bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubbing Phenomena in Rotor-Stator Contact
Authors: Feng Z. C. , Zhang Xiao-Zhang 
Published: November 2021

Abstract
This paper discusses the vibration phenomena of a rotor rubbing with a stator caused by an initial perturbation. The analytical model consists of a simple disc-shaft rotor and a fixed stator. The perturbation is an instantaneous change of the radial velocity when the rotor is rotating in its normal steady state. It is found that under certain conditions, the rotor will remain rubbing with the stator, even if the initial perturbation no longer exists. In the case of no friction on the contact surface between the rotor and the stator, the full rubbing behaves as forward whirling. When friction is present, the full rubbing behaves as backward whirling.
Hamilton’s Principle for External Viscous Fluid-Structure Interaction
Authors: Benaroya Haym , Wei Timothy 
Published: November 2021

Abstract
In this paper, Hamilton’s principle is extended so as to be able to model external flow-structure interaction. This is accomplished by using Reynold’s Transport theorem. In this form, Hamilton’s principle is hybrid in the sense that it has an analytical part as well as a part that depends on experimentally derived functions. Examples are presented. A discussion on implications and extensions is extensive. In this work, the general theory is developed for the case where the configuration is not prescribed at the end times of the variational principle. This leads to a single governing equation of motion. This limitation can be removed by prescribing the end times, as is usual. This is outlined in the present paper, and will be the subject of a future paper.
Robust Tracking Control of a Shape Memory Alloy Wire Actuator
Authors: Song Gangbing , Quinn Dane 
Published: November 2021

Abstract
Tracking control of shape memory alloy (SMA) actuators is essential in many applications such as vibration isolation. Due to the hysteresis, an inherent nonlinear phenomenon associated with SMAs, control design based on linear methods has proven inadequate for tracking control of these actuators. In this paper, a novel tracking controller employing a nonlinear robust compensator is proposed for SMA actuators. The control design uses the sliding-mode approach and requires no detailed information of the SMA model. To test the effectiveness of the proposed controller, a single SMA wire test stand is built. A titanium-nickel SMA wire stretched by a bias spring is used as an actuator for tracking control. Experimental results show that the SMA wire actuator under the robust control can precisely follow a sinusoidal path and the effectiveness of the proposed control strategy is demonstrated.
Adaptive Vibration Control of Machining via PZT Actuator
Authors: Zamora Solórzano Efraín , Galíndez José A. Sánchez , Boya Eduardo Sasía , Irigoien Joseba Albizuri , Rodrigues María H. Fernandes 
Published: November 2021

Abstract
At present, the techniques developed to control machine tool vibration have been dominated by passive features, focusing on manipulating the cutting parameters such as feed rate, cutting speed, and depth of cut. Since productivity is affected when modifying cutting parameters, other control methods must be investigated. To that end, electroactive actuators and robust control algorithms have attributes that make them potentially effective in reducing the vibration level. In this paper, the successful use of an adaptive control with a piezoelectric actuator to decrease the vibrations in a machine tool is reported.
Disordered Dynamic Systems Resulting From Approximate Modeling and Analysis
Authors: Bhat R. B. , Stiharu I. 
Published: November 2021

Abstract
Some dynamic systems exhibit curve veering behavior or avoided crossings when their natural frequencies are plotted against a system parameter, while some other show a curve crossing behavior or frequency coalescence. The curve veering behavior is also observed in disordered systems where the symmetry of the system is slightly perturbed and a mode localization takes place. In some systems while the exact analysis shows a curve crossing trend, approximate analyses show a curve veering behavior. Earlier studies have shown that there is a common pattern in curve veering systems and disordered systems. In the present study the exact analysis is recognized as representing the actual system while the approximate analysis of the same system renders it a disordered system by perturbing the eigenvalues and eigenfunctions from their true values. Since the responses of disordered systems can sometimes show violent changes for small perturbations in the system parameters, the response of a simply supported plate has been obtained both exactly and approximately using the Rayleigh Ritz method, and compared. The conclusions have far reaching implications from the point of the accuracy of the response quantities obtained by approximate methods such as finite element method, the Rayleigh Ritz and Galerkin methods.
Preliminary Optical Performance Analysis of the Space Interferometer Mission Using an Integrated Modeling Methodology
Authors: Basdogan Ipek , Grogan Robert , Kissil Andy , Sigrist Norbert , Sievers Lisa 
Published: November 2021

Abstract
The Space Interferometer Mission (SIM) scheduled for launch in 2008, is one of the premiere missions in the Origins Program, NASA’s endeavor to understand the origins of the galaxies, of planetary systems around distant stars, and perhaps the origins of life itself. The precise tolerance required by the SIM instrument facilitates the investigation of many design options, trades, and methods for minimizing interaction between the actively controlled optics and the structure. One of the activities that addresses these technological challenges is the integrated modeling methodology development and validation at Jet Propulsion Laboratory (JPL). The methodology integrates structural, optical, and control system modeling into a common computational environment and enables end-to-end performance evaluation of complex optomechanical systems.
This paper provides an overview of the integrated modeling methodology and introduces the most recent SIM Reference Design model. The SIM integrated model is used in system requirement trade studies and performance analyses to support the overall system design and ongoing error budget efforts.
Optical performance in interferometry is typically measured in terms of optical pathlength difference (OPD) and differential wavefront tilt (DWT). This paper focuses on the OPD performance metric and investigates the OPD jitter resulting from reaction wheel assembly (RWA) disturbances. The RWA is the largest anticipated disturbance source on the spacecraft. Therefore, assessing the impact of the wheel disturbance frequency content and magnitude levels on the optical performance is essential for the success of the mission. Broadband and discrete frequency models of a reaction wheel are used to perform the disturbance analysis. The overall system design can benefit from such analysis results by identifying the critical regions in the frequency domain and decoupling the dynamics of the optical and structural components from the disturbance spectrum and the control bandwidth. The preliminary performance results show that the current SIM Reference Design meets the mission requirements with respect to RWA induced disturbances. However, some of the modeling assumptions and component models must be validated by experimental studies before the subsystem requirements are finalized.
Nonlinear Axial and Transverse Oscillation and Control of a PZT Laminated Distributed Structronic System
Authors: Tzou H. S. , Ding J. H. , Chai W. K. 
Published: November 2021

Abstract
Piezoelectric laminated distributed systems have broad applications in many new smart structures and structronic systems. As the shape control becomes an essential issue in practical applications, the nonlinear large deformation has to be considered, and thus, the geometrical nonlinearity has to be incorporated. Two electromechanical partial differential equations, one in the axial direction and the other in the transverse direction, are derived for the nonlinear PZT laminated beam model. The conventional approach is to neglect the axial oscillation and distributed sensing and control of the distributed laminated beam is evaluated, excluding the effect of axial oscillation. In this paper, influence of the axial displacement to the dynamics and distributed control effect is evaluated. Analysis results reveal that the axial displacement, indeed, has significant influence to the dynamic and distributed control responses of the nonlinear distributed PZT laminated beam structronics systems.
Modeling the Progressive Nature of Milling Tool Wear
Authors: Fish Randall K. , Ostendorf Mari , Bernard Gary D. , Castanon David , Shivakumar Hariharan 
Published: November 2021

Abstract
A particularly important step during industrial machining operations is the detection and classification of tool wear. Past research in this area has demonstrated the effectiveness of various feature sets and binary classifiers. The goal of the research discussed here is to develop a classifier which makes use of the dynamic characteristics of tool wear in a metal milling application and replaces the standard binary classification with a gradient measure that is the posterior probability (or confidence) that the tool is worn given the observed feature sequence. This classifier tracks the dynamics of sensor data within a single cutting pass as well as the evolution of wear from sharp to dull. We discuss topology design and training model parameters in an application with sparsely-labeled training data. We were able to achieve better than 90% accuracy across changing cutting conditions even with a limited feature set drawn from a single sensor.
End Milling Process Vibration Signal Enhancement by Stochastic Resonance
Authors: Klamecki Barney E. 
Published: November 2021

Abstract
The possible enhancement of vibration signals by the addition of a random signal component (stochastic resonance) was investigated. Vibration measurements during end milling were made using an accelerometer mounted on the workpiece. A large number of tests were run with varying spindle speed, table speed, axial depth of cut, radial depth of cut and tool condition. Signal frequency spectra were dominated by the cutting edge passing frequency and so individual cutting edge generated events could not be identified easily in the signal spectra. Enhancement of spectra peaks associated with individual cutting edge events by adding a random signal component to accelerometer signals was demonstrated in numerical experiments using actual accelerometer signals. The effects of initial spectrum peak magnitude, measurement system threshold level and added noise level on signal enhancement were determined.
Reactive Processing of CVD Diamond Substrates in Liquid Ambient by Second Harmonic of Nd:YAG Laser
Authors: Park Beom S. , Malshe Ajay P. , Brown William D. , Adhi Kiran P. 
Published: November 2021

Abstract
The objective of this investigation is to study the effects of laser radiation at 532 nm, the second harmonic of Q-switched Nd:YAG laser on polycrystalline diamond in air and liquid (water and H2O2) ambient. Phase changes and laser-induced stress due to structural deformations are analyzed using Raman spectroscopy. Surface morphology of the processed region of diamond and formation of microcracks is studied by scanning electron microscopy. Drilling of diamond substrates, in water ambient, is observed to be faster, 1.364 times, than that in the air. Enhancement in the drilling speed and uniformity of the drilled hole are discussed from the view of presence of reactive hydrogen and / or oxygen radicals liberated during the interaction of laser radiation with the diamond surface in water ambient.
Thermal and Dimensional Process Characteristics in Laser-Aided Rapid Manufacturing
Authors: Kahlen Franz-Josef , Kar Aravinda 
Published: November 2021

Abstract
Three-dimensional cylindrical and wall-like structures of copper, Ti-6Al-4V, aluminum, and stainless steel 304 were fabricated by melting the powders of these materials with a CO2 laser beam. A vapor-plasma plume is generated at the top of the melt layer. The emission spectra of the plume were recorded using an optical multichannel analyzer, and the plume temperatures are determined to be in the range of 4920 K to 6720 K. A one-dimensional model is developed to calculate the plume temperature, deposition geometry and melt pool characteristics. The model accounts for the transmission of the laser beam through the plume, energy transfer in the molten phase and the phase changes at the solid-liquid and liquid-vapor interfaces. The surface temperature at the molten surface is found to exceed the normal boiling temperature causing the pressure to be higher than one atmospheric pressure. The calculated plume temperatures are in good agreement with the values obtained from the spectral data. Also, the model predictions for remelt layer depth, deposition height and plasma height compare well with experimental data.
Vibration Analysis Based Modeling and Defect Recognition for Flip Chip Solder Joint Inspection
Authors: Liu Sheng , Erdahl Dathan , Ume I. Charles 
Published: November 2021

Abstract
A novel approach for flip chip solder joint quality inspection based on vibration analysis is presented. Traditional solder joint inspection methods have their limitations when applied to flip chip solder joint quality inspection. The vibration detection method is a new approach which has advantages such as being non-contact, non-destructive, fast and can be used on-line or during process development. In this technique, a flip chip was modeled as a thick plate supported by solder bumps. Changes in solder joint quality produce different vibration responses of flip chip, and change its natural vibration frequencies. In this paper, the vibration frequencies of a flip chip on a ceramic substrate were calculated using the finite element method. Based on vibration analysis, a laser ultrasound and interferometric system was developed for flip chip solder joint quality inspection. In this system, chips with good solder joints can be distinguished from chips with bad joints using their vibration responses and frequencies. Defects recognition methods were developed and tested. Results indicate this approach offers great promise for solder bump inspection in flip chip, BGA and chip scale packages.
Parametric Studies of the Thermal Performance of a Tape Ball Grid Array (TBGA) Package
Authors: Tonapi Sandeep S. , Sathe Sanjeev B. , Srihari K. , Sammakia Bahgat B. 
Published: November 2021

Abstract
This paper deals with parametric studies to evaluate the thermal performance of a Tape Ball Grid Array (TBGA) package. A cover plate is attached to the back side of the chip to enhance heat transfer from the module. The package is attached to an organic carrier and placed in a vertical channel. A conjugate heat transfer model is used accounting for conduction in the package and the card and convection in the surrounding air. The effect of location of the TBGA on a card with 0, 1 and 2 power planes is evaluated for thermal performance. Five different locations of the TBGA on the card are investigated. Heat dissipation is studied for forced convection (2, 1, and 0.5m/s). No significant difference in chip junction temperatures for the different locations is observed. Temperature distribution along the card centerline and the module centerline are used to discuss the physical phenomenon that is occurring.
Optimization of Forging Dies by Means of Simulation
Authors: Biba Nikolai , Vlasov Alexey , Lishny Andrey , Stebounov Sergei 
Published: November 2021

Abstract
Due to relatively high cost of the tooling in closed die forging the increasing of tool life is vitally important. The dies can failure due to cracks caused by overloading, low cycle fatigue or abrasive wear. On the other hand, the die deflection can cause deterioration of the forged part shape. The paper presents the ways for increasing of tool life and product accuracy by means of implementation of simulation. It can be done by modification of die design that reduces stress concentration in fillets or by using assembly dies that have splits in critical areas in combination with shrink rings and inserts. Finite element simulation allows to analyze the effectiveness of different variants of die design and to select the most effective ones in terms of tooling cost. Simulation also generates profiled shape of the die that compensates elastic deformation of tooling set and provides precise geometrical accuracy of a forged part.
Recent Developments in Thixoforging
Authors: Baur Jens , Messmer Guenther 
Published: November 2021

Abstract
During the process of thixoforging, the forming process of the metallic material takes place between the solidus and liquidus temperatures. Between these temperatures, both solid and liquid phases coexist. In comparison with the thixoforming methods, the process of thixocasting corresponds with die casting, while thixoforging has similarities with die forging.
Superimposing Ultrasonic Waves on Tube and Wire Drawing
Authors: Siegert Klaus , Ulmer Jochen 
Published: November 2021

Abstract
The drawing forces during wire and tube drawing can be reduced by ultrasonically oscillating dies. A major problem of conventional wire and tube drawing is to introduce high forces into the forming area. Compared to conventional wire and tube drawing, the forming process limits can be extended by superimposing ultrasonic waves due to decreasing drawing forces. Different techniques can be used to exite the die. One possibility is the variation of the vibration mode. In tube and wire drawing, the dies are usually exited longitudinally. If the vibration direction is parallel to the drawing direction, the main influence will be on the friction between workpiece and die. The Institute for Metal Forming Technology of the University of Stuttgart, Germany started a project to investigate the effect of ultrasonic waves on the tribology and on the the formability of the workpiece. The objective of this investigation is to separate the ultrasonic effect on the surface from the volume effects. This paper shows, that the reduction of the sliding friction between a longitudinal oscillating die and the workpiece can be explained by the so called Sliding Friction Vector Effect (SFVE). A statistical evaluation of roughness-measurements makes it possible to show the effect of the ultrasonic vibration on the friction and gives an insight into the operation of the SFVE. The results are compared with wire and tube drawing experiments of copper and Ti-alloys. New tube- and wire-drawing experiments with longitudinally vibrating dies support the theoretical approach. The surface-quality of the manufactured workpieces can be improved and the productivity increases.
Comments on a New Anisotropic Yield Criterion
Authors: Banabic D. , Balan T. , Comsa S. D. , Mueller W. , Poehlandt K. 
Published: November 2021

Abstract
A new yield criterion, derived from the Hosford criterion, is investigated. The new yield criterion is compared to experimental data for steel and aluminum sheets, respectively. The yielding predictions of this criterion are also compared to those provided by the Hill’s family criteria. It appears that the new yield criterion can predict the yielding behavior better than the Hill’s family. In the range of definition of the Hill’93 criterion, it has a similar user-friendly (but homogeneous) mathematical form and identification procedure.
Cutting Fluid Mist Formation in Turning via Atomization: Part 1—Model Development
Authors: Yue Y. , Gunter K. L. , Michalek D. J. , Sutherland J. W. 
Published: November 2021

Abstract
Cutting fluid mist is becoming an increasing concern for manufacturers as additional information is obtained on the health risks that it poses. This two-part paper is focused on investigating cutting fluid mist formation via an atomization mechanism in a turning process. Models will be established to predict the fluid mist mean drop size as well as the drop size distribution. Predictive relationships will also be presented for the settling behavior of the fluid mist and the mass concentration. Part 1 of the paper is devoted to the development of the requisite models to describe the mist creation and settling phenomena. In Part 2 of the paper, the mist formation models will be validated through a series of experiments.
Laser-Assisted Surface Engineering of Silicon Nitride to Minimize the Surface Defects Generated During Grinding Operation: Part I
Authors: Chinnakaruppan Palaniappan , Malshe Ajay P. , Yedave Sharad N. , Park Beom Soo , Schimdt William F. , Gordon Matthew H. , Batzer Stephen A. , Brown William D. 
Published: November 2021

Abstract
Silicon Nitride (Si3N4), a structural ceramic, is being increasingly used for various applications such as bearings, rotors, valves, etc., due to its highly useful mechanical and physical properties. To achieve the desired close tolerance and better surface integrity for such applications, abrasive machining using diamond wheel grinding, is primarily used. Due to the extreme mechanical properties of the silicon nitride, sub-surface and surface defects like micro-cavities, micro-cracks, smeared areas and debris are formed on the ground surface of the component due to grinding. The final flexural strength of the components are jeopardized to a greater extent due these surface defects. In this research work, a novel process is developed and established to eliminate/minimize these surface defects. The process involves annealing of defects using continuous wave carbon-dioxide (CW CO2, λ = 10.6μm) laser radiation. The laser is applied as a radiation source to selectively soften and reflow the secondary non-Si3N4 phase material to fill/anneal the defects present in the surface and sub-surface. Experiments were performed at three different power densities and at a constant scanning speed in air ambient. Power densities and scanning speed were selected based on the output of the model. It is found during the investigation that the laser treatment reduces the surface roughness and increases the micro-hardness without any change in the surface stoichiometry. Also, the sub-surface and surface defects are minimized and the flexural strength, which is an important property for the related applications, is found to be increased after treatment. The detrimental influence of machining defects on the mechanical failure of the sample during the four-point bend testing was found to be significantly reduced.