bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear Power Hazard and Economic Risk Assessment
Authors: Margulies T.
Published: March 2022

This paper addresses a complex debate of national importance related to the safety of existing light water reactors and preventing, mitigating, or improving emergency preparedness for response to severe reactor accident releases of radioactivity for operating reactors. The costs and benefits of several key alternatives are assessed for the NUREG-1150 reference plants, as well as, a representative medium population density site. Annual levelized cost calculations using a 105 annual release rate were made using ICRP annuity factors for potential safety improvements resulting in cost-beneficial justifications for engineering safety improvements such as supplemental filtering and scrubbing to the present containments, and for instrumentation and monitoring to minimize a bypass scenario. Probabilistic risk financing formulas for expected continuous discounting are presented. Improvements to emergency preparedness measures such as stockpiling potassium iodide for the population would not have the additional protection benefits of reducing substantially non-inhalation pathway contributions to offsite health effects, as well as, protecting land from contamination.
An Experimental Study on Galloping of a Square Prism With a Splitter Plate Through Indicial Lift Response
Authors: Hirata Katsuya , Nakamura Yasuharu , Iwasaki Tohru
Published: March 2022

To elucidate the aerodynamic mechanism of galloping, the authors attempt another approach in the time domain relative to this oscillatory instability. As a test body, the present study takes up a square-section prism with a stationary long splitter plate in its wake. A black-box theory of galloping is presented. Wind-tunnel experiments are reported on the indicial pressure responses together with flow visualizations. The corresponding Reynolds numbers were approximately 1.9 × 104 and 8.9 × 103, respectively. In addition to the measurement of the indicial pressure responses, the sinusoidal pressure responses are also measured by forcedly oscillating the same model. As a result, the indicial body motion produces the separation-induced vortices on two sides parallel to the uniform flow, and these vortices are responsible for the lift force related to the onset of galloping. The quantitative agreement between theory and experiment is reasonable for slowly oscillating galloping.
Experimental Study of Vibration and Acoustic Radiation of a Pipe Induced by Fully-Developed Turbulent Air Flow
Authors: Durant C. , Robert G.
Published: March 2022

Experimental results are presented concerning the vibro-acoustic response of a pipe excited by an internal fully-developed turbulent air flow. The internal wall pressure field generated by the flow, the vibration response and the external acoustic field were measured for Reynolds numbers Re = UoD/v ranging from 5.3 × 105 to 12.5 × 105.

The measured statistical properties of the wall pressure field include power spectral densities and cross-spectra. Power spectral density is analyzed after cancellation of a contaminating acoustic component of the wall pressure fluctuations. Convection velocity and correlation lengths are calculated from measured cross-spectra to complete a Corcos model for the cross-spectrum of the turbulent wall pressure fluctuations. The ratio of convection velocity to centerline velocity ranges from 0.7 to 0.8. The coefficient α1 of the standard Corcos model is calculated from the longitudinal correlation length and is found to be around 0.18. To have further information about the convection velocity and correlation lengths in a lower frequency range than presented here, the measured cross-spectral data need to be decontaminated from the acoustic component of the wall pressure.

The acceleration response of the pipe wall shows the influence of the structural modes of the test section. Only some of them have a significant influence on the external acoustic field.
Computation of Jet Noise Using Large-Eddy Simulation and Lighthill’s Analogy
Authors: Schein David B. , Meecham William C.
Published: March 2022

Computational aeroacoustics involves numerical study of the acoustic field generated by unsteady fluid motion. An area of significant interest is unsteady turbulent flow in free jets and resultant far field acoustic pressure fluctuations. Since Lighthill’s mathematical formulation for jet noise generation in the early 1960’s, a search has continued for a physical interpretation of his formal results and, in particular, the noise source term. Far field measurements have not provided a clear picture concerning the nature of the acoustic source. Therefore, industry standard procedures for prediction of far field noise from exhaust jets rely on semi-empirical methods to calculate mean sound pressure levels and directivity. Our objective is to contribute to a more thorough understanding of the acoustic source from a shear flow using Large-Eddy Simulation (LES) turbulence modeling.

Published work for direct numerical simulation of these flows has been confined to low Reynolds number (< 3000) with Mach numbers up to 2.0, to study the physics of sound generation and test aeroacoustic prediction methods (Mitchell, et al, 1995). While furthering understanding of jet noise generation, these cases limit exhaust dimensions to millimeters and make it difficult to compare results to measured data. Here we address large Reynolds numbers and high subsonic Mach number (compressible) flow combined with realistic geometries more representative of aircraft engine exhausts.

Standard turbulence models compute the average flow field, which cannot be used to calculate the aeroacoustic field. Temporal fluctuations are required and can be obtained using LES, with a spatial filtering operation applied to the equations of motion. The technique is based on computing only large scale motions directly subject to the problem’s boundary conditions, while small scale motions are assumed to be more universal and their statistics and effect upon large scales are predicted using a “subgrid-scale” model. The motivation for this approach is that experimental observations of turbulent flows show that large scale turbulent structures vary markedly from one flow situation to another, while small scales show less variation from case to case.

The acoustic radiation calculation consists of three steps; 1) an approximate result for the mean flow field using a compressible flow code employing a k-ϵ turbulence model, 2) unsteady turbulent fluid field simulation using the CFD code appended with a LES turbulence model (the k-ϵ prediction serving as an initial guess) and 3) far field acoustics obtained using Lighthill’s analogy. Extensive far field noise data from ground static measurements of a WR19-4 mini-turbofan engine are being drawn from for comparisons between computed results and measurements.
Dynamics of Axially Moving Beams
Authors: Behdinan K. , Tabarrok B.
Published: March 2022

In this investigation we consider the lateral motion of axially rigid sliding beams protruding from a stationary rigid wall. The main objective is to consider the large rotations and small strains and to examine the nature of the motion of sliding beams and point out the salient features of the motion.

Once we obtain the equation of motion for geometrically nonlinear sliding beams, we compare them with those for pipes conveying fluids and we show similarities in these equations for the two physically different systems. Next we use the Galerkin method and obtain the transient response of the problem. To verify the formulation and its computational implementation we analyse several examples and compare our findings with those reported in the literature.
Free Surface Effects on the Dynamics of Cylindrical Shells Partially Filled With Liquid
Authors: Lakis A. A. , Neagu S.
Published: March 2022

This paper presents an analytical model for the dynamic analysis of thin cylindrical shells partially filled with liquid. The method used is a combination of finite element analysis and classical shell theory, and the objective is to determine the specific displacement functions which best represent the real deformations.

The effect of oscillations of the free surface of the liquid on fluid-shell vibration is studied, and consideration is given to the influence of such parameters as: the circumferential mode, the axial mode, the structural damping, the length of the shell and the forces induced by the liquid.

The shell is divided into cylindrical finite elements and the displacement functions are derived using Sanders’ thin shell theory. The stiffness and mass matrices of the shell are derived analytically.

For the liquid contained in the shell, boundary conditions are prescribed and the behaviour of the liquid is expressed by a potential function. The kinetic and potential energies of the liquid are evaluated in order to establish the influence of surface oscillation on fluid-shell vibration.
Vibration Analysis of Single-Anchor Inflatable Dams
Authors: Mysore Guruprasad V. , Liapis Stergios I. , Plaut Raymond H.
Published: March 2022

Inflatable dams are flexible, cylindrical structures anchored to a foundation. They are used for various purposes, e.g., diverting water for irrigation or groundwater recharging, impounding water for recreational purposes, and raising the height of existing dams or spillways. Early inflatable dams were anchored along two of their generators, but recently-constructed dams are anchored along a single line. They also have a fin near the top which is useful in overflow conditions. The vibrations of such dams in the presence of external water are considered in this paper.

The dam is modeled as an elastic shell inflated with air and resting on a rigid foundation. First the equilibrium shape of the inflated dam is determined. Next, the dam is clamped with this cross-sectional shape at its two ends, and then water is applied on the anchored side with a height less than the “dry” equilibrium height. The new equilibrium configuration is obtained and small vibrations of the dam about this equilibrium shape are analyzed. The water is assumed to be inviscid and incompressible, and potential theory is used. The infinite-frequency limit is assumed on the free surface. A boundary element technique is utilized to determine the behavior of the water, and the finite element method is applied to model the structure using ABAQUS with a shell element (ABAQUS, 1994). Three-dimensional vibration frequencies and mode shapes are computed. The effect of the internal pressure of the dam is investigated, and the results are compared to those for the dam in the absence of external water.
Random Excitation by Fluid Forces Acting on a Single Flexible Tube in Bundles Subjected to Cross-Flow
Authors: Romberg Oliver , Popp Karl
Published: March 2022

This paper reports on investigations using a new pressure test tube, that provides the non-stationary pressure distribution simultaneously at 30 points on the circumference and at 15 points across the tube. The tube motions due to fluidelastic instability as well as to turbulent buffeting can be measured together with the acting fluid forces. The investigations has been carried out for normal and rotated square arrays as well as normal and rotated triangular arrays. In the last case the investigation has been carried out for two different pitch to diameter ratios. The tests show clearly, that the correlation length of the non-stationary lift and drag forces, which has been determined at the whole circumference of the tube, decreases within the first three to four tube rows depending on the tube bundle configuration. The results show further that in case of instability due to galloping the correlation length increases suddenly to large values. For certain configurations the fluid forces are correlated well for the whole tube when galloping is dominant. Moreover, it can be shown that very thin tripwires put on the surfaces of the tubes destroy the correlation. This could be a possible explanation for the significant stabilization effect by tripwires for certain tube bundle configurations. Reflecting on turbulent buffeting the amplitudes are calculated as a function of the reduced gap velocity using the covariance method. Therefore, an excitation model deduced from the power spectral density of the measured fluid forces has been developed. Finally, a comparison of calculated and measured amplitudes for some examples is given.
Probabilistic Methods for the Prediction of Damage in Process Equipment Tubes Under Nonlinear Flow Induced Vibration
Authors: Sauvé R. G. , Morandin G. , Savoia D.
Published: March 2022

The use of deterministic methods in the assessment of process equipment tube integrity due to flow-induced vibration has become general practice. In cases were susceptibility of the tubes to fretting wear is addressed, nonlinear structural dynamic simulations are often required in order to quantify the work rate. In operating process components such as nuclear heat exchangers and steam generators the range of values for the key parameters such as flow regime, support clearances, manufacturing tolerances, tube/support material, etc. can vary to quite an extent. As a result, probabilistic techniques are proposed to account for the lack of well-posed input parameters needed for the nonlinear flow-induced vibration predictions. In this paper, a Monte Carlo simulation that incorporates an existing nonlinear time domain solution for tube response is described. An application of the technique to a nuclear steam generator is presented. The effect of variability of a number of key parameters on work rate is discussed along with the attendant implications.
Eliminating Air Flow-Induced Acoustic Vibration in Coal Pulverizers
Authors: Eisinger Frantisek L.
Published: March 2022

A novel method is presented here for eliminating acoustic vibration within coal pulverizers. The method emerged from the study of an acoustic vibration which developed within the casing of a coal pulverizer at low to medium loads. The vibration was characterized by an acoustic quarterwave driven by swirling air flow of parallel high velocity air jets issuing from a rotating multi-air port arrangement. By converting the single frequency excitation energy of the air jets into turbulent energy utilizing a new air port design with strongly interacting (colliding) air jets, the vibration was eliminated. The theoretical background and results of the pre- and post-modification operational tests are presented.
Dynamics of an Inline Tube Array in HCFC-123 Two Phase Flow: Comparison With Steam-Water Two Phase Flow
Authors: Hirota K. , Nakamura T. , Mureithi N. , Ueno T. , Tomomatsu K.
Published: March 2022

Comprehensive flow induced vibration tests have been conducted on an inline array. HCFC-123 is used as the test fluid. HCFC-123 stands for Hydrochlorofluorocarbon, whose chemical formula is CHCl2CF3. The critical flow velocities and two phase flow induced damping were compared with the steam-water two-phase flow test results. For that purpose, the same test equipment as steam water two-phase flow test one were used. The responses of three essentially isolated flexible cylinders at different depths within the array were simultaneously measured. Unsteady fluid forces were also measured. Tests were conducted corresponding to some thermal hydraulic conditions. First, two-phase flow test at high pressure (0.76Mpa, 98°C), homogeneous void fraction β = 0.90, was conducted. This condition can simulate the flow pattern of the steam water two phase flow (5.8MPa, 273°C) because the density ratio between gas and liquid is equal for both fluids. Second, a single-phase liquid flow test at atmospheric conditions was conducted. Finally, a single-phase flow test at high pressure (0.76Mpa) in HCFC-123 vapor was conducted. The characteristics of fluidelastic vibration were very close between HCFC-123 and steam-water two phase flow.
Nonlinear Models for Long Cylindrical Squeeze Films Incorporating Elliptical Velocity Profiles
Authors: Han Yingke , Rogers Robert J.
Published: March 2022

In this paper, nonlinear models for infinitely long, cylindrical squeeze films with arbitrary inner cylinder motion have been derived using three approximation methods. Two kinds of fluid velocity profiles are employed in the derivation with the aim to see the differences caused by using the two profiles, parabolic and elliptical. Each term in the squeeze film force equations is a nonlinear function of cylinder position (or eccentricity). The only differences in the final squeeze film force equations, due to the three approximation methods and the two different velocity profiles, are in the four constant coefficients. Comparing the present nonlinear expressions with existing models shows that: (1) the viscous, unsteady inertia and convective inertia terms, acting in the normal direction, are essentially the same as in other studies; (2) the normal-direction centripetal inertia term shows similar variations with position as one published study, but very different from another study; and (3) the three tangential-direction force terms show variations with position which are very different from a previous published study.
Elimination of Pulsations in a Chemical Plant: A Combination of Measurements, Calculations and Scale Model Experiments
Authors: van Bokhorst E. , Goos F. , Korst H. J. , Bruggeman J. C.
Published: March 2022

The aim of the work described in this paper was to trace and eliminate vibration sources in a low pressure system with high flow velocities.

Considerable vibration on the pipe system between a flashing vessel (6.5 m diameter) and heat-exchangers resulted in leakages and subsequent shut downs of a chemical production plant.

As compressors or pumps were not directly involved in the process, we considered aero-acoustic pulsations as the main cause of the high vibration levels. Analysis of the flow in the pipe system showed that mean flow velocities could rise up to 50 m/s, which is rather high considering the speed of sound in the gas of 195 m/s. Furthermore separation of the flow from the pipewall occurs at the outlets of a flashing vessel, which resulted in estimated flow velocities of over 100 m/s in the vena contracta.

This paper provides an overview of the analysis done by a one-dimensional acoustical and a mechanical finite element model.

The recommended modification consists of a perforated pipe-section between the outlets of the vessel and has been tested in a scale model. Tests have been performed with airflow at identical Mach numbers for different configurations with perforation ratios from 70 to 36%.

The modification with a perforation ratio of 50% shows a reduction of a factor 5 of the pressure pulsation and vibration levels over the entire frequency range.

The net pressure loss for this configuration is similar to that in the original lay-out without the perforated tube.

This modification was implemented during a plant shutdown in October 1996 and proved to be very effective. The results are well in line with the predicted levels and on the basis of this success a similar design has been planned for two new installations.
Simulation of Housing Separation in a Rotatable Mechanical Prosthetic Heart Valve
Authors: Ryder Kenneth
Published: March 2022

Today the mechanical heart valve prosthesis offers a number of advanced features which enhance the performance relative to the early valve designs. Most notable is the ability to rotate the valve housing in situ, that is after the valve is sewn in place [1]. In some cases, anatomical obstructions may exist which would preclude optimum valve function without proper valve orientation. Additionally, the position of the pivot mechanism relative to the coronary ostia is a placement constraint for some surgeons. Rotatability in situ offers the surgeon the ability to make decisions about final valve placement after the valve is in the anatomy as opposed to outside the chest during the suturing process. However, this advantage does not come without additional reliability requirements. The rotation feature requires the housing have mechanical clearance from the sewing cuff. Some designs feature sewing cuffs with stiffening elements and others do not. The structural reliability must be proven against a new set of potential failure modes.
Recordings of Cavitation Bubble Oscillation and Acoustic Shock Emission in Intracorporeal Electrohydraulic Lithotripsy
Authors: Lu Quang , Chuong C. J. Charles
Published: March 2022

Intracorporeal electrohydraulic lithotripsy (IEHL) has been used in the treatment of urinary tract stone diseases. To better understand the interaction of the energy delivered and its resulting stone fragmentation, we recorded the cavitation bubble oscillation and the corresponding acoustic shock emission.
Effect of the Age-Dependent Properties of the Braincase on the Response of the Infant Brain to Impact
Authors: Thibault Kirk L. , Kurtz Steven M. , Margulies Susan S.
Published: March 2022

Finite element models of the adult human head have been used to determine intracranial deformation of the brain under traumatic loading conditions [1]. Development of similar models for the infant head has been hindered by the lack of material property data for the pediatric brain and skull. Recent determination of these properties [6] has facilitated the construction of an idealized infant head model which can be used to demonstrate the effect of age-dependent properties of the braincase on the response of the infant brain to impact. The long-term goal of this research is to quantify the intracranial deformation of the neural and vascular tissue within the brain during traumatic loading and to apply these findings to the development of specialized head injury tolerances for the pediatric population.
Muscle Balance at the Knee During Internal and External Knee Rotation
Authors: Stewart A. A. , Buford W. L. , Ivey F. M. , Malone D. J. , Patterson R. M. , Nguyen D. , Nelson C.
Published: March 2022

The human leg functions as it does partially because of an inherent muscle balance at the knee that provides adequate range of motion and strength. Disturbing this muscle balance can alter the functionality of the leg. Mechanical systems, such as the human knee, cannot be completely described without knowledge of the forces and moments associated with them.
Measurements for the In Vitro Failure of Multi-Level Instrumented Cervical Spine
Authors: DiAngelo Denis J. , Jansen Thomas H. , Eckstein Eugene C. , Foley Kevin T. , Dull Scott T.
Published: March 2022

Cervical spondylotic myelopathy, a commonly seen entity among the elderly, is often treated surgically to prevent progressive neurologic deterioration. There is a trend toward multi-segmental anterior surgical decompression and fusion in these cases [2]. Multi-level anterior cervical plates are frequently used to supplement these fusions. Previous in vitro experimental studies of anterior plating systems have been limited to one or two motion segment spine models [3,4].
Effect of Cervical Spine Position on Moment-Generating Potentials of Neck Muscles
Authors: Li Siping , Vasavada Anita N. , Delp Scott L.
Published: March 2022

The stability of the head/neck system is achieved through the interplay of the passive ligamentous cervical spine and active neck musculature under neural control (Panjabi, 1992). Neck muscles provide forces and moments to generate movements of head/neck and maintain their stability. Many previous analyses have used muscle geometry at the neutral head position to calculate the forces and moments produced by the muscles. These studies, in general, have not examined how changes of muscle moment arms and muscle lengths affect their force and moment-generating capacities. It is yet not clear how the moment-generating capacities of individual neck muscles vary and how their relative contributions to total strength change with head/neck posture. Quantification of the moment-generating potentials of individual neck muscles at different positions of the cervical spine will provide insight into the contributions of the neck muscles to head movement and spine stabilization. The objective of this study was to quantify the variation of maximal isometric moment-generating potentials of neck muscles with flexion-extension, lateral bending, and axial rotation.
The Present and Future of Micromachining in Industrial Production of Surgical Tools
Authors: Tolkoff M. J.
Published: March 2022

Surgery is the removal of obstructions and replacement or realignment of structures allowing the body to heal itself. What can micromachining add to this practice? Devices smaller than achieved before which are good for detecting problems, removing obstructions so biological repair can commence, and creating structures (scaffolds) for speeding repair. With the advent of micromachining industry can begin to create devices which are similar in size to the cells themselves. This will allow the creation of devices which mimic biology, for example needles as small as a mosquito’s, valves the size of tiny blood vessels, or structures which allow cells to grow creating new functioning tissue.

Micromachining’s promise allows the engineer to take into account the cells’ “view” of devices. Devices can now be made as small as a red blood cells (8μ) and with passages of 50μ, critical for healthy cell growth. In pores larger than this cells can’t bridge the space for transport of nutrition, oxygen, carbon dioxide, etc. In smaller pores cells clog the passageways and get quickly trapped.

The mechanical design engineer can use micromachining to:

• See things: diffraction gratings, lenses, optical elements

• Filter things: segregate cells, move drugs and nutrients without moving the cells

• Do work: move/remove tissue, make tiny surgical tools, make tiny nozzles for water jet cutting

• Support things: make scaffolds for cells, stent open body passages

• Make surfaces biologically friendly: textured surfaces, surfaces filled with materials friendly to the cells

• Make better tools: sharper cutting edges, tiny mechanisms, valves, controls

These and other possible micromachined devices will be discussed.
A Method for Determining the Anterior-Posterior Motion of Tibiofemoral Contact During Simulated Gait in Total Knee Arthroplasty
Authors: Sheshadri V. B. , Rullkoetter P. J. , Hillberry B. M.
Published: March 2022

A description of the motion of the centers of tibiofemoral contact, during gait, can provide insight into the constraint of a given prosthetic design. It has been shown that increased joint constraint can have a negative effect on the performance of a prosthetic, such as increasing the risk of tibial loosening[1,2]. This paper will describe a method to evaluate the anterior-posterior motion of the tibial centers of contact.
Finite Element and Experimental Test Results for Peek Composite Intramedullary Implants
Authors: Corvelli Amy A. , Biermann Paul J. , Roberts Jack C.
Published: March 2022

Stress-shielding between the implant material and the bone is closely linked to the loosening of current metallic (titanium) orthopedic implants. A material having properties that closely match those of bone will decrease this shielding problem and improve implant fixation (1). This study uses a composite of polyetheretherketone (PEEK) to produce an isoelastic intramedullary implant (i.e., an implant with a stiffness equivalent to that of bone). A finite element model (FEM) was developed and numerical results were confirmed by experimental bending tests.
The Effect of Auditory Cues on the Haptic Perception of Stiffness in Virtual Environments
Authors: DiFranco David E. , Beauregard G. Lee , Srinivasan Mandayam A.
Published: March 2022

To explore the possibility that multisensory information may be useful in expanding the range of haptic experiences in virtual environments, psychophysical experiments examining the influence of sound on the haptic perception of stiffness were carried out. In these experiments, subjects utilized the PHANToM, a six-degree-of-freedom haptic interface device with force-reflection along three axes, to feel the stiffness of various virtual surfaces. As subjects tapped on the different virtual surfaces, they were simultaneously presented with various impact sounds. The subjects were asked to rank the surfaces based on their perceived stiffness. The results indicate that when the physical stiffnesses of the surfaces were the same, subjects consistently ranked the surfaces according to sound, i.e., surfaces paired with sound cues that are typically associated with tapping harder surfaces were generally perceived as stiffer. However, when sound cues were randomly paired with surfaces of different mechanical stiffnesses, the results were more equivocal: naïve subjects who had not used the PHANToM previously tended to be more affected by sound cues than another group of subjects who had previously completed a set of stiffness discrimination experiments without sound cues. The possible implications of this result for the design of multimodal virtual environments and its comparison to prior work by some of the authors on the effects of vision on haptic perception are discussed.
Experimental Investigation of Planar Two-Arm Friction Assisted Grasping Tasks
Authors: Desai Jaydev P. , Kumar Vijay
Published: March 2022

We study human manipulation tasks requiring the coordination of two arms with grasps that rely on frictional forces for stable prehension. Specifically, we investigate tasks in which an object is grasped with open palms and moved from one position and orientation to another in a horizontal plane. We are particularly interested in the force distribution and object trajectory in voluntary, relaxed movements. The first important observation is that there is a significant degree of repeatability in the kinematic data across trials and across subjects. Secondly, we show that all trajectories are characterized by asymmetries that cannot simply be explained by the dominance of one arm over the other. Finally, we show that the internal forces can play an important role in trajectory generation. While these are repeatable across trials, they vary significantly from subject to subject. The results of this paper are potentially important for the design of bimanual machine interfaces and for robot control and coordination.
Noncollocated Adaptive-Passive Vibration Control
Authors: Buhr Craig A. , Franchek Matthew A. , Bernhard Robert J.
Published: March 2022

Presented in this paper is the development of a control law for tuning a variable stiffness vibration absorber to attenuate single frequency excitation in a noncollocated situation. The control law is comprised of two distinct parts. First, a ±90° phase condition between the motion of the vibration absorber and the location of interest is used to determine tuning direction. Next, a feedback based tuning strategy is used to precisely tune the vibration absorber for performance maximization. The feedback tuning strategy is based on the classical feedback structure of a regulating system. The absorber is tuned such that the accelerometer voltage resulting from the measurement of vibration of the point of interest is minimized. An experimental verification of this control law is shown.
Monitoring of Loading Status Inside Rolling Element Bearings Through Electromechanical Sensor Integration
Authors: Holm-Hansen Brian T. , Gao Robert X.
Published: March 2022

This paper presents a systematic design approach for a sensor-embedded “smart” ball bearing. An embedded acoustic emission sensor is used as part of a condition monitoring system to provide self-diagnostic capabilities to the bearing. Integration of the sensor involved a structural modification to the bearing raceway and the configuration of a miniaturized acoustic emission sensing element. The design parameters were the size, geometry, location and material properties of the sensing element as well as the dimensions of the bearing raceway modification in which the sensor is embedded. A combination of analytical and coupled-field finite element models were used in the design process. The raceway was analyzed by evaluating the stress and deflection of the bearing, and the embedded sensor was analyzed in terms of its frequency response. This work shows how both analytical and finite element modeling methodologies can be combined effectively in the development of a smart mechanical component with improved fault detection capabilities.
A Simplified Three-Way Catalyst Model for Use in On-Board SI Engine Control and Diagnostics
Authors: Brandt Erich P. , Wang Yanying , Grizzle Jessy W.
Published: March 2022

Automotive emissions are severely regulated. Since 1980, a three-way catalyst (TWC) has been used to convert harmful emissions of hydrocarbons, carbon monoxide, and oxides of nitrogen into less harmful gases in order to meet these regulations. The efficiency of conversion of these gases is dependent on the mass ratio of air to fuel (A/F) in the mixture leaving the exhaust manifold and entering the catalyst, the velocity of the exhaust mass, and the temperature of the catalyst. The goal of this paper is to develop a dynamic, control-oriented model of a TWC. First, the importance of developing such a model will be explained. Then, a simplified dynamic catalyst model that can be determined on the basis of medium bandwidth A/F measurements and low bandwidth temperature and emission measurements will be introduced and validated.
Non-Newtonian Lubrication With the Second Order Fluid
Authors: Sawyer W. Gregory , Tichy John A.
Published: March 2022

In certain applications where the lubricant is subjected to rapidly changing conditions along its flowing path (such as an elastohydrodynamic contact), the inherently time dependent nature of the lubricant may be significant. The simplest type of model to correctly account for such time dependence is the second order fluid, which is a systematic small departure from Newtonian behavior, involving higher order rate-of-rate-of strain tensors. Using a regular perturbation in the Deborah number, with the conventional lubrication case as the leading term, a solution can be obtained. Viscoelasticity may raise or lower pressure depending on the nature of edge boundary conditions.
Settling and Interactions of Spheres in Non-Newtonian Fluids
Authors: Zhu Qinsheng , Clark Peter E.
Published: March 2022

Settling of particles in both Newtonian and non-Newtonian fluids has been the subject of a number of studies. In Newtonian fluids, the settling process is well understood. The process is less well understood in non-Newtonian fluids. Multiple particle settling in non-Newtonian fluids has not received a great deal of attention, but it is important in a number of industrial processes.

In this study, we have examined the behavior of multiple spheres falling in non-Newtonian fluids. For two spheres of different diameters dropped sequentially, we find that the spheres will aggregate and fall together under certain well defined conditions. Both the diameter of the spheres and the rheological properties of the fluid determine settling behavior. Data will be presented for settling of multiple particles (up to five). Interactions between more than two particles settling together are complex. Our experiments indicate that the relationship between settling velocity and the number of the spheres follows some regular pattern. Theoretical work describing the mechanism and conditions under which the two particles with different sizes will settle together in non-Newtonian fluids is also discussed in this paper.
Flow Characteristics of Electrorheological Fluids
Authors: Tsukiji Tetsuhiro , Hori Ken-ichi
Published: March 2022

Microscopic behavior of ER suspension structure between two fixed electrodes is visualized for the stationary and flowing ER fluids with high speed video camera fitted with a microscope under application of electric fields. The ER fluids used in the present study consist of cellulose suspended in silicone oil. Unipolar and bipolar sine-waves electric fields, and constant ones are used. The frequencies of the electric fields are from 0.1 to 1000 Hz. The pressure drop of ER fluids between two parallel-plate electrodes is also investigated under application of the electric fields for constant flow rates. Dependence of the pressure drop on electrical excitation frequency is investigated. Furthermore the flow characteristics of ER fluids which flow in an axial direction without the radial velocity component between two closely fitting concentric cylinders are examined. The pressure drop/flow rate performance of the ER fluids between concentric cylinders is measured under constant electric fields. The relationship between the pressure drop and the flow rate are calculated using the commonly quoted Bingham model.
Efficient Algorithms for Non-Smooth Dynamics
Authors: Roßmann Thomas , Pfeiffer Friedrich , Glocker Christoph
Published: March 2022

In this paper the dynamics of rigid body systems with stick-slip transitions are examined. Thereby unilateral contacts and bilateral guiding devices are considered and the validity of the Coulomb friction law is assumed. The equations of motion together with the constraint equations and the contact laws are transformed into a linear complementary problem. For three dimensional problems this is done by using a linearized friction cone. All the described methods can be used for systems with dependent constraints. Finally, some practical examples are given in which the described methods are applied.
Nonlinear Phenomena in a Stochastically Excited Dynamic System
Authors: van de Wouw N. , de Kraker A. , van Campen D. H.
Published: March 2022

The response of strongly nonlinear dynamic systems to stochastic excitation exhibits many interesting characteristics. In this paper, excitation forms like white noise and Gaussian band limited noise are applied to a bilinear system. The nonlinear characteristics cannot be represented sufficiently accurate using statistical linearization techniques. Integration techniques have to be used. The emphasis lies on frequency domain phenomena. Phenomena like multiple resonance frequencies and multiple solutions are investigated along with their origin. The stochastic response characteristics are clarified by comparing them to periodic response features of the system. Furthermore, stochastic response phenomena can provide information on the periodic response characteristics of the system.
Time and Reason for the Beginning of Railroad Axle Rotation
Authors: Sakamoto Haruo , Hirakawa Kenji
Published: March 2022

Axles for aircraft, automobiles, and horse wagons do not rotate. From the chariot of around B.C. 2,000 to horse wagons of the wild west, axles for vehicles have not rotated except for the railroad. Why and when railroad axles started to rotate is the subject of this report.

Stevens’ locomotive exhibited in the Museum of Science and Industry in Chicago is called the first locomotive to run on a track in America in 1825 and has stationary axles. On the other hand, Locomotion by Stephenson in England, which is the first train on a public railroad in England in 1825, has rotational axles. In the US, all axles seem to have started to rotate around 1834, when the Mississippi was inaugurated.

This report tried to investigate the time and reason for the beginning of railroad axle rotation. As a result, the axles for wheel drive locomotives are considered to be needed to rotate with wheels from the viewpoint of maximum friction power. However, the reason of axle rotation for the trailing wheel at the beginning of the railroad is not explicit. Further investigation is required.
CFD Analysis of Thermal Mixing and Stratification in AP600 Auxiliary Lines
Authors: Harkness Alexander W. , Schwirian Richard E. , Dymacek Petr
Published: March 2022

Computational Fluid Dynamics (CFD) was used to evaluate thermal stratification in two auxiliary piping systems of the Advanced Passive 600 mW Pressurized Water Reactor (AP600).
Real-Time Resin Temperature Measurements for Polymer Processing Using Fluorescence Spectroscopy
Authors: Bur Anthony J. , Migler Kalman , Vangel Mark G. , Johnsonbaugh David S.
Published: March 2022

We have developed a measurement methodology for measuring resin temperature and temperature profiles during processing using fluorescence spectroscopy. The technique consists of mixing a temperature sensitive fluorescent dye with a polymer resin at very low concentration, on the order of 10−6 molar concentration, and monitoring the temperature dependence of the fluorescence spectra. Two classes of fluorescent dyes are used: (a) excimer producing dyes such as bis-(pyrene) propane, and (b) band broadening dyes such as perylene and benzoxazolyl stilbene. Because the fluorescence measurement reflects the temperature in the neighborhood of the dye molecule, true resin temperature is observed and effects due the large thermal mass of the processing machine are minimized. Real-time monitoring was achieved using optical fiber sensors which were inserted into the process line at existing instrumentation ports. We monitored both injection molding and extrusion observing effects due to shear heating, crystallization and thermal diffusion. Temperature profiles in a flowing resin were measured using a sensor with confocal focusing optics. With this sensor, excitation light is focused to a point in the resin and the temperature at that point is deduced from the resultant fluorescence. In most cases, the fluorescence data must be corrected for effects due to pressure in order to yield an accurate temperature measurement.
Creation of Conducting Networks of Particles in Polymer Melts by Chaotic Mixing
Authors: Danescu R. I. , Zumbrunnen D. A.
Published: March 2022

Chaotic mixing of a nonconducting thermoplastic melt and initially coarse clusters of conducting particles has been investigated to assess opportunities for the in-situ formation of extended particle networks. Upon capture by solidification, such extended networks may render the composite electrically conducting. Chaotic advection of small, spherical, non-interacting particles was studied computationally and experimentally ill a cavity formed between two offset cylinders. Numerical tracking of individual particles was performed under conditions where global chaotic mixing prevailed. Formation mechanisms were identified at various stages of mixing. After mixing, networks comprising interconnected particles were identified as electrical pathways. Micrographs of composites produced experimentally by two-dimensional chaotic mixing of thermoplastics with conducting carbon black showed structures resembling those predicted by the simulations and provided further insights into formation mechanisms. The electrical resistivity of the composites is also compared to composites produced by conventional means.
Damage in Composite NiMH Positive Electrodes
Authors: Sastry A. M. , Choi S. B. , Cheng X.
Published: March 2022

Mechanical degradation in fibrous composite electrodes in use in NiMH (nickel metal hydride) batteries is being studied. NiMH cells exhibit failure in the positive plate due to swelling induced during the electrochemical reaction, which leads to gradual breakdown of the connectivity of the substrate microstructure. Particularly, loss of electrical conductivity as related to losses in mechanical properties upon cell cycling (constant current cycles with substantial overcharge) are being investigated experimentally. These properties are measured for the dry substrate material before and after battery cycling, and the losses observed suggest key failure mechanisms include mechanical damage. Results suggest tradeoffs between use of higher density nickel substrates and improved energy densities using mechanical and resistivity proof tests.
Toughness Enhancement in Blends of Dissimilar Polymers Due to the In-Situ Formation by Chaotic Mixing of Fine-Scale Extended Structures at Low Minor Phase Concentrations
Authors: Liu Y. H. , Zumbrunnen D. A.
Published: March 2022

Experimental results are presented to demonstrate that significant improvements to the impact properties of a polystyrene (PS) matrix can be achieved by the addition of only 9% by volume of low density polyethylene (LDPE). Polymer blends of LDPE and PS were combined in the molten state within a cylindrical cavity where a quiescent, three-dimensional chaotic mixing process was performed. Whereas a minor phase normally adopts the form of highly distributed droplets in conventional processing techniques, minor phase bodies were stretched and folded recursively to yield fine-scale extended and interconnected structures. The structures were largely preserved upon solidification. Impact tests were carried out on specimens which were machined from the solidified blend. Fracture surfaces of the impact test specimens were examined by scanning electron microscopy. Blends achieved a maximum impact toughness 69% higher than that of PS. Results demonstrate potential improvements in properties that may be obtained if favorable and unique microstructures are formed directly in the melt during processing, even when major and minor phases are dissimilar.
Raman Investigation and Mechanical Behavior of Zirconia
Authors: Gogotsi George G.
Published: March 2022

Raman microprobe analysis was performed of partially-stabilized ZrO2 ceramics and single crystals using the samples which were preliminary indented with a Vickers indenter at room temperature or subjected to bending at low temperatures. The addition of ferric oxide into Y-PSZ ceramics was found to intensify martensitic phase transformation in it and to enhance its fracture toughness. For single crystals the tetragonal-to-monoclinic phase transformation was found possible at fracture. It was established that inelastic Mg-PSZ ceramics at −50°...−60°C becomes in fact elastic but no relevant changes in Raman spectra were observed. A conclusion was made that further investigations are required to specify the known micromechanisms which govern the behavior of ZrO2 materials under loading.
Strength Distribution and Size Effects for the Fracture of Fibrous Composite Materials
Authors: Phoenix S. Leigh , Beyerlein Irene J.
Published: March 2022

Random network models have recently been developed in the physics literature to explain the strength and size effect in heterogeneous materials. Applications have included the breakdown of random fuse networks, dielectric breakdown and brittle fracture. Unfortunately, conventional scaling approaches of statistical mechanics have yielded incorrect predictions, and new approaches have been proposed which build on field enhancement occurring near the tips of critical, random clusters together with the statistical theory of extremes. New distributions and size scalings for strength have been proposed and supported through Monte Carlo simulation. Here we consider an idealized, one-dimensional model for the failure of such networks where elements of constant strength may be initially present or absent at random. Our idealized rule for local stress redistribution near breaks reflects features we find in a discrete mechanics model that has limiting forms consistent with continuum theories for cracks. We obtain rigorous asymptotic results for the strength distribution and size effect with constants and exponents that are known. The validity of various analytical approximations in the literature is then discussed.