bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elastic Guided Waves in a Pre-Stressed Compressible Layer Imbedded in a Pre-Stressed Two-Material Structure
Authors: Sotiropoulos D. A. 
Published: December 2021

Abstract
Elastic guided waves in a pre-stressed compressible layer imbedded in a pre-stressed two-material structure are examined. The waves propagate parallel to the planar layer interfaces as a superposed dynamic stress state on the statically pre-stressed layer. The stress condition in the layer and in the surrounding materials is arbitrary as are their strain energy functions. To gain understanding of the propagation characteristics, the mathematically tractable model of the materials having common principal axes of strain, one of which is perpendicular to the layering, is employed. The dispersion equation is derived in explicit form yielding guided wave phase and group speeds in terms of wavelength, stress and elastic parameters, and mass densities of the three materials. Limiting cases of the above dispersion equation give the dispersion equation of guided waves in a pre-stressed surface layer overlying a pre-stressed half space, the secular equation of interfacial waves in two semi-infinite pre-stressed materials, the secular equation of non-dispersive Rayleigh surface waves in a half-space, and the frequency equation of guided elastic waves in a pre-stressed compressible plate. Analysis of the dispersion equation reveals the propagation characteristics and their dependence on material and stress parameters. For small interlayer thickness the phase and group speeds are obtained in explicit form. This yields parameter conditions under which the structure acts as a mechanical filter to guided wave propagation. For arbitrary layer thickness, material parameter combinations are also found for which propagation cannot occur. Special attention is paid to the possible existence of interfacial standing waves as a limiting solution of the dispersion equation. Regions of material and stress parameters are defined in which standing waves exist. Numerical computations complement the analytical results for several classes of materials.
On the Steady-State Characteristics of Circumferential Waves in a Two-Layered Cylinder
Authors: Valle Christine , Qu Jianmin , Jacobs Laurence J. 
Published: December 2021

Abstract
A two dimensional, infinitely long hollow cylinder with an inner shaft is considered in this paper. The interface is assumed to be a perfect, infinitely thin layer of inviscid fluid, and the outer surfaces of the cylinder are traction free. Thus the shear stress is assumed to be zero at the interface, but the normal stress and radial displacements are continuous. The problem of steady state, time harmonic waves propagating along the circumference is studied. The dispersion equation is obtained through the exact equations of elasticity and the dispersion curves are calculated for the first five propagating modes. Displacement profiles along the radial direction are included for those same modes. Comparisons are made with the dispersion curves of a full cylinder of same outer radius, and a hollow cylinder of the same dimensions as the one holding the inner shaft. The material is the same for all cases, and assumed to be isotropic and linearly elastic.
It is found that the Rayleigh wave mode is almost identical for the full cylinder and the hollow cylinder with the shaft, and in fact those two cases have mostly similar dispersion branches, except for low frequencies. However the dispersion curves of the hollow cylinder by itself are quite different from the other two, especially at low frequencies.
Failure of a Fiber Composite Lamina Under Three-Dimensional Stresses
Authors: DeTeresa Steven J. 
Published: December 2021

Abstract
The efficient use of thick-section fiber composites requires a proven three-dimensional failure model. Numerous failure criteria have been proposed, but the lack of critical experimental results makes it difficult to assess the accuracy of these models. It is shown that the various predictions for failure of a lamina due to the simple state of uniaxial stress plus superposed hydrostatic pressure are disparate. These differences are sufficient to allow evaluation of failure criteria using data that has the normal scatter found for composite materials. A high-pressure test system for fiber composites is described and results for the effects of pressure on the transverse and longitudinal compression strengths of a carbon fiber/epoxy lamina are discussed. Results are compared with a few representative failure models.
Subsonic and Intersonic Dynamic Crack Growth in Unidirectional Composites
Authors: Coker Demirkan , Rosakis Ares J. , Huang Yonggang Y. 
Published: December 2021

Abstract
Some recent experimental observations of highly dynamic crack growth events in thick unidirectional graphite fiber-reinforced epoxy matrix composite plates are presented. The composite plates were symmetrically (mode-I) and asymmetrically (mode-II) loaded in a one-point bend configuration with an edge pre-notch machined in the fiber direction. The lateral shearing interferometric technique of coherent gradient sensing (CGS) was used in conjunction with high-speed photography. Symmetric, mode-I cracks initiated at 1300 m/s and subsequently accelerated up to the Rayleigh wave speed but never exceeded it. For asymmetric, Mode-II types of loading, the results reveal highly unstable and intersonic, shear-dominated crack growth along the fibers. The intersonic cracks propagated with unprecedented speeds reaching 7400 m/s, more than three times the shear wave speed of the composite, and featured a shock wave structure typical of disturbances travelling with speeds higher than one of the characteristic wave speeds in the solid.
Influence of Delamination on Strength of Externally Pressurized Glass/Epoxy Cylinders
Authors: Davies Peter , Carlsson Leif A. 
Published: December 2021

Abstract
The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the fracture resistance increases with increasing winding angle and mode II (shear) fraction (GII/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamination damage on the implosion behavior of cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure.
High Strain Rate Response of Resin Infusion Molded Sandwich Composites
Authors: Mahfuz Hassan , Al Mamun Wahid , Mohamed Hisham , Vaidya Uday , Haque Anwarul , Jeelani Shaik 
Published: December 2021

Abstract
Foam core sandwich composites have been tested under high strain rate (HSR) loading in the thickness direction. The regular Split Hopkinson Pressure Bar (SHPB) has been modified by replacing the steel transmitter bar by a polycarbonate bar. This modification resulted in stronger signals from the transmitter bar, which would otherwise be very feeble especially when testing soft materials. New sets of mathematical formulations have been derived to account for the impedance mismatch between the incidence and transmitter bars. The modified equations are first verified with a known material and then used for sandwich composites. Three types of core with various densities have been tested under compression at strain rates ranging from quasi-static to 1000 S−1. The compressive failure stress has been observed to be directly proportional to the core density, as well as to the strain rate. The strain rate sensitivity was moderate, and the sandwich composites mostly failed by the collapse of the foam-cell. Delamination did not play a major role in the failure process. Details of the mathematical derivations and the analysis of the HSR behavior are presented in this paper.
An Integrated Model for Electromagnetic Field and Heat Transfer in a Cylindrical Silicon Tube Growth System
Authors: Roy A. , Chen Q.-S. , Zhang H. , Prasad V. 
Published: December 2021

Abstract
Edge-defined Film-fed Growth (EFG) processes are widely used to grow silicon sheets and hollow cylinders of different shapes, e.g., octagon, nonagon and circular. Growth of large diameter silicon tube can bring further advancements in the photovoltaic technology. In the present investigation, a two dimensional axisymmetric numerical model has been developed for a cylindrical silicon tube growth system. The growth furnace is inductively heated. Magnetic vector potential equation and energy equation are solved to obtain the induced magnetic field and temperature distribution in the system. Selected results for magnetic and thermal fields have been presented for a range of parameters. The effect of using graphite afterheater in the system has also been investigated. The goal of the investigation is the system optimization with respect to the temperature field in the global system and the thermal profile in the grown tube.
High-Resolution Wafer Surface Topology Measurement Using Phase-Shifting Shadow Moiré Technique
Authors: Wei Songbin , Guan E. , Kao Imin , Chiang Fu-Pen 
Published: December 2021

Abstract
The traditional shadow moiré technique has been employed, using the fringe pattern information and numerical interpolation, to construct the wafer surface topology. In this paper, phase-shifting shadow moiré technique is discussed and applied to the measurement of wafer surface topology with high resolution. The phase-shifting technique takes advantage of the gray level information to increase the physical resolution of the measurement. A series of fringe patterns are recorded while they are shifted by moving the wafer along the direction perpendicular to wafer surface. The phase is encoded in the variations in the intensity pattern of the recorded fringe images, and a simple point-by-point calculation recovers the phase. The needs to locate the fringe centers and interpolation are eliminated. Since the depth variation of wafer surface is very small, usually within the range of 0.1 to 20 microns, very fine grating is required in order to capture the small depth variation. However, very fine grating will introduce strong diffraction effect which blurs the fringe patterns. In this study, the Talbot distance is applied to obtain images with good contrast. The phase shift is realized by moving the wafer to change the distance between the wafer surface and the reference grating. A four-step phase wrapping algorithm is used to calculate the phase. The phase pattern recovered from four fringes patterns is presented. Future work such as how to reduce the noise, how to do phase unwrapping and calibration is also discussed.
Fundamental Analyses of Smart Tooling for Assembly of Thin Flexible Circuit and Board Systems
Authors: Chen Ruijun , Baldwin Daniel F. 
Published: December 2021

Abstract
Flexible nature of flexible circuits/boards poses new fixture tooling challenges for standard surface mount assembly equipment. The flexible substrates experience significant transverse displacements under perpendicular assembly forces during solder paste printing and component placement processes. The displacements result in misregistration of the component leads and substrate bond pads, leading to assembly process defects. Solder reflow process further complicates the issue due to the thermo-mechanical warpage induced. Reengineered and specialized dedicated tooling for fixturing flexible substrates in standard assembly equipment is becoming extremely important. This paper focuses on developing analysis methodologies and theories for implementing Smart Tooling. The primary goals being to determine the impact of fixturing on assembly process quality and to determine optimum fixturing configurations for thin flexible circuit board assemblies based on circuit board design data. A mathematical model to describe both transverse and perpendicular displacements of flex substrates is developed, and its close-form solution for transverse displacements is obtained. Using a “near” optimum fixturing configuration to minimize transverse displacements is verified.
A Study of the Aperture Filling Process in Solder Paste Stencil Printing
Authors: Pan Jianbiao , Tonkay Gregory L. 
Published: December 2021

Abstract
Stencil printing has been the dominant method of solder deposition in surface mount assembly. With the development of advanced packaging technologies such as ball grid array (BGA) and flip chip on board (FCOB), stencil printing will continue to play an important role. However, the stencil printing process is not completely understood because 52–71 percent of fine and ultra-fine pitch surface mount assembly defects are printing process related (Clouthier, 1999). This paper proposes an analytical model of the solder paste deposition process during stencil printing. The model derives the relationship between the transfer ratio and the area ratio. The area ratio is recommended as a main indicator for determining the maximum stencil thickness. This model explains two experimental phenomena. One is that increasing stencil thickness does not necessarily lead to thicker deposits. The other is that perpendicular apertures print thicker than parallel apertures.
Constitutive and Cyclic Damage Model of 63Sn-37Pb Solder
Authors: Stolkarts V. , Keer L. M. , Fine M. E. 
Published: December 2021

Abstract
The proposed model describes constitutive behavior of 63Sn-37Pb solder including effects of size, thermomechanical loading and cyclic damage. Its application to the uniaxial fatigue data shows a good agreement with the experiments.
A Dual-Phase-Lag Diffusion Model for Predicting Thin Film Growth
Authors: Chen J. K. , Beraun J. E. , Tzou D. Y. 
Published: December 2021

Abstract
A dual-phase-lag diffusion (DPLD) model, which extends Fick’s law by including two lagging times, τj for the mass flux vector and τρ for the density gradient, is developed to predict thin film growth. Depending upon the phase lag ratio τρ/τj, the proposed model uniquely characterizes four types of growth kinetics as reported in the literature. The model validation with the experimental data of silicon oxidation and Hg1-xCdxTe film deposition demonstrates that the DPLD model captures the anomalous behavior of thin film growth from the very beginning of the process to relatively long times very well.
Effect of Volume on Ceramic Ball-Grid Array Solder Life
Authors: McKeown Stephen A. , Sahay Chittaranjan 
Published: December 2021

Abstract
Paper describes the effect of solder volume on solder life based on linear finite element analysis using ANSYS. The results indicate an optimal volume for the solder life. Any increase or decrease in the solder volume from the optimum volume decreases the fatigue life of solder joints. Solder joint life was also experimentally determined for the same temperature excursion with a 2-hour thermal cycle. The experimental results compare well with the results estimated by finite element modeling. Studies for one elastic-plastic analysis has also been carried out. Initial results indicate substantial increase in strain concentration factor.
In-Situ Warpage Measurement During Thermal Cycling of Dielectric Coated SS Substrate for Large Area MCM-D Packaging
Authors: Dang Anh X. H. , Ume I. Charles , Bhattacharya Swapan K. 
Published: December 2021

Abstract
Feasibility of using stainless steel (SS) as a base substrate material for a large area MCM-D packaging is reported in this paper. A test vehicle was fabricated using 0.008 inch thick and 12-inch × 12-inch SS panel with laser drilled 0.01-inch vias. A dielectric material (Parylene N) was deposited on the SS panel and around the inside via walls in order to electrically isolate the via filling material from the body of the SS substrate and also making the SS surface non-conductive. Vias were filled using a commercially available conductive via-plug material. The test structure was exposed to elevated temperatures to simulate the thermal excursion the substrate would be subjected to during the MCM-D thin film process. The end objective of this work is to be able to fabricate large area (24 inch × 24 inch) SS substrates for the next generation MCM-D packaging with reduced warpage. This paper reports results of the dynamic warpage measurement during thermal cycling of a 12-inch × 12-inch SS substrate.
Changes due to Scission in an Elastomeric Cylinder Undergoing Circular Shear and Heat Conduction
Authors: Wineman Alan 
Published: December 2021

Abstract
Research in the prediction of durability and service life for elastomeric products has been actively pursued over the past decade because these materials are finding increasingly abundant applications in the automotive, aerospace and medical industries. Elastomers are used in many critical service applications that require long trouble free life, such as gaskets, seals, bridge pad bearings, tires, medical components and rocket fuel binders. For example, elastomeric seals are used in many applications where seals are relatively inaccessible and cost of replacement is too great. Thus, a fifty year service life for seal life is now a clearly stated objective for the energy industry (Hertz, 1997). The life expectation for elastomeric components on vehicles has changed dramatically over the past few years. Previously, many rubber components were viewed as items that would be replaced once or more during the life of a vehicle. Now, elastomeric components are expected to last the life of the vehicle, which is currently defined as 10 years/150,000 miles for both passenger cars and light trucks (Pett, 1997).
Prediction of the Initial Crack Tip Microstructure in a Single Crystal of CuAlNi
Authors: Vasko Galyna M. , Leo Perry H. , Shield Thomas W. 
Published: December 2021

Abstract
The austenite to martensite pseudoelastic transformation induced by the anisotropic elastic crack tip stress field in a single crystal of shape memory alloy is considered. It is proposed that the orientation of the initial austenite-martensite interface that forms can be predicted based on knowledge of the stress field, the crystallography of the transformation and one of two selection criteria. These criteria are based on the work of formation of the martensite in stress field and the crack opening displacement the martensite causes at the crack. Predictions of the criteria are compared to experiments on three single edge notched CuAlNi single crystal specimens. Results indicate that the maximum work criterion accurately predicts the orientation of the austenite-martensite interfaces that initially form near a crack.
Adiabatic Processes and Constraints in Thermoelasticity
Authors: Rajagopal Kumbakonam R. , Srinivasa Arun R. 
Published: December 2021

Abstract
The aim of this paper is to briefly outline an approach to the thermomechanics of thermoelastic solids based on the notion of multiple natural states and the use of adiabatic processes. We use a statement of the second law attributed to Kelvin for certain special cycles and show that the work done in adiabatic cycles of deformation is non-positive. With these and other assumptions on the nature of thermoelastic solids, we demonstrate the existence of an entropy function and the absolute temperature scale. In this, we closely follow the arguments of Caratheodory (1976). Finally, we briefly address the issues of a class of thermomechanical constraints and show that they naturally lead to considering constraints on adiabatic processes.
The principal results are the following:
1. Demonstration of the existence of the absolute temperature and entropy functions based on the consideration of adiabatic processes
2. A one-to-one correspondence between the stress-free states and the entropy, leading to a “decomposition” of the deformation gradient as Fκr = FκnG(η).
3. Physical interpretation of the constraints of the form f(Eκr,η) = 0.
Shocks in Thermoelastic Rods
Authors: O’Reilly Oliver M. , Varadi Peter C. 
Published: December 2021

Abstract
A theory of a thermoelastic rod is presented in this paper. The theory is based on the work of Green and Naghdi, supplemented by singular supplies of momenta, energy and entropies at a discontinuity. In addition, several aspects of the theory in the presence of internal constraints are presented. The theory is suited to the study of numerous applications, including studies of phase transformations, propagation of shock and acceleration waves and axially moving rods.
A Numerical Evaluation of Protection Strategies for Cab Car Crashworthiness
Authors: Stringfellow Richard , Mayville Ronald , Rancatore Robert 
Published: December 2021

Abstract
The operator and passengers in cab cars are particularly vulnerable to collisions with objects or with other trains because of their proximity to the point of collision. We present one part of a larger study in which we examined several strategies for improving the protection afforded to the operator and the passengers in cab car collisions. These strategies include: strengthening key cab-end structural elements, such as corner posts, collision posts and end beams; locating the operator between the collision posts rather than to one side of the control cab; and implementing crush zones into the ends of the cab as part of a crash energy management design for the entire train. Here we focus on the first of these strategies, evaluating the effectiveness of strengthened cab-end structures through explicit dynamic finite element-based calculations simulating the crush behavior of the cab car. There calculations were made for conditions representative of a number of collision scenarios based upon recent accidents, including several oblique collisions. The results of these calculations suggest that such strengthening can significantly increase the tolerable collision speeds that can be withstood without compromising the operator and passenger volumes.