, a charge air cooler, and an oil cooler, a 500mm-diameter, axial fan is designed to have a 8,800 m3/hr at a resistance of 20mm Aq static pressure with a sound power level less than 86 LwA. The design parameters of sweep angle amplitude, wavelength of sweep angle change, airfoil type, and stagger angle are examined in terms of fan performance and its sound power generation. The surface curvatures generated by the sinusoidal sweep angle variation in the radial direction are proved to result in quite different flow patterns, thereby different types of specific sound power characteristics at the same flowrate. The acoustic noise sources are examined and discussed by using an acoustic imaging technique.
Computational Evaluation of Stability in Slosh Dynamics of Tank Vehicles Using Zero Moment Point
Authors: Usman M. , Sajid M.
Published: November 2019

Sloshing characterized by inertial waves has an adverse effect on the directional dynamics and safety of partially filled tank vehicles, limiting their stability and controllability during steering, accelerating or braking maneuvers. A mathematical description of the transient fluid slosh in a horizontal cylindrical tank should consider the simultaneous lateral, vertical and roll excitations assuming potential flows and a linearized free-surface boundary condition. While the determination of vehicle stability would require coupling this model to a dynamic roll plane model of a tank vehicle resulting in a computationally expensive analysis. Considering the need for a simpler method to predict roll stability for partially filled tank vehicles, we explore the Zero Moment Point of a liquid domain as a novel solution to this challenge. Numerical investigations are carried out in a three-dimensional partially filled tanks while tracking the movement of the liquid-air interface by employing the volume of fluid method in OpenFOAM. The center of Mass and Zero Moment Point were calculated from the computational results using analytical expressions. The movement of free surface is found to be in good agreement with available literature. The center of mass of the liquid domain was traced as a practical means to quantify the slosh in the tanker. The analyses are performed for different fluid fill heights at varying speeds. The results suggest that the roll stability of tank vehicles can be efficiently analyzed using the zero moment point with significantly lower computational effort.
An Optical Method for Measuring Water Wave Profiles
Authors: Dan Kazuhide
Published: November 2019

When sunlight waves travel into the interface between water and air sunlight waves refract at this interface and produce the fringe pattern in brightness or the light intensity profiles on the sandy bottom in coast. These fringe patterns related to wave profiles are experimentally recorded at the observation board below the transparent glass test channel using an artificial light inside a laboratory. It is possible to calculate the wave profile by applying Suzuki-Sumino method to this fringe pattern in experiment by recording a video closely in front of the inspection area and by using a plano convex lens in order to produce parallel waves. The purpose of this research is to show an optical method to measure gravity wave profiles in experiment. In this paper the modified method is shown to measure the wave profile correctly to collaborate an optical method using a plano convex lens and a calibration method using a capacitance-type wave meter.
Requirements Culture: A Case Study on Product Development and Requirement Perspectives
Authors: Elena Maria Vittoria , Wentzky Chase , Summers Joshua D.
Published: November 2019

A desire to better understand requirements and their uses within product development inspired this case study conducted at a large power tool company. Researchers were interested in determining if a requirements culture existed within the company investigated, how this culture varied across departments, and how individuals at the company viewed requirements in engineering design. Ten semi-structured interviews were conducted by five teams of interviewers over the course of two months to answer these questions. Employees in various positions across the company were interviewed in the study including Project Engineers, a CAD Designer, an Industrial Designer, Project Managers, and Vice Presidents. Through a detailed analysis of the interview transcripts and documentation, it was determined that the company did have a definite requirement culture and that the transfer of requirements across departments must remain consistent for the individual groups to be effective. Furthermore, it was found that employee engagement with requirements was more significant with those who were involved in the early stages of product development.
Simultaneous Resonance and Anti-Resonance in Dynamical Systems Under Asynchronous Parametric Excitation
Authors: Karev Artem , Hagedorn Peter
Published: November 2019

Since the discovery of parametric anti-resonance, parametric excitation has also become more prominent for its stabilizing properties. While resonance and anti-resonance are mostly studied individually, there are systems where both effects appear simultaneously at each combination resonance frequency. With a steep transition between them and a high sensitivity of their relative positions, there is a need for a concurrent study of resonance and anti-resonance. The semi-analytical method of normal forms is used to derive approximate analytical expressions describing the magnitude of the stability impact as well as the precise locations of stabilized and destabilized areas. The results reveal that the separate appearance of resonance and anti-resonance is only a special case with synchronous parametric excitation. In particular, in circulatory systems the simultaneous appearance is expected to be much more common.
The Effect of Starvation on a Thermal Mixed EHL Line Contact
Authors: Li Sheng , Masse Danielle
Published: November 2019

To investigate the effect of the inlet starvation severity on the flash temperature, which dictates the scuffing failure, a thermal mixed elastohydrodynamic lubrication model is developed for line contacts operating under the starved lubrication condition. The scuffing failure of high speed gearing applications is commonly associated with the very high sliding condition occurring in the vicinity of either the root or the tip, where the shear thinning effect that decreases the lubrication film thickness and increases the contact pressure is significant. Utilizing a generalized Newtonian Reynolds equation, the lubricant viscosity dependence on the shear rate, as well as on the pressure and temperature, is incorporated for the proper and accurate modeling of the tribological behavior under the high sliding condition. A film fraction parameter is employed in the Reynolds equation to include the starvation and cavitation description, eliminating the need for the measured or assumed meniscus location in the inlet zone. Considering different operating and surface roughness conditions, a parametric study is performed to show an asymptotic relationship between the flash temperature and the inlet starvation severity.
Geometric Simulation for Thick Origami
Authors: Kwok Tsz-Ho
Published: November 2019

Origami is an art that creates a three-dimensional (3D) shape only by folding. This capability has drawn much research attention recently, and its applied or inspired designs are utilized in various engineering applications. Most current designs are based on the existing origami patterns and their known deformation, but origami patterns are universally designed for zero-thickness like a paper. To extend the designs for engineering applications, simulation of origami is needed to help designers explore and understand the designs, and the simulation must take the material thickness into account. With the observation that origami is mainly a geometry design problem, this paper develops a geometric simulation for thick origami, similar to a pseudo-physics approach. The actuation, constraints, and mountain/valley assignments of origami are also incorporated in the geometric formulation. Experimental results show that the proposed method is efficient and accurate. It can simulate successfully the bistable property of a waterbomb base, two different action origami, and the elasticity of origami panels when they are not rigid.
A Novel Hybrid Modeling Method for Contact Problems
Authors: Liu Qian , Li Haiquan , Ma Ou
Published: November 2019

Accurately modeling of many practical contact scenarios such as robotic grasping and assembly is a challenging problem because of complex contact geometry and surface uncertainties. This paper presents a new hybrid contact model (HCM), which combines a traditional physical model and a data-driven model to make a more accurate description of a contact dynamics phenomenon. When a physical model is employed to describe a complex contact case, it usually has error from an experimental data measured from the contact case to be modeled because of inevitable unmodeled and/or unknown factors. The data-driven model is used to represent this error, which is an artificial neural network model trained from experimental data using a machine learning technique. A bouncing ball example is presented to demonstrate the feasibility of the presented approach.
Vibrations of a Double Beam Structure Carrying a High-Pressure Driven Projectile
Authors: Khair Alexander , Yang Bingen
Published: November 2019

In this paper, a mathematical model of a double beam structure carrying a high-pressure driven projectile is developed for investigation of the physical behaviors of gun barrels during firing. The dynamic response of such a weapon system is particularly interesting when reduction of muzzle vibrations and relevant dynamic stress in the structure is needed to improve the life cycle of the gun. In the model presented, the Timoshenko beam theory is implemented, and realistic characteristics of the physical system are considered. Numerical simulation results are presented for the displacement and rotation of the two beams, and the rigid-body projectile mass.
An Improved Model for Calculating the Mesh Stiffness of Helical Gears
Authors: Wei Jing , Hou Shaoshuai , Zhang Aiqiang , Zhang Chunpeng
Published: November 2019

Time-varying mesh stiffness (TVMS) is one of the important internal excitations of gear transmission systems. Accurate solution of meshing stiffness is the key to research the vibration response of gear transmission system. In the traditional analytical method (TAM), the TVMS of single-teeth engaged region consist of bending, shearing, axial compression deformation stiffness, fillet-foundation stiffness, and Hertzian contact stiffness, the TVMS of double-tooth engaged region is the sum of the single-tooth engaged region, which will lead to repeated calculation of the fillet-foundation stiffness. In order to overcome this shortcoming, considering the coupling effect between two pairs of meshing tooth, an improved method of fillet-foundation is adopted to calculate to TVMS of each slice gear. According to the ‘slicing method’, the helical gear is divided into slice gear. Considering the coupling effect of each slice gear, the TVMS of helical gear can be obtained. The improved analytical method (IAM) is verified by comparing with finite element method (FEM) and TAM. Based on the IAM, the effects of the helical angle, face width, the number of gear, and modification coefficient on the mesh characteristics are analyzed. The results show that the IAM is consistent with the FEM and also consistent with TAM in single-tooth engagement. However, there is obviously error with the TAM in double-tooth or multi-tooth engagement.
Research on Prediction Method of Transmission Accuracy of Harmonic Drive
Authors: Hu Qiushi , Liu Zhifeng , Cai Ligang , Yang Congbin , Zhang Tao , Wang Guang
Published: November 2019

Harmonic drive is an indispensable device for robotic joint, and transmission accuracy of harmonic drive is one of its most important performance indexes. Due to the unsystematic research on the accuracy of harmonic drive, the accuracy consistency of harmonic drive is poor, and the prediction accuracy is seriously insufficient. This study focuses on modeling of transmission error system and prediction of transmission accuracy. Through tracing analysis of transmission error of harmonic drive, a transmission error model including manufacturing, assembly and tooth profile error is established. Based on Rayleigh distribution of error sources and considering multi-tooth meshing effect of harmonic drive, the transmission accuracy prediction model is built. Tooth profile error is measured by gear measuring center, dimension error and geometric tolerance are gauged by coordinate measuring machine. The transmission accuracy of three types harmonic drive (SHG14, SHG20 and SHG25) is measured by harmonic transmission error test bench under rated conditions. The comparison results show that the difference between the predicted and experimental values is less than 15%, which proves the validity of the accuracy prediction model. Prediction method play a crucial role for accuracy control of harmonic drive system.
Dynamical Modelling and Control of Snake-Like Motion in Vertical Plane for Locomotion in Unstructured Environments
Authors: Javaheri Koopaee Mohammadali , Pretty Christopher , Classens Koen , Chen XiaoQi
Published: November 2019

This paper introduces the equations of motion of modular 2D snake robots in the vertical plane. In particular, the kinematics of pedal wave motion (undulation in vertical plane) of modular snake robots is presented and using the Euler-Lagrange method, the equations of motion of the robot are obtained. Moreover, using the well-known Spring-Damper contact model, external contact forces are taken into account and pedal wave locomotion on uneven terrain is modelled and simulated. Enabled by the dynamical model of the robot, an adaptive controller based on external force feedback in gait parameter space is proposed and implemented, resulting in the robot to successfully climbing over a stair-type obstacle without any prior knowledge about the environment.
Complete Bifurcation Trees of Independent Period-2 Motions to Chaos in a Parametrically Excited Pendulum
Authors: Guo Yu , Luo Albert C. J.
Published: November 2019

In this paper, bifurcation trees of independent period-2 motions to chaos are investigated in a parametrically excited pendulum. The implicit discrete mapping method is employed to obtain periodic motions in such a system. Analytical predictions of periodic motions are based on the mapping structures and peroidicity. The bifurcation trees of independent period-2 motions to chaos are studied, and the corresponding stability and bifurcation analysis are completed through eigenvalue analysis. Finally, sampled period-2 motions are simulated numerically in comparison to the analytical predictions. The infinite bifurcation trees of independent period-2 motions to chaos can be obtained.
Theoretical Modeling and Performance Analysis for Electromagnetic Energy Harvesting From Galloping
Authors: Tan Ting , Sun Weipeng , Yan Zhimiao , Zhang Wenming
Published: November 2019

Galloping-based energy harvester was developed for scavenging small-scale wind energy. An electromechanical coupled distributed parameter model is proposed based on the Euler-Bernoulli beam theory, quasi-steady approximation and Gauss law for electromagnetic energy harvesting from the galloping. The analytical solutions are derived using the equivalent structure method and confirmed by the numerical solutions of the full coupled model. In addition to the aerodynamic properties, modal shape and structural damping, the onset speed to galloping, tip displacement and harvested power are also functions of the electric damping and modified natural frequency. Such two critical variables depend on the natural frequency, coil inductance, coupling factor, load resistance and coil resistance. The bifurcation and performance analyses are conducted. Two optimal load resistances are found for the maximal power at fixed resistance ratio. When the resistance ratio changes, the optimal load resistance is unique. Larger resistance ratio, larger electromagnetic coupling factor and higher wind speed lead to higher maximal power. For small resistance ratio, there is an optimal magnet position to maximize the power. For large resistance ratio, the power increases monotonously with the magnet position. With small electromagnetic coupling factor, the power is higher with lower tip displacement at smaller coil inductance. The maximal power occurs at the medium coil inductance with large electromagnetic coupling factor.
Investigation on Adaptive Filter for On-Line Detection and Active Control of Chatter Vibration in Milling Process
Authors: Wan Shaoke , Li Xiaohu , Su Wenjun , Hong Jun
Published: November 2019

On-line detection and active control of chatter vibration have always been important issues in milling process respectively. To some extent, the signals obtained with sensors determine the performance of on-line detection and active control of chatter. However, due to the characteristics of milling process, the obtained signals are mainly consisted with spindle rotation frequency and its harmonics, and the chatter components are usually submerged by these stable harmonics, imposing negative effects for the detection and active control of milling chatter. Then, it is highly needed to design a real-time filter to filter out the spindle rotation frequency and its harmonics. In this paper, an adaptive filter is designed to filter out the spindle speed related components. Moving average (MR) model and adaptive filter theory is utilized to estimate these periodic components. The influence of filter order and step size factor on the filter characteristics are also analyzed. Considering that the filter order needs to be adjusted under different cutting conditions, which will alter the filter’s performance, an improved adaptive filter is proposed. Experiments are also performed and the experimental results show that, not only the spindle speed related components can be filtered out effectively, but the chatter frequency components are amplified with appropriate initial step factor, which is beneficial for the detection of milling chatter at early stage. Meanwhile, the periodic components caused by the installation error and the other spindle speed related components can be effectively filtered out real-timely, preventing the saturation of actuator caused by these stable components.
Investigating Optimal Communication Frequency in Multi-Disciplinary Engineering Teams Using Multi-Agent Simulation
Authors: Arezoomand Mojtaba , Austin-Breneman Jesse
Published: November 2019

Complex engineering design tasks require teams of engineers with different skills and unique knowledge sets to work together to develop a solution. In these contexts, team communication is critical to successful design outcomes. Previous research has identified effective management of communication frequency as an important dimension of team communication leading to improved design outcomes. Organization research literature has demonstrated a curvilinear relationship in which both frequent and infrequent communication may hamper organizational performance. In contrast, recent work in engineering design research has found an inverse relationship between frequency and technical system performance for simple design tasks. This paper extends this work quantifying the impact of communication frequency on technical system performance by examining multi-disciplinary problems. Results from a multi-agent simulation on a six discipline parameter design task for minimizing the weight of a geostationary satellite are presented. Simulation results suggest that the form of relationship between frequency and performance changes significantly depending on the communication pattern. The evidence suggests that for the same design task a planned periodic communication pattern results in a curvilinear relationship, whereas for a stochastic communication pattern a less pronounced monotonic inverse relationship is found.
Water-Egressing Mobility of an Amphibious Vehicle With a Controllable H-Driveline
Authors: Vantsevich Vladimir V. , Gorsich David J. , Paldan Jesse R. , Sandomirsky Sergey
Published: November 2019

A new H-driveline system with controllable planetary gear sets for terrain and amphibious combat vehicle applications is presented. This new driveline system is based on two major components/innovations: 1) controllable distribution of power between individual driving wheels in response to specifics of operation profile, and 2) upgrading and reconfiguring the design of the driveline system to reduce the unsprung mass. Introducing Controllable Planetary Gear Sets makes the vehicle’s wheel-hub planetary gear sets controllable. The gear ratio of each CPGS can be individually managed in order to deliver to the wheels specific drive torques/rotational speeds in response to the wheel-terrain conditions of an operation profile. This individual wheel power distribution provides major contribution to mobility and energy saving. The reconfigured layout of the H-driveline reduces the wheel assembly weight (unsprung mass) and, thus, can improve the smoothness of vehicle ride and supports additional fuel saving. This paper analytically proves a potential of the H-drive system to improve mobility of an 8 × 8 amphibious vehicle when the vehicle egresses water.
Two Way Coupled Analysis of Fluid Force in the Annular Plain Seal and Vibration of the Rotor System Using Shooting Method
Authors: Kunori Yudai , Inoue Tsuyoshi , Miyake Kenjiro
Published: November 2019

In turbomachinery, the rotor dynamic (RD) fluid force generated in a fluid element is one of the causes of shaft vibration. RD fluid force is caused by the interaction between shaft vibration and fluid force, and its precise prediction for various rotor’s orbit is difficult. This study performs a two-way coupled analysis of the fluid flow in the annular plain seal and shaft vibration using the shooting method. The frequency response is obtained and compared with that obtained from a direct numerical simulation of the coupled system, and the validity of the analysis is confirmed. The onset speed of instability is effectively and accurately obtained using the two-way coupled analysis with the shooting method, and the effects of the parameters on it are investigated.
Integrative Design of Product Architecture and Assembly Process Plan
Authors: Toi Masato , Sawai Kana , Kobayashi Masahide , Nomaguchi Yutaka , Fujita Kikuo
Published: November 2019

This paper proposes an integrative design method of product architecture and assembly process plan by introducing a matrix-based modeling and analysis scheme. Design structure matrix (DSM) has been used to analyze and design the conceptual structure of product architecture. An assembly sequence diagram, such as a fishbone diagram, has been used as a representation scheme of the assembly process in the design-for-assembly (DFA) framework. The method of this paper is composed of a DSM-based procedure for generating an assembly sequence plan and its integration with a DSM-based design method of product architecture. In this paper, after general meanings of integration in product design are reviewed, the overall method for integration and mathematical procedure for optimizing an assembly sequence plan by compromising with components modularity are described. The procedure for generating an assembly sequence plan is demonstrated with an example of a desktop stapler, and the integrative design is demonstrated with a case study of air-conditioner units. This paper concludes with some discussion on the role of the proposed framework toward the integrity of product design.
A New Robotic Hand for Automotive Sheet Panels
Authors: Gao Dalong , Huang Ninja , Ransom Lance , Janis Richard
Published: November 2019

As the market goes to more diversified segments, automotive manufacturing needs to be more flexible in order to adapt to the market changes effectively. Meantime in flexible tooling/clamp design it is not acceptable to sacrifice the production requirements — holding force, working envelop, size, etc. in exchange for higher flexibility. In this paper we present a new innovative robotic hand for sheet panel applications for automotive body assembly. The new robotic mechanism of the hand enables the fingers to access sheet panels in different locations and orientations, while providing large and consistent holding force needed during production cycle. The mechanism design and validation tests of first prototype were presented. The results showed that the robotic hand satisfied the basic specifications as an automotive body assembly gripper and could be used in multi-style tools to lower manufacturing cost.
Topology Optimization of Multi-Material Lattices for Maximal Bulk Modulus
Authors: Kazemi Hesaneh , Vaziri Ashkan , Norato Julián
Published: November 2019

In this paper, we present a method for multi-material topology optimization of lattice structures for maximum bulk modulus. Unlike ground structure approaches that employ 1-d finite elements such as bars and beams to design periodic lattices, we employ a 3-d representation where each lattice bar is described as a cylinder. To accommodate the 3-d bars, we employ the geometry projection method, whereby a high-level parametric description of the bars is smoothly mapped onto a density field over a fixed analysis grid. In addition to the geometric parameters, we assign a size variable per material to each bar. By imposing suitable constraints in the optimization, we ensure that each bar is either made exclusively of one of a set of a multiple available materials or completely removed from the design. These optimization constraints, together with the material interpolation used in our formulation, make it easy to consider any number of available materials. Another advantage of our method over ground structure approaches with 1-d elements is that the bars in our method need not be connected at all times (i.e., they can ‘float’ within the design region), which makes it easier to find good designs with relatively few design variables. We illustrate the effectiveness of our method with numerical examples of bulk modulus maximization for two-material lattices with orthotropic symmetry, and for two- and three-material lattices with cubic symmetry.