bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma Spraying of Functionally Graded NiCoCrAlY/Yttria Stabilized ZrO2 Coatings Using Composite Powders
Authors: Khor K. A. , Gu Y. W. , Dong Z. L. , Srivatsan T. S. 
Published: March 2022

Abstract
Pre-alloyed, plasma spheroidized powders were used as feedstock in the plasma spraying of functionally graded ZrO2/NiCoCrAlY coatings. The advantage of using pre-alloyed powders was to ensure chemical homogeneity and promote uniform density along the graded layers, and these pre-alloyed powders could be successfully used to prepare the different inter-layers of functionally graded coatings. The microstructure, density and microhardness changed gradiently in the ZrO2/NiCoCrAlY coatings. The bond strength of ZrO2/NiCoCrAlY coatings with different graded layers was measured. Results showed that for as-sprayed coatings with the same thickness, the bond strength increased with the number of graded layers. The bond strength of the coatings with five graded layers was about twice as high as that of the duplex coatings because of the significant reduction of the residual stress in the coatings. Experimental results also showed that the bond strength of as-sprayed coating increased significantly after hot isostatic press (HIP) and vacuum heat treatments, and the reason can be attributed to the densification of the microstructure, the decrease of defects in the coatings, inter-diffusion between layers and further reduction in the residual thermal stress.
Damage Development, Toughening, and the Design and Performance of Ceramic Composite Systems
Authors: Kerans Ronald J. 
Published: March 2022

Abstract
The remarkable toughening effect resulting from proper combination of three brittle phases in the form of fiber, coating and matrix is a consequence of a particular sequence in the development of damage It is understood that there are both beneficial and detrimental ways for damage to develop; hence, successful design of composites requires the management of the progression of such damage. The conception and design of alternative crack deflecting coating systems is greatly facilitated by, if not dependent upon, understanding such details. In addition, the same damage that is beneficial to toughness in one type of loading may be detrimental to other properties. The development of sufficient understanding of the benefits and penalties is necessary to design such materials with well chosen engineering compromises.
Self-Healing Composites Using Embedded Microspheres
Authors: Jung D. , Hegeman A. , Sottos N. R. , Geubelle P. H. , White S. R. 
Published: March 2022

Abstract
A self-repairing polyester matrix composite material is described which utilizes embedded polyoxymethylene urea (PMU) microspheres to store a crack filling agent to be released into the crack and rebond the crack faces. The developed repair mechanism uses naturally occurring functional sites in the polyester matrix network to trigger the repair action. The repair agent is mostly composed of styrene monomers and high molecular weight polystyrene. Microscopic observations of the microsphere/crack interaction are presented. Of particular interest is the process with which the microspheres break and release their content when encountered by a crack. The effects of the microspheres on the stiffness and toughness of the polyester resin are also studied. Using standard tensile samples, the composite elastic modulus has been found to decrease with the volume fraction of microspheres, while the fracture toughness of tapered double cantilever beam (TDCB) specimens is shown to reach a maximum value at approximately 10% volume fraction. Examinations of the fracture surfaces show tails extending from the microspheres, indicating crack pinning and crack front bowing as the primary toughening mechanisms. An enhanced level of adhesion between the microsphere and matrix has been found to decrease the composite fracture toughness and increase the incidence of sphere breakage on the fracture surface.
Effect of Sandblasting on Adhesion Strength of Diamond Coatings
Authors: Zhang Bi , Zhou Lanying 
Published: March 2022

Abstract
Premature failure of a diamond coated tool often results from a poor adhesion of the coating to and shortens the lifetime of the tool. This study presents the results of increasing the adhesion strength of diamond coatings on cutting tool inserts by pretreating the inserts with sandblasting technique to obtain a desirable surface morphology of the inserts. A geometric model representing the ideal surface morphology is established to enhance the nucleation density and adhesion strength of diamond coatings. Diamond coating experiment is conducted on the substrates of four different sample groups. Indentation and wear tests are performed on diamond coated inserts to evaluate the effect of sandblasting on the adhesion strength of the coatings. A theoretical analysis is provided on the formation and growth of atom clusters in terms of the contact angle and the thermodynamic barrier of a substrate to predict diamond nucleation. The theoretical prediction has a good agreement with the experimental results obtained in this study and by Dennig et al. [1, 2].
Process Modeling and Interfacial Behavior in the VSPA Package
Authors: Harries Richard , Sitaraman Suresh 
Published: March 2022

Abstract
Interfacial delamination is a cause for concern in electronic packages consisting of several dissimilar material systems. Even if current designs do not experience delamination as a failure mode, it is necessary to understand the effect of material and geometry properties on interfacial stresses to lower the potential of interfacial delamination in future designs. The objectives of this work are to model current and future versions of a novel peripheral array package and examine the possibilities for interfacial delamination.
This paper employs 2D plane-strain parametric finite-element models to study interfacial stresses. Element birth and death features have been used to simulate the complete manufacturing process of the package. The effect of encapsulant material properties and die-attach properties on interfacial stresses is discussed. These results will serve to aid in the selection of appropriate die attach and encapsulant materials for enhanced future designs. Delamination is also studied from a fracture mechanics perspective. A separate 2D model is constructed with a crack inserted between the encapsulation/backplate interface. Principal stress vectors are plotted along the interface to qualitatively determine the potential for crack extension. Crack growth is simulated by incrementally extending the length of the crack in the mesh.
Failure Mechanism of Metallization Layer of a Multichip Module Substrate
Authors: Rastani Mansur 
Published: March 2022

Abstract
The work described in this paper concentrates primarily on the multichip module type D. In MCM-D technologies, the interlayer vias have been identified as potential failure sites due to fatigue caused by temperature cycling and the CTE mismatch between the dielectric and metal layers. The selected model for this study uses an MCM-D structure, implementing aluminum-silicon (Al-Si) metallization layers separated by a silicon dioxide (SiO2) interlayer dielectric.
A 3-D finite element analysis has performed on the model to determine the effect of accelerated temperature cycling and thermal shock. The resulting non-linear, elasto-plastic stress-strain response was obtained, under the von-Mises yield criterion, using PATRAN code. The fatigue life of the via was then estimated and compared with the experimental results.
Thermal Stresses in a Layer due to a Train of Laser Pulses
Authors: Hetnarski Richard B. , Hector Louis G. , Kim Woo-Seung 
Published: March 2022

Abstract
A solution of a thermoelastic problem dealing with the effects of the radiation generated by a repetitively pulsing laser directed toward a thin thermoelastic layer bonded to an inert semi-space is presented. Both the thermoelastic potential method and the Love stress function are employed. The temporal variation of each pulse is modeled mathematically as a function with three constants, while the radial intensity distribution of each pulse is taken as a Gaussian distribution. Results are presented in the form of graphs.
Singular Solutions of Multi-Material Wedges Under Thermomechanical Loading
Authors: Yin Wan-Lee , Jane Kuo-chang , Lin Chien-Chang 
Published: March 2022

Abstract
Multi-material wedges associated with free edges, matrix and interface cracks, adhesive joints, skin-stiffener attachments and other types of discontinuities in composite structures generally incur singular stress fields at the vertex of the wedge. Accurate elasticity solutions of the wedge under thermo-mechanical loads may be obtained by combining eigensolutions with appropriate coefficients and a particular solution associate with the loading. When the wedge is under a temperature load, or when the two exterior edges of the wedge are subjected to non-vanishing traction loads, the elasticity solution may differ significantly from the asymptotic solution as given by the dominant singular term. In such cases, a failure criterion in terms of the asymptotic solution or the stress intensity factors may not be appropriate.
Properties of Sandwich Structures With Reinforced Core
Authors: Sun C. T. , Hasebe R. S. , Hua Y. 
Published: March 2022

Abstract
Sandwich panels with a Rohacell core reinforced with composite laminates were constructed. The effective properties of the reinforced core were derived and verified by three point bending tests of a sandwich beam. The equilibrium equations for the sandwich plate with the composite reinforced core were derived. Impact experiment was also conducted by use of a drop tower. Damage modes and levels of damage in sandwich panels containing bare and reinforced Rohacell cores were investigated and compared. Several NDI methods were employed to inspect the damage in the sandwich panel and their merits were compared.
Bending of Curved Sandwich Panels With Transversely Flexible Cores: Closed-Form High-Order Theory
Authors: Frostig Y. 
Published: March 2022

Abstract
The bending behavior of a curved sandwich panel with a transversely flexible core, i.e. “soft” in the out of plane direction, is derived. It is formulated using a rigorous systematic closed-form approach based on variational principles. The effects of the transversely flexible core are incorporated resulting in non-linear patterns, denoted also as high-order effects, for the inplane and the transverse deformations through the height of the core. The governing equations along with the associated boundary and continuity conditions for a general type of sandwich panels, i.e. unidentical skins, composite laminated or metallic and a “soft” core are derived. General type of boundary conditions, including spring conditions, as well as different conditions at the upper and the lower skins at the same section are implemented and the effects of “stiff edge inserts, denoted as global boundary conditions, along with the induced localized effects are considered. Localized effects at support regions with or without edge stiffeners, with movable and immovable supports, and in the vicinity of concentrated loads are studied. The effects are described in terms of the internal resultants and displacements of each skin, peeling (transversely normal) stresses and shear stresses at the skin-core interfaces, and stress and displacement fields in the core through its height. Numerical results of a typical curved panel used in a test set-up and comparisons with experimental data are presented. A comparison, that is in very good agreement, between the analytical results and the experimental ones is conducted. The effects of a global boundary conditions, such as a “stiff” edge beam, and similar local boundary conditions on the localized effects are presented and discussed. The stress concentration involved in case of a concentrated load especially in its near vicinity is described.
A Refined Theory for the Analysis of Sandwich Beams and its Application to Local and Global Stability Investigations
Authors: Meyer-Piening Hans-R. 
Published: March 2022

Abstract
An analytical method is proposed to study the local and global instability of three-layered assymmetric sandwich beams with arbitrary relative face thicknesses ranging from very thin faces to a vanishing core height. The method accounts for extensional orthotropy, shear elasticity, Poisson’s ratio effects and lateral compressibility within each layer. As each layer is modelled in an identical manner and all stress and displacement related interface conditions are satisfied, there is no limitation with regard to geometry relations, except for numerical instabilities or convergence criteria. The displacement functions are represented by Fourier series which leads to a set of 12 linear equations for each value of the harmonic m The eigenfunction associated with the minimum load will then represent the (local or global) design buckling (or wrinkling) mode.
The results can be compared with buckling formulas like that proposed by Hoff [1] or the formula related to a beam on elastic foundation [2], as well as the approximation for Euler columns accounting for shear elasticity. It becomes evident that modifications to the aproximate methods may be suitable for some geometric relations and material properties.
Formation of Large Disturbances in Separated Fluid-Fluid Flows
Authors: McCready M. J. , Uphold D. D. 
Published: March 2022

Abstract
If flow regime transitions to slugging or annular flow occur from an initially stratified state, growth of long wavelength waves to large amplitude has been implicated by previous researchers (e. g., Barnea, 1991) as an important mechanism. Thus it is not surprising that various linear stability theories have been used to predict when such waves will grow and therefore the onset of such transitions. However there is much evidence that longwave disturbances do not grow directly from infinitesimal amplitude by linear processes (e.g., Fan et al., 1993) and thus the use of linear stability theory to predict flow regime transitions may not be reliable. This paper compares experiments into wave formation with predictions of linear theory. It is seen that linear theory provides only part of the story of wave formation. Waves must be linearly unstable to grow to significant amplitude, but observed subharmonic and low mode formation or even saturation of the linearly growing peak, are not predicted by linear theory. Weakly nonlinear theories can predict wave mode interactions and stabilization, but experiments with paddle-induced waves suggest that there is no dramatic destabilization for wavenumbers below the peak as suggested from the positive value of the Landau coefficient in this range.
Computational Flow Simulation and Interfacial Shear for Annular/Stratified Condensing Flows
Authors: Yu G. , Narain A. 
Published: March 2022

Abstract
External and internal flows of pure vapor experiencing film condensation on an appropriately cooled wall are computationally simulated. The stratified/annular flow regimes considered here are such that the vapor flow is either laminar or turbulent while the liquid condensate flow is always laminar. For negligible droplet entrainment into the vapor phase, both smooth and wavy interface situations are considered. A full two dimensional numerical solution strategy is presented. This strategy is then implemented for smooth interface laminar/laminar flows. The simulations for the classical problem of film condensation on a tilted (horizontal to vertical) plate are in very good agreement with established classical solutions. For wavy interface turbulent/laminar flows, only a one dimensional approach is implemented. This approach employs suitable semi-empirical interfacial shear models for wavy flows which yield predictions in reasonable agreement with experiments.
Two-Phase Flow Regime Maps for Straight and Coiled Spirally Fluted Tubes
Authors: Ewing Mark E. , Priedeman Douglas K. , Wynn Bruce E. , Bohon Richard N. , Christensen Richard N. 
Published: March 2022

Abstract
Two-phase flow patterns in spirally fluted tubes were investigated through visual observation. Both straight (horizontal) and coiled fluted tubes were studied using adiabatic flow of air and water in transparent castings. The same types of patterns which occur in smooth tubes (i.e. annular, stratified, wave, plug, slug, and bubble) were observed in both the straight and coiled fluted tubes. For these tubes, experimental data support the use of a flow regime map of the type proposed by Breber et al. (1980), which was developed for condensation in smooth tubes. Based on results of the testing of two straight and three coiled fluted tubes, a generalized, modified Breber-style map is proposed for the prediction of flow regimes in spirally fluted tubes.
Effect of Apparent Solid’s Viscosity on the Hydrodynamics of Fluidized Beds
Authors: Gera Dinesh , Tsuji Yutaka 
Published: March 2022

Abstract
The dynamics of bubbles, the flow of gas and solids through the emulsion phase, and interchange of flowing gas between these two phases play a dominant role in heat transfer, mass transfer and solid-catalyzed chemical reactions. The pattern of gas flow through the bubbles has an effect on the degree of gas-solids contacting and under certain conditions a high degree of by-passing can occur. This research is aimed at understanding the aspects of bed hydrodynamics, especially to investigate the gas flow patterns inside the bubbles and solids’ mixing in a fluidized bed.
Numerical Study of Two-Phase Flow Field in a Simplified Swirl Cup Combustor
Authors: Park Tae W. , Roquemore William M. , Katta Viswanath R. , Aggarwal Suresh K. 
Published: March 2022

Abstract
A numerical study was performed to investigate the two-phase flow field in a geometrically simplified swirl cup in a gas turbine combustor. The actual combustor has a hybrid-atomization feature with pressure atomization from the nozzle and airblast reatomization for the liquid film at the tip of venturi wall. The amount of fuel formed in venturi tube could play an important role in characterizing the flow field of this combustor. The present study first investigates the effects of the swirl mode and temperature of the primary and secondary air on the gas-phase flow field and then the effect of droplet injection characteristics in terms of velocity and location on the droplet transport and vaporization behavior. The detailed plots of droplet trajectory are used to identify the size ranges of the droplets which can form a liquid film by their impaction on the venturi tube wall. In general, the results indicate that the droplet injection characteristics have the dominant effect on the cut-off droplet diameter for droplet impaction on the venturi wall.
Medical Atomization Design for Inhalation Therapy
Authors: Corcoran T. , Mansour A. , Chigier N. 
Published: March 2022

Abstract
The medical community has lately shown increased interest in drug administration via the internal surfaces of the lung. Administration of medication to the lungs is typically performed using either an aerosol or a spray, that is inhaled by the patient. Spray droplet size distribution is a primary determinant of whether medication will deposit effectively within the lungs. Spray liquid flow rates will determine required treatment time. Examination of three typical atomizer (nebulizer) designs used to generate inhalation sprays is presented. The separate stages in the design of these nebulizers include entrainment (jet pump), atomization, and conveyance stages. Mass flow rate of liquid in the sprays delivered from all examined designs was at least two orders of magnitude less than the mass flow rates of liquid pumped through the atomization stages. This indicated that liquid typically circulated through the atomization stages many times before being completely administered. Visualization was performed on the atomization stages showing less than ideal mechanisms for break up. Final outlet droplet cumulative number distributions obtained via Phase Doppler Particle Analyzer (PDPA) demonstrate that approximately 80% of the droplets generated by each design are within the range of sizes generally considered desirable for inhaled administration. (1–5 μm).
Recent Developments in Spray Technology: Agricultural Applications
Authors: Hitchman Alec Keith 
Published: March 2022

Abstract
The use of high efficiency water spray systems for outdoor climate control has become more popular of late; the 1996 Olympic Games in Atlanta being a well-publicized recent example. The increase in popularity has initiated the consideration of these inexpensive systems for use in other applications as well. The application of these water spray systems inside buildings has as their primary function the delivery of humid air to large indoor areas at a minimum of cost. Such water spray systems have proven their effectiveness in the bulk storage of both potatoes and wine. If used as the sole means of humidity control, or in conjunction with more traditional means of environment management, high efficiency water spray systems can reduce the product losses associated with the long term storage of potatoes and wine.
Effect of Initial Conditions on Turbulent Pipe Mixing
Authors: Hansen Lisa J. , Klewicki Joseph C. 
Published: March 2022

Abstract
Despite its use in numerous industrial applications, the specific mechanisms governing mixing in pipe flow are not fully understood. Recent experiments by Guilkey et al. (1997) indicate that simple changes in the geometry of the inlet at which the scalar is introduced can lead to substantial differences in the rate of scalar variance decay downstream. In an effort to better understand this phenomenon, the effects of two different initial conditions on mixing in turbulent pipe flow were investigated. The present results are compared with three earlier turbulent mixing experiments. Overall, the results of these experiments demonstrate that the method used to introduce two constituents to be mixed in pipe flow can profoundly affect the downstream mixing rate.
Models of Fracture-Matrix Interactions During Multiphase Heat and Mass Flow in Unsaturated Fractured Porous Media
Authors: Ho Clifford K. 
Published: March 2022

Abstract
Models of liquid, gas, and heat flow between fractures and matrix elements in dual-permeability models are presented in this paper. Heterogeneities necessitate scaling the liquid geometric conductance between fracture and matrix elements to account for a reduction in the wetted area available for liquid flow while maintaining reasonable conductances for gas and heat flows. The models in this study consisted of conductance multipliers that were either constant, a function of upstream saturation, or a function of upstream relative permeability. Numerical analyses were performed using TOUGH2 to determine hydrologic and thermal parameters that are sensitive to the various fracture-matrix models. Results showed that for thermohydrologic simulations of the potential repository at Yucca Mountain, the ambient hydrology (e.g., matrix liquid saturations and fracture liquid flow) was strongly dependent on the fracture-matrix interaction model. The thermal response of the system was less sensitive to the different fracture-matrix models in the dual-permeability systems.