bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Peripheral Milling of Flexible Structures
Authors: Altintas Y. , Montgomery D. , Budak E.
Published: March 2013

A dynamic model for peripheral milling of very flexible plate type structures has been presented. The structural dynamics of a cantilevered plate structure is modelled at the tool-workpiece contact zone. The interaction of the very flexible plate structure and rigid end mill during dynamic milling is modelled. The variation in surface, chip thickness, and structural dynamics of the plate are considered in determining the milling forces. The proposed model provides surface finish form errors displacements at the tool-workpiece contact zone, and cutting forces for dynamic end milling operations.
Use of Audio Signals for Chatter Detection and Control
Authors: Delio T. , Tlusty J. , Smith S.
Published: March 2013

This paper compares various sensors and shows that a microphone is an excellent sensor to be used for chatter detection and control. Comparisons are made between the microphone and some other common sensors (dynamometers, displacement probes, and accelerometers) regarding sensing of unstable milling. It is shown that the signal from the microphone provides a competitive, and in many instances a superior, signal tht can be utilized to identify chatter. Using time domain milling simulations of low-radial-immersion, low-feed, finishing operations it is shown that for these cuts (especially at relatively high speeds) chatter is not adequately reflected in the force signal because of the short contact time, but that it is clearly seen in the displacement signal. Using the dynamics of existing production milling machines it is shown how the microphone is more suitable to chatter detection than other remotely placed displacement sensors, especially in cases that involve flexible tooling and workpieces. Aspects important for practical implementation of a microphone in an industrial setting are discussed. Limitations of the microphone are addressed, such as directional considerations, frequency response, and environmental sensitivity (i.e., workspace enclosure, room size, etc). To compensate for expected unwanted noises, commonly known directionalization techniques such as isolation, collection, and intensity methods are suggested to improve the ability of the microphone to identify chatter by reducing or eliminating background and extraneous noises. Using frequency domain processing and the deterministic frequency domain chatter theory, a microphone is shown to provide a proper and consistent signal for reliable chatter detection and control. Cutting test records for an operating, chatter recognition and control system, using a microphone, are presented; and numerous examples of chatter control are listed which include full and partial immersion, face-and end-milling cuts.
A Model of the Sequential Bending Process for Manufacturing Simulation
Authors: Hardt D. E. , Constantine E. , Wright A.
Published: March 2013

The process of sequential bending has many applications, but the most common is for developing cylindrical shapes from plate. The objective of this work is to develop a process model for use in simulation of the manufacturing of such objects, to provide design sensitivity information, and to explore the potential for improved process control. The process is modeled here as a series of overlapping two-dimensional three-point bends, where the overlap includes the plastic zone from previous bends. This deformed zone is modeled both as a non-flat initial geometry for the next bend and as a locally strain-hardened material with residual stresses. For process simulation the model is incorporated into a measurement and control simulation that allows either operator-controlled algorithms or automatic control to be employed. A series of experiments were performed on plates of steel, aluminum, and brass to examine the accuracy of the model. Good agreement was found, but only after adjusting the assumed material parameters. Results show that the prior bending history has a marked effect on the basic process resolution, and therefore on the effective precision and sensitivity of the process.
An Intelligent Planning Environment for Automated Dimensional Inspection Using Coordinate Measuring Machines
Authors: Menq Chia-Hsiang , Yau Hong-Tzong , Wong Ching-Li
Published: March 2013

This paper presents a basic structure of an intelligent planning environment for automated dimensional inspection using coordinate measuring machines (CMMs). Three levels of automation technology, ranging from the facility automation to information and decision automation, are discussed. At the facility level, the operations of the CMMs are examined for the dimensional inspection of various manufactured objects. In this research the dimensional inspection of objects having complex and sculptured surfaces is emphasized. At the information level, a CAD-directed inspection system is implemented. The system is composed of three key elements: CAD/CMM inspection planning module, CAD model based localization algorithm, and comparative analysis module. In addition, the concept of inspection attributes is introduced. Inspection attributes are some pieces of information that are stored in the CAD database along with the design model for inspection application. Typical inspection attributes include functional tolerances and manufacturing capability. At the decision making level, an inspection planner is proposed in conjunction with the CAD directed inspection to provide links between the CAD/CMM system and inspection goal. The planner is a knowledge based system which utilizes artificial intelligence technologies to automate the decision making in inspection planning.
Behavior of Interface Pressure Distribution in a Single Bolt-Flange Assembly Subjected to Heat Flux
Authors: Itoh S. , Shiina Y. , Ito Y.
Published: March 2013

This paper describes the thermal behavior of a single bolt-flange assembly, emphasizing the correlation between the thermal contact resistance, thermal deformation of joint surroundings and interface pressure distribution, i.e., mechanically-thermally closed loop effect. Through a series of experiments, the major findings are as follows: (1) The thermal behavior of the bolted joint is dependent upon the sinusoidal-like distribution of the interface pressure, for instance, it showing the additional heat flow in radial direction under the axial heat flux. (2) The bolted joint with ordinarily geometric specification is in thermal stability except for a short period after thermal loading.
Optimization Strategies for Machine Tool Spindle-Bearing Systems: A Critical Review
Authors: Brandon J. A. , Al-Shareef K. J. H.
Published: March 2013

After a period of relative quiescence, optimization of the design of high performance machine tools has become the subject of considerable recent research activity. Advances in the general areas of optimization theory and signal processing have enabled effective solutions to problems regarded as intractable by earlier analysts. There is, however, a danger that valuable early research may be discounted or overlooked when there is a substantial period of dormancy in a discipline. The survey links early work with current activity in the optimization of machine tool spindle bearing systems.
Machining Parameter Optimization for Specified Surface Conditions
Authors: Jang D. Y. , Seireg A.
Published: March 2013

In previous papers [1] and [2], the authors presented models for predicting surface roughness, maximum cutting temperature, and residual stress distribution on the machined surface based on the parameters of machine tool and cutting conditions in turning. This paper presents a general procedure for the selection of the machining parameters for a given machine which provide the maximum metal removal rate for any specified surface quality and tool life. Numerical results show that the procedure can be used to considerable advantage in specifying the machining variables in order to achieve the stated objective.
Error-Free Interpolation of Parametric Surfaces
Authors: Gan J. G. , Woo T. C.
Published: March 2013

A Digital Differential analyzer (DDA) is a cost effective implementation for interpolating parametric curves and surfaces. However, the problems of register overflow and integer round-off have prevented it from being adopted by industry. Contrary to intuition, an increase in register capacity is shown to have no bearing on the register overflow problem. It is shown that there is a minimum number of interpolation steps Kl below which register overflow occurs. Correspondingly, it is also shown that there exists a maximum number of interpolation steps Ku above which the accumulation of integer round-off errors exceeds the acceptable limit. But, when Kl>Ku, conflict arises. A solution is given to resolve the possible conflict and to yield an error-free interpolation of curves and surfaces.
A Multi-Degree-of-Freedom Measuring System for CMM Geometric Errors
Authors: Ni J. , Huang P. S. , Wu S. M.
Published: March 2013

A precision multi-degree-of-freedom measuring (MDFM) system has been developed and implemented for the simultaneous measurement of straightness, pitch, yaw, and roll errors of the moving axes of a CMM. The system is based on the principles of laser alignment and autocollimator. Its measurement principles and the influence of laser beam drifts on its measurement quality have been investigated and some improvement schemes have been implemented. Through the measurements of actual as well as artificially created geometric errors of the CMM, it has been found that the system’s accuracy of measuring straightness error components is better than 1 μm and its accuracy for angular error measurements is better than 0.5 arcsec.
Generation of Milled Surfaces Including Tool Dynamics and Wear
Authors: Ismail F. , Elbestawi M. A. , Du R. , Urbasik K.
Published: March 2013

In this paper, a mechanistic model for surface generation in peripheral milling, which includes the effects of cutter vibrations, run out, as well as flank wear is presented. The surface roughness parameters, and characteristic features of the surface profile were examined using computer simulations. The results of the simulation runs were verified experimentally and a good agreement was obtained. The results demonstrated clearly the importance of including tool wear in surface generation predictions. It has been shown that the model is capable of predicting the smearing of the surface generated due to increased tool wear. Also, the ploughing force acting on the wear land considered in the model influenced the resulting profile error significantly.
Intelligent Real-Time Predictive Diagnostics for Cutting Tools and Supervisory Control of Machining Operations
Authors: Ramamurthi K. , Hough C. L.
Published: March 2013

Machining economics may be improved by automating the replacement of cutting tools. In-process diagnosis of the cutting tool using multiple sensors is essential for such automation. In this study, an intelligent real-time diagnostic system is developed and applied towards that objective. A generalized Machining Influence Diagram (MID) is formulated for modeling different modes of failure in conventional metal cutting processes. A faster algorithm for this model is developed to solve the diagnostic problem in real-time applications. A formal methodology is outlined to tune the knowledge base during training with a reduction in training time. Finally, the system is implemented on a drilling machine and evaluated on-line. The on-line response is well within the desired response time of actual production lines. The instance and the accuracy of diagnosis are quite promising. In cases where drill wear is not diagnosed in a timely manner, the system predicts wear induced failure and vice versa. By diagnosing at least one of the two failure modes, the system is able to prevent any abrupt failure of the drill during machining.
A Labeling Algorithm for the Navigation of Automated Guided Vehicles
Authors: Huang J. , Palekar U. S. , Kapoor S. G.
Published: March 2013

Material handling is an important component of most automated manufacturing systems. AGVs are commonly employed for this function. Efficient use of the AGV system requires proper routing and scheduling of vehicular traffic. This problem is modeled as a shortest path problem with multiple time windows on arcs and at nodes of a network. A polynomial-time labeling algorithm has been developed. The algorithm has complexity O(D2logdD), where D is the total number of time windows in the problem. The data required for the model is easy to maintain.
Active Contact Problems in Epitrochoid Generated ‘Floating Axis’ Orbital Rotary Piston Machines
Authors: Maiti R.
Published: March 2013

The patterns of contact stresses and rolling-sliding motions at the active contacts of the rotary piston machine (ROPIMA) type hydrostatic units, having “epitrochoid” generated rotor-stator set with epicyclic motion of the “floating axis” rotor, have been investigated. A dimensionless analytical technique, based on Hertz’s contact theory, has been developed. As the stress problem in such machines is a statically indeterminate type a numerical iterative scheme has been adopted for solutions. It is found that the gaps are generated even at the “transition contacts”. Effects of profile modifications on these constraints have been studied. Some results have also been supported experimentally. Optimum values of modifications have also been suggested in most generalized form.
Qualities of High-Strength Lightweight Concrete Used for Construction
of Arctic Offshore Platform
Authors: Tachibana D. , Imai M. , Okada T.
Published: March 2013

Concrete employed in oil exploration and production platforms for use in shallow offshore zones of the Arctic Ocean is required to be lightweight, yet high strength, and moreover possess adequate resistance to freezing and thawing. Generally speaking, lightweight concrete, using artificial lightweight aggregate, has lower freeze-thaw resistance and this presents a serious problem. The study reported here was carried out on the freeze-thaw durability, constructibility and other properties of high-strength lightweight concrete. This paper especially points out the governing factors influenzing freeze-thaw durability of this type of concrete and describes a method of manufacturing concrete possessing superior durability.
Brittle Fracture in Heavy Section Welded T-Joints: Correlation
Between Stress Intensity at Fracture and Small-Specimen Toughness
Tests
Authors: Tyson W. R. , Vosikovsky O. , Faucher B. , Burns D. J.
Published: March 2013

A fracture mechanics analysis has been made of brittle fractures encountered during a program of fatigue tests of welded plate T-joints. Fracture toughnesses are in reasonable agreement with small-sample test results, if the following factors are taken into account: a specimen size effect (with larger samples having lower toughness); existence of a substantial contribution to the stress intensity factor from residual stresses; and shakedown of residual stresses, with shakedown increasing with increasing applied stress.
Probabilistic Pseudo-Static Analysis of Risers
Authors: Ahmad Suhail , Datta T. K.
Published: March 2013

Under many sea states, the marine risers behave in a quasi-static manner. The statistics of the response of the marine risers to random sea states producing quasi-static loading is determined using the spectral description of the sea states. The analysis procedure is similar to that proposed by Burrows [2] for offshore structures. The distribution of the response obtained by the proposed method is compared with those derived from the simulation studies in which ensemble of response time histories is computed from artificially generated histories of water particle kinematics for a given sea state. The results of the study indicate that the distribution of the quasi-static response can be adequately modeled by Pierson-Holmes [4] distribution.
Structure-Wave Interaction Under Earthquake
Excitation
Authors: Kokkinowrachos K. , Thanos I.
Published: March 2013

A method for the hydrodynamic analysis of large bottom-fixed offshore structures under earthquake action is presented. The investigation deals with arbitrarily shaped vertical bodies of revolution, to which the so-called macroelement method can be applied. The structure is considered here as rigid, the compressibility of the surrounding water has been taken into account. Numerical results for several bottom-mounted structures give information on the earthquake-induced hydrodynamic forces and their parts (added mass and damping). The effectiveness of the macroelement method is demonstrated. The influence of geometrical shape, relative dimensions, water depth and water compressibility is shown.
Wave Attenuation, Mudslide, and Structural Analyses for Mississippi
Delta/Main Pass Caisson
Authors: Clukey E. C. , Maller A. V. , Murff J. D. , Goodwin R. H. , Miller M. C. , Ebelhar R. J.
Published: March 2013

The environmental loads associated with the design of a caisson-type structure in a mudslide region are largely dependent upon the interaction of waves with the seabottom. This wave-seabottom interaction results in both an attenuation of wave energy as the waves propagate over the soft soils, as well as the generation of mudslide loads at the platform site. These effects were investigated for the design of a 14-ft-dia caisson in the Main Pass region of the Mississippi Delta. The proposed structure was planned for installation in about 100-ft water depth in very soft underconsolidated soils, typical of the Mississippi Delta region. The potential for wave attenuation was investigated analytically by considering the change in response spectra from deep water to the platform site. Regional soil conditions were used for this part of the investigation. The results obtained from the analytical modeling were in good agreement with field measurements obtained from another part of the Delta. Mudslide thicknesses were determined based on site specific soil data and the design wave for the platform site. The predicted mudslides also agreed favorably with the geological interpretations for the area. Once the design waves and mudslide thicknesses were determined, structural analyses were performed to determine the bending moments and dynamic response for the caisson. Overall, the improved analytical methodology used in the investigation and the availability of field data to verify the results allowed for a more economic platform design.
Regional Design Ground Motion Criteria for the Southern Bering
Sea
Authors: Vyas Y. K. , Crouse C. B. , Schell B. A.
Published: March 2013

This paper discusses the development of earthquake design criteria for the Southern Bering Sea—Aleutian Shelf region. The study reported herein was primarily motivated by a high level of seismic activity along the Aleutian Shelf and its potential impact on the design of future offshore and onshore facilities in the region. The criteria were developed for the Strength Level Earthquake (SLE) and Ductility Level Earthquake (DLE). The SLE has an average return period of 200 yr, while the DLE has a return period on the order of 1000’s of years. The criteria were based on the results of probabilistic and deterministic seismic hazard analyses of the region. The probabilistic seismic hazard analyses (SHA) were performed to establish 5 percent damped pseudovelocities (PSV) associated with an average return period of 200 yr for various sites in the region. Although seven seismotectonic provinces were considered, the larger moment magnitude events (Mw > 8.5) occurring in the shallow subduction province contribute most to the 200-yr PSV. A DLE event of Mw 9.2 was selected deterministically to be the maximum earthquake likely to occur in the region based on the tectonics and the historic seismicity. Both SLE and DLE events are associated with major ruptures along the postulated Shumagin-Unalaska seismic gap. Because no earthquake records exist for such severe earthquakes, the design ground motion criteria were partly established using a computer program to simulate ground motions for giant subduction zone earthquakes. Because the SLE and DLE events are similar and because ground motions do not increase significantly beyond Mw = 8.5, the DLE pseudovelocity spectra are about only 10 to 20 percent greater than the SLE spectra. The SLE spectra were compared with the API RP 2A [1] design spectra for this region and significant differences were noted for the region north of the Aleutian Islands. The revised zoning map recommended in this study is believed to provide more realistic standards for the seismic design of future facilities in the region.
Dynamics of Disconnected Risers Under Rigid and Compliant
Hang-Off
Authors: Patrikalakis N. M. , Yoon D. Y.
Published: March 2013

An efficient solution scheme to simulate the nonlinear motions of hanging risers based on an adaptive nonuniform grid finite difference method and an implicit time integration scheme is presented. Dynamic buckling-type response of hanging risers under rigid hang-off due to heave acceleration of the support platform in extreme excitation conditions is studied, and the important parameters affecting the response are identified. Significant reduction of motions and resulting stresses is obtained by employing compliant hang-off.
Axial Rupture in Underwater Pipelines
Authors: Crentsil K. , Hauptmann E. G. , Hill P. G.
Published: March 2013

The propagation of axial cracks in underwater pipelines was investigated by means of small-scale pipe experiments. The purpose of the experiments was to determine the effect of external water environment on crack opening characteristics. The development of the axial rupture was recorded by high-speed photography; measurements were made of the internal depressurization transient and the axial strain field. The measured depressurization histories agreed with the predictions of a one-dimensional transient fluid flow code. Results presented for underwater and in-air tests show that the external water environment produces a slower crack and a smaller crack opening area. A steady-state energy balance analysis was performed to investigate the various energy dissipation mechanisms present during pipe rupture. This analysis confirmed that the added inertial mass effect of the surrounding water may account for the reduction in crack speed and opening area.
Design Accuracy of Offshore Gas Pipelines Operated in the Two-Phase
Flow Mode
Authors: Oliemans R. V. A. , Pots B. F. M. , Wu H. L.
Published: March 2013

The predictive power of a two-phase flow design method, consisting of one-dimensional flow models depending both on flow regime and pipe inclination, has been investigated by comparing predicted pressure losses and liquid hold-ups with pipeline data collected under actual conditions. For this purpose, Shell’s database of controlled field tests in large-size gas pipelines was extended with data obtained in an 8-in. high-pressure two-phase flow test facility with gas and condensate as flowing media. It was concluded that the predictive power was reasonable for wide ranges of flow conditions, but that liquid entrainment is to be incorporated in models to remove conservatism from liquid hold-up predictions.
The Lateral Drifting Forces and Moments on Two Ships in Proximity in
Waves
Authors: Fang M.-C. , Kim C. H.
Published: March 2013

An analytical procedure for evaluating the lateral drifting forces and moments between two ships in oblique waves by near-field method is presented in this paper. The velocity potential, including the hydrodynamic interactions are evaluated by a two-dimensional sink-source technique. Then the strip theory is applied to calculate the sectional force and the drifting forces and moments of the whole ships can be obtained by Simpson rules. Four components of the mean drifting force are obtained in which the relative wave term is dominant, whereas the Bernoulli quadratic component is secondary. The negative drifting force is observed at some frequency for the ship which is in the weather side of the wave. The lateral drifting force even occurs while the ships are in the head or following seas, which is consistent with the real physical phenomena at sea. The present technique offers the theoretical explanation for nonlinear phenomena between two ships in waves and will be helpful for the further practical study in random waves.
A Three-Dimensional Dynamic Model for Determining the Equilibrium
Configurations of Buoyantly Unstable Icebergs
Authors: Jessup R. G. , Venkatesh S.
Published: March 2013

This paper describes a dynamic model developed for the purpose of determining the final equilibrium configurations of buoyantly unstable icebergs. The model places no restrictions on the size, shape, or dimensionality of the iceberg, or on the variation range of the configuration coordinates. Furthermore, it includes all six degrees of freedom and is based on a Lagrangian formulation of the dynamic equations of motion. It can be used to advantage in those situations in which the iceberg has a complicated potential function and can acquire enough momentum and kinetic energy in the initial phase of its motion to make its final configuration uncertain on the basis of a static potential analysis. The behavior of the model is examined through several model simulations. The sensitivity of the final equilibrium position to the initial orientation and shape of the iceberg is clearly evident in the model simulations. Model simulations also show that when an iceberg is released from a nonequilibrium initial state, the time taken for it to settle down varies from about 40 s for a growler to nearly 400 s for a large iceberg. While these absolute times may change with better parameterization of the forces, the relative variations with iceberg size are likely to be preserved.
The Lift Force on a Cylinder Vibrating in a Current
Authors: Moe G. , Wu Z.-J.
Published: March 2013

This paper reports an extensive program of forced and free vibration tests on a single circular cylinder moving mainly perpendicularly to a uniform current. For both free and forced vibration tests, two cases were investigated: one in which the cylinder was restrained in the in-line direction and the other in which it was supported on suitable springs. The cross-flow vibrational response and hydrodynamic forces on the cylinder were measured. Large variations of motion frequency in the “lock-in” range were found from the free vibration tests. This leads to two different definitions of reduced velocity, namely, a so-called nominal reduced velocity based on one reference frequency and the true reduced velocity based on the actual vibration frequency. When different results are compared, the true reduced velocity should be used. The forced vibration tests showed, as may be expected, that the transverse force in the “lock-in” range on the average will add energy to the cylinder at moderate motion amplitudes and subtract energy at large amplitudes. Some conditions resulting in a steady-state vibration of a flexibly mounted cylinder were analyzed. The actual force traces also show very large and apparently random deviations from the average force amplitude. The results from the forced and the free vibration tests are consistent with each other if the true reduced velocity and reduced amplitude are the same.
Model Study of the Wave-Driven Impact of Bergy Bits With a Semi-Submersible Platform
Authors: Lever J. H. , Colbourne B. , Mak L.
Published: March 2013

This paper describes model bergy bit/semi-submersible impact tests conducted in the 58-m wave tank at Memorial University. The objective of the tests was to develop a method to accumulate statistics on the locations and velocities of wave-driven iceberg/structure impacts. We used a single irregular sea state and conducted 30 trials in each test series to accumulate the desired statistics. During each run, a camera system tracked the motions of both the bergy bit and the semi-submersible. We transferred this data and the geometry of both bodies to a CAD facility, which then recreated each test by redrawing the positions of the two bodies at each time step. In this manner, we determined the impact locations and times without the obstruction of the water surface, and computed automatically the desired impact velocities and kinetic energies. This paper describes the test and analysis techniques, and presents results for one test series. It also describes a new method to estimate impact kinetic energies using only open-water velocity data.
The Dean Eccentricity Parameter and Data Condition
Authors: Hudspeth R. T. , Nath J. H.
Published: March 2013

The ability to identify the empirical force coefficients used in the Morison wave force equation depends on the condition of the wave kinematic data and the measured force data. Herein the condition of these data is evaluated by three methods: two geometric and one numerical. The Dean error ellipse method is shown to depend explicitly on the Keulegan-Carpenter parameter, K, for simple harmonic kinematics via the Dean eccentricity parameter (E=3K/2π2). For simple harmonic data, the alignment of the semi-minor axis of the Dean error ellipse is shown to be parallel to the Cd–Cm-axes and to depend on K. When E<1.0, then K<11.40 and the semi-minor axis of the error ellipse is parallel to the Cm-axis. When E>1.0, then K>11.40 and the semi-minor axis is parallel to the Cd-axis. When E=1.0, then K=11.40 and the error ellipse is a circle with zero eccentricity. The Dean error ellipse method is compared geometrically with the amplitude/phase error analysis in which the condition of the data is demonstrated geometrically by the slopes of contours of dimensionless coefficient ratios passing through a zero phase error. These two geometric methods are shown to be related by the Dean eccentricity parameter, E. The matrix A condition number is also shown to depend on E. The matrix for simple harmonic kinematics is Hermitian, unitary and becomes a unit matrix with a unit condition number when K=13.16 and E=1.15. There is only a 15-percent difference between K=11.4 and K=13.16, which is usually well within the data scatter band for wave force tests on vertical smooth cylinders near these values of K. Three sets of physical data show that at K values where the data are equally well conditioned to determine both Cd and Cm, a stable condition of periodic, repetitive vortices are formed. For such stable vortex shedding in periodic flow, the force on the cylinder is stable periodic, yielding repetitive values for Cd and Cm from cycle to cycle.
Thickness Effect and Fatigue Crack Development in Welded T-Joints
Authors: Yee R. , Burns D. J. , Mohaupt U. H. , Bell R. , Vosikovsky O.
Published: March 2013

The effect of section thickness on the fatigue life of welded plate-to-plate T-joints was studied experimentally and theoretically using various linear elastic fracture mechanics models. Fatigue crack depth and shape development were monitored using potential drop techniques, ink staining and beachmarking. These data are used to define initiation and propagation lives, and to show the importance of crack coalescence in the propagation phase. The effects of attachment plate thickness and weld geometry are also discussed.
Recent Progress of Japanese Research on Condensation Heat Transfer
Authors: Tanasawa Ichiro
Published: March 2013

A state-of-the-art review is presented on the research activities in Japan on condensation heat transfer during these nine years. The papers published on the Trans. JSME (Series B for thermal and fluids engineering) from 1980 until 1988 are chosen as the main target of the review, since it is considered that the majority of principal achievements in condensation research in Japan are contained in these volumes. The papers printed elsewhere on other publications or prior to 1980 are referred to only whenever it is needed. The author classifies the subjects into five items. They are (1) Film condensation of single-component vapor, (2) Film condensation of multi-component vapor, (3) Enhancement of condensation heat transfer, (4) Dropwise condensation, and (5) Direct contact condensation and other forms of condensation. However, the author’s effort is focussed mostly on the item (3) on the techniques of enhancement of condensation heat transfer. Dropwise condensation is another subject that is discussed in some detail. Only the outlines are presented for the remaining items. In the concluding remarks of this article the author’s personal comments on the future trends of the condensation research is presented.
Acoustic Resonance Scattering by Submerged Elastic Shells
Authors: Gaunaurd G. C. , Werby M. F.
Published: March 2013

We review a number of instances in which classical acoustic wave scattering from submerged elastic shells can be analyzed in the resonance region of their spectra. We recently reviewed (Refs 42, 43, 12) the cases dealing with acoustic resonance scattering from solid elastic bodies, or with elastic resonance scattering from fluid or solid inclusions in elastic media. It only remains for us to address the works dealing with submerged shells, which we analyze here. We study scattering by bare or viscoelastically coated spherical and cylindrical shells in water, by means of (exact) normal-mode solutions, and by spheroidal shells by numerical approaches, particularly via the T-matrix method. We consider the shell responses mostly in unbounded media and when the interrogating waves are plane and c.w., although some recent findings valid for pulsed incidences and in the vicinity of environmental boundaries are also included. We use the methodology of the resonance scattering theory (RST) as much as possible, emphasizing its post-1981 results. High-frequency findings, obtained by asymptotic methods, are extrapolated to lower frequencies, to confirm RST predictions for the intermediate spectral regions in which the most important structural resonances are known to reside. A large number of bibliographical entries are collected and discussed in connection with our approach.
A Review of Certain Inverse Methods for the Design of Ducts With 2- or 3-Dimensional Potential Flow
Authors: Stanitz John D.
Published: March 2013

This article reviews the author’s work on inverse methods of flow-field design with prescribed velocity distributions on the boundaries. Such design methods are of some importance, because these velocity distributions, on the boundaries of fluid-handling equipment, determine the boundary-layer behavior and thereby affect the equipment efficiency. The work is limited to design methods for stationary channels with incompressible or subsonic compressible flow. Both two- and three-dimensional design methods are reviewed. The two-dimensional work was done in the early 1950’s and the three-dimensional work in the 1980’s.
Research on Inverse Design and Optimization in Germany
Authors: Sobieczky Helmut
Published: March 2013

This article tries to illustrate efforts to develop and apply design and optimization methods in German universities, research institutes and the aerospace industry. Applications are shown solely in turbomachinery and aircraft aerodynamics. With restriction to aerodynamic problems, it is shown that efforts to improve theoretical models to become knowledge-based computational tools overlap with operational methods based on the designer’s experience but resulting in hardware concepts for next generation aircraft components.
Inverse Problems for Multi-Dimensional Parabolic Partial Differential Equations
Authors: Hensel Edward
Published: March 2013

The parabolic inverse boundary value problem is defined, and the major characteristics common to multi-dimensional parabolic inverse problems are discussed. These include sensitivity to measurement error and noise, the value of future time information, the nonuniqueness of estimates, and the effects of temperature dependent thermal properties. The importance of quantifying resolution degradation and estimate variances is discussed.
A Comparison of Film Temperatures and Oil Discharge Temperature for a Tilting-Pad Journal Bearing
Authors: De Choudhury P. , Barth E. W.
Published: March 2013

An experimental program was conducted to relate bearing film temperatues to oil discharge temperature. Results for a five-shoe tilting-pad journal bearing show that film temperatures are substantially higher and more sensitive to load and speed changes than is discharge oil temperature. Conversely, film temperature is less sensitive to changes in flow. It was also noted that the rate of change of film temperature is significantly greater than the rate of change of discharge oil temperature when the bearing is subjected to load change, which is a desirable characteristic for a monitoring and control system. These results should provide a more rational basis for the evaluation of bearing performance when film temperatures are reported.
Centrifugal Effects in Thrust Bearings and Seals Under Laminar Conditions
Authors: Pinkus Oscar , Lund J. W.
Published: March 2013

An analysis is conducted and solutions are provided for the effect of centrifugal forces on the hydrodynamics of high-speed thrust bearings and seals. First, a scrutiny of the individual inertia terms of the Navier-Stokes equations delineates the circumstances under which the centrifugal term (u2/r) becomes the dominant component. A Reynolds equation incorporating centrifugal forces is then derived for finite sectorial configurations operating under incompressible laminar conditions. Thermal effects are included. The equation is solved by finite difference methods. The results show that at the upper limits of laminar operation centrifugal forces reduce considerably the load capacity and alter the pattern of lubricant flow. As a result, at sufficiently high velocities the inflow of lubricant at the inner radius of a sectorial configuration may bring about the scavenging of lubricant from wide portions of the bearing surface, producing a form of thrust bearing cavitation. Design features which would reduce the negative consequences of centrifugal action are outlined, including the introduction of radial tapers.
Performance of Computer-Optimized Tapered-Roller Bearings to 2.4 Million DN
Authors: Parker R. J. , Pinel S. I. , Signer H. R.
Published: March 2013

The performance of 120.65-mm (4.75-in.) bore high-speed design tapered roller bearings was investigated at shaft speeds of 20,000 rpm (2.4 million DN) under combined thrust and radial load. The test bearings design was computer optimized for high-speed operation. Temperature distribution and bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rates, and lubricant inlet temperature. The high-speed design tapered roller bearing operated successfully at shaft speeds up to 20,000 rpm under heavy thrust and radial loads. Bearing temperatures and heat generation with the high-speed design bearing were significantly less than those of a modified standard bearing tested previously. Cup cooling was effective in decreasing the high cup temperatures to levels equal to the cone temperature.
An Advanced Apparatus for the Study of Roller and Cage Slip in High-Speed Roller Bearings
Authors: Markho P. H. , Smith B. V. , Lalor M. J.
Published: March 2013

This paper describes a sophisticated research facility for the study of roller bearings at DN values of over one million with provisions for the measurement of such parameters as cage and roller speeds, bearing torque and load, and bearing ring temperatures. Particular features of the apparatus are a laser Doppler anemometer (LDA) system, with the ability to measure an instantaneous roller speed at any position in the bearing, an infrared radiation thermometer for measuring the bearing inner ring temperature, hydrostatic mounting of the test spindle, and aerostatic bearings which insure a good axial location of the test bearing and form important elements of torque and load measuring facilities which are, at once, integral and independent.
The Adhesion, Friction, and Wear of Binary Alloys in Contact With Single-Crystal Silicon Carbide
Authors: Miyoshi Kazuhisa , Buckley D. H.
Published: March 2013

Sliding friction experiments were conducted with various iron-base alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a single-crystal silicon carbide (0001) surface in vacuum. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is as an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.
Failure of Thin Film Lubrication—The Effect of Running-In on the Load Carrying Capacity of Thin-Film Lubricated Concentrated Contacts
Authors: Begelinger A. , de Gee A. W. J.
Published: March 2013

The effect of running-in under low speed - high load conditions on the load carrying capacity at high speed of sliding crossed cylinders of steel AISI 52100, thin film lubricated with a marine diesel engine oil of 60°C, is described for three values of the initial composite roughness Rc, i.e. 0.14 μm, 0.42 μm and 0.71 μm. It is shown that—irrespective of the initial surface roughness—the surface of the (smaller) stationary cylinder becomes very smooth (Ra ≤ 0.1 μm), that of the (larger) rotating cylinder remaining virtually unaffected. As the local radius of curvature increases as a result of running-in, the load carrying capacity, expressed in terms of total force on the contact, increases considerably, i.e. 600 percent at Rc = 0.14 μm, 500 percent at Rc = 0.42 μm and 150 percent at Rc = 0.71 μm. This is not accompanied by a correspondingly large increase in Hertzian contact pressure at film collapse, pHc. In fact pHcincreases 45 percent at Rc = 0.14 μm and 15 percent at Rc = 0.42 μm and decreases 20 percent at Rc = 0.71 μm. It is further found that run-in surfaces show the phenomenon of delayed EHD-film collapse, meaning that the transition from the (partial) EHD to the scuffing regime may take from 1 to 40 s after application of the normal force. The test method should contribute significantly to the functional characterization of lubricants and—more in particular—running-in fluids, as candidates for use in concentrated contact situations.
Friction and Wear Results From Sputter-Deposited Chrome Oxide With and Without Nichrome Metallic Binders and Interlayers
Authors: Bhushan Bharat
Published: March 2013

Friction and wear tests were conducted on optimized sputtered Cr2O3 and Cr2O3 with metallic binder coatings. The coatings were applied on the bearing surface of journal foil air bearings and were tested against chrome-carbide-coated journal surfaces. The objective of the study was to develop a coating system which would withstand 9000 start-stops and high-speed rubs (maximum acceleration, 100 gs) in temperatures ranging from room temperature to 650° C. The Cr2O3 coating completed the test sequence and the coating consisting of Cr2O3 with metallic binders completed 3000 start-stops. The coefficient of friction of the coatings at 650° C was found to be about half that at room temperature. It was concluded, therefore, that the coatings should perform much better in a high temperature environment alone. The decrease in friction at high temperature is attributed to oxidation and interactions of the coatings and substrates at the interface temperature.
The Wear of a Chromium Carbide Hard Facing: The Effect of High Gas Pressure on Wear Transitions
Authors: Skinner J.
Published: March 2013

The wear of a chromium carbide hard coating, LC1B, has been investigated in CO2, argon and air at pressures between 2 and 42 bar. In CO2 the wear rate of the shaft (but not the pin) is strongly gas pressure and load dependent. Post-test observations have suggested the presence of up to three wear regimes: (i) initial wear is short lived and probably results from the mechanical interlocking of asperities, (ii) adhesive wear involves the homogenization of surface layers and the preferential transfer of material to the static pin which then protects the pin from further wear, and (iii) mild wear which is in part abrasive, but in which oxidative wear provides the major contribution. Wear in argon is adhesive, that in air is primarily mild, but in CO2 a transition from adhesive to mild wear occurs after a sliding distance which is dependent upon sliding contact parameters and on gas pressure. The above observations and deductions have been developed analytically to explain the unusual results obtained in CO2. It has been shown how, in CO2, the sliding distance to the second transition (adhesive to mild wear), may be explained by the development of equations for the depletion of CO2 at the wearing interface. It is postulated that after its formation, wear debris is reactive to CO2 only for a very short time (∼ 5 × 10−9s) and that the transition to mild wear occurs when the depleted CO2 pressure increases to a level at which a monolayer of reaction product can form in this reaction time.
An Experimental Investigation of the Effect of Lubricant Properties on Temperature and Wear in Sliding Concentrated Contacts
Authors: Seireg A. , Hsue E.
Published: March 2013

The study reported in this paper is undertaken to investigate the effect of some of the physical properties of lubricants on the contact temperature and wear in heavily loaded Hertzian Contacts under sliding conditions. The surface temperature and wear in a rotating mild steel shaft are measured under different loads applied by a Tungsten Carbide slider. The carbide tip and the shaft are used as part of a dynamic thermocouple system to monitor the contact temperature. Tests are conducted for Hertzian pressures ranging from 1250 to 2140 MPa (1.81×105–3.10×105 psi) and sliding speeds from 0.4 to 1.3 m/sec (943–3142 in./min). Temperature and wear data are given from tests with a heavy duty oil (SAE 80W-90), a high viscosity residual compound, a vegetable oil, and water miscible cutting fluid (0.0476 percent emulsifiable oil by volume). The results show that, for the considered tests, viscosity does not appear to be the significant property of the lubricant temperature rise and wear rate as indicated by the scar depth under similar test conditions.
A Film Thickness Analysis for Line Contacts Under Pure Rolling Conditions With a Non-Newtonian Rheological Model
Authors: Gecim B. , Winer W. O.
Published: March 2013

The non-Newtonian constitutive equation proposed by Winer and Bair [1] is applied in a conventional isothermal film thickness analysis of line contact lubrication of rolling elements. The present analysis provides four different dimensionless film thickness equations for four different regimes of lubrication. Due to the formulation technique used in deriving the governing pressure-gradient equation, the present study is recommended for high viscosity, high rolling speed, and low limiting shear stress cases where Newtonian models fail to match the experimental data. Comparison of the present film thickness equations with the Newtonian correspondences in each lubrication regime shows a considerable difference, but the analysis suffers from the fact that the limiting shear stress parameters of these high viscosity lubricants need to be determined experimentally. The present analysis assumes a reasonable range of limiting shear stress which is smaller than the corresponding values for low viscosity lubricants which are predominantly Newtonian in behavior (unless severe rolling and/or sliding with high loads is applied).