bluuebunny/crossref_metadata_2025_split huggingface dataset:
Longitudinal Wave Response of an Elastic-Viscoelastic-Elastic Laminate With a Shear Voigt Damping Core
Authors: Douglas B. E. 
Published: March 2022

Abstract
The equations of motion for the longitudinal (i.e. in-plane) wave response of an elastic-viscoelastic-elastic laminated beam containing a generalized shear Voigt viscoelastic core are derived along with closed form expressions for the complex flexural wavenumbers. Comparisons with experiment are made in a mechanical mobility format. The existence of this form of damping is supported through the agreement observed between theory and high resolution sine wave dwell measurements of the driving point mechanical mobility of two damped laminates. The generalized shear Voigt damping core is shown to have a significant effect on the damping performance for anti-resonance modes of the laminate with free-free boundary constraints within the spectral band governed by out-of-phase, in-plane motion between the base and constraining layers. This spectral band for shear Voigt damping is determined from consideration of the limiting case of a lumped parameter mass-spring-mass model. In addition, the resonance modes of the free-free laminate showed a waveguide behavior where the damping is equivalent to the internal damping of the base structure. Finally, this analysis coupled with experimental results show the shear Voigt damping mechanism is dominant in elastic-viscoelastic laminates with relatively soft damping cores and/or stiff constraining layers.
Enhancing the Performance of Constrained Layer Damping by Confining Vibrational Energy
Authors: Allaei Daryoush , Tarnowski David J. 
Published: March 2022

Abstract
A feasibility study was conducted to demonstrate that the combination of Constrained Layer Damping (CLD) and Vibration Control by Confinement (VCC) is an effective and viable approach to today’s noise and vibration problems. The objective of this paper is to report on the degree of improvement of CLD when used in conjunction with VCC. Two panel-type structures, resembling a simplified model of the panel section of a car door, are examined. The entire upper surface of the first panel was covered by CLD. On the other hand, only 63% of the second panel is covered by CLD. A confining rib was added to the second panel to localize the vibrational energy to the remaining 37% of its surface over which no CLD was added. The finite element method was employed to model both structures and generate the numerical results presented in this article. Four equally distributed points were identified to excite and measure the response. The plate was subjected to transient and harmonic excitations. Our preliminary results clearly show that not only VCC can be used as a stand-alone mechanism to suppress or isolate vibrations but also can be combined with CLD to significantly improve performance. Furthermore, additional ramifications of the VCC approach as they apply to passive or active vibration control systems are discussed.
Active Vibration Control Using Modal Techniques
Authors: Hooper Tyler F. , Greif Robert 
Published: March 2022

Abstract
By aligning the coordinates of the control algorithm with the modal coordinates of the flexible structure being controlled, Independent Modal Space Control (IMSC) uses the orthogonality of the mode shapes to minimize the computational requirements of control systems. With an objective of minimizing settling time, a comparison is made of several vibration control algorithms, which use IMSC theory.
For optimal control, this paper presents an incremental search technique to estimate the preferred R values for a given set of initial conditions. Modified Independent Modal Space Control (MISMC) utilizes a time sharing strategy to share a small number of actuators between a greater number of modes. This technique produced discontinuities in the actuator forces which results in spillover and reduces its effectiveness. The Total Independent Modal Space Control (TIMSC) method, introduced in this paper, avoids significant force discontinuities by using all the available modal information.
Additional (non-optimal) comparisons include a method for varying R values during the control process, and also control strategies involving actuator force saturation.
Nonlinear Systems With Multiplicative and Additive Perturbation Under State Space Constraints
Authors: Colonius Fritz , Kliemann Wolfgang 
Published: March 2022

Abstract
Realistic models of mechanical systems often depend on various parameters, such as controlled inputs, material constants, tunable parameters, and uncertainties. Uncertain parameters can be (time varying) deterministic perturbations or stochastic excitations whose influence on the system depends on the perturbation dynamics (multiplicative or additive), the perturbation range, and its statistics in the stochastic case. For a given operating region of the system, i.e. for a set of state space constraints, the behavior of the system within this region depends strongly on the type of perturbation dynamics and on its range. We present some basic theory for additively and multiplicatively perturbed systems, where the uncertainty can be a family of time varying functions, or a Markov diffusion process. The uncertainty range plays the role of a bifurcation parameter and determines concepts like discontinuities of control sets and supports of invariant measures, stability radii, and invariance radii with respect to the constraint set. It turns out that in many instances the stochastic and the deterministic bifurcation scenarios agree, and the cases in which they differ are related to a nonuniform behavior of the stochastically perturbed system. The example of a model of ship roll motion is treated in detail, revealing some of the fundamental agreements and disagreements of the two bifurcation scenarios.
Vibration Absorber for Flexible Structures: Experimental Study Under Random and Sinusoidal Excitations
Authors: Cuvalci O. , Ertas A. , Cicek I. , Ekwaro-Osire S. 
Published: March 2022

Abstract
The dynamic response of a model that simulates a one-story building with a tip mass attached as a passive vibration absorber subjected to sinusoidal and random excitations has been investigated experimentally. The effect of the forcing frequency, forcing amplitude, mass ratios and frequency ratios on the system response in the neighborhood of the autoparametric region have been studied. The main objective of this study was to conduct a series of experiments for different system parameters to investigate the autoparametric interaction between the two modes of the system.
Mechanism of Paper Feeding on the Roller Overlapped Friction Feeder
Authors: Okayama Masao , Nagasawa Yutaka , Ichikawa Ryoichi , Utsumi Itsunori 
Published: March 2022

Abstract
We study on roller overlapped type friction feeder in which the rotating feed roller and stationary gate roller are overlapped in a direction to the roller’s radius, to increase its rehability. The paper traction forces created by the feeder and the paper double feeding mechanism are also studied.
It is found that the characteristics of the reaction forces between the two rollers and paper which is buckled in three dimensions, and paper traction forces depend upon the position at which a sheet of paper is delivered. It is also found that the paper traction forces increase in proportion to the number of sheets of paper which are fed into the roller overlapped mechanism. The ratio of the overlapped area of the double feeding sheets of paper depends upon the degree of force to deliver the second paper.
A Numerical Solution of the Euler’s Equations With Nonlinear Source Terms in Modeling the Fluid Dynamics of an Air Reverser
Authors: Müftü Sinan , Lewis Timothy S. , Cole Kevin A. 
Published: March 2022

Abstract
A theoretical analysis of the fluid mechanics of the air cushion of the air reversers used in web-handling systems is presented. A two-dimensional model of the air flow obtained by averaging the equations of conservation of mass and momentum over the clearance between the web and the reverser is solved numerically. The effect of the pressure holes in the surface of the air reverser are represented by nonlinear source terms in the modified Euler’s and mass conservation equations. The results of the numerical solution axe compared with a 1D analytical solution of these equations, an empirical formula and the one-dimensional air-jet theory developed for hovercraft. Conditions that maximize the air pressure supporting the web are analyzed and design guidelines are deduced.
Free Vibration of a Rotating Disk/Spindle System With Hydrodynamic Bearings
Authors: Jintanawan Thitima , Shen I. Y. 
Published: March 2022

Abstract
This paper is to study free vibration of a rotating disk/spindle system with hydrodynamic bearings (HDB). The disk/spindle system consists of multiple circular disks clamped on a rigid spindle, which allows infinitesimal rigid-body translation and rotation (rocking). Also, the spindle is mounted on a stationary, flexible, cantilever shaft through two identical radial HDB and a thrust HDB. Equations of motion were first derived in terms of the rigid-body translation and rocking of the spindle, the shaft bending, and the disk vibration. Then an eigenvalue analysis was performed to obtain natural frequencies, modal damping factors, and mode shapes of the rotating disk/spindle system. For a special case of rigid shaft and decoupled translation/rocking spindle, one pair of transverse modes and two pairs of rocking modes were observed. For the transverse modes, the disk/spindle system whirls transversely as a rigid body at half of the rotational speed (i.e., half-speed whirl). In addition, the backward whirl is heavily damped while the forward whirl is lightly damped. The first pair of rocking modes is similar to those found in disk/spindle systems with ball bearings and is lightly damped. The second pair of rocking modes occurs at low frequency. One of these modes is lightly damped and has natural frequency very close to half of the rotational speed. For the general case of a flexible shaft and coupled translation/rocking motion, eight coupled modes were obtained. Three of them occur at the half-speed frequency. Compared with systems with rigid shaft, the other five modes have significantly lower natural frequencies because of the shaft flexibility.
Design of Servo Code and Synchronous Clock Writing Scheme on a High Capacity Disk Drive
Authors: Zhou Jingli , Yu Sheng Sheng , Ma Joseph T. 
Published: March 2022

Abstract
A disk drive servo code and synchronous writing scheme is described in this paper. The encoding and decoding of the servo code; the writing and detecting of the synchronous clock writing can be realized in this system. In this paper, a synchronous clock writing with variable frequency method is discussed. The mathematical analysis of the variable frequency clock writing, the system design, and the writing and detecting of the servo code are presented.
Examples of Chaotic Motion of Railroad Vehicles in Theory and Experiment
Authors: True Hans 
Published: March 2022

Abstract
The dynamics of moving railroad vehicles is a challenging problem of nonlinear dynamical multibody systems. Already the fundamental guidance system with the flanged steel wheelset on steel rails introduces both kinematic and dynamic nonlinearities in the equations of motion of the vehicle, but there exist also other sources of nonlinearities in moving railroad vehicles. Examples are: Nonlinear responses of suspension elements to actions, play and impacts and hysteresis effects from air springs or dry friction contact.
Stub-Sill Tank Car Damage Tolerance Analysis Full-Scale Validation Test
Authors: Smith Keith B. , Cardinal Joseph W. , McKeighan Peter C. 
Published: March 2022

Abstract
This paper describes the Simuloader, a full-scale multiaxial servohydraulic test bed for railcars; Damage Tolerance Analysis, a fracture mechanics based methodology used to establish inspection intervals for fatigue cracked structures; and the use of the former to validate the latter in the Stub-Sill Tank Car Research Program being undertaken by the railroad tank car industry in North America. This paper describes a work in progress; subsequent papers and reports are expected covering the results and conclusions of the program.
A Simple Method for Estimating Railcar Wheel Tread Temperature Rise During Braking
Authors: Moyar G. J. , Carlson F. G. 
Published: March 2022

Abstract
One of the important tools needed to assess the severity of various braking cycles and quantify the capacity of braked wheel treads to resist thermal spalling is a reliable and easy to use computational method for predicting the associated tread temperature rise. Such a simple analytical procedure is developed and satisfactorily correlated with available experimental results in this paper.
It is based on a transient one dimensional thermal solution for surface and near surface temperature histories and takes into account tread heat transfer losses to the rail as well as to the air stream. The procedure is implemented in a spread sheet computer program that accepts any train operation and air brake system input history and computes the resulting train speed and tread temperature histories.
Correlations and comparisons are made to published results as well as some previously unpublished test data obtained by the Association of American Railroads (AAR). The method proposed is well suited to predict the results of stop braking and short time drag braking histories but its analytical assumptions are less satisfactory for long time drag braking simulations.
Capacity Planning & Order Promising in a Remanufacturing Shop
Authors: Shivpuri K. 
Published: March 2022

Abstract
Remanufacturing of Locomotives, Passenger and Freight cars is highly prevalent in the Railroad industry due to the high initial cost associated with these assets. Production scheduling in a remanufacturing shop poses a special challenge as the scope of work involved is not known with great certainty. This uncertainty translates into wide variability in lead times and production inefficiencies. Traditional methods of production planning, more suitable for new manufacture, either fail to give suitable results or are cumbersome to use in the highly dynamic environment. Hence, a novel approach is suggested which gives accurate projections and at the same time is robust enough to cater to the changing ground situation.
Engineering Studies in Support of the Development of High-Speed Track Geometry Specifications
Authors: El-Sibaie Magdy , Jamieson David , Tyrell David C. , Dorsey J. Christopher , Mee Brian , Whitten Brian , Kesler Kevin 
Published: March 2022

Abstract
The Federal Railroad Administration has been directing engineering studies to support the development of high speed track geometry standards. These standards are intended to cover train operating speeds from 110 mph to 200 mph. The studies conducted include evaluation of the use of measuring track geometry with offsets from several chord lengths, computer simulations of vehicle response to track surface and alignment variations, application of the proposed specifications to previously measured track geometry, and comparison of proposed specifications to foreign practice.
The proposed standards use multiple chords to control surface and alignment geometry. Single isolated geometry variations are allowed greater amplitudes than three or more repeated geometry variations. The results of the engineering studies indicate that use of multiple chords is effective in controlling a wide range of geometry variation wavelengths, from less than 30 feet to greater than 250 feet. The computer simulation studies show that at high speed, wheel/rail interaction dominates vehicle response to short wavelength (less than ∼100 feet) alignment variations, while carbody motions dominate vehicle response to long wavelength variations. Derailment and carbody accelerations are the principal concerns in vehicle response to track geometry variations. Application of the proposed specifications to previous measurements of high speed track on the Northeast Corridor indicates a relatively modest number of exception locations (∼1 location every 3 miles). Comparison of the proposed specification with foreign practice indicates that the proposed specification provides a generally similar level of control of track geometry.
Bethsy Test 6.9C Mid-Loop Operation Phenomena Identification Using RELAP5 NPA
Authors: Petelin Stojan , Mavko Borut , Jurkovic Mihael 
Published: March 2022

Abstract
Test 6.9c OECD ISP-38 was performed on “BETHSY” facility, France on April 14. 1992 and simulated loss of RHR system during Mid-Loop operation at 0.5% of nominal value core power. Initial liquid level in RCS was at horizontal axis of the hot legs. Pressurizer and steam generator manways were opened 1 s after the transient was initiated. The paper presents the test observation to the physical phenomena comparing to the experimental data using RELAP5 NPA (Nuclear Plant Analyzer) graphical postprocessor. The most important and interesting turned out to be coolant distribution around the loops.
Study on the Flow Distribution Around a Bathtub Vortex in a Cylindrical Vessel
Authors: Sakai S. , Madarame H. , Okamoto K. 
Published: March 2022

Abstract
Flow field around a bathtub vortex in a cylindrical vessel was measured. A gas core of the bathtub vortex was stationarily formed at the center of the vessel. An inlet open channel and an outlet pipe were equipped at the top tangentially and at the bottom center, respectively. Flow field was visualized using ink tracer or particle tracers, resulting in the velocity distribution measured. The downward velocity in the central region was found to be proportional to the distance from the original surface without the gas core except in the neighborhood of the outlet. Using the Laser Doppler Velocimeter, radial distribution of the downward velocity in the vessel was measured. The velocity distribution in the central region was found to be very complex. In the lower flow rate condition, the highest velocity position was the center. However, with increasing the flow rate, the highest position moved to outside. The inside of the central region was almost stagnant. The flow rate through the central region was 10 ∼ 50 % of the total flow rate. Formation of the stagnant region was related to the determination of the downward velocity gradient.
Heat Transfer Modeling of the LSTF Passive Residual Heat Removal System
Authors: McCreery Glenn E. , Kullberg Craig M. , Schultz Richard R. , Yonomoto T. , Anoda Y. 
Published: March 2022

Abstract
Data from a model Passive Residual Heat Removal (PRHR) system operated in the ROSA facility during simulated loss-of-coolant accidents were compared with heat transfer calculations using a one-dimensional steady-state computer model. The calculations agree reasonably well with the data. The PRHR consists of a “C” shaped tube bundle submerged in a large tank filled with water. The calculations show that subcooled nucleate boiling occurred near the heat exchanger inlet. The boiling region was followed by turbulent and then laminar natural convection regions for horizontal and vertical the tubes. Transition boiling, with intermittently occuring patches of steam attached to the tubes, may have occurred near the inlet for the higher heat transfer tests, but did not significantly affect the overall heat transfer process.
Integrated Simulations of Structural Performance, Molding Process and Warpage for Gas-Assisted Injection Molded Parts
Authors: Chen Shia-Chung , Cheng Nien-Tien , Hu Sheng-Yan 
Published: March 2022

Abstract
Integrated simulations of part structural performance, processing characteristics and warpage for the gas-assisted injection molded parts were carried out using a unified CAE model. An analysis algorithm based on DKT/VRT elements superimposed with beam elements representing gas channels of various section geometry was first developed to evaluate part structural performance. During melt/gas filling stage, a mixed control-volume/finite-element/finite-difference method combined with dual-filling-parameter technique was implemented to trace the advancements of melt and gas fronts. For the prediction of secondary gas penetration, flow model of isotropic-shrinkage origin was introduced. Cooling analysis was executed utilizing cycle-averaged boundary element approach considering hollowed core geometry within gas channels. Thermal-induced residual stress was then calculated to predict part warpage. The analysis accuracy from this unified model of 2 1/2-D characteristics show reasonable accuracy when compared with molding experiment and part bending tests. The only difference between process simulation and structure/warpage analyses is that different values of equivalent diameters assigned to beam element representing gas channel should be used, respectively.
Rotational Molding of Low-Density LLDPE Foams
Authors: Liu Guobin , Park Chul B. , Lefas John A. 
Published: March 2022

Abstract
This paper presents plastic foam processing for the manufacture of LLDPE foams in rotomolding. In order to better understand the mechanisms of foaming, a fundamental study on the foaming process in rotomolding has been conducted. First, the decomposition behavior of the chemical blowing agents was studied by a thermogravimetric analyzer (TGA). The rheological properties of zero-shear viscosity and melt elasticity for LLDPEs were measured using a rotational stress rheometer. Also, an optical microscope with a hot stage was effectively used to study the cell nucleation, growth, coalescence and coarsening in LLDPE melts which provide an improved understanding of the foaming dynamics with a chemical blowing agent in rotational molding. Finally, the actual foaming behavior in rotomolding has also been studied. The experimental results indicate that the amount of blowing agent, the heating time, and the processing temperature play an important role in determining the cell morphology in rotational foam molding.
Semi-Empirical Process Modeling: Model and Database Integration
Authors: Wang H. P. , Perry Erin M. , Lee Martin K. 
Published: March 2022

Abstract
Process modeling has been successfully used in the plastics injection molding industry over the past decade. However, mathematical descriptions in certain areas of plastics processing are either not very well understood or are too complicated to be formulated. An alternative method, such as the semi-empirical approach which integrates models with data bases, has been found to be very effective in helping the tooling engineer with the following problems: understanding the interactions between product design, process conditions, and materials; identifying the process windows; and shortening the tooling design cycle time. Two semi-empirical process models, for the polyurethane foaming and profile extrusion processes, are discussed here to illustrate this useful methodology.
Numerical Simulation of Heat Transfer During Thermoforming
Authors: Wang C. H. , Nied H. F. 
Published: March 2022

Abstract
Heat transfer during thermoforming can be conceptually modeled in three distinct stages. In the first stage, the polymer sheet is heated to a temperature above its glass transition temperature in preparation for forming. Heating during this stage is usually accomplished using radiant heaters and causes sagging of the plastic sheet. Once the sheet has attained the necessary forming temperature, the second stage of heat transfer occurs when the polymer sheet is subjected to large stretching during rapid inflation. Heat transfer during this inflation stage is strongly influenced by the large increase in surface area that accompanies stretching of the plastic. Finally, in the third conceptual heat transfer stage, the plastic contacts the metal mold surface and heat is conducted from the hot plastic to the cooler metal surface. Of particular interest in this paper, is the calculation of the cooling that occurs during the rapid inflation phase of polymer processing. Sample calculations are presented for various thermoforming scenarios that illustrate the nature of this cooling mechanism.