bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Phase Air-Oil-Water Flow Patterns
Authors: Odozi Utomi A. , Mendes-Tatsis Maria A. , Hewitt Geoff F.
Published: January 2022

In this paper, the flow patterns observed during three-phase (air/oil/water) flow experiments are described. These experiments have been carried out in the Imperial College WASP High Pressure Facility with the test section (77.92 mm I.D) downwardly inclined at an angle of 1.5° to the horizontal at system pressures of 0, 5 and 10 bar(g).

The results for the flow pattern have been plotted on three-phase horizontal flow pattern maps and these comparisons show that the small downward inclination angle has a pronounced effect on the flow regimes. The system pressure also has a strong effect on the flow pattern transitions. In addition to these, no complete separation was observed between the oil and water layers. The flow pattern transitions were compared with the theoretical predictions of Taitel and Dukler (1976) and this was revealed to be inadequate in predicting the three-phase flow patterns and the effect of pressure.
An Experimental Study of Droplets Impacting on Horizontal Screens
Authors: Hung L. S. , Yao S. C.
Published: January 2022

An experimental investigation of the water droplets impacting on horizontal wire screens at isothermal condition was conducted Mono-size droplets of 350 μm in diameter were generated using a piezoelectric droplet generator. For droplets impacting on coarse screens, they wetted the wires by forming thin liquid lumps. As these lumps of water film accumulated around the wires, dripping drops were produced on the bottom side of the wire. This phenomenon was very similar to the dripping drops from a single wire situation. For finer screens, the liquid film on the top surface permeated through the fine mesh openings and formed liquid ligaments at the bottom side of the screen. This ligament continued to grow in the form of a pendant drop. This situation resembled a dripping phenomenon from the bottom side of a flat surface. Eventually, when the weight of the pendant drop was large enough to overcome the surface tension effect associated with the contact surface of the screen, the drop detached from the wire and dripped off.
Experimental Study of Large Steam-Air Bubbles Condensing in a Suppression Pool
Authors: Meier Markus , Andreani Michele , Yadigaroglu George
Published: January 2022

The injection of air and of a steam-air mixture into water at 60 to 90°C through a downward tube of 50 mm diameter is investigated. Steam at up to 40 l/s and air at up to 24 l/s were injected, leading to the formation and break-up of large bubbles. Instrumentation included video, high-speed video, high-frequency pressure measurement and resistance probes for phase detection.

Air tests show a strong dependence of bubble-formation frequency and thus bubble size on the capacitance or length of the piping. Only at higher flow rates, the equation of Davidson and Schüler (1960) predicts bubble frequency and size well.

For steam-air experiments, total flow-rate, and a maximum-volume-reduction factor are used for defining a test matrix. These parameters effectively describe the fluid dynamics of bubble formation and after break-up, and are useful for visual volume estimations. The pool temperature also has some influence.

Experiments show a very irregular, chaotic, turbulent flow. For some cases, bubble volumes at detachment could be estimated and compared with the given parameters. These tests show that condensation is very strong even before bubble detachment and break-up. The height of complete break-up could be approximately correlated. After complete break-up, uncondensed steam is virtually impossible.
Tomographic Interpretation of Visible Emission From the Fuel-Rich Premixed Flame
Authors: Ha Kwangsoon , Choi Sangmin
Published: January 2022

Visible emission characteristics of a fuel-rich methane/air flame with both the luminous and non-luminous zones have been investigated. An optical train with a two-axis scanning mirror system was used to record the two-dimensional emission data from the flame. A spectrograph with an intensified detector array produced spectrum data for each spatial location. The CH radical and broad band soot emission was separated for the wavelength region of 400–500 nm after confirming the gray behavior of the soot. The line of sight integrated emission data from the axi-symmetric flame was further processed tomographically to provide local intensities. Cross-sectional structure of the flame was discussed based on the tomographically reconstructed spectral emission data.
Development of Liquid Crystal Thermometry for Three-Dimensional Temperature Measurement and its Application to Thermal Convection Phenomena
Authors: Fujisawa N. , Saito R. , Matsuura T. , Nakabayashi T.
Published: January 2022

Field temperature measurement technique using the flow visualization with the liquid crystal has been investigated and is applied to the three-dimensional temperature measurement by scanning the thermometry. The color to temperature calibration of the liquid crystal is carried out using the neural networks, where the effect of view angle relative to the light sheet is considered by distributing the networks over the image plane and with an optimum smoothing technique. The calibration error of temperature due to the view angle is much reduced by the present technique and is proved to be useful by application to the temperature measurement of the thermal convection over a heated surface. The three-dimensional temperature distributions of the thermal convection is reconstructed from the measured temperature field and the structure of thermal plumes is examined.
A Study of Characteristic Length for Natural Convection Heat Transfer to Ice Spheres Melting in Air
Authors: Janna William S. , Jakubowski Gerald S.
Published: January 2022

Three different diameter ice spheres were formed and allowed to melt in air. Each sphere was suspended by a string from a cantilevered beam, which had strain gages attached. A four active element Wheatstone Bridge was used to measure the output of the strain gages. The output signal was calibrated to measure weight of the sphere at any time during the phase change process. Data on weight versus time were thus obtained using a recorder.

The objective of this study is to relate Nusselt number to Rayleigh number, as is done in the literature. Characteristic length is needed to find the Nusselt and Rayleigh numbers, but because of the changing geometry of the melting ice spheres, defining characteristic length to appropriately correlate the data becomes difficult.

A number of researchers have proposed equations for characteristic length for melting ice objects. Three different characteristic lengths were determined based on previous work with melting ice spheres, and used to calculate values of Nusselt and Rayleigh numbers at various instants in time. The geometry of each sphere changed during the melting process as did surface area and volume. Three different Nusselt vs Rayleigh number graphs resulted, which are contrasted and compared.

A fourth characteristic length was proposed for the data of this study, which yielded excellent results. An equation relating Nusselt number to Rayleigh number was derived with a correlation coefficient of 0.975. Rayleigh numbers ranged 1.0 × 104 to 1.2 × 107, while Nusselt number ranged from 4 to 10.2. It was found that the Nusselt number could be predicted with

Nu = 1.45 Ra0.126
A New Correlation for Temperature Rise Correction of Heat Flux Gages
Authors: Mukerji Debjit , Eaton John K. , Moffat Robert J.
Published: January 2022

Experimental and numerical studies of turbulent heat transfer near a step change in wall temperature have been conducted in connection with an error analysis of small, transient, heat flux gages. The surface temperature of such a gage typically rises above the temperature of the surrounding metal wall, which influences the heat flux to the gage. Data from such gages must be corrected for the effect of this temperature rise. The correction is typically made by superposition using an unheated starting-length correlation, a procedure that has been in practice for many years.

In the present work, experimental data from a small, isothermal calorimeter were compared with output from STAN7, a 2-D turbulent boundary layer code, and with predictions based on a textbook correlation. The experiments and the numerical predictions agree within +/−6%, but the correlation underpredicts the required correction by 15–20% over the first half-boundary layer thickness downstream of the step change. As a consequence, data from small gages cannot be properly corrected using the accepted correlation.

A new expression is proposed for Stanton number downstream of a step in wall temperature, which can be used as an accurate correction algorithm for use with small gages.
Local Hyperthermic Treatment of Solid Tumors: Interplay Between Thermal Dose and Physiological Parameters
Authors: Griffin Robert J. , Ogawa Atsushi , Shakil Abdus , Song Chang W.
Published: January 2022

Reduction of tumor blood flow during hyperthermia may impair the ability of the tumor vasculature to dissipate heat and lead to greater tumor cell killing. We are currently testing a new compound (KB-R8498) which has been found to reduce tumor blood flow. One hour after an i.v. or an i.p. injection of KB-R8498 the blood flow in SCK tumors of A/J mice was reduced to 40%–70% of control. The blood flow in 6 A/J mouse normal tissues one hour after drug treatment was mostly unchanged. Control tumors grew to four times the starting volume in 6 days. An injection of 10 mg/kg KB-R8498 caused a growth delay of about 2 days. After tumors were heated at 42.5°C for 60 min, there was a delay of 4 days in tumor growth. When i.p. or i.v. injections of KB-R8498 were given and the tumors were heated at 42.5°C for 60 min, there was a growth delay of over 10 days. The implications for clinical hyperthermia treatments are discussed.
The Kinetics of Thermal Damage: Estimation and Evaluation of Model Coefficients
Authors: Pearce John , Liao Wen Huang , Thomsen Sharon
Published: January 2022

Successful use of kinetic models of thermal damage processes depends critically upon the identification of a quantitative measure of thermal damage. Most clinically relevant processes are qualitative in nature and are not easily studied by the standard Arrhenius formulation. Quantitative markers of thermal damage include: 1) loss of birefringence properties in muscle and collagen, 2) loss of hemoglobin from red blood cells, 3) uptake of enzymatically active dyes and 4) diffusion of dyes across vessel walls. When a quantitative marker is used the kinetic coefficients estimated from experiments over different time scales are significantly different. Application of coefficients determined in long term studies (exposure times on the order of hours) to short term exposures (electrosurgical coagulation or short laser pulses) is questionable and often leads to counter-intuitive predictions of damage boundaries. Short term exposures, on the other hand, are by definition not of constant temperature and often defy estimation of the coefficients from the transient history. We present and compare several sets of estimated thermal damage coefficients for similar and differing processes and a preliminary method for extracting estimates from transient histories.
A Theoretical FE-Based Model Developed to Predict the Relative Contribution of Convective and Diffusive Transport Mechanisms for the Maintenance of Local Equilibria Within Cortical Bone
Authors: Tate Melissa L. Knothe , Niederer Peter
Published: January 2022

Whereas diffusion has been shown to be the major contributing mechanism for mass transfer in the extravascular spaces of organs and soft tissues, it is unlikely that diffusion alone can account for sufficient molecular transport in the porous yet relatively impermeable tissue of cortical bone. An alternate mechanism for such mass transfer is intrinsic to the functional role of cortical bone in transferring loads within the musculoskeletal system. Namely, it has been proposed that mechanical loading causes minute deformations within the poroelastic tissue of cortical bone, resulting in extravascular fluid displacements. This biophysical phenomenon is referred to as load-induced interstitial or extravascular fluid flow.

In order to establish the role of convective transport mechanisms for maintenance of healthy bone metabolism and to investigate the potential role of convective transport (via load-induced fluid flow) for processes associated with functional adaptation, we developed a theoretical osteon model based on finite element methods. A study designed to simulate short term transport (circa 1 second or half a gait cycle) in a single osteon corroborated the hypothesis that diffusion alone is insufficient for molecular transport between the blood supply and remotely lying bone cells. Simulations of long term transport (circa one day) showed that convection via load-induced flow can be expected to improve this transport significantly.
Use of a Genetic Algorithm in Near-Infrared Imaging
Authors: Jones Matthew R.
Published: January 2022

The development of noninvasive medical imaging techniques over the last several decades has greatly increased the ability of physicians to detect and diagnose disease and injury. Near-infrared imaging is a modality which uses red and near-infrared radiation to probe biological tissues. There are several advantages to using near-infrared radiation. One advantage is that information regarding both the structure and functional status of tissue can be obtained. Another advantage is that it is possible to continuously monitor tissue using near-infrared imaging. However, unlike x-rays near-infrared radiation is highly scattered by biological tissues, so conventional image reconstruction techniques are not applicable. This paper describes a preliminary investigation into the use of an image reconstruction technique based on a genetic algorithm. Numerical simulations of continuous-wave relative transmission measurements through a cylindrical object are used as the inputs to the image reconstruction algorithm. Tomographic images of the object obtained using a genetic algorithm are compared with an image obtained using a gradient based algorithm. These results show that the genetic algorithm is more robust than the gradient based algorithm.
Ice Front Propagation Monitoring in Tissue Using Visible Light Transmission: Behavior Prediction Using Photon Diffusion Model
Authors: Otten David M. , Rubinsky Boris
Published: January 2022

A two-dimensional finite difference diffusion model was developed to analyze the effects of a propagating ice front on the continuous wave intensity transmission across a tissue sample. The calculated diffusion model transmissions for a transilluminating emitter/detector fiber configuration were compared to experimentally obtained transmissions for consecutive ice front positions within the tissue sample. The diffusion model was able to predict the transmission behavior for this fiber configuration given the absorption and scattering coefficients of the frozen and unfrozen tissue. Calibration algorithms for similar fiber probe placements based on this model may eventually be used with real-time transmission measurements to allow visible light monitoring of ice front position in tissue. This demonstration has potentially important medical applications in cryopreservation (freezing of biological materials for preservation) and cryosurgery (destruction of tissue by freezing).
Energy Level Concept and its Application to Improvement of Absorption Heat Transformer
Authors: Ishida Masaru , Ji Jun
Published: January 2022

A graphical exergy study based on energy-utilization diagrams (EUDs) is performed on the multiple-compartment generator and multiple-compartment absorber in close-to-equilibrium operation in a single stage absorption heat transformer (SAHT). The working fluid considered for the heat transformer is water-lithium bromide. This analysis provides detailed information on internal phenomena such as the driving forces and the distribution of the exergy loss in each subsystem. The results show that the multiple-compartment absorber can improve the temperature lift and exergy efficiency, whereas the multiple-compartment generator can extend the heat source temperature range. The effect of solution concentration is also investigated.
Modeling and Experimental Investigation of Dynamics of a Directly Combined Binary Turbine System Using Steam and R123
Authors: Tanzawa Yoshiaki , Terashima Yukio , Amano Yoshiaru , Kato Ryo , Hashizume Takumi , Usui Akira
Published: January 2022

The binary turbine system that employs steam as the primary working fluid has used R11 as the secondary working fluid, because R11 has good characteristics as a working fluid in power plants. However, substitute LBMs (low boiling-temperature mediums compared with water) are being developed because of the destruction of the ozone layer by CFCs. In this paper, modeling and experimental investigations into the dynamics of a directly combined binary turbine system using R123 instead of R11 are described. The system consists mainly of a steam- and an R123-turbine, an R123 vapor generator, and an AC generator. The dynamic behavior of the system is discussed from the viewpoint of the network theory. The components of the system are represented as two- or three-port elements of the network and the vapor flow rate and shaft torque are appropriated as the through variable, and the vapor pressure and rotational speed as the across variable. As a result, a very simple network model based on the dynamics of various turbine systems like this was derived. The validity of the model was proven through comparison with our experimental results, which are the frequency responses examined with respect to generator load changes. In addition, we demonstrate that the model is very effective in predicting the dynamic behavior and power generation mechanism of directly combined binary turbine systems.
How the Water Section in the Hat Cycle Can Be an Efficient Power Output Modulator
Authors: Di Maria Francesco , Desideri Umberto
Published: January 2022

After a long period during which theoretical analyses were presented on evaporative gas turbine cycles, such as the HAT (Humid Air Turbine) and CHAT (Cascaded Humid Air Turbine), the first experimental plant with water recovery is currently under construction at the Lund Institute of Technology in Sweden. The pilot plant is due to start in evaporative mode in May 1998, and this represents the first step for the validation of the humid air turbine concept.

One of the main points of interest is the power modulation which should be possible controlling the evaporated water flow rate. If the whole compressed air flow rate is introduced into the evaporator the possibilities to vary its water content are scarce if the temperatures in the recuperator are not changed. A solution to this problem has been patented by Vattenfall AB, and consists in bypassing a fraction of the air entering the evaporator directly into the recuperator.

In this paper a detailed study of the different evaporation modes is presented from the point of view of both the first and second law analysis. The thermodynamic analysis will also be compared with the operational flexibility that the by-pass solution offers. Applications to some commercial turbines, which are most suited to use in HAT cycle mode, will also be presented.
The Impact of Imperfect Intercooling on Combined Cycle Performance
Authors: Sivasubramanian J. , Balasubramaniam L. , Ramayya A. Venkata
Published: January 2022

The effect of imperfect intercooling of the compression stages on the combined cycle performance is studied by characterizing the alteration in performance in terms of degree of imperfect intercooling. A combined cycle configuration with a two stage compressor and a two stage reheat turbine is considered and irreversibilities of various components are studied with regard to the effectiveness of intercooler by making energy and exergy balances. The first and second-law efficiencies are discussed as a function of the level of intercooling and the trade of involved between the additional work input and the availability gain at compressor exit. The irreversibilities of various components are found to increase with a higher level of intercooling while the first and second-law efficiencies of the combined cycle are shown to exhibit a maximum at an optimum pressure ratio. Compared to the case of perfect intercooling, imperfect intercooling is found to result in a significant improvement in the magnitudes of first and second-law efficiencies of the combined cycle.
Loops and Thermodynamics
Authors: Ishida Masaru , Suzuki Takahiro , Yamamoto Masashi
Published: January 2022

Cycles such as a Rankine cycle, Calvin cycle, etc. play important roles. They consist of a set of specific processes and exhibit specific functions by this whole set of processes.

Two methods to examine those specific functions graphically are presented based on thermodynamics. The first method is to trace the ratio of the exergy gained to the energy gained by the circulating substance. The second method is to display release and acceptance of heat-equivalent as well as work-equivalent energies. Those methods reveals that loops have three important features; work (or work-equivalent energy) integration, creation of specific fields, and functions to purify a target component and to reduce wastes. All of these features are keys to create a sustainable society.
On the Definition of Entropy and Temperature and on the Energy Interactions
Authors: Kouremenos D. A.
Published: January 2022

The thermodynamic systems considered here are those that can be described by using only two macroscopic variables. For this purpose the specific volume v and the specific internal energy u are used while the pressure function p(u,v) is supposed to be known. It is shown that by a suitable mathematical transformation of variables, the pair (u,v) can be replaced by the pair of functions temperature T(u,v) and entropy s(u,v) that are defined simultaneously by a proposed generic system of differential equations without using the concept of heat. To show the authenticity of these definitons some solutions of this generic system of differential equations are given and in addition to, the special case of the perfect gas is obtained as one of the results. It is proposed to add to the conventional concepts of work and heat a third constitutive component, the throttling. With it the local efficiency η of a differential themodynamic change can be defined. In addition this allows for the deduction of the relation (pdv + du) ≥ 0 as a consequence. The heat-work energy interactions with a thermodynamic system are taking place mostly through an enclosing boundary wall. As these two different forms of energy flow cross the boundary wall, they undergoe some transformation. As a result, the heat and work flow through the wall from/to the outer space to/from the system considered may change, although its algebraic sum, the total energy transfered, retains its initial value. Vector notation is used to facilitate the description of this transformation of energy crossing a boundary wall.
United States Department of Energy Large Commercial Absorption Chiller Development Program
Authors: Garland Patricia Welesko , DeVault Robert C. , Zaltash Abdi
Published: January 2022

The U.S. Department of Energy (DOE) is working with partners from the gas cooling industry to improve energy efficiency and U.S. competitiveness by using advanced absorption technologies that eliminate the use of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), refrigerants that contribute to ozone depletion and global warming. Absorption cooling uses natural gas as the heat source, which produces much lower NOx emissions than oil- or coal-generated electricity. Gas-fired chillers also have the advantage of helping reduce peak electrical usage during summer months. To assist industry in developing advanced absorption cooling technologies, DOE sponsors the Large Commercial Chiller Development Program. The goal of the program is to improve chiller cooling efficiency by 30–50% compared with the best currently available absorption systems.
Compressible Fluid Flow and Heat Transfer Navier-Stokes Predictions on Unstructured Grids
Authors: Marques Nelson P. C. , Pereira José C. F.
Published: January 2022

A second-order accurate finite volume method for solving compressible 2D flows on hybrid structured-unstructured grids is presented. Separate reconstruction and evolution steps are taken to discretize the convective terms. For the reconstruction step, a data-dependent Least-Squares procedure is used, while for the evolution step two recent flux functions are included: the HLLC approximate Riemann solver and the AUSM+ flux vector splitting. Steady-state solutions are obtained with an implicit backward Euler scheme. The assembled system is solved by iterative means (BiCGSTAB, GMRES) with ILU pre-conditioning.

Two internal, steady, 2D flow test cases are presented to validate the code: a supersonic 10° ramp inside a channel and a laminar flow through a double-throated nozzle.

The code proved accurate with the use of both flux functions when comparing the computed results with both an analytical (ramp) and a reference solution (nozzle). The GMRES solver generally required less CPU time until convergence for the inviscid test-case while the BiCGSTAB solver got the edge for the viscous calculations.
Heat Transfer in Reciprocating Compressors: A Review
Authors: Prasad B. G. Shiva
Published: January 2022

Heating is an undesirable effect of the compression process at least as far as compressors are concerned and heat transfer is nature’s way of driving systems towards stability. This has not only provided food for thought for researchers trying to understand its influence and quantify its effects, but also challenged designers to mitigate its impact and develop safe and efficient designs. Also, just as any other unwanted phenomenon would spur curiosity and inventiveness, this has led to the development of a host of new materials both metallic as well as non-metallic to withstand the vagaries of high temperatures, in addition to the toxic environment present in many gas compressors used in pumping and process industries. This paper is an attempt to present some of the problems created by this unwanted phenomenon, review the contributions of some of the past investigators, and kindle more interest for furthering the advancement of compressor technology.
Transient Heat Transfer Approximations for Ground-Source Heat Pump Design
Authors: Stevens James W.
Published: January 2022

Design of ground-source heat pump systems requires an estimation of the heat transfer between a buried pipe and the surrounding ground. Since heat pumps normally operate intermittently, the heat transfer with intermittent boundary conditions is important. While a variety of useful tools exist for numerically determining the heat transfer characteristics of any given system, it is unwieldy to use such tools for rough or preliminary estimates of system sizes. This paper describes the development of accurate simple approximations for the heat transfer from a round pipe buried in an infinite medium with the pipe wall intermittently changing between isothermal and adiabatic conditions. It is shown that the steady-boundary case provides an upper bound on the time-averaged heat transfer from the pipe and a lower bound on the instantaneous heat transfer rate. For a low thermal diffusivity medium, the time averaged intermittent heat transfer rate approaches that of the steady boundary case, while for a high value of thermal diffusivity, the time averaged heat transfer decreases faster than it does in the steady boundary case. The overall heat transfer can be well correlated with simple functions over a range of thermal diffusivities, intermittence intervals, and time.
Comparison of Analytical and Experimental Effectiveness of Four-Row Plate-Fin-Tube Heat Exchangers With Water, R-22 and R-410A
Authors: Chen Tony D. , Conklin James C. , Baxter Van D.
Published: January 2022

The analytical solutions of heat exchanger effectiveness for four-row crossflow, cross-counterflow and cross-parallelflow have been derived in the recent study. The main objective of this study is to investigate the effect of heat exchanger flow configuration on thermal performance with refrigerant mixtures. Difference of heat exchanger effectiveness for all flow arrangements relative to an analytical many-row solution has been analyzed. A comparison of four-row cross counterflow heat exchanger effectiveness between analytical solutions and experimental data with water, R-22, and R-410A is presented.
Numerical Modeling of Conjugate Heat Transfer During Free Liquid Jet Impingement
Authors: Rahman Muhammad M. , Bula Antonio J. , Leland John E.
Published: January 2022

The paper presents the results of numerical simulation of a free jet of high Prandtl number fluid impinging perpendicularly on a solid substrate of finite thickness containing electronics on the opposite surface. The numerical model was developed considering both solid and fluid regions and solved as a conjugate problem. Equations for the conservation of mass, momentum, and energy were solved in the liquid region taking into account the transport processes at the inlet and exit boundaries as well as at the solid-liquid and liquid-gas interfaces. In the solid region, only heat conduction equation was solved. The shape and location of the free surface (liquid-gas interface) was determined iteratively as a part of the solution process by satisfying the kinematic condition as well as the balance of normal and shear forces at this interface. The number of elements in the fluid and solid regions were determined from a systematic grid-independence study. A non-uniform grid distribution was used to adequately capture large variations near the solid-fluid interface. Computed results included the velocity, temperature, and pressure distributions in the fluid, and the local and average heat transfer coefficients at the solid-fluid interface. Computations were carried out to investigate the influence of different operating parameters such as jet velocity, heat flux, plate thickness, and plate material. Numerical results were validated with available experimental data. It was found that the local heat transfer coefficient is maximum at the center of the disk and decreases gradually with radius as the flow moves downstream. The average heat transfer coefficient and the maximum temperature occurring in the solid decreased with increase of disk thickness and increase of thermal conductivity of the disk material.
Crack in a Bimaterial Functionally Graded Multilayered Media
Authors: Muju Sandeep
Published: January 2022

The macroscopically anisotropic homogenization of a multilayered media implicitly assumes that the spatial wavelength of material inhomogeneity is smaller than the macroscopic quantity of interest and hence, is a reasonable approximation of the bulk behavior. However, close to the crack tip, gradients in field quantities are strongly influenced by the local heterogeneity, which the isotropic or anisotropic homogenization fails to capture.

The present work addresses the issues related to the influence of material inhomogeneity on local crack tip driving force. It is shown that to the first order, the effect of moduli inhomogeneity, residual stresses and inelastic strains on crack tip stress intensity factor are superposable.

Detailed analytical model is developed for quantifying the effect of moduli inhomogeneity for the case of bimaterial multilayered media with functional interfaces, i.e., compositionally graded finite thickness interfaces.

This method provides an efficient means to study thermoelastic crack problems in complex heterogeneous media, alleviating the numerical or analytical difficulties associated with the traditional methods. The results show that the material inhomogeneity plays a significant role in effecting the crack tip driving force.
Inputs for Successful Target Costing
Authors: Clifton Brad , Townsend Wes
Published: January 2022

Cost management is becoming as widespread as quality control was in the 1970’s and 1980’s1. Target Costing is an effective, structured approach to cost management. We have all faced the limitations of trying to reduce costs when a product is already designed and in manufacturing. This is the most expensive phase of the product realization cycle to make a change, so often good cost reductions ideas are not implemented. Target Costing addresses this limitation because it brings the strength of the whole enterprise into the early stages of a product’s development cycle.
Process Quality in Rapid Manufacturing
Authors: Kahlen Franz-Josef , Kar Aravinda
Published: January 2022

The subject of this presentation is the qualification of a rapid manufacturing process in terms of the created product. The analysis was based on using a high power CO2 laser as energy source for parts creation, material under investigation is Stainless Steel SS304. The incident CO2 laser beam power was varied from 300 W to 400 W, with the laser beam showing a Gaussian intensity distribution. The laser beam was focused to a focal diameter of 460 μm using a 127 mm (5“) focal length lens.

This study investigates, for a variety of operating conditions, the smoothness of the material deposition, the process’ inherent susceptibility to lateral misalignment, geometrical characteristics of the process, and the permissible yield and ultimate tensile strengths. The yield strength is close to isotropic (250 MPa, same as wrought SS304), despite the expectation that the joints between the layers would turn out as the weakest link in the chain, and height deviations were well within 10% of the deposition height for high powers and small substrate translation speeds. The impact of a lateral misalignment is comparable to values for other laser materials processing situations.
Design Optimization of Rolling Element Bearings
Authors: Fu Wen , Rhodes John H. , Good Bruce R. , Dong Jian (John)
Published: January 2022

This study presents an efficient method for optimizing Basic Dynamic Load Rating (BDLR) of rolling element bearings such as spherical roller thrust bearings. An optimizing model and program have been developed using the Solver feature within MS Excel. The program searches for the ideal combination of roller diameter, length and quantity to maximize BDLR within certain predetermined constraints. Results show that significant increases in load rating can be achieved when compared with existing designs in product offerings. This program thus enables the designer to efficiently create enhanced products while reducing the level of design experience required. This methodology is currently being applied to rolling element bearings manufactured by the Fafnir Division of The Torrington Company.
Design of a Computer-Aided Modeling System: A Case Study
Authors: Lotko John , Bzymek Zbigniew M. , Garrett Richard E. , Billatos Samir B.
Published: January 2022

This paper describes a computer algorithm capable of seamlessly transforming a Cadkey part into tool paths that can produce a model using a Computer-Aided Modeling (CAM) machine. This was accomplished utilizing rules based on known machining practices developed in conjunction with Cadkey and Cutting Edge designers. The rules used for designing this software consist of fundamental principles of machining. In the conventional approach, these are the rules that are supplied by the designer and applied to the problem using a programs such as Cutting Edge. The basic set of rules and the original Computer-Aided Design (CAD) design were sufficient to create the needed tool paths with the user’s time and input replaced by a computer algorithm. A developed computer algorithm is much less flexible, but significantly quicker than a designer, so where applicable more robust rules which required greater time or iterations were chosen. The algorithm is general but can be applied to any CAD system. However, the specific design work was performed with Cadkey as the target low cost system and a Roland desk-top Computer-Aided Modeling Machine (CAMM-3) as the target cutting device. All assumptions made for this test case were based on the criteria of user’s convenience and economy. All the tests performed proved that the algorithm works and is capable of adding one more output device — a cutter as an output system.
Sound Absorption of Solid-State PETG Foams
Authors: Lee Nathaniel , Reinhall Per G. , Kumar Vipin
Published: January 2022

The sound absorption characteristics of PETG foams have been investigated experimentally. The normal incidence sound absorption coefficient was measured using an impedance tube designed according to ASTM 1050-90. The effect of both the cell size and the density of the foam on the absorption coefficient were investigated. The absorption coefficient was shown to be sensitive to both these parameters. The larger cell size (800μm) foam exhibited a significant increase in absorption around 3700 Hz making the absorption coefficient highly dependent on the frequency content of the incoming acoustic energy. It is also shown that thin foam sheets can be layered to achieve an acoustic treatment with high absorption characteristics.
E/M Impedance Health Monitoring of Spot-Welded Structural Joints
Authors: Giurgiutiu Victor , Reynolds Anthony , Rogers Craig A. , Chao Yuh Jin , Sutton Michael A.
Published: January 2022

Experimental results obtained during fatigue testing of a spot-welded lap-shear structural-joint specimen are presented. In these experiments, the electro-mechanical (E/M) impedance technique was used for structural health monitoring, damage detection, and NDE. The test specimens were instrumented with piezo-electric wafer transducers, and the base E/M impedance signature was recorded over the relevant frequency range. Fatigue testing was applied to initiate and propagate crack damage of controlled magnitude. Preliminary tests were performed to correlate stiffness decrease with damage progression and remaining life. Then, during the health monitoring tests, the specimens were continuously monitored for stiffness decrease indicative of damage. E/M impedance signatures were periodically recorded, as the damaged progressed. Signature data was processed, and the damage index was calculated. The initiation and propagation of damage, i.e., structural crack, was successfully correlated with the E/M impedance measurements. Damage index values were observed to increase as crack damage increases. Sensing and the localization principles of E/M impedance NDE method were confirmed. Rejection of spurious information was also confirmed. Through these experiments, the E/M impedance technique has been, once again, proved to be a powerful tool with good potential for damage detection, health monitoring, and NDE.
Active Control of Crane-Load Vibrations on Ship Vessels
Authors: Li Y.-Y. , Balachandran B.
Published: January 2022

In order to suppress crane load vibrations on ship vessels, a novel mechanism called a mechanical filter was developed by us recently. This mechanism was implemented on the basis of the premise that by actively and passively controlling the pivot point about which the load oscillates, one can effectively suppress crane load motions. In the present efforts, it is demonstrated that with an aid of a static feedback control law, one can effectively eliminate bifurcations that can lead to large changes in the crane load motions from the window of the considered ranges of disturbance frequency and disturbance amplitude parameters. The response amplitude of the crane load to ship-roll motions is attenuated to a low magnitude over the disturbance parameter window. Variations in the control input with respect to the crane-load mass are also investigated.
New Maintenance (Inspection) Method for Ground Machines
Authors: Egawa Koichi
Published: January 2022

The main purpose of this paper is to forecast maintenance (inspection) technology in the near future which will be led by the introduction of the Intelligent (smart) materials and structures (IMS) concepts into this technology. Concerning the IMS concepts, many research works have been conducted and many proposals are still being offered, but it remains as an idea or a mere concept. But, the author would like to say that it already takes practical, concrete form in some places in the technological, engineering world. As an example, the change of maintenance ways of about 120 die-casting machines in a factory is presented here. It would be thought that this change would bring about introducing IMS’s primary stage concept, sensory structure; however, even maintenance people in that factory are not conscious about what IMS concept is.
Front End Design of Aluminum Vehicle for Crashworthiness
Authors: Farooq Rehan
Published: January 2022

This paper discusses the methods and techniques in designing a mid-size Aluminum vehicle front end for crashworthiness. Aluminum was used in place of steel in order to reduce weight, hence the fuel consumption, this change allowed a reduction of about 53% in total weight of BIW as compared to steel one with same size and crush strength. For maximum energy absorption, concept of progressive localized buckling of vehicle components was used. To develop the most efficient energy absorbing cross-sections for front end components a computer beam code SECOLLAPSE is used. Cross sectional properties (Peak and Mean loads) of these sections were compared to the steel cross sections. Front end components then modeled and analyzed by using the non linear Finite Element crash code V-CRUSH and the final design was verified by comparing with existing steel design of similar configuration. Testing of this structure and its various front end component is under way and results will be presented in a later study.
Occupants Safety due to Mass and Stiffness of Vehicles in Head-on Collision
Authors: Jawad Saad A. W.
Published: January 2022

Compatibility of vehicles of different mass and stiffness in head-on collisions was studied in earlier paper(13). It was concluded that mass ratio was the most important parameter in the mechanics of head-on collision. To improve compatibility, it was also suggested that stiffness might be reduced with longer crumple zone for heavier vehicles. This paper continues the study by considering the impact of changing stiffness of a vehicle on the level of protection the vehicle provides to its own occupants when colliding with similar vehicle. Such study is prompted by the fact that there is a strong link between aggressivity of a vehicle to the partner vehicle’s occupants and the level of protection the vehicle provides to its own occupants. In other words safer vehicles are usually more aggressive. A compromise between the level of protection and aggressivity of the vehicle design need to be investigated using basic laws of mechanics of head-on collisions. An eight-degrees of freedom, two-dimensional lumped-mass simulation model was used for this purpose.

Three injury risk criteria have been considered in this study; delta V or change in velocity of vehicle after impact, maximum acceleration sustained by the passenger compartment throughout impact, and length of deformation sustained by the car front Both mass and stiffness are crucial for the occupants safety. Higher mass provides protection to its occupant as well as aggressivity to occupants of the partner vehicle. Higher stiffness provides little protection to its occupants in terms of the intrusion injury criterion but more aggressive to its own occupants as well as occupants of the partner vehicle in terms of other injury criteria. A slightly softer and longer crumple zone is proposed for heavier vehicles to achieve better protection for occupants of both colliding vehicles.
Side Airbag Design Using an Enhanced MADYMO SID Model
Authors: Deng Yih-Charng , Peng Julie , Setru Prabhu
Published: January 2022

In this study, we evaluated and enhanced a SID model in the MADYMO database. It was found that the original MADYMO model exhibited discrepancies with the SID responses measured from the barrier impact test. After a number of improvements were made to the thorax region the revised model showed better correlation with the test results. Design exercises were performed using the SID model to study the design of a side airbag for a large car, including the effects of different sizes for the vent, inflator and bag. Occupant responses indicated that a large vent is beneficial whereas low sensitivities were found for the inflator and bag size variations.
Application of Foam in Reducing Lower Leg Injuries
Authors: Chen Roger , Belwafa Jamel E.
Published: January 2022

Occupant safety has been, and always will be, one of the Auto-makers main objective and concern. For the past ten years, widespread use of airbags has reduced the risk of head and chest injuries making lower extremity injuries relatively more important. The purpose of this paper is to study the feasibility of using energy absorbing material in the toeboard area in order to reduce lower leg high axial and bending force levels. The study consists of comparing and evaluating the physical properties and dynamic impact performance characteristics of different recoverable foams. The choice of the tested foams was based on their energy absorbing potential. Although preliminary results showed benefits in using foam in the toeboard area to absorb some of the energy transferred to the occupant feet, further studies were recommended to ensure that the selection of a particular foam is best suitable for this application.
Modeling Human Brain Movability Effect on Brain Response During Impact
Authors: Hu Hao , Rosenberg William S. , Nayfeh Adnan H.
Published: January 2022

Brain responses due to its movability during impact was investigated by using sliding interface approach. A new 3D 50th percentile human head finite element model has been generated in which sliding interfaces totally separate the brains and cerebrospinal fluid (CSF)/cranium. So, the brains can move to some extent. It becomes an equivalent one to most widely used brain/CSF (cranium) coupled models by switching interface type from sliding to tied. The model was partially validated by using available experimental and computed data in frontal impact. Compared with brain/CSF (cranium) coupled models, the new model predicts higher brain stress levels at sites such as corpus callosum, brain stem, and the vicinity of the ventricles etc. and more realistic deformation patterns. The results suggest that a fluid-solid interaction approach should be used to better model brain movement during impact to correctly interpret the brain injuries and to evaluate proposed head injury mechanisms.
Advanced Material Distribution Measurement in Multiphase Flows: A Case Study
Authors: George D. L. , Ceccio S. L. , O’Hern T. J. , Shollenberger K. A. , Torczynski J. R.
Published: January 2022

A variety of tomographic techniques that have been applied to multiphase flows are described. The methods discussed include electrical impedance tomography (EIT), magnetic resonance imaging (MRI), positron emission tomography (PET), gamma-densitometry tomography (GDT), radiative particle tracking (RDT), X-ray imaging, and acoustic tomography. Also presented is a case study in which measurements were made with EIT and GDT in two-phase flows. Both solid-liquid and gas-liquid flows were examined. EIT and GDT were applied independently to predict mean and spatially resolved phase volume fractions. The results from the two systems compared well.
Three-Dimensional Tomography Methods in Flow Visualization
Authors: Pickalov Valery V.
Published: January 2022

The paper gives a review of modern optical tomography techniques, and corresponding two- and three-dimensional algorithms are also discussed. Special emphasis is laid on the synthesis of tomography approaches with the new image processing technique.

Some examples of the new methods of tomography for incomplete data, local tomography of high gradient structures are discussed. The role of Vainberg image for three-dimensional object visualization is shown.