bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non-Reflective Boundary Conditions for a Consistent Model of Axisymmetric Electro-Magneto-Hydrodynamic Flows
Authors: Ko Hyung-Jong , Dulikravich George S. 
Published: December 2021

Abstract
In this paper, the non-reflective boundary conditions for the axisymmetric electro-magneto-hydrodynamic (EMHD) flows have been derived. The electro-magneto-hydrodynamics (EMHD) deals with the motion of electrically conducting incompressible fluids under the combined influence of externally applied and internally generated electric and magnetic fields. A consistent axisymmetric EMHD flow model with linear constitutive relations and artificial compressibility was expressed in cylindrical coordinates. After some simplifications, the resulting EMHD system comprised of modified Maxwell equations for the electro-magnetic fields and modified Navier-Stokes equations for the flow-field, was transformed to a characteristic form, and the non-reflective boundary conditions were derived. The results show the strong mutual interactions between the axisymmetric flow-field and the electro-magnetic fields. The limiting cases, including the conventional axisymmetric flow-field model and the electro-magnetic field model in vacuum, are recoverable from these results.
Effect of Particle Size and Distribution on the Viscosity of a Model Electrorheological (ER) Fluid
Authors: Chen Ying , Conrad Hans 
Published: December 2021

Abstract
The zero-field viscosity of model ER fluids consisting of glass beads in silicone oil was determined as a function of average particles size (D¯ = 3–75 μm), volume fraction (ϕ = 0.1–0.3) and bimodal mixtures of two sizes. The viscosity increased with ϕ and decreased with D¯. The viscosity of the suspensions ηs in all cases was described reasonably well by the following relation:ηs=ηs,o(ϕ)+b(ϕ)D¯2/D¯3 where ηs,o(ϕ) and b(ϕ) are constants which increase with ϕ. Reasonable agreement with the Mooney crowding equation occurred for the single size particles, giving for the crowding factor k = 1.3 + 1.5/D¯. For ϕ &lt; 0.2 the viscosity of the bimodal mixtures could be described by a modification of the Mooney equationηsηo=exp(2.76ϕ11-k1ϕ1)exp(2.76ϕ21-k2ϕ2) where ηo is the viscosity of the silicone oil, ϕi the volume fraction of each particle size Di and ki the normal crowding factor for that size. At ϕ = 0.3 the measured values of ηs for the bimodal mixtures became appreciably larger than those calculated from the modified equation. The decrease in particle size leads to both an increase in surface area of the particles per unit volume of the suspension and to a decrease in spacing (crowding); both factors probably contributed to the increase in ηs.
Velocity, Potential, and Temperature Distributions in Molten Metals During Electromagnetic Stirring: Part I — Experimental Measurements
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A. , Meir Amnon J. , Schmidt Paul G. 
Published: December 2021

Abstract
An experimental technique has been developed to measure the local velocity in molten metals. Couette flow of liquid aluminum, lead, tin and low melting alloy in cylindrical container was chosen for calibration of the experimental technique and the magnetic probe. Velocity and temperature profiles for liquid aluminum rotating in cylindrical container at different angular velocities are obtained for two different values of the depth. We determined that the velocity values increase with magnetic induction, and the relationship between the normalized azimuthal velocity and the magnetic induction can be expressed by quadratic function.
Flow in a Hele-Shaw Cell With Restrictions Above and Below the Entrance
Authors: Clark Peter E. , Zhu Qinsheng 
Published: December 2021

Abstract
The question of how slurries are transported and placed during hydraulic fracturing treatments was first broached by Kern et al. (Kern, Perkins et al., 1959), in 1959. In the early 90’s, Cleary and Fonseca (Cleary and Fonseca Jr., 1992) suggested that gravity acting on the slurry as a whole would cause the heavier slurry to fall through the fluid in the fracture and that this would dominate individual particle settling in determining the final distribution of proppant. This sparked a healthy debate concerning the nature of flow into a fracture and brought about a renewed interest in fracture fluid flow. A fracture is analogous to a Hele-Shaw flow cell. However, most experimental studies that deal with flow in fractures assume that the fracture is globally uniform with constant height and width. This is hardly the case in real fractures. Downhole cameras have revealed that fractures are anything but uniform. There are wide and narrow regions coupled with abrupt changes in uniformity. In addition, pressure analysis indicates that, in many cases, the height of the fracture changes during most of the treatment. These all serve to disturb not only bulk slurry flow but also the settling behavior of the particles that make up the slurry. While it is difficult to simulate the growth of a fracture experimentally, width non-uniformities can be simulated and their effect on slurry flow determined. A method that can be used to predict the behavior of the slurry in the presence of a non-uniformity will be presented. These techniques can be incorporated into computer models to improve predictive capabilities.
Temperature Distribution in a VLSI Chip due to Dynamic Power Density
Authors: Jahanian Shahriar , Delalic Z. J. 
Published: December 2021

Abstract
High speed computation is driving VLSI custom chips into smaller micron sizes and scale down power supplies. To accomplish very high speed, industry is developing shut down methods and short channel devices. Going below 0.5 micron technology speed is accomplished but hot spots, power density, and die failure are increased. Failure accumulated knowledge has not yet established a classic theory. In this paper, the STEPS method is used to determine the power dissipation in a CMOS circuit The experiment demonstrates dynamic power dissipation and assumes that static power dissipation is negligible in the CMOS devices. Each node is examined individually as signals are propagated through the chip. At each node the power distribution in the form of heat is determined.
Stress Analysis and Strength Evaluation of Single-Lap Adhesive Joints Combining Rivets Subjected to External Bending Moments
Authors: Liu Jiemin , Sawa Toshiyuki 
Published: December 2021

Abstract
Stress analysis and strength evaluation of single-lap adhesive joints combining rivets subjected to external bending moments are conducted by three-dimensional finite element analysis (FEA). In this analysis, the effects of the ratio of Young’s moduli of the rivets to that of the adherends, the initial tightening force produced in the rivets, the adhesive layers between the rivet heads and the adherends, and the positions of the rivets on the stress distributions at the interfaces between the adherends and the adhesives are examined. The rupture process of the single-lap adhesive joint combining rivets is demonstrated. The strength of single-lap adhesive joints combining rivets is evaluated by the maximum principal strain criterion using the maximum principal strain at the adhesive interfaces. The FEA results show that the failure of single-lap adhesive joints and single-lap adhesive joints combining rivets with thinner adherends are due to large elasto-plastic deformation of the adherends. For single-lap adhesive joints of thick adherends, the rupture is initiated from the edge of the adhesive interface. Experiments to measure the strength of single-lap adhesive joints, single-lap riveted joint and single-lap adhesive joints combining rivets were carried out. The failure types of single-lap adhesive joints and single-lap adhesive joints combining rivets obtained from the experiments coincide with the FEA results. The experimental results also show that the failure of single-lap riveted joints with thinner adherends is due to large plastic deformation of the adherends. However, for single-lap riveted joints with thick adherends it is shown that their failure is caused by the rupture of the rivets. Finally, it is found that fitted rivets in single-lap adhesive joints of thick adherends can enhance the joint strength.
The Strength of Joints Combining Adhesives With Bolts (Case Where Adherends Are Pipe Flanges of Which the Interfaces Are Bonded Partially)
Authors: Yoneno Masahiro , Sawa Toshiyuki , Ishihara Tomoya , Kawamura Hiroshi 
Published: December 2021

Abstract
The stresses of joints combining the bonding force of adhesives with the clamping force of bolts is analyzed using axisymmetrical theory of elasticity and FEM, when an internal pressure is applied to the combination joint in which two pipe flanges are clamped together by bolts and nuts with an initial clamping force after being joined by anaerobic sealant. The anaerobic sealant is applied at the interfaces partially instead of formed gaskets in pipe flange connections. In the numerical calculations, the effect of the bonding area and position and Young’s modulus of sealant (epoxy adhesive) on the contact stress at the interfaces are clarified. In addition, using the interface stress distribution, the strength of the combination joint is predicted. Experiments are performed and the analytical results are consistent with the experimental results concerning the variation in axial bolt force and the strength of combination joints. It is found that the joint strength changes as the bolt pitch circle diameter, the bonding position and the area, the initial clamping force and the adhesive material properties change. Furthermore, it is seen that the sealing performance of such combination joints in which the interfaces are bonded partially is improved over that of pipe flange connection with metallic gaskets.
Selective Use of Rubber Toughening to Optimize Lap-Joint Strength
Authors: Sancaktar Erol , Kumar Sumeet 
Published: December 2021

Abstract
This paper introduces a novel approach to increasing the lap joint strength, different than the traditional methods of either increasing the lap joint area or changing the joint geometry. This is accomplished by the selective use of rubber toughening in epoxy to optimize lap joint strength. This was accomplished in three stages, in the first stage an adduct was prepared, this was used to make bulk tensile specimens to calculate the bulk properties for various concentrations of rubber, i.e. 0, 10 & 20 parts per hundred parts of resin (epoxy). In the second stage finite element models were developed using the bulk properties previously obtained. Interfacial stresses were used to access the trends obtained by the selective use of rubber toughening at different location of the overlap in different configurations. The modeling of adhesive joints was done using ALGOR 2-D, linear and nonlinear Finite Element Analyses (FEA). In the third stage, conducting tensile shear tests on the lap joints validated the trends from the finite element models.
Finite element modeling and meshing of the lap joints having 25.4 mm and 50.8 mm adhesive overlap lengths were completed. Different configurations of rubber toughened and untoughened adhesive were tried in these two overlaps. The validation was done by tensile lap joint tests conducted on an Instron mechanical tester coupled with an extensometer.
Comparable strengths were obtained for completely toughened overlap and the configuration where only the edges of the adhesive overlap were toughened and the region in-between was untoughened. Also, the nonlinear FEA was shown to represent the experimental results more closely than the linear approach.
Influence of Rates and Duration of Stress Waves on Residual Strength of Adhesively Bonded Joints After Single Impact or Repeated Impacts
Authors: Sato Chiaki , Ikegami Kozo 
Published: December 2021

Abstract
Residual strength after Impact (RSAI) of adhesively bonded joints was investigated experimentally. Impact Loads were applied to the joints using a split Hopkinson bar equipment. Residual strength of the joints was measured by static tests after a single impact or repeated impacts. Tubular specimens, which included tubular butt joints, were used for the experiments. Since the shape of the specimens was similar to hats, they were called ‘hat specimens’. Materials for the specimens were carbon steel adherends and an epoxy resin adhesive.
The hat specimens were subjected to impact loads by the split Hopkinson bar equipment that consisted of an input bar, an output tube and an air gun. The collision of strikers, which were accelerated by the air gun, to the end of the input bar caused compressive stress waves in the input bar. The compressive stress waves were changed to tensile stress waves in the hat specimen, and consequently high rate tensile loads could be applied to the joints.
The impact tests were conducted with several conditions of maximum stress, duration and rate of impact loading. The maximum stress and the duration of the stress waves depended on the velocity and the length of the strikes, which could be selected. Stress rates were chosen by using buffers, which were inserted between the strikes and the input bar.
Residual strengths of the joints after impact tests were smaller than the strength without impacts. However, the decrease of the strength was relatively small. The influence of the repeated impacts was remarkable on the decreases of the joint strength although the influence of the maximum stress, the duration and the rate of the impact loading were very small.
Estimation of Yield Clamping Force Based on Rigid-Plastic Model
Authors: Tsuji Hirokazu , Maruyama Kazuo 
Published: December 2021

Abstract
Yield clamping force of a bolt in plastic region tightening depends on yield point load of the bolt under combined loads of axial tension and thread torque induced by the tightening process. A new estimation method using interaction curve for yield is proposed, which is applied to the yield clamping force and maximum additional tension under external force. This estimation method utilizes the general yield criterion based on the rigid-plastic solution for combined loads of tension and torsion. The yield of the bolt is expressed by the point of the intersection between the interaction curve and loading path of the bolt in tightening or external loading. Considering the coefficient of friction at the flank of the thread and the residual thread torque after tightening, yield clamping force and maximum additional tension are obtained respectively by the simple formulas. The yield clamping force and the maximum additional tension of the bolt are examined experimentally by a combined load testing machine which can apply combined tensile and torsional loads on the threaded portion of the bolt. Estimated values by the proposed method shows good agreement with the experimental results. The proposed estimation method is superior to the conventional one which takes into account only the local yield criterion. Finally, the target zones of initial clamping force controlled by elastic region tightening, yield point tightening and plastic region tightening are examined. Usefulness of the yield clamping force is demonstrated based on the rigid-plastic model.
An Alternative Mechanical Peel Testing Method for Composite Fiberglass Foam Core Sandwiches
Authors: Zych John L. , Adamick Scott A. , Jones Daniel K. , Wilson Dru M. , Boyer Wayne A. 
Published: December 2021

Abstract
Nondestructive and destructive testing are vital in the composite material industry to determine the mechanical properties of different designs. This paper presents a novel approach to measuring the mechanical peel strength that may be used for a variety of fiberglass foam core sandwiches. The objective of this study was to develop a testing method that was simple and easily reproduced in other laboratories. The goal was to measure the mechanical peel strength using a device that may be used for a variety of sample sizes and materials. An additional goal was to provide benchmark data on the mechanical peel strength of two particular composite designs. The new testing method may have applications to a wide range of composite structures, and it may eventually lead to a new ASTM standard.
In-Situ Continuous Process for Bonding Glass-Fiber Reinforced Polypropylene to Wood
Authors: Ramani Karthik , Smith Michael , Dai Heming 
Published: December 2021

Abstract
Process conditions are developed for the manufacture of composite reinforcement for oak. Commingled glass and polypropylene fibers are consolidated in-situ on the surface of oak. Processing times from 30 to 120 seconds and pressures from .34 MPa to 1.4 MPa are tested. Micrographs of the composite and bond line reveal anisotropic fiber distribution in the composite, dry reinforcing fibers, voids, and incomplete consolidation. These microstructures are correlated with the processing problems which cause them, including insufficient heating time, poor matrix/glass mixing, and insufficient pressure to suppress void development. Lap shear strength and failure modes are related to microstructural features.
Development and Characterisation of a Oxazolidone-Isocyanurate-Urethane Modified Diglycidyl Ether of Bisphenol A Epoxy Resin
Authors: Chian K. S. , Yi S. 
Published: December 2021

Abstract
Epoxy resins are very versatile polymers generally known not only for their adhesive and mechanical strengths but also their inherent thermo-oxidative stability. These properties have been widely exploited in many applications ranging from composites used aerospace components to electronics packaging. However neat epoxy materials suffer from relatively poor strain bearing ability and attempts to improve this brittle behaviour have been an area of many research interests. Toughening of epoxy using elastomers is not new and this is reflected in numerous publications and some have been successfully commercialised.
This paper presents a relatively new method of incorporating a rubber modifier into Diglycidyl ether of Bisphenol A (DEGBA) epoxy resin via the formation of an isocyanurate-oxazolidone-urethane structure. The synthesis involves several simultaneous reactions involving the following reactions: (a) epoxide and the isocyanate to form the oxazolidone, (b) trimerisation of the isocyanate to form isocyanurate and (c) isocyanate with polyols to form polyurethane. The synthesis and characterisation of the modified DEGBA resin will be presented. In addition, the effects of rubber content on the thermomechanical behaviour of the cured resin will also be discussed. In summary, it was found that the introduction of the isocyanurate-oxazolidone-urethane chemical groups into the epoxy molecular chain not only enhances the fracture toughness of the final resin but also improves on the thermal stability. This rubber-modified epoxy system shows excellent promise for adhesive and structural applications where thermal stability and fracture toughness are pre-requisites.
Design and Analysis Techniques for Filament-Wound Composite Pressure Vessel Domes
Authors: Howard William E. , Widera G. E. O. 
Published: December 2021

Abstract
The use of filament-wound composite pressure vessels has expanded into many new markets in recent years, creating the need for better design and analysis techniques, particularly for the end domes. In this paper, design and analysis techniques are developed for elliptical-conical dome profiles with planar filament winding patterns. The effects of wide winding bandwidth are included by dividing the band into sub-bands and considering any point on the dome contour to be a laminate made up of the sub-bands. The slippage tendency of the band at its edges is also calculated.
Strengthening of Cracked Reinforced Concrete Beams Through Crackfilling With Polymeric Materials
Authors: Ayyar R. S. , Burgul S. P. 
Published: December 2021

Abstract
In this paper, an attempt is made to study the nature of weakening of R.C.C. beams due to crack formations and the extent of strengthening of the beam achieved through filling of the cracks by polymeric materials having high bond and flexural strength in tension. The study of crack formation is carried out through a sequence of incremental loading till the stage of impending failure. The progressive reduction in flexural rigidity with the growth of cracks is compared with the improvement in the same after crack filling. A finite element method has been developed for this study.
Flow Image Compression Using Wavelets
Authors: Li Hui , Lu Yan , Takei Masahiro , Ochi Mitsuaki , Saito Yoshifuru , Horii Kiyoshi 
Published: December 2021

Abstract
The wavelet compression technique was applied to turbulent image processing for reducing physical storage and extracting the compact dominant features in this study. The two compression methods, called zone and threshold compression, were employed. It was found that a high order wavelet basis provided good compression performance for compressing turbulent images and two compression methods exhibited almost same performance. It was realized that the compressed image had both lower compress ratio and larger correlation coefficients. By changing compression ratio the compressed images exhibited different scale structures in turbulent jet. This indicated clear that large-scale structure dominates the jet.
Hydrodynamics of Pulse-Stabilized Fluidization at Incipient Fluidization
Authors: Gan Subhadeep , Beasley Donald E. 
Published: December 2021

Abstract
A laboratory scale experimental facility which models a Pulsed Atmospheric Fluidized Bed Combustor (PAFBC) has been developed; this facility is designed to examine the effect of an opposing secondary flow having an oscillatory component on a bubbling fluidized bed. The secondary flow is oriented in a vertical direction. The secondary flow is introduced into the bubbling bed through a tailpipe that extends through the bed and ends just above the porous polyethylene distributor. A pulsed flow simulator that employs a small displacement of a relatively large piston with variable drive radius and speed provides the oscillatory component of the secondary flow. The fluidized bed test section has a cross-sectional flow area of 30.5 by 30.5 cm with a height of 53 cm. Heat exchanger surfaces are modeled by two symmetric horizontal cylinders housed in the test section. The following test parameters are controlled: the primary flow rate, the mean secondary flow rate, the pulsation frequency and the amplitude of the secondary flow. Pressure taps are located just above the distributor and in the freeboard region to measure overall bed pressure drop. The facility is operated with a range of particles from 345 μm to 715 μm and a range of superficial fluidization velocities corresponding to the bubble flow regime.
Fluidization curves were generated for traditional fluidization, using the primary flow through the porous distributor, with both primary and a steady secondary flow, and with primary and a pulsed secondary flow. Significant departures from the linear Darcy flow curves in the fixed bed region were observed, and attributed to significant local fluidization. Time resolved measurements of the overall bed pressure drop clearly indicate phase-locking behavior of the overall bed pressure drop with imposed frequency. Bubbles formed in pulse-stabilized fluidization are significantly smaller than in traditional fluidization, as observed through video recording of the present bed.