bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Stress Redistribution and Notch Sensitivity in Ceramic Matrix Composites (CMCs)
Authors: Roberts Mark C. , Mackin Thomas J.
Published: March 2022

Damage tolerance, which depends upon inelastic mechanisms, is crucial to the general utility of ceramic matrix composites (CMCs). Recent experiments have confirmed several damage mechanisms and revealed that stress redistribution does occur in CMCs. The current composite paradigm relies on fiber coatings to achieve this damage tolerance. More recently, an Al2O3/ Al2O3 CMC was developed which attains damage tolerance through the use of a porous matrix. To evaluate this all-oxide material, tensile experiments were conducted on double edge-notched test specimens. An infrared imaging technique, known as thermoelastic stress analysis, was used to classify the damage mechanism and measure the extent of stress redistribution in double edge-notched specimens. Results indicate that the subject alumina/alumina composite exhibits a measurable degree of ductility by developing shear band damage zones.
Stress Redistribution and Notch Sensitivity in Ceramic Matrix Composites (CMCs)
Authors: Mackin Thomas J. , Roberts Mark C. , Anderson David
Published: March 2022

A new generation of relatively ‘ductile’ CMCs is being developed that expands the general utility of structural ceramic composites. These new materials rely on inelastic mechanisms such as interface failure, matrix cracking, fiber failure and fiber pullout to redistribute stress away from locations of stress concentration (Evans et al., 1995). The combined effect of these mechanisms can be summarized in three macroscopic damage classifications (Mackin et al., 1995): Class I damage is the development of a single matrix crack bridged by fibers; Class II damage involves the development of multiple cracks in the matrix; and Class III damage involves the development of a shear damage zone. The operative damage mechanism depends upon the composite constituent properties, while the extent of stress redistribution depends upon the damage mechanism.
In Situ Control of Interface Coatings on Fibers Using CVD
Authors: Jones John G. , Busbee John D. , Jero Paul D. , Kent David J. , Liptak David C.
Published: March 2022

Most ceramic matrix composites (CMC’s) require a fiber interface coating in order to exhibit the desirable properties that make them potentially useful high temperature structural materials.6,9 Although interface coatings are widely recognized as a key to these properties, fiber coating technology has received relatively little attention, hindering successful application of CMC’s. Additionally, in today’s search for new oxidation resistant interfaces, the inability to deposit coatings of controlled chemistry, thickness, and morphology is a significant problem.5
Computational Analysis of Mixed-Mode Delamination Crack Growth in a Woven Laminated Ceramic Matrix Composite
Authors: Krishnappa M. , Newaz G. M.
Published: March 2022

Mixed-mode delamination crack growth characteristics in a SiC/SiC woven laminated ceramic matrix composite is analyzed. Delamination crack growth under mixed mode conditions was investigated using a computational mechanics approach. For the purpose of this study the CMC specimen considered was in 4-point bending. A notch, of 1/3 of the specimen width was considered in the analysis. In this paper only symmetric delamination crack growth were investigated and results presented. Effects of other parameters, such as loading configuration, material properties, crack configuration, and effect of temperature on the energy release rates were also investigated.
Experimental and Numerical Analysis of Ceramics With Microcracking
Authors: Yin Gang , Xu Ling , Jiang Lin
Published: March 2022

The application of ceramic materials in engineering structure has increased significantly for their outstanding hardness and yield stress under compressive loading. However, fracture behavior of ceramic materials is closely related to microcracking. Continuum damage mechanics is considered as a powerful theoretical framework. It is fairly difficult to obtain analytically as well as experimentally evolution equations for ceramic with microcracking. In the present study, an effective computational procedure is employed in a dynamic fracture analysis of ceramic materials with microcracking. The computational analysis is carried out for simulation of fracture experiment using notched specimens. This procedure can be used for better interpretation of experimental data as well as fracture simulations of complex structural models. Additionally, ceramic specimen is applied to the finite element analysis of microcracking near the microcrack-tip in a tensile stress field. The simulations were not only consistent with the experiments, but also revealed a possible damage mechanism which helps to explain the experimental data.
Vibration and Flutter Analysis of Stiffened Composite Plate Considering Thermal Effect
Authors: Lee In , Oh Il-Kwon , Lee Dong-Min
Published: March 2022

Vibration and flutter analyses have been performed for stiffened composite laminated plates considering thermal effect. The FSDT (First order Shear Deformable plate Theory) and Timoshenko beam theory are used for the finite element modeling of a skin panel and stiffeners, respectively. The von Karman nonlinear strain-displacement relation is adopted to consider a large deflection due to the thermal buckling loads and severe aerodynamic loads. The first order piston theory is used for the modeling of aerodynamic loads. The temperature distribution is assumed to be constant over the surface and has a thermal gradient through the thickness of the plate. It is assumed that a degradation of the elastic properties of the constituent materials is a function of the temperature field itself. Guyan reduction method is employed to reduce the problem size and computational time. Newton-Rhapson iteration method is used to obtain the postbuckled deflection. Complex eigenvalue solver with LUM/NTF approximation method is used to obtain vibration and flutter characteristics. The effects of various parameters, such as ply orientation, temperature gradient, material property degradation and the stiffening scheme on flutter characteristics are investigated through some numerical examples. The degradation of material properties affects the aero-thermo-postbuckled deflection, vibration characteristics and flutter boundary. The selection of proper stiffening scheme results in great improvements of flutter characteristics of laminated panels without introducing considerable weight penalty.
Minimum Deflection Design of Piezothermoelastic Laminated Composite Plates
Authors: Tauchert Theodore R. , Adali Sarp , Verijenko Viktor E. , Richter Alexander A.
Published: March 2022

The converse piezo effect is used to minimize the deflection of a given point for antisymmetrically laminated rectangular plates. The piezoelectric layers are bonded to the top and bottom surfaces of the laminate and are subjected to an electrical field. The deformation generated by the piezo effect counteracts the deflections induced by mechanical and/or thermal loads. Moreover, the ply angles can be used as additional design variables to minimize the deflection. In the numerical examples, the mid-point of the plate is specified as the point deflection of which is to be minimized. It is shown that, depending on the magnitudes of the mechanical and thermal loads, the deflection of this point can be reduced to zero by applying a certain voltage to piezoelectric layers.
On the Response of a Sandwich Panel With a Bilinear Core
Authors: Sikarskie David L. , Mercado Lei L.
Published: March 2022

Sandwich panels can fail in a variety of ways. In the present paper one type of failure is investigated and modeled which has a number of important applications, e.g., marine hulls. Here core yielding is assumed to initiate and grow in the sandwich panel while the face sheets remain bonded, unbuckled and in the elastic range. For elastic face sheets, the core shear stresses can be determined from equilibrium of the face sheets independent of core yield. Core shear strains can then be found from the stress-strain curve and an algorithm is constructed for determining shear deflection. Bending deflection is found from the elastic solution. This approach works well except when the bilinear stress strain behavior approaches the perfectly plastic core. With the aid of a detailed finite element solution it is shown that the classical sandwich theory assumptions begin to break down and that the face sheets now carry an appreciable part of the shear load. This effect is shown in detail for four point beam bending where the classical sandwich solution is 20∼30% below the ABAQUS results and the experimental data. For the bilinear case, not close to perfectly plastic, however, the extension of the classical theory to the core yielding problem provides excellent results.
Variability of Rotor Wake Interactions and Airfoil Unsteady Aerodynamics
Authors: Sanders Albert J. , Fleeter Sanford
Published: March 2022

Multistage interaction effects on rotor blade-to-blade wake variability and the resulting downstream vane row unsteady aerodynamic response are experimentally investigated in a high speed fan stage. Multistaging effects on the rotor wake are quantified by acquiring data over two complete rotor revolutions at each of several IGV clocking positions relative to downstream stationary probes. The resulting downstream vane response data are acquired over a range of steady loading conditions, with both design and off-design operation of the rotor considered. Multistage interactions are shown to significantly affect the rotor wake characteristics and lead to the generation of rogue wakes. The fundamental periodicity of these interactions is one complete rotor revolution due to the unequal number of blades and vanes in the machine. The rotor wake and resultant vane row unsteady aerodynamic response variability are also quantified. Off-design rotor operation results in wakes with the largest variability, on the order of the average velocity deficit. The vane response variability is even more pronounced, being as large as 160% of the maximum average unsteady lift over one blade pass period.
Microphysics of Turbulent Transport Processes at Gas-Liquid Interface
Authors: De Angelis V. , Banerjee S.
Published: March 2022

Gas and moisture transfer at continuous interfaces between turbulent air and water streams are controlled by layers ∼ O(10−2mm) and ∼ O(1mm) thickness, respectively. This suggests that direct numerical and large eddy simulations could be used to clarify microphysical processes controlling scalar transfer rates, since such scales are resolvable with available computational resources. To this end, numerical procedures using a pseudospectral method, together with a projection algorithm, have been developed and applied to coupled gas-liquid flows. The initial studies focused on flows under conditions where interface deformations were small — a situation corresponding to a series of laboratory experiments where detailed measurements of the near-interface turbulence characteristics were made. The simulations agreed very well with measurements. The next step was to calculate gas flow over wavy solid surfaces, where the wavelengths corresponded to those of capillary waves. The simulation maintained spectral accuracy, and agreed with experimental data, which included waves of sufficient steepness that separation occurred behind the crests. Finally, simulations were conducted for conditions under which capillary waves developed at the interface — the physical properties being those of air and water at atmospheric conditions. The program of simulations, supported, where possible, by experiments, clarified that the scalar transfer rates on each side of the interface were correlated with the sweeps on each side, i.e. fourth-quadrant events which bring high speed fluid close to the interface, forming regions of high shear stress and high scalar transfer rates. Furthermore, the simulations, and experiments indicated that the sweep frequency could be expressed in terms of the frictional drag, but not in terms of the total drag, which includes form drag. From this, using surface renewal theory, it was found that simple parametrizations for the scalar transfer rates could be derived in terms of the frictional drag, with no adjustable parameters. It appeared that capillary wave characteristics affect the scalar transfer rates by affecting the frictional drag, i.e. indirectly, by affecting sweep frequencies, and by affecting the Sc numbere dependency in the case the flow shows recirculation. Parameterizations based on these considerations are in excellent, agreement with large-scale laboratory experiments, some of which were done after the parametrizations were proposed.
Entrained Fraction in Inclined Annular Gas/Liquid Flow
Authors: Azzopardi B. J. , Zaidi S. H. , Jepson D. M.
Published: March 2022

Light scattering measurements have been used to determine entrained liquid flow rates in annular gas/liquid flow. Data have been obtained for vertical upflow and horizontal flow as well as for inclined flow at 10° intervals in between, The vertical flow data show trends similar to previous published work. In particular, they suggest that, unlike at higher gas velocities, at lower gas velocities the entrained fraction increases with decreasing gas velocity. The inclined flow data show that this parameter does not react to inclination as rapidly as does the asymmetry in film thickness.
Measurement of Two-Phase Mass Flow Rate and Quality Using Venturi and Void Fraction Meters
Authors: Moura Luiz F. M. , Marvillet Christophe
Published: March 2022

The measurement of the mass flow rate and quality of a two-phase gas-liquid flow is of interest in many fields of engineering such as refrigeration, power cycles, chemical processes, nuclear plants and petroleum production. This paper presents the use of a venturi and a void fraction meter for the measurement of refrigerant R-134a liquid-vapor mass flow rate and quality in vertical pipes.

Measuring a single-phase mass flow is comparatively easy. The medium is a continuum with either a laminar or a turbulent flow. Measurements of the pressure drop produced by a venturi meter allow the instantaneous mass flow rate to be determined unequivocally and with great accuracy. In two-phase flow, the phases occurring in the flow channel are discontinuous. There may be such flow regimes as bubbly, slug, churn, annular and dispersed flows, which are difficult and expensive to identify. Even pressure drop measurements do not allow the mass flow to be derived unequivocally and precisely because there is a strong dependency on the flow regime and the vapor quality (vapor mass fraction). Since these quantities are not known in practical measurements, the measuring errors of such techniques frequently range between 5 and 20%.

Fundamental improvements in the accuracy of measuring two-phase flows can only be attained with the measurement of at least two independent parameters. These are typically a measure of velocity or volumetric flow rate and a measure of the mixture density or void fraction.

Differential pressure instruments, such as orifice, venturi, and nozzle meter, were the earliest and simplest forms of metering devices used in two-phase mass flow rate and quality measurements. The venturi meter induces the lowest pressure loss relative to the other differential pressure instruments.

In this work, the measurement of the pressure drop in a venturi meter is complemented with the measurement of the void fraction by a electrical impedance sensor. Then, the two-phase mass flow rate and quality were determined from a theoretical model. It was found that proposed theoretical model provides a good accuracy for all experimental conditions.
Thermal-Hydrologic-Mechanical Analyses of the In Situ Single Heater Test, Yucca Mountain, Nevada
Authors: Francis Nicholas D. , Sobolik Steven R. , Ballard Sanford
Published: March 2022

The single heater test (SHT) is up to an eighteen-month-long heating and cooling experiment begun in August, 1996, located underground within the unsaturated zone near the potential geologic repository at Yucca Mountain, Nevada. Experimental measurements at the test site include temperature measurements made at various radial locations and along the length of the heater, moisture concentration measurements around the heater zone, and rock displacement measurements resulting from the development of thermal stresses.

Three-dimensional thermal-hydrologic calculations were performed with an integrated finite difference code. This computer code determines the simultaneous transport of heat and mass in response to a thermal perturbation resulting from an emplaced heat source. The working range in rock permeability (5.1 millidarcy to 5.3 darcy) results in predicted temperature differences of approximately 10°C or less. The high permeability simulations resulted in lower predicted temperatures around the heater along with the formation of an asymmetrical dry-out zone resulting from the development of buoyant gas-phase convection cells. The low bulk permeability simulations resulted in higher predicted temperatures and a symmetrical dry-out zone.

Three-dimensional, elastic thermal-mechanical calculations were performed with a finite element nonlinear structural mechanics computer code. The temperature predictions from the thermal-hydrologic calculations were used as the input temperatures for the thermal-mechanical calculations. Total displacements along the multi-point borehole extensometers (MPBX’s) are predicted to be no more than ∼3 mm for the conditions and properties used.
Improving the Snap-Off Process in Solder Paste Stencil Printing via the Enhancement of Wall Slip
Authors: Mimura Toshinori , Liu Sheng , Asada Haruhiko
Published: March 2022

To successfully print solder paste onto circuit boards using stencils, a properly controlled fill-in process must be followed by an efficient snap-off. Due to the non-Newtonian nature of solder paste, its flow behavior during a snap-off is highly complex and difficult to analyze. In this paper, solder paste is modeled as a dense suspension that flows with a slip at the wall boundary. Based on a visualization technique, the wall slip behavior is studied and its influence on the snap-off process is discussed. In particular, it is found that at higher temperatures, wall slip can be enhanced and the snap-off success rate can be improved. Based on the study of wall slip, practical methods for improving snap-off are proposed.
Numerical Studies on the Transportation of Water Mist for Fire Suppression Applications
Authors: Hung L. S. , Yao S. C.
Published: March 2022

Some phenomena of spray dynamics of water mist for fire suppression are studied numerically. The transport of fine mist sprays is very different than that of the typical large water sprinkler drops because water mist may have a better ability to follow the air streams and to penetrate into hidden locations behind obstructions or through opening slots where fire occurs. First, the free falling of fine droplet in stagnant air is examined to reveal the time delays and change of volumetric number density of the spectrum of droplets. Then, the 2-D numerical simulations of a two-phase gas droplet flow based on Navier-Stokes equations are performed to study the motion of droplets around a rectangular strip obstruction. The deposition of the droplets on the strip and the flow around the strip are investigated. The collection efficiency on the strip is computed numerically as a function of the inertial impaction parameter. In addition, flow over a single strip in a domain with various widths is also examined to reveal the characteristics of the flow over an array of repeated strips. No major variation on the collection efficiency with respect to the single strip is observed if the blockage fraction (B), which is the fraction of the size of strip to the total width of the flow domain, is less than about 0.33. The penetration efficiency of the mist droplets through an array of slots can be evaluated based on the collection efficiency and the geometric fraction of the strip to the flow domain configuration.
A Hybrid Technique for Coupling Chemical Kinetics and Hydrodynamics Computations in Multi-Phase Reacting Flow Systems
Authors: Chang S. L. , Lottes S. A. , Zhou C. Q. , Petrick M.
Published: March 2022

A hybrid technique to couple hydrodynamics and chemical kinetics calculations in a multi-phase, multi-species, turbulent reacting flow simulation has been developed. It divides a flow simulation into two parts: a reacting flow hydrodynamic simulation with a small but sufficient number of lumped reactions to compute flow field properties followed by a many subspecies (of order 10 to 100) reaction kinetics and transport calculation. This technique has been incorporated in a computational fluid dynamics (CFD) code to predict concentrations of many subspecies in a reacting flow where complex chemical reactions take place, and it can be applied to many applications such as combustors. The application presented in this paper is the flow simulation of a fluid catalytic cracking (FCC) riser reactor. Applying the technique in the FCC riser application has shown that it can be used to identify critical processes and operating parameters including the trends and relationships that are necessary to the improve the quality and quantity of FCC products.
A Steady-State Three Dimensional Thermo-Fluid Mathematical Model of a Continuous Glass Furnace
Authors: Rodicio Sandra Coutín , Chapman Kirby S.
Published: March 2022

A three dimensional thermo-fluid mathematical model of the load tank of a continuous natural gas glass furnace has been developed. The main objective of this work is twofold: the successful coupling of this model and an existing combustion gas model, which simulates the combustion process; and the study of the variation of several furnace operating conditions and their impact in the overall furnace performance and glass thermal behavior. This model provides important information about the heat transfer characteristics of a commercial type glass and how these are affected by the variation of the radiative properties of the load (glass) surface and refractory surfaces in the combustion space, as well as by the incoming air temperature to the combustion chamber. This paper includes the results of three-dimensional velocity and temperature profiles of the glass flowing through the furnace. In addition, the results of a parametric study on the glass surface emissivity, refractory emissivity and preheat air temperature are included.
Parallel Computing Strategies for a Disperse Phase Flow and Combustion Model
Authors: Fiveland W. A. , Parker K. L. , Gansman R. F.
Published: March 2022

Flow and combustion models are being used to evaluate new designs and retrofit options for various industrial combustion systems. Combustion models being used today are often very modular and, since they apply serial algorithms, require long run times to produce results. It is common for solutions to take several days, and the use of finite rate chemistry and Lagrangian based particle models can lengthen run times to a week or more. The modularity of these methods makes them candidates for parallel computing.

This paper presents results for a distributed computing algorithm using the PVM software, which is applied to the finite rate chemistry and particle transport modules. It is based on a master-slave algorithm in which the master doles work to a number of independent processors. A load balancing scheme is used to account for the variability in the time the slaves complete their work.

PVM was successfully used for parallel computations in the finite rate chemistry and particle modules. Significant speedups were found for both modules, but the work clearly indicates the need to control granularity and the need to optimize the algorithm specifically for the processors being used. Future work is planned to improve the algorithms presented here as well as extending the work to other parts of the combustion model.
Batch Fabrication of Pneumatic Valve Arrays by Combining MEMS With Printed Circuit Board Technology
Authors: Cheung Patrick , Berlin Andrew A. , Biegelsen David K. , Jackson Warren B.
Published: March 2022

This paper introduces a novel approach that combines Printed Circuit Board (PCB or PC board) Technology with MEMS technology to batch-fabricate large-area arrays of released mechanical structures that are of macro-scale size. As an initial demonstration of this approach. we have batch-fabricated a passively-addressed array of 256 electrostatically-actuated valves and air jets, intended for use in a “Smart” application. Preliminary experiments have been performed showing that these valves can switch a substantial air flow multiple times per second. The electrostatic voltage required to maintain valve closure was found to be many times higher than predicted analytically through modeling of the geometries, flow rates, and forces involved, indicating a need for further analysis and experimentation to better understand the physical effects that come into play at this macroscopic scale. Using PCB technology as a means for extending the MEMS design and fabrication methodologies has the potential to enable batch fabrication of macro-scale arrays of sensors, actuators, conduits, and other elements of a complete system.
Mechanism of Thermally-Induced Optical Transition in Polypentapeptide (PPP) Elastin
Authors: Morgan Tyler J. , Majumdar Arun
Published: March 2022

Polypentapeptide (PPP) elastin undergoes a reversible transparent-opaque optical transition in the visible spectrum when the temperature is changed across a transition temperature, Tt. To discover the mechanism of this transition, transmissivity and reflectivity measurements of a PPP membrane were made in the wavelength region of 500–1050 nm. Analysis of the measured data using a two-flux radiative transfer model showed that above the transition temperature the scattering albedo varied with wavelength as that of a Rayleigh scattering particle. It is proposed that the optical transition occurs due to scattering by three-dimensionally folded chains of PPP which are formed above the transition temperature when water pentamers are broken and intramolecular hydrophobic interactions are induced.
Thermal Characterization of Two-Phase Heat Transfer in Porous Materials: An Experimentally Confirmed Method in Non-Dimensionalized Form
Authors: Dickey J. T. , Peterson G. P.
Published: March 2022

Investigations of a relatively new heat transfer scheme, were conducted. This system combines two-phase heat transfer with forced flow through porous materials and has the ability to absorb high heat fluxes at low and extremely uniform surface temperatures. To predict the heat transfer attributes of the system, a semi-analytical model was developed using the conservation equations of mass, momentum and energy along with the apparent physical properties of the composite material. Verification of the analytical model is demonstrated through experimental confirmation. The resulting model predicts the liquid vapor interface and surface temperature profile for a channel to which a constant heat flux is applied to within ±5 % of the channel width and ±0.1 °C. In addition, a non-dimensionalized method for predicting the heat transfer attributes of these systems was developed.
On the Interface Instability During Rapid Evaporation in Microgravity
Authors: Juric Damir
Published: March 2022

The rapid evaporation of a superheated liquid (vapor explosion) under microgravity conditions is studied by direct numerical simulation. The time-dependent Navier-Stokes and energy equations coupled to the interface dynamics are solved using a two-dimensional finite-difference/front-tracking method. Large interface deformations, topology change, latent heat, surface tension and unequal material properties between the liquid and vapor phases are included in the simulations. A comparison of numerical results to the exact solution of a one-dimensional test problem shows excellent agreement. For the two-dimensional rapid evaporation problem, the vapor volume growth rate and unstable interface dynamics are studied for increasing levels of initial liquid superheat. As the superheat is increased the liquid-vapor interface experiences increasingly unstable energetic growth. These results indicate that heat transfer plays a very important role in the instability mechanism leading to vapor explosions. It is suggested that the Mullins-Sekerka instability could play a role in the instability initiation mechanism.
Windage Power Loss of High-Speed Generators
Authors: Durkin Edward B. , Schauer John J.
Published: March 2022

Direct-drive electromachines that are designed to operate at higher rotating speeds will have a windage drag that is a more significant loss factor; this loss will require greater attention in the initial machine design. Switched-reluctance machines with poled rotors can further increase windage by fluid pumping and mixing between the rotor poles. Reliable windage data for highspeed poled rotors was unavailable, so an experimental study was initiated to determine the total air friction power loss and the contributing factors to this loss. The first rotor test was with concentric cylinders to establish a valid viscous film theory. The parametric analysis then proceeded with a matrix of tests for various rotor, stator, and air gap geometries. Later tests with rotor end “shrouds” then demonstrated reduced windage loss by reducing the induced airflow and mixing in the rotor pole gaps.
Use of Extended Exergy Analysis as a Tool for Assessment of the Environmental Impact of Industrial Processes
Authors: Creyts J. C. , Carey V. P.
Published: March 2022

Traditional applications of exergy analysis have focused upon the design and optimization of parameters in thermal systems. The success of the technique as applied to these systems is well documented. In this paper, an extended form of exergy analysis is introduced in which the basic principles of traditional analyses are applied generically to industrial energy and material flows. This Extended Exergy Analysis produces an energy-based metric useful for the assessment of the potential environmental impacts of industrial processes. This information can be used to evaluate the environmental performance of industrial systems of varying degrees of complexity. Several important points emerge from the discussion. The first is the importance of the ground state in determining a material stream’s exergetic value. It is shown that by qualifying the definition of these states to include provisions for environmental acceptability, exergy analysis can be used to provide insight into the environmental compatibility of industrial processes. Secondly, the paper demonstrates the importance of two distinct ways of calculating exergy. The process path approach, a method based upon envisioning idealized thermodynamic processes that transform residual streams from harmful to environmentally benign states, is shown to be useful in cases where rigorous design optimization is the goal. A second approach involving use of property data in conjunction with standard exergy equations and efficiency factors, represents an expedient alternative for instances where order-of-magnitude data will suffice. Finally, it is shown that the technique’s usefulness is not limited solely to industry. Use of Extended Exergy Analysis by legislators and policy analysts can help these groups understand the impacts that changes in environmental standards and legislation are likely to produce. The paper concludes with the discussion of a simulated example in which the Extended Exergy Analysis is applied to analyze the environmental impact of material flows through a metal machining process.
On the Quest for Objective Equations in Exergy Costing
Authors: Lazzaretto Andrea , Tsatsaronis George
Published: March 2022

Exergy costing may be performed using different approaches each one being characterized by a different level of subjectivity. The SPECO methodology, a new process-based methodology for exergy costing, is aimed at minimizing the subjectivity associated with the definitions of fuel and product for various components and the auxiliary cost equations. In the SPECO methodology, the auxiliary cost equations are obtained by directly registering the exergy and cost additions and removals along the exergy streams of a thermal system.

This paper demonstrates how the “fuel” and “product” rules suggested by this methodology for formulating the cost equations are obtained by depicting the process of cost additions and removals in each exergy stream. The application to a cogeneration system highlights the features of the methodology which is here combined with both the Last In First Out (LIFO) and the Average Costing (AVCO) approaches.
Lumped Parameter Thermodynamic and Heat Transfer Modeling of a Scroll Pump
Authors: Sunder Sankar , Smith Joseph L.
Published: March 2022

We present a lumped parameter thermodynamic model for the internal processes of a scroll pump. This model serves as a tool with which to quickly predict scroll pump thermodynamic performance without worrying too much about details of scroll pump geometry. The model described here selectively incorporates sources of irreversibility in the scroll compression process and iteratively solves for the resultant thermodynamic states of the compression cycle. Inputs to the model are scroll pump displacement volumes, pump inlet state, pump discharge pressure, and motor operating speed. Descriptions of suction and discharge heat transfer, internal leakage, kissing heat transfer and wall conduction are also incorporated into the model. Outputs of the model are mass flow rate of the machine, pump discharge state, closed process polytropic coefficient and pump wall temperatures. Additional sources of irreversibility can also be incorporated into the model using the methodology outlined in the paper.
Vibratory States in and Radiation From a Framed Cylindrical Shell With Internal Complexity
Authors: Houston Brian H. , Photiadis Douglas M. , Bucaro Joseph A. , Simpson Harry J.
Published: March 2022

Understanding the structural acoustics of stiffened shells with complexities is central to advancing the acoustic design of many aerospace and marine vehicles. Some of the mechanisms that have been studied to date include the scattering of structure-borne energy by discontinuities1–7 and the coupling of this energy into internal vibratory states leading to storage and dissipation phenomena1,8–9. Recently, we have reported the results of experiments where complex internal structure has been demonstrated to dramatically influence the scattering cross-section of fluid-loaded shells10–12 and that these effects can be predicted using spatially varying local admittance functions13. We report here for the first time measurements of the vibratory response of a ribbed fluid-loaded shell with a large number of internally attached oscillators (∼1000). Comparisons are made to the response of an identical framed shell with no internal complexity.
Energy Absorption and Dissipation Characteristics of Pultruded Glass-Graphite/Epoxy Hybrid Composite Beams
Authors: Kowsika Murthy V. S. L. N. , Mantena P. Raju , Balasubramaniam K.
Published: March 2022

The response of pultruded glass-graphite/epoxy hybrid composites is evaluated under two different incident impact energy conditions. A high incident energy (HIE) and a low incident energy (LIE) of impact are chosen to cause either complete fracture or induce delamination, respectively, for assessing the energy absorption characteristics and delamination fracture toughness of these hybrid composites. From the HIE instrumented drop-weight impact tests, the energies required for damage initiation, propagation as well as total absorbed energies and other parameters necessary for evaluating the impact performance of composites were derived from the load-deformation behavior of each sample. The influence of hybridization on the energy absorption characteristics of pultruded composites was investigated. A parametric study was also performed to correlate the energy absorption characteristics with the energy dissipative mechanisms attributed to the inherent material damping capacity of these composites. The qualitative assessment of the impact performance using inherent damping capacity as a non-destructive testing parameter is highlighted.

The samples that were subjected to LIE impact testing were examined using ultrasonic C-scan tests to ascertain the changes in the extent of delamination crack propagation as a result of hybridization. Finite element modeling was performed to simulate delamination crack propagation at various levels through the thickness. The strain energy release rate computed using the virtual crack closure technique was monitored to determine the likelihood of delamination crack propagation with increment in crack growth. The results obtained from LIE impact tests and ultrasonic C-scan tests were used to corroborate the predicted delamination fracture toughness of pultruded hybrids.
Ballistic and Damping Characteristics of ECPE/Glass Hybrid Composites
Authors: Bhatnagar Ashok , Rammoorthy Madhu , Glaser Raymond , Nori Chandrasekhar V. , Mantena P. Raju
Published: March 2022

Lightweight ballistic composites offer a host of advantages over traditional metal armor for stopping bullets and fragments in armored vehicles. Military and civilian vehicles armored with metal require higher horsepower engines, heavy suspension systems, and heavy duty hinges. Lightweight composites, however, are easy to install and remove, and increase vehicle life by as much as 50%. Another advantage lightweight composites offer is damping to the vehicle system. Composites reduce vibration and thus increase the comfort and fatigue life of other vehicle components. In this paper the damping behavior of four types of ballistic composites using combinations of glass and extended chain polyethylene (ECPE) is characterized. These composites provide a low cost, lightweight, easy to mold material for vehicle armor. A study of ballistic properties is included and compared to damping behavior.
A Comparison of Experimentally Determined Swimbladder Resonances in Two Species of Fish
Authors: Derenburger Corrie J. , Hastings Mardi C. , Finneran James J.
Published: March 2022

Acoustical backscattering is used in determining the presence of fish in many bodies of water. Since the characteristics of this backscatter are predominantly determined by those of the swimbladder, knowing the frequency response of a fish’s swimbladder a priori could allow identification not only of size, but also of species. A noninvasive, non-contact ultrasonic measurement system was used to determine the in vivo frequency responses of the swimbladders of two different species of fish, the goldfish (Carassius auratus) and the oscar (Astronotus ocellatus). Experimental results showed a difference in both the resonance frequency and sharpness of resonance of the swimbladder between the two species even though all the animals tested were approximately the same size.
Line Impedance Method in 2-D Gas Pulsation Modeling
Authors: Lai Peter C.-C. , Soedel Werner
Published: March 2022

A general procedure for the analysis of curved or flat, thin two dimensional gas cavities such as thin compressor or engine manifolds or so-called thin shell type muffler elements, which can efficiently utilize the limited space of hermetically sealed compressors or small engine compartments, has been developed by the authors (1996a and 1996b), as long as the thickness of the cavities is substantially small compared to the shortest wavelength of interest. However, for an acoustic system which consists of two different thin gas cavities sharing a common line like boundary, some modifications of this general procedure are required. In this study, a simplified refrigeration compressor manifold model, whose geometry is similar to a circular disk box attached to a cylindrical cavity, is investigated. In order to use the general formulations to solve for the forced responses, the natural frequencies and natural modes of this compressor model have to be first determined by a line impedance method proposed by the authors (1996c). Line impedances are formulated, in analogy to line receptances in structural analysis, from the pressure responses of the cylinder and disk cavities to the line volume flow rate inputs which are distributed harmonically along the circular interface of the two subsystems. The frequency characteristic equation is derived and then solved for the natural frequencies and mode shapes of the compressor model. The acoustic four poles and transfer function are finally obtained by substituting the natural frequencies and mode shapes into the general formulations.
Online Estimation of Surface Roughness by Recurrent Fuzzy Inference in Grinding Process
Authors: Kobayashi Futoshi , Arai Fumihito , Fukuda Toshio , Onoda Makoto , Marui Norimasa
Published: March 2022

Grinding process is frequently used to produce a smooth surface in the manufacturing system. Recently, for using a whetstone for a long time, grinding system needs to measure the surface roughness. However, it is difficult to measure the surface roughness and it takes a long time to measure it in process. Thus, we have to estimate surface roughness in process by online sensing information. In this paper, we propose a Recurrent Fuzzy Inference (RFI) with recurrent inputs and is applied to a multi-sensor fusion system for estimating the surface roughness. The membership functions of RFI are expressed by Radial Basis Function (RBF) with insensitive ranges. The learning method of RFI is based on the steepest descent method and incremental learning which can add new fuzzy rules. Where, the shape of new fuzzy rules is determined by the fitness of previous fuzzy rules.
Experimental Investigation of Tapped Thread Surface Roughness for Cast Aluminum Alloys
Authors: Cao Tengyun , Batzer Stephen A. , Sutherland John W.
Published: March 2022

Thread surface roughness is an important issue both in terms of thread quality and the lubricating effect of cutting fluid in the tapping process. In this work, experiments were conducted to investigate the flank surface roughness of tapped threads produced in cast aluminum alloy workpieces. A full factorial experiment was performed to study the effects of the machining parameters (workpiece material, cutting fluid and spindle speed) on the resulting thread flank surface roughness. Metallographic and Scanning Electronic Microscope (SEM) examinations of the thread flank surfaces were performed. Effects were calculated for the variables under study. Workpiece material type was identified as a statistically significant variable in influencing the thread surface roughness. Several other factors that appeared to play a role in producing the thread surface roughness variation observed in the experiments were also examined.
Mechanics of Polishing
Authors: Bulsara Vispi H. , Ahn Yoomin , Chandrasekar Srinivasan , Farris Thomas N.
Published: March 2022

A model has been developed to determine the number and sizes of abrasive particles involved in material removal in polishing, and the forces acting on these particles. The effect of particle size on these parameters has been simulated for a range of particle sizes. It is shown that when polishing with abrasive powders having relatively broad size distributions, only a very small percentage of the particles are involved in material removal. Further, these particles are comprised of the larger particles occurring in the tail end of the particle size distribution. The average force on a particle is found to be in the range of 5–200 mN under typical polishing conditions, which is of the order of loads used in micro-indentation hardness testing. These predictions of the model are consistent with observations pertaining to polished surfaces and the polishing process.
Real Time Monitoring and Simulation of Thermal Deformation in Plastic Package
Authors: Zhu Jiansen , Zou Daqing , Liu Sheng
Published: March 2022

Thermally-induced failure is a major reliability issue for electronic packaging. Due to highly nonlinearity of packaging materials, the electronic packages exhibit uneven thermal deformation in the whole temperature range during thermal cycling. This behavior will affect the buildup of thermal strain and thermal stress within packages, which may affect the reliability of the packaging. Therefore, a real time method is needed to monitor the thermal deformation of packages during the thermal cycling. In this study, the real time moiré interferometry technique is used to monitor the thermal deformation of a plastic package. A grating is transferred onto the cross section of the sample at room temperature. Then the sample is placed in a thermal vacuum chamber and the temperature is increased from room temperature to high temperature. A moiré interferometry setup is used to monitor the thermal deformation of the package with the increase of temperature. The fringe patterns are recorded by a CCD camera system and are compared with the displacement contours of nonlinear finite element simulations. The results show that the real time moiré interferometry technique is an effective way to monitor the thermal deformation of electronic packaging and also provide a powerful validation method for finite element analysis. The comparison between the moiré fringe patterns and finite element results also shows a good agreement.
Modeling Stresses of Contacts in Wiresaw Slicing of Polycrystalline and Crystalline Ingots: Application to Silicon Wafer Production
Authors: Li Ji , Kao Imin , Prasad Vish
Published: March 2022

Wiresaw is a cost-effective technology with high surface quality for slicing large diameter silicon wafers. Though wiresaws have been deployed to cut polycrystalline and single crystal silicon ingot since early 1990s, very little is known about the fundamental cutting process. We investigate this manufacturing process and propose a contact stress model of wiresaw slicing which illustrates the interactions among the wire, ingot, and abrasives (e.g., SiC) carried by the slurry. Stresses created by wiresaw slicing silicon wafers are analyzed in this paper. During the cutting process, the wire moves at high speed (5–15 m/s) with respect to the silicon ingot. The abrasives in the slurry are lose third-body particles caught between the wire and ingot at the contact surface. The forces applied by the wire carry the abrasive particles and cause them to roll on the surface and at the same time to be constrained to indent the surface. Such rolling-indenting interactions result in the formation of isolated chips and surface cracks. The cracks and discontinuity on the surface also cause high stress concentration. As a result the material is cut and removed. The stress fields of a single circular cone of the abrasive particle indenting on silicon crystal with normal and tangential forces can be calculated and analyzed from the modeling equations and boundary conditions. The stresses are expressed with dimensionless stress measures, as functions of normalized geometric parameters. The results show that the maximum normal stress occurs at the indentation point while the maximum shear stress (σzx) occurs below the surface of contact, as expected. Such subsurface shear facilitates the peeling effects of the silicon cracks. Both the normal and tangential forces applied at the contacts are incorporated in the model. The model is very effective in explaining and predicting the behaviors and distributions of stresses during the cutting process, and can be used to determine the optimal geometry of the abrasive particles in the rolling-indenting process.