bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanistic Force Models for Chip Control Tools
Authors: Zhu Rixin , Athavale Shounak M. , Kapoor Shiv G. , DeVor Richard E. 
Published: March 2022

Abstract
A mechanistic modeling approach to predicting machining forces for grooved tools is developed. The models are solely based on the grooved tool geometry and the specific cutting energy and friction energy for flat tools. Special grooved tools (M2 grade HSS) were designed and fabricated and orthogonal cutting tests were performed to validate the model. The workpiece material used was Al 6061-T6. The force predictions from the model are found in good agreement with the measured forces. The effects of groove design parameters on the cutting forces are also determined.
Influence of the Clamping Mechanism on Tool Failure During Dry High Speed Machining
Authors: El-Wardany Tahany I. , Elbestawi Mohamed A. 
Published: March 2022

Abstract
This paper studies the effect of the clamping conditions on the brittle fracture of the poly-crystalline cubic boron nitride (PCBN) insert during dry high speed machining of gray cast iron. Dry high speed face turning tests are performed on a composite design disc brake rotor to investigate the brittle fracture of the PCBN insert. Scanning electron microscopic analysis is used to examine the fractured surface. A thermo-elasto-plastic finite element analysis is employed to determine the stresses induced in the insert due to thermal and mechanical loading generated during cutting. Different clamping conditions, tool holder materials and clamping torques are considered. The analysis reveals that a steeper temperature drop on the PCBN tool rake face results when a carbide chip breaker is used between the clamp and the insert and also when a Mallory 100 M or Aluminum tool holders are used. As a result high thermal stresses are obtained on the insert rake face. The brittle fracture of the insert is originated at the rake face at a local maximum of tensile stress. The results also indicate that reducing the clamping torque and or removing the chip breaker reduces the local maximum tensile stresses on the rake face and increases the tool life by tenfold.
Performance Analysis of Parallel Manipulator Architectures for CNC Machining Applications
Authors: Kim Jin Wook , Park Changbeom , Kim Jongwon , Park F. C. 
Published: March 2022

Abstract
Parallel manipulators of the Stewart-Gough Platform type have been receiving increasing attention as mechanical platforms for universal machining centers. In this paper we investigate the performance of various parallel manipulator architectures for CNC machining applications. The kinematic characeristics that are most often cited as important in universal machining include qualities like manipulability, joint and link stiffness, and workspace volume. Here we quantify these various performance measures using differential geometric techniques, and investigate the performance of two six degree-of-freedom parallel manipulators which have been built as commercial products or research prototypes. The analytical methodology presented here, in combination with the graphics-based CAD software we have developed, can serve as a useful tool to designers of future high-performance parallel manipulator-based machine tools.
Stability Analysis in Face Milling Operations: Part 2 — Experimental Validation and Influencing Factors
Authors: Jensen Steve A. , Shin Yung C. 
Published: March 2022

Abstract
This paper presents the rigorous experimental validation results of the stability algorithm as developed in the part 1. The two experiments which will be presented here focus on; first, a workpiece whose vibrational modes constitute the weakest part of the overall system, and second, a machine tool whose vibrational modes are the weakest part of the system. Next, it discusses some of the influencing factors that affect the on-set of chatter in face milling processes. The factors considered include cutting conditions, entry and exit angles, axial dynamics, cutter geometry, material properties and structural dynamic parameters. Lastly, it presents the effect of structural dynamic change under operating condition on stability lobes.
Forward and Inverse Kinematic Solutions of a New Three Dimensional Metrology Frame
Authors: Schinstock Dale E. , Cuttino James F. 
Published: March 2022

Abstract
A concept for a three dimensional, non-contacting metrology system is presented. Both the forward and the inverse kinematics solutions for the system are developed using a line geometry, resulting in an efficient representation that may describe a general assembly of the kinematic system and error parameters determined through calibration. The inverse kinematics solution is a general solution, assuming very little about the assembly of the system. The forward kinematics solution is less general and resorts to making a few assumptions. In the development of the forward and inverse kinematics solutions singularities of the system are identified.
High-Speed Scanning of Piezo-Probes for Nano-Fabrication
Authors: Croft Donald , McAllister David , Devasia Santosh 
Published: March 2022

Abstract
Low scanning speed of piezo-probes has been a fundamental limitation of scanning probe based nano-fabrication techniques. Typical scan-rates achieved are limited, by structural vibrations of the piezo-probe, to about 1/10th the fundamental vibrational frequency of the piezo-probe. Faster scanning of piezo-probes is achieved here (experimental results are presented) by using inversion of the piezo-dynamics — this approach uses a feedforward input voltage, applied to piezo-probe, to compensate for piezo vibrations.
Improving Electronic Packaging Manufacturing Through Product and Process-Driven Analysis: A PWB Case Study
Authors: Scholand Andrew J. , Peak Russell S. , Fulton Robert E. 
Published: March 2022

Abstract
This paper demonstrates how the use of product analysis combined with process data can provide information about the product quality impact of high-level process decisions. A specific case study involving the warpage of two PWB designs as they move through a reflow oven is presented. A new approximate thermal model is derived which analyzes processing rate dependent warpage, an important metric of product quality for ovens with edge support conveyance systems. Agreement between the theoretical model and prior published experimental results was found to be strongly dependent on the precise temperature dependent material property values used, underlining the need to have accurate thermo-mechanical characterizations of PWB constituent materials. A set of property values based on data published in the literature was assembled which provided a fair match to experimental results, giving sufficient confidence to apply the model predictively. For the case study presented, the model predicts a 10% decrease in processing time will increase board warpage by at most 11.5%. This case study illustrates how product analysis can arm production managers with the information they need to make informed, effective decisions which trade off the economic gains realizable by implementing process improvements against the product quality impact of those improvements.
In Process Stress Analysis of Flip Chip Assemblies During Underfill Cure
Authors: Palaniappan Prema , Baldwin Daniel F. 
Published: March 2022

Abstract
The electronics industry is currently evaluating flip chip technology for high performance, miniaturized assembly applications. This is primarily because of the high I/O density, small form factor, and superior electrical performance provided by flip chip on board technology. Flip chip on low cost circuit boards (FCOB) furnishes a reliable interconnection provided underfill materials are used. Underfills overcome the thermomechanical reliability issues associated with the thermal expansion coefficient mismatch between the board and die. The selection of underfill material is critical to achieving the desired performance and reliability. Processing of underfills during assembly can result in large residual stresses within the silicon die. In some instances these stresses can be large enough to cause die fracture.
In this work, low cost flip chip on board assemblies are analyzed during the underfill cure process. In situ stress measurements are performed over the active face of the die during processing and relative in-plane stresses are measured. Experimental measurements are made using flip chip test vehicles based on Sandia National Laboratories’ ATC04 Assembly Test Chip. Four different commercial underfill materials have been evaluated and a relative comparison is presented. Significant stress variations are observed between the four underfills studied. Correlation’s between the glass transition temperature (Tg) and storage modulus (G’) are made relative to residual stresses produced during underfill cure.
Accelerated Reliability Testing Method for Sensors With a Pulsing Membrane Structure
Authors: Guo Yifan , Sarihan Vijay , Lee Tom 
Published: March 2022

Abstract
In chemical sensors, the sensing element is heated to a high temperature (around 450°C) for optimizing sensitivity and selectivity. In order to minimize power dissipation, the power supply for the heating is operated in a pulsed mode. The duration of the high temperature period is set by the required sensor response time for low gas concentrations. In qualification of chemical sensors, it is important to test the reliability of the membrane structures under realistic conditions of pulsed-mode operation. From these data, it is possible to link time-to-failure with changes in material or layout design. Under the operation condition, the cyclic power input generates local heat and thermal gradient in the membrane as well as physical deformation and local stress. The regular reliability test — thermal cycles with isothermal temperature distribution — cannot simulate the membrane stress or induce the failure processes that occur in the membrane, heater or sensor films under real operational conditions. This paper describes a unique testing technique which is suited for reliability tests and field life prediction in a pulsed sensor. The methods of determining the acceleration factor and the procedures to execute the life test are discussed. Using this testing method, the fatigue life of the sensor configurations can be evaluated within a much shortened testing time.
A Window Based Graphics Interface for Phase Shifting Analysis in Moire Interferometry
Authors: He Xiaoyuan , Zou Daqing , Liu Sheng , Guo Yifan 
Published: March 2022

Abstract
A window based graphics interface for phase shifting in a moiré interferometry system is introduced in this paper. VISUAL C++ is used in the software programming. The phase shifting is accomplished by driving the reference grating in the moiré interfermetry system with a low voltage piezo stack. Four images from three shifts and one original image are used to derive the phase diagram, which is used for displacement and strain calculations. Automatic fringe numbering is achieved by the phase shifting, which significantly simplifies the traditional fringe-counting process. The strain calculation is also automatic by space derivative of displacement. The displacement distribution is obtained by unwrapping the phase diagram. Various help menu functions are provided, facilitating the ease use of the software. A 3-point bending beam is used for the demonstration. The technique is also applied to the analysis of thermal deformations in a flip-chip electronic package.
The MicroDAC Method: A Powerful Means for Microdeformation Analysis in Electronic Packaging
Authors: Michel Bernd , Vogel Dietmar , Schubert Andreas , Auersperg Jürgen , Reichl Herbert 
Published: March 2022

Abstract
Besides different accelerated testing methods finite element analysis (FEA) of stressed components together with appropriate failure hypothesizes allow to estimate life time characteristics. However, most of structures of interest are rather complex and often all necessary material laws or parameters are not available. For simplified simulations the problem arises, whether the results describe adequately the real component under stress. MicroDAC — an established versatile approach to measurement of displacement and strain fields on thermally or mechanically stressed specimens can help to overcome the problem. The underlying measurement principle is a correlation based computer algorithm. It allows to track a set of local object pattern on optical or scanning electron micrographs for different load conditions. The resultant displacement and strain fields are being compared with finite element analysis (FEA) findings or used as an independent source of data. The measurement method has been applied mainly to solder interconnects at flip chip assemblies and chip scale packages.
Nonlinear Spin-Up of a Rotating Stratified Fluid: Experimental Method and Preliminary Results
Authors: Hewitt Richard E. , Davis Peter A. , Duck Peter W. , Foster Michael R. , Smith Fraser W. 
Published: March 2022

Abstract
We consider the nonlinear spin-up of a rotating stratified fluid in a conical container. An analysis of similarity-type solutions to the relevant boundary-layer problem (Duck, Foster & Hewitt, 1997) has revealed three types of behaviour for this geometry. In general, the boundary-layer evolves to either a steady state, a growing boundary-layer, or a finite-time singularity depending on the initial to final rotation rate ratio, and a “modified Burger number”.
We emphasise the experimental aspects of our continuing spin-up investigations and make some preliminary comparisons with the boundary-layer theory, showing good agreement. The experimental data presented is obtained through particle tracking velocimetry. We briefly discuss the qualitative features of the spin-down experiments which, in general, are dominated by non-axisymmetric effects.
The experiments are performed using a conical container filled with a linearly stratified fluid, the generation of which is non-trivial. We present a general method for creating a linear density profile in containers with sloping boundaries.
Flow Structure in a Rayleigh-Bénard Cell Upon Impulsive Spin-Up
Authors: Vorobieff Peter , Ecke Robert E. 
Published: March 2022

Abstract
We investigate convection in a cylindrical Rayleigh-Bénard cell with radius-to-height ratio Γ = 1/2. The cell is subjected to impulsive spin-up about its vertical axis. We use TLC (thermochromic liquid crystal) for temperature field measurements and PIV (particle image velocimetry) for the velocity reconstruction of the transition in the range of Rayleigh numbers R from 5 × 107 to 5 × 108 and dimensionless rotation rates Ω from 0 up to 8 × 104. The initial (at rest) and the final (in steady rotation) states of the system are those of turbulent convection. The most persistent transient feature is a sharply defined ringlike pattern characterized by a decrease in temperature, axial velocity directed downward and high azimuthal shear. The latter leads to formation of an azimuthally regular structure of Kelvin-Helmholz vortices. During the final stage of the transition, this vortical structure loses azimuthal regularity and an irregular pattern of vortices characteristic of turbulent rotating convection forms.
Transient Character of Positively and Negatively Buoyant Turbulent Jets
Authors: Pantzlaff Lars , Lueptow Richard M. 
Published: March 2022

Abstract
The transient character of the jet issuing from an upward nozzle centered in the bottom of a vertical cylindrical tank into bulk liquid of a different density was measured for varying jet Reynolds numbers and ratios of fluid densities using flow visualization and PIV. Positively buoyant jets penetrate to the free surface, driven by both momentum and buoyancy in the upward direction. The lighter jet fluid stratifies in a layer above the bulk liquid. Upon starting, a negatively buoyant jet has three stages. First the jet penetrates to its maximum height in the tank. Then the jet penetration decreases due to the downward backflow of heavier fluid surrounding the jet, which reduces the jet’s upward momentum. Finally the jet penetration height fluctuates around a mean value about 70% the maximum height of penetration. For small negative densimetric Froude numbers (−6075 ≤ Fr ≤ −250), the flow is fountain-like. The downward flow turns radially outward as it reaches the bottom of the tank and eventually an annular recirculation zone forms at the bottom of the tank with vortical motion opposite the vorticity of the inflowing jet. For large negative Froude numbers (Fr ≤ −7770), the spreading of the jet extends far enough so the annular downward flow is along the walls of the tank resulting in a large annular recirculation zone. Scaling the jet penetration and time with the buoyancy flux and the jet momentum flux results in collapse of the transient jet penetration over a wide range of Froude numbers.
Cavitation Predictions Using a Panel Method
Authors: Mueller A. C. , Kinnas S. A. 
Published: March 2022

Abstract
A boundary element method is used to predict the time-dependent cavitation on a propeller subject to non-axisymmetric inflow. The convergence of the method is studied. The predicted cavities agree well with those observed in CAPREX, an experiment performed at MIT’s variable pressure water tunnel. The method is modified so that prediction of cavities detaching at mid-chord regions is possible. An algorithm for predicting the cavity detachment location on the blade is described and applied on a blade geometry which exhibits mid-chord cavitation.
Wave-Generated Forces and Moments on Submersibles: Models for Dynamic Simulation at Periscope Depth
Authors: Chhabra Narender K. , Scholten James R. , Lozow Jeffrey B. 
Published: March 2022

Abstract
Analysis of the wave-induced motion of underwater vehicles near the ocean surface is a difficult task. First, the action of the fluid must be decomposed into ideal (inviscid) and real (viscous) effects. Next, each effect must be modeled as to its interaction with the submerged body. The effect of the body on the waves must be considered. In shallow water, the ocean bottom has many effects: energy-dissipation tends to reduce wave height; land-proximity restricts the wave direction; and the bottom boundary changes the shape of the waves, attenuating the vertical (but not the horizontal) component of motion. This paper presents mathematical models for predicting realistic wave-generated forces and moments on submersible vehicles. Included are models which generate typical wave spectra for deep and shallow waters, models for wave kinematics as affected by flat or sloping bottoms, and models for forces and moments on submersibles due to these surface waves.
Forces and moments are computed using two alternative methods. One is a fast method based on analytical integration of dynamic pressure forces over the surface of an elongated ellipsoidal body. It gives first-order forces and moments limited to horizontal and restrained bodies. The second method, based on the Froude-Krylov approach, uses numerical integration of dynamic pressures to give forces and moments on any shape hull in any attitude. Unlike the first method, it can be extended to include broaching of the sea surface by the body. Hydrodynamic forces due to an unrestrained body’s motion are accounted for with “added mass” terms.
These mathematical models have been implemented in the C language in a real-time computer simulation. They are actively used to study the dynamic performance and control of submersibles at periscope depths.
Objective and Self-Reported Physical Activity and Risk of Falling Among Community-Dwelling Older Adults From Southern Brazil
Authors: Bielemann Renata M. , Oliveira Ricardo , Bertoldi Andréa Dâmaso , Tomasi Elaine , Demarco Flávio Fernando , Gonzalez Maria Cristina , Bohm Andrea Wendt , Brage Soren , Ekelund Ulf 
Published: March 2022

This study evaluated prospective associations between self-reported and objectively measured physical activity (PA) and risk of falls among older adults. A cohort study started in 2014 with 1,451 community-dwelling older adults living in Pelotas, Brazil. Leisure-time PA was obtained by the International Physical Activity Questionnaire and 7-day raw accelerometer data evaluated for total, light PA, and moderate to vigorous PA. In 2016–2017, participants recorded their falls in the previous 12 months. Around 23% of the 1,161 participants followed-up in 2016–2017 experienced a fall in the last 12 months. Participants who did not spend any time in self-reported leisure-time PA at baseline had on average 34% higher risk of falls, and individuals in the lowest tertile for moderate to vigorous PA had on average 51% higher risk of falls compared to those in the highest tertile. Low levels of self-reported and objectively measured moderate to vigorous PA were related to higher risk of falling among Brazilian older adults.
Detailed mapping and paleostress analysis of active faults in the northern Vettore–Bove fault zone, Sibillini Mountains, Italy
Authors: Stewart Kevin G. , Boulter Rachel 
Published: March 2022

ABSTRACTThe Sibillini Mountains, which make up the southern part of the Umbria-Marche Apennines, were struck by a series of earthquakes in 2016, including five with magnitudes greater than 5. The largest event, Mw 6.5, occurred on 30 October 2016. A Mw 5.9 earthquake on 26 October ruptured several faults in the northern third of the Vettore–Bove fault system, and the Mw 6.5 event produced surface ruptures along the entire 30-km length. Ground surveys conducted shortly after these earthquakes showed that many, but not all, of the surface ruptures corresponded to previously mapped faults. Also, some faults that had been mapped as Quaternary did not produce surface ruptures during the earthquakes. In this study, we present the results of detailed field mapping that was conducted prior to the 2016 earthquakes and provide evidence that all of the surface ruptures in the northern part of the Vettore–Bove fault system occurred along preexisting faults. Paleostress analysis shows that the reactivated faults had been active prior to 2016 in stress fields with similar orientations to the modern-day stress field. In addition, we show that one fault segment, which is the southern continuation of a major fault that slipped during the 2016 earthquakes, was not reactivated because it was unfavorably oriented.