bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Stress Intensity Factor Due to Concentrated Loads on Semi-Infinite Cracks in Orthotropic Materials
Authors: Rubio-Gonzalez C. , Wang C.-Y. , Mason J. J. 
Published: November 2021

Abstract
The transient elastodynamic response due to concentrated normal or shear impact loads on the faces of a semi-infinite crack in orthotropic materials is examined. Solution for the stress intensity factor history around the crack tip is found. Laplace and Fourier transforms together with the Wiener-Hopf technique are employed to solve the equations of motion in terms of displacements. An asymptotic expression for the stress near the crack tip is analyzed which leads to the dynamic stress intensity factor in modes I and II. Similar to the isotropic case, it is found that the stress intensity factor has a singularity and discontinuity when the Rayleigh wave emitted from the load arrives at the crack tip. Results are presented for a typical orthotropic material.
Impact Failure Analysis of Glass/Epoxy Textile Composites
Authors: Adanur Sabit , Onal Levent 
Published: November 2021

Abstract
The production parameters of composites are effective on the impact properties of the material. The effects of the number of layers, thickness, manufacturing characteristics such as molding time, molding temperature, molding pressure and the mixing ratio of epoxy resin and curing agent were examined at the same volume fraction ratio. There is an optimum point for most of the variables. Parameters below and above of this point lead an increase in deflection level. Impact velocity is effective on the composite properties as well.
Evaluation of P-Q Controllers for an Injection Moulding Machine
Authors: Guerrier Paul K. , Edge Kevin A. 
Published: November 2021

Abstract
There are a number of problems surrounding traditional velocity and pressure controllers used on injection moulding machines. Injection moulding machines are also very expensive and full scale testing is often not appropriate at the beginning of new controller evaluation. This paper presents results for a half scale ‘hardware-in-the-loop’ load emulation of the filling and packing phases of injection moulding, suitable for controller evaluation. The problems linked to the current industry standard velocity and pressure controller are discussed along with alternative strategies. Schemes including single controller fuzzy logic and neural network solutions are discussed and ruled out in favour of ones containing separate velocity and pressure controllers. Results for a model reference adaptive pressure controller are presented and compared with those obtained using a closed loop PI controller experimentally and in simulation. Experimentally the model reference adaptive controller outperforms the PI controller but does suffer from gain drift.
Fluid Power in Large Downhole Seismic Sensor Arrays
Authors: Cole Jack H. 
Published: November 2021

Abstract
High-resolution subsurface seismic imaging that places sources and receivers in wellbores is an emerging exploration technology that can help petroleum companies find and recover more oil and gas. Successful commercialization of this enabling technology requires the development of receiver arrays that can couple fifty or more three-component sensor modules to the wellbore in a reliable manner. Although electrical clamping systems have been successfully used in small arrays, hydraulic clamping is required for more than ten modules. Both inflatable-bladder and cylinder-actuated clamp arrays have been designed However, when arrays must operate in 200° C environments, elastomer bladders become unsuitable. Research at the University of Arkansas has produced a failsafe fluid power system design makes feasible the successful development of large seismic sensor arrays that can operate in deep well bores.
The Role of Dissolved and Nascent Air in Oil-Hydraulic Systems
Authors: Stern Hansjoerg 
Published: November 2021

Abstract
In modern, high performance hydraulic systems the transient behavior of dissolving, dissolved and nascent air under changing dynamic conditions of pressure and temperature is emerging as an increasingly important factor, capable of creating undesirable operating conditions. The paper discusses the question of how to predict the performance of pump inlets and valve discharges, where we have known for some time that cavitation and cavitation-like conditions exist and can cause significant damage. The steady state conditions at which nascent air evolves from saturated air-in-oil solutions is normally one or two orders of magnitude above the vapor pressure of the system fluid. To what extent, therefore, is “cavitation” in these systems an air-oil problem? Or is it an oil-vapor problem that is analogous to cavitation in water hydraulic pumps and turbines? Or have we created the combination of the two, a three-phase system of liquid, gas and vapor?
An Investigation Into the Characteristics of a “2D” Flow Control Valve
Authors: Ruan J. , Burton R. , Ukrainetz P. 
Published: November 2021

Abstract
In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve, (defined as a “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.
Flowing Granular Materials and the Maxwell-Boltzmann Velocity Distribution
Authors: Boyle Edward J. 
Published: November 2021

Abstract
The single-granule velocity distribution function is shown to be Maxwell-Boltzmann for hard-sphere granular flows at steady-state exhibiting no gradients and absent a body-force. This is accomplished by approximating the two-granule velocity distribution function as the product of two single-granule velocity distribution functions and a correlating function and by applying to a canonical ensemble a function analogous to Boltzmann’s H-function.
A Semi-Analytic Model for Free Vibration Analysis of Longitudinally Loaded Cantilever Shaft-Disk Systems
Authors: Sheu Hong-Cheng , Chen Lien-Wen 
Published: November 2021

Abstract
A semi-analytic model is proposed to study the critical speeds and critical loads of the cantilever shaft-disk systems subjected to longitudinal loads. In the present work, both the exact and approximate stiffness influence coefficients of the longitudinally loaded cantilever shafts are derived. In order to obtain deeper insight into the dynamic behavior of such a shaft-disk system, the present shaft mathematical model has taken account of shear deformation effect. Because the exact stiffness influence coefficients of the shaft are transcendental and difficult to get their characteristics on longitudinal load intuitively, each stiffness influence coefficient is expanded in a Taylor’s series about the longitudinal load. Based on the present approximate stiffness influence coefficients, the critical speeds and critical loads of the cantilever shaft-disk systems can be easily and quickly obtained. Numerical simulations show that the present results are seen to be quite in agreement with the exact solutions.
Effect of Core Plasticity on the Post-Buckling Behavior of Debonded Sandwich Beams
Authors: Sankar Bhavani V. , Narayanan Manickam , Sharma Abhinav 
Published: November 2021

Abstract
Nonlinear finite element analysis was used to simulate compression tests on sandwich composites containing debonded face sheets. The core was modeled as an elastic-perfectly-plastic material, and the face-sheet as elastic isotropic. The effects of core plasticity, face-sheet and core thickness, and debond length on the maximum load the beam can carry were studied. The results indicate that the core plasticity is an important factor that determines the maximum load.
Short Range Atmospheric Dispersion From Evaporation of Explosively Disseminated Liquid Drops on a Sandy Soil Surface
Authors: Mellsen Stanley B. 
Published: November 2021

Abstract
A series of field trials using a chemical simulant was conducted on sandy soil in the Experimental Proving Ground of the Defence Research Establishment Suffield, located near Medicine Hat, Alberta, Canada. Seven trials were conducted with methyl salicylate thickened to a zero shear viscosity of six poise. Explosive dissemination was used to provide liquid drops. The measured total dosage fifty metres downwind of the contaminated area was predicted by means of a previously developed mathematical model. The results of these trials are compared to those of similar trials conducted on prairie grassland.
A Study of Electrostatic Charges on Pneumatically Conveyed Solids
Authors: Zhang Jianyong , Coulthard John , Cheng R. , Keech R. P. 
Published: November 2021

Abstract
Non-restrictive, electrostatic methods have been used for measuring solids concentration of pneumatically conveyed solids under ‘lean-phase’ conditions. The passive measurement is based on the phenomena that, during pneumatic transportation, the solids particles can become naturally charged due to particle-particle interaction, particle-pipe wall impact, friction between particles and the air stream etc. The charges can be measured and, under certain conditions, can be used as an indication of the level of solids concentration. This method has been observed experimentally [1], [2] [3] [4] [9] and confirmed on full-scale power plant by the authors [5]. Several attempts have been made to derive a theoretical relationship between the solids concentration and the resultant charge, for example Gajewski [3] and Masuda [6].
This paper further develops a relationship between the solids concentration and the charges carried by flowing solids particles after making certain limiting assumptions. The solids generate stochastic signals on the electrodes and this is expressed mathematically and related to the charge level. This theory is shortly to be tested on pneumatically conveyed solids as part of a European funded research project at Nottingham university and at Kingsnorth power station in the U.K. [7]. A method of measuring average particle size is also proposed using a combination of measuring techniques.
Effects of Applied Electric Fields on Interface Dynamics and Microstructure Formation During Directional Solidification of BiMn/Bi Eutectic
Authors: Zheng L. L. 
Published: November 2021

Abstract
This paper is to demonstrate that the presence of an electric field can be used to control materials microstructure formation. Special efforts have been made to identify the foremost process control parameters that affect the interface dynamics, and thermoelectric effects on materials microstructure formation during directional solidification. A computational model that integrates microscopic analysis to macroscopic model has been developed and applied to directional solidification of BiMn/Bi eutectic in the presence of electric fields. Numerical results demonstrated that in addition to process parameters, microstructure formation strongly depends on intensity, polarity and duration of applied current, and it changes spontaneously as an electric field is applied. Predicted patterns of microstructures have qualitatively agreed with the experiments. The results indicate the feasibility of utilizing electric fields to control microstructure formation during eutectic growth.
Simulation of Spray Cooling in a Desublimer
Authors: Andrews Malcolm J. , Zwick David 
Published: November 2021

Abstract
Three-dimensional Computational Fluid Dynamics (CFD) simulations are presented for water spray cooling of a Phthalic Anhydride desublimer. The multiphase CFD modeling includes a fully coupled Eulerian/Lagrangian formulation for the carrier gas and water spray, and a quasi-steady model for the desublimation process. The use of a Lagrangian description for the spray enables a drop size distribution, but also necessitates running the simulation through the transient to obtain a steady operation result. The simulation has been used to study effect of drop size, spray dispersion and spray location/orientation.
High Performance Computing: A Mathematical Aerodynamic Model for Vehicle Driving Simulations
Authors: Kao Ben G. , Miller Ronald H. , Greenberg Jeffry A. , Strumolo Gary S. 
Published: November 2021

Abstract
Aerodynamic lift force can affect automobile handling characteristics and wind gust can affect vehicle directional stability. Experimental measurements of the drag forces are usually made for fuel economy estimation and hence do not cover large wind angles that are important for vehicle stability studies of wind gust or extreme maneuvers. The Virtual Aerodynamic Wind Tunnel (VAWT) which uses PowerFlow is an ideal numerical tool in the early vehicle design stage to provide the aerodynamic forces from a vehicle model. The numerical technique is also advantageous over experimental measurements because it does not need a hardware prototype and the computer model is relatively easier to set up for design iterations. Since the dynamic effects of aerodynamic forces on a vehicle and its driver are best studied with a driving simulator in a real time environment, the VAWT calculated air drag coefficients are reduced to a mathematical function suitable for the real time driving simulations. Available test measurements are used to ensure the practicability of the mathematical function. A vehicle model is then used to test the aerodynamic model and study the effects of the aerodynamics on the vehicle directional stability.
The Physics of the Secondary Flows of Viscoelastic Fluids in Straight Tubes
Authors: Siginer Dennis A. 
Published: November 2021

Abstract
A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored together with the difficulties in detecting weak secondary flows (dilute, weakly viscoelastic solutions) in a laboratory setting. Recent new work by the author and colleagues which explores for the first time the structure of the secondary flow field in the pulsating flow of a constitutively nonlinear simple fluid, whose structure is defined by a series of nested integrals over semi-infinite time domains, in straight tubes of arbitrary cross-sections is summarized. The transversal field arises at the second order of the perturbation of the nonlinear constitutive structure, and is driven by first order terms which define the linearly viscoelastic longitudinal flow in the hierarchy of superposed linear flows stemming from the perturbation of the constitutive structure. Arbitrary conduit contours are obtained through a novel approach to the concept of domain perturbation. Time averaged, mean secondary flow streamline contours are presented for the first time for triangular, square and hexagonal pipes.
Laminar Flow Through a Circular Pipe With Side Inlets
Authors: Umina John A. 
Published: November 2021

Abstract
This study focuses on steady axisymmetric flows of a Newtonian incompressible fluid through circular pipes with side inlets. Circular tubes with a set of holes along their sidewalls are used in a number of medical procedures as straight catheters to transfer fluid into or out of the human body. We argue that all previous work on the analogous problem of flow through porous ducts is inapplicable to the problem of fluid flow through side holes of a straight pipe, due to unrealistic side inlet conditions. In this paper, we present a linear, quasi one-dimensional analysis to predict the flux of fluid that each inlet transfers based on hydraulic resistivities of both the inlets and the duct. We also perform numerical simulations to predict this inlet flux for a more complicated three-dimensional case. Finally, we show that a nonlinear analysis is necessary to determine the resistivities for this complicated flow.
Effect of Tube Diameter on Wall Shear Stress Measurements Using Preston Tubes
Authors: Sutardi  , Ching C. Y. 
Published: November 2021

Abstract
The effect of tube diameter (d) on wall shear stress (τw) measurements using Preston tubes has been investigated in a zero pressure gradient turbulent boundary layer. Five different outside diameter tubes of 1.46, 1.82, 3.23, 4.76 and 5.54 mm, corresponding to (d/δ) of 0.022, 0.027, 0.048, 0.071 and 0.082 were used to measure τw at Reynolds numbers based on momentum thickness (Rθ) of 2800 to 4100. The calibration curves of Patel (1965) and Bechert (1995) are both dependent on the tube diameter. The maximum difference in the τw measurements from the different tubes using Patel’s calibration is about 8%, while Bechert’s calibration gives a maximum difference of approximately 18%. Based on the present measurements, a new Preston tube calibration equation that is less sensitive to the tube diameter is proposed.
Flow Visualization of a Chemically Reacting Boundary Layer
Authors: Crepeau John C. , McIlroy Hugh M. 
Published: November 2021

Abstract
This paper gives results of an experimental study to determine the effect that a surface reaction has on a boundary layer flow. An innovative technique has been developed to visualize the effect a surface reaction has on a flat plate boundary layer flow. A mixture of mineral oil and hexanoic acid flowed at low Reynolds number over a metal plate embedded with a small piece of sodium. The reaction between the hexanoic acid and the sodium metal produced hydrogen bubbles, which rose to the surface. Upstream of the reaction, dye was injected into the laminar flow, and the interaction between the bubbles and the dye was recorded. Results show that bubble entrainment stretch and bend the dye filaments, convect fluid away from the reaction, and create vortices downstream and to the sides of the reaction. These results show that a surface reaction can introduce velocity fluctuations into an otherwise laminar flow. Farther downstream the flow relaminarizes.
A 3D Unsteady Flow Analysis in a Doubly Constricted Tube
Authors: Rathish Kumar B. V. , Yamaguchi T. , Liu H. , Himeno R. 
Published: November 2021

Abstract
Unsteady flow dynamics in a doubly constricted vessel is analyzed by using a time accurate Finite Volume solution of three dimensional incompressible Navier-Stokes equations. Computational experiments are carried out for various values of Reynolds number in order to assess the criticality of multiple mild constrictions in series and also to bring out the subtle 3D features like vortex formation. Studies reveal that pressure drop across a series of mild constrictions can get physiologically critical. Further this pressure drop is found to be sensitive to the spacing between the constrictions and also to the oscillatory nature of the inflow profile.
Peristaltic Pumping
Authors: Tadjfar M. , Yamaguchi T. , Himeno R. 
Published: November 2021

Abstract
Peristaltic pumping in a cylindrical tube is simulated. The unsteady, three-dimensional, incompressible Navier-Stokes equations are solved numerically. A flow solver written for parallel architecture and capable of dealing with moving boundaries and moving grids is used. The solver uses a second-order in time and third-order upwind finite volume method for solving time-accurate incompressible flows utilizing pseudo-compressibility technique. In this study, the flow of an axisymmetric “Wine-glass” shaped, single, peristaltic wave is analyzed. The wall wave, quickly, establishes a pressure wave in the flow which pumps fluid in the tube as it moves down the tube. The pressure wave, established by the contracting geometric wall wave, grows and diffuses into the upstream and downstream direction in time due to the action of viscosity.
Complex Fluid-Structure Interaction in Ink Jet Printer Mechanisms
Authors: Reich Alton J. , Dionne Paul J. 
Published: November 2021

Abstract
Recent advances in the ability to couple fluid and structural analyses have made it possible to simulate the behavior of increasingly complex physical systems. This paper focuses on the simulation of the fluid-structure interaction within a typical ink jet printer. The simulations demonstrate several different methods that may be used to eject a droplet of ink from a reservoir. In each case a membrane at the bottom of the ink reservoir is deformed. The movement of the membrane imparts the momentum necessary for droplet ejection to the fluid. The simulations were performed with a commercial CFD code (CFD-ACE+) that uses a modular simulation approach. This approach allows the tight coupling of the different physical phenomena that contribute to the droplet ejection process.
The Use of the 3D-Viscous Codes in the Analysis of High Speed High Pressure Ratio Centrifugal Impellers
Authors: Mekhail Tarek , Hui Du Zhao , Ping Chen Han , Janson Willem 
Published: November 2021

Abstract
The flow inside a centrifugal impeller has various complex three dimensional phenomena (flow separation, jet-wake structure, shock wave, etc.). In this study, the internal flow field calculation of Samsung, high pressure ratio, high speed, centrifugal impeller with splitter blades is obtained by commercially available CFX-Tascflow code with CFX-Turbogrid for grid generation. The results are compared to that obtained previously by Denton and Dawes codes. The impeller is used in the first stage centrifugal compressor of an industrial gas turbine. The CFX-Tascflow results showed some differences Mach number contours. Also, the calculations are performed for Krain’s backswept impeller and the results are compared to the experimental measurements. Simulation of tip clearance has been done and the results were in a good agreement with the previous experiments.
Enabling the Transition to ECP Braking
Authors: Dougherty Bryan A. 
Published: November 2021

Abstract
This paper addresses the limitations of conventional freight train air brake systems, the stalled adoption of Electronically Controlled Pneumatic (ECP) brakes and a cost-effective industry transition to ECP technology.
There are two types of ECP train braking systems (cable and radio) and three types of electronically controlled freight car brake control valves. This paper describes the different types ECP braking systems and their limitations and provides a clear path to enable a fleet wide railcar transition to ECP braking technology.