bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of Acoustic Emission, Scanning Electron Microscopy and 3D Topography Data to Investigate the Ground Ceramic Condition
Authors: Maksoud Talal M. A. , Mokbel Amin A. , Morgan John E.
Published: December 2021

This paper considers the grinding parameters, which affect the initiation and propagation of surface and sub-surface cracks formed during the surface grinding of engineering ceramics. The results given in this paper are chosen from a much larger series of experiments, and can be shown to be representative in correlating the principal grinding parameters with a number of observed and measured properties. During grinding tests, for a range of grinding conditions, acoustic emission (AE) measurements, 3-D surface topography measurements, and scanning electron microscope (SEM) images are brought together in an effort to relate the initiation and propagation of surface and sub-surface cracks with specific grinding parameters. Subsequent results from three point bend tests carried out on ground specimens are also used to confirm the type and extent of sub-surface cracking produced during grinding.
The Application of Titanium Castings for Primary Structure in Commercial Airframes
Authors: Allison Daniel J.
Published: December 2021

As commercial airframers such as Boeing focus on improving profitability, low cost options for primary structure such as titanium castings are being seriously considered. Titanium castings offer nearly equivalent static strength properties as their equivalent wrought competition, but offer a potential for major reductions in machining. In addition to reduced machine time, castings can allow for dramatic design simplifications, employing fewer parts and fasteners and opening the door to more production friendly design philosophies such as Design for Manufacturing (DFM) and Determinant Assembly (DA). [1]
“Design Consultant”: A Network-Based Concurrent Design Environment
Authors: Ahn Sung-Hoon , Roundy Shad , Wright Paul K. , Liou Shuh-Yuan
Published: December 2021

In today’s globally distributed business environment, resolution of the communication problems between team members is a critical issue. A project named the Design Consultant has been launched to improve inter/intra-departmental communications. Leveraging available Internet technology, the Design Consultant enables designers to share design information with other team members including colleague designers, CAE analysts, manufacturing engineers, and marketing engineers. The network accessible DFX modules assist designers to simulate manufacturability and to estimate cost and time for fabrication resulting in faster product development. Building blocks of the Design Consultant were established based on a 3-tier client/server architecture, and feasibility tests were successful. As part of the feasibility tests, the Design Consultant for Part Reuse and the Design Consultant for Rubber Molding were implemented to prove the concept of the network-based Concurrent Engineering.
Geometry Modeling and Adaptation by Infrared and Laser Sensing in Thermal Manufacturing With Material Deposition
Authors: Doumanidis Charalabos , Kwak Yong-Min
Published: December 2021

A lumped-parameter, analytical model of material and thermal transfer is established in this paper for metal deposition by a moving, concentrated source. This is a dynamic description of the distinct width, height, length and temperature of the ellipsoidal molten puddle, expressed with respect to the torch power, material feed and angle, and the source motion. This is established through scalar mass, momentum and energy balances of the puddle control volume, and thermal conduction in the substrate. The model is validated by GMA Welding experiments, through measurements by an infrared camera and a Laser profilometry scanner. These sensors are next employed for real-time identification of the model efficiency parameters. Open-loop testing with parameter adaptation was conducted for the bead cross section profile during changes of the torch velocity, and the applicability of such geometry regulation to geometry control is discussed.
Diagnosis of Multiple Simultaneous Faults in Manufacturing Systems
Authors: Li Wei , Hu S. Jack , Ni Jun
Published: December 2021

In manufacturing systems, multiple faults often occur simultaneously and generate complex fault patterns. However, most of the previous research on multiple fault diagnosis assumes that faults either occur one at a time or have linearly additive fault patterns. In this paper, we present a new approach for multiple simultaneous fault diagnosis. A comprehensive pattern modeling approach is developed for prediction based on functional regression. With the complete set of fault patterns, a minimum distance pattern classifier is designed for diagnosis. The proposed approach is demonstrated to be successful with a simulation study. An example from the resistance spot welding process is also provided. In this case, an 88% success rate for fault classification is achieved based on the predicted fault patterns.
Characteristics of White Layers Formed in Steels by Machining
Authors: Akcan S. , Shah S. , Moylan S. P. , Chhabra P. N. , Chandrasekar S. , Farris T. N.
Published: December 2021

White layers, produced by machining cylinders of AISI 52100, AISI 4340, and AISI M2 steels, are characterized using nano-indentation hardness tests, and microstructural analysis through optical microscopy, transmission electron microscopy and X-ray diffraction. Microstructural observations show that the white layer is composed primarily of martensite. The martensite structure in the white layer is found to have a mean hardness of 12.6 GPa, which is significantly greater than the hardness values of martensite produced by heat treatment or ausforming processes. Furthermore, its grain size is shown to be in the sub-micron range with values ranging, typically, between 50 nm and 500 nm. These two novel characteristics of the white layer martensite distinguish it from martensite structures formed in other operations. The formation of the white layer is promoted by conditions of high cutting speed (100 m/min to 200 m/min) and moderate to large values of tool flank wear. Based on these observations, it is hypothesized that white layer formation involves three steps, austenitization of the steel surface, followed by deformation of the high temperature austenite to large plastic strains, and finally, rapid quenching of the austenite by the bulk of the material to form a martensite structure.
The Tool Life, Mechanics, and Economics in Conventional and Ultraprecision Machining
Authors: Venkatesh V. C. , Awaluddin M. S. , Ariffin A. R.
Published: December 2021

Conventional machining that is discussed here covers the use of the Taylor tool life equations and Merchant’s theory for the machining of aluminum silicon alloy with diamond coated carbide as well as the newly developed diamond coated silicon nitride tools. Gilbert’s economics of machining is described, and its application is extended to grinding to show the advantages of a 4 axis CNC Machining Centre over its 5 axis equivalent. Scattergood et al’s theory of ultra-precision turning of brittle materials for determining the critical depth of cut is highlighted together with the first author’s work on silicon showing how yc, the critical depth of cut, can be experimentally obtained in a much easier and rapid way.
A Self-Calibration Method for Robotic Measurement System
Authors: Gong Chunhe , Yuan Jingxia , Ni Jun
Published: December 2021

Robot calibration plays an increasingly important role in manufacturing. For robot calibration on the manufacturing floor, it is desirable that the calibration technique be easy and convenient to implement. This paper presents a new self-calibration method to calibrate and compensate for robot system kinematic errors. Compared with the traditional calibration methods, this calibration method has several unique features. First, it is not necessary to apply an external measurement system to measure the robot end-effector position for the purpose of kinematic identification since the robot measurement system has a sensor as its integral part. Second, this self-calibration is based on distance measurement rather than absolute position measurement for kinematic identification; therefore the calibration of the transformation from the world coordinate system to the robot base coordinate system, known as base calibration, is not necessary. These features not only greatly facilitate the robot system calibration but also shorten the error propagation chain, therefore, increase the accuracy of parameter estimation. An integrated calibration system is designed to validate the effectiveness of this calibration method. Experimental results show that after calibration there is a significant improvement of robot accuracy over a typical robot workspace.
Prediction of Springback in Straight Flanging Operation
Authors: Cao Jian , Liu Zhihong , Liu Wing Kam
Published: December 2021

A straight flange problem is investigated with the expectation that this will lead to a better understanding of the deformation mechanism and to more complicated flanging problems. The “in-die” shape of the part is subdivided into a number of segments and individual springback of each segment is investigated, by releasing the elastic energy element by element, using the Finite Element Method (FEM). Typical distribution of the springback angle along the blank is obtained and found to be quite different from the widely used constant springback assumption for the curved part of the flange. A new model incorporating a non-uniform moment distribution at the curved part is proposed which reflects the above observation. Explicit analytical formulae are derived and the analytical predictions match with the experimental results very well.
Mathematical Modeling of a Variable Displacement Axial Piston Pump
Authors: Dobchuk Jeff W. , Burton Richard T. , Nikiforuk Peter N. , Ukrainetz Paul R.
Published: December 2021

The variable displacement axial piston pump has been the subject of much research, having been studied from the controls, noise reduction, and design perspectives. The resulting body of research is large and very diverse in content. A review of the available publications was conducted for this paper in order to identify those works that would be most helpful in developing a complete and accurate mathematical model of an axial piston pump.

Most of the available publications can be classified into one of two general groups; those describing a small group of components to understand specific phenomena or those describing the entire pump for control or design purposes. The significant mathematical developments in various publications regarding specific phenomena, particularly those works involving nonlinear friction or pressure transients, were identified by the authors in this paper. When the mathematical developments of the phenomena specific effects are combined with the widely accepted kinematics equations for the pump, an accurate numerical model can be developed.

Works on linearized lumped parameter models and parameter sensitivity were examined for this paper and the limitations of these types of models were addressed. While linearized models offer mathematical simplicity, they suffer from poor accuracy over a wide range of operating conditions and do not reflect instantaneous swashplate dynamics.

This paper offers insight into the required complexity of a mathematical model that is necessary to achieve a desired accuracy as well as providing the appropriate references to develop that model.
Injection Moulding Simulation for Hydraulic Valve-Actuator System Controller Design
Authors: Guerrier Paul K. , Edge Kevin A.
Published: December 2021

In the development of advanced injection controllers and more effective control valves, full scale testing is often too expensive. This paper is concerned with virtual testing using simulation and experimental testing using a ‘hardware-in-the-loop’ technique in which a servovalve-actuator system emulates the moulding process. Simulation results for the purely simulated load and a ‘hardware-in-the-loop’ emulated load are compared with experimental data. Good agreement is achieved. Although the particular case of an hydraulic injection moulding machine has been considered, the model of the moulding process would be equally valid for studies of an all-electric machine.
A New Approach of Direct Digital Control for Spool Valves
Authors: Ruan J. , Burton R.
Published: December 2021

In many applications, digital valves driven from stepping motors are often characterized by quantitative errors and in some cases, slow response. A new means of direct digital control is introduced for a spool valve actuated by a stepper motor. With this control strategy, both excellent speed of response and accuracy are simultaneously sustained for the valve. By way of illustration, the characteristics of a digital spool valve are theoretically and experimentally investigated. This paper also deals with the design of the controller and some concepts concerning the digital control of a valve, such as initialization, false protection, etc. An example is given to demonstrate the effectiveness of this digital control approach for a practical electro-hydraulic control system.
Porous Media and Mixture Models for Hygrothermal Behavior of Phenolic Composites
Authors: Sullivan Roy M. , Stokes Eric H.
Published: December 2021

Theoretical models are proposed to describe the interaction of water with phenolic polymer. The theoretical models involve the study of the flow of a viscous fluid through a porous media and the thermodynamic theory of mixtures. From the theory a set of mathematical relations are developed to simulate the effect of water on the thermostructural response of phenolic composites. The expressions are applied to simulate the measured effect of water in a series of experiments conducted on carbon phenolic composites.
Mesoscopic Heat-Actuated Heat Pump Development
Authors: Drost Kevin
Published: December 2021

Battelle, Pacific Northwest Division (Battelle) and Pacific Northwest National Laboratory1 (PNNL) are developing a miniature absorption heat pump. Targeted applications include microclimate control ranging from manportable cooling to distributed space conditioning. The miniature absorption heat pump will be sized to provide 350 Wt of cooling2. A complete manportable cooling system, which will include the microscale heat pump, an air-cooled heat exchanger, batteries, and fuel, is estimated to weigh between 4 and 5 kg. For comparison, alternative systems weigh about 10 kg. Size and weight reductions in the microscale heat pump are possible because the device can take advantage of the high heat and mass transfer rates attainable in microscale structures.
Optimization of Miniature Pulse-Tube Cryocoolers
Authors: Shire J. M. , Mujezinovic A. , Phelan P. E.
Published: December 2021

This work introduces optimization techniques for designing pulse-tube coolers with the focus on coolers of smaller size. Methods are presented to select two geometric design parameters: pulse-tube length to regenerator length ratio, and system length to diameter ratio. The optimum values of these parameters are a function of the conduction heat loss down the tube walls, the regenerator effectiveness as a function of its length, and the pressure drop along the pulse tube. Results indicate that the optimum regenerator length/pulse tube length ratio increases with decreasing system length, and the optimum system length/diameter ratio increases with decreasing system volume.
Experimental Verification of a Universal Accumulator Heat Exchanger Design Procedure Used to Achieve Liquid Overfeeding Effects in Small Air Conditioning Systems
Authors: Wood Craig W. , Meyer Josua P.
Published: December 2021

This study involves the experimental verification of a universal heat exchanger accumulator design procedure. A heat exchange accumulator was manufactured according to a mathematical model developed by the authors and installed into a small air conditioning system. Experimental results show that the addition of the heat exchanger accumulator results in a liquid overfeeding operation that replaces the previously utilized direct expansion operation. It provides an improved air conditioning system that has a 7.5% increase in coefficient of performance and a 4.4% increase in refrigerant mass flow rate. A pressure ratio reduction has a positive effect on the compressor performance and life span. Liquid overfeeding increases the cooling capacity of the system by 6.5%. When compared to direct expansion systems, this basic heat exchanger accumulator provides a reduction in cycling losses and power consumption, an increase in suction pressure and an improvement in isentropic compressor efficiency.
Impacts of the Split Conjugated Pistons in Conjugated Cylinders of a Multiple Stage Reciprocating Compressor in Start Duration
Authors: Deng Jianqiang , Gu Zhaolin , Yu Yongzhang
Published: December 2021

Split pistons allow more precise manufacturing and easier assembly of conjugate-piston multi-stage reciprocating compressors. Their disadvantage is that during start up, the high pressure stage piston may impact with both its cylinder head and the low-pressure stage piston. To determine the magnitude of these impacts and how they can be minimized, a simple mathematical model was constructed to analyze the pressure build-up within the compressor and the movement of the high-pressure stage piston. It is shown that above a minimum threshold value of pressure in the high-pressure stage, the pistons remain attached and move together without impact. The calculation of this minimum pressure along with the contact stresses, during rounds of impacts when the forces are greatest is demonstrated. A mathematical model is also provided to help minimize the impact stresses involved in such an arrangement. It is shown that by appropriate piston design and choice of piston material, selection of the optimum stroke and volume of the discharge system as well as the electric motor, split-conjugate pistons can be used in high-pressure multi-stage compressors.
Transient Flow of the Oil-Refrigerant Mixture Through the Radial Clearance in Rolling Piston Compressors
Authors: Gasche José L. , Ferreira Rogério T. S. , Prata Álvaro T.
Published: December 2021

Unsteady flow of oil and refrigerant gas through radial clearance in rolling piston compressors has been modeled as a heterogeneous mixture, where the properties are determined from the species conservation transport equation coupled with momentum and energy equations. Time variations of pressure, tangential velocity of the rolling piston and radial clearance due to pump setting have been included in the mixture flow model. Those variables have been obtained by modeling the compression process, rolling piston dynamics and by using geometric characteristics of the pump, respectively. An important conclusion concerning this work is the large variation of refrigerant concentration in the oil-filled radial clearance during the compression cycle. That is particularly true for large values of mass flow rates, and for those cases the flow mixture cannot be considered as having uniform concentration. In presence of low mass flow rates homogeneous flow prevail and the mixture tend to have a uniform concentration. In general, it was observed that for calculating the refrigerant mass flow rate using the difference in refrigerant concentration between compression and suction chambers, a time average value for the gas concentration should be used at the clearance inlet.
The Experimental Analysis of Local Heat and Mass Transfer Data for Vertical Falling Film Absorption
Authors: Miller William A. , Keyhani Majid
Published: December 2021

In pure heat transfer, specifications of effectiveness, fluid properties, and flows enable calculation of the heat exchanger area. In the case of falling film absorption, a simultaneous heat and mass transfer governs the performance of the absorber. The exchange of mass across the liquid-vapor interface involves the generation of heat. The heat effects associated with the mass exchange increase the temperature, which affects the equilibrium state of the pressure and composition and in turn affects the mass. The falling film flow rate coupled to the physical properties of kinematic viscosity and surface tension govern the flow regime of a vertical falling film. Wavy-laminar, roll-wave laminar, and turbulent flows will develop convective contributions that can enhance the transfer of mass into the film.

The combined interaction of all these factors makes the absorption process very difficult to analyze and predict. A study of simultaneous heat and mass transfer was therefore conducted on a vertical falling film absorber to better understand the mechanisms driving the heat and mass transfer processes. Falling films are characteristically unstable, and a wavy-laminar flow was observed during the experimental study. The wavy flow further complicates the problem; therefore, only limited information is known about the temperature and concentration profiles along the length of the absorber that describe the local heat and mass transfer rates.

Hence, this study presents much-needed experimental data on the heat and mass transfer processes in the absence of heat and mass transfer additive. Absorption experiments were conducted in a mini-absorber test stand at various falling film flow rates, at various absorber pressures, and with various compositions of the binary salt solution. Thermographic phosphors were successfully used to measure the temperature profile along the length of the absorber test tube. These measures of the local variations in temperature enabled calculation of the bulk concentration along the length of the absorber. The bulk concentration varied linearly, from which one may infer that the concentration gradient in the direction of flow is approximately constant. The implication is that the mass flux, and therefore the absorber load, can be solved for by using a constant flux approximation.
Estimation of the Thermodynamic Properties for Branched Hydrocarbons
Authors: He Hui , Metghalchi Mohamad , Keck James C.
Published: December 2021

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures with special attention to the branched molecules. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A method to determine the number of degrees of freedom for different motion modes (bending and torsion) has been established. Branched rotational groups, such as CH3 and OH, have been considered. A modification of the characteristic temperatures for different motion mode has been made which improves the agreement with the exact values for simple cases. The properties of branched alkanes up to 2,3,4-Trimthylpentane have been calculated and the results are in good agreement with the experimental data. A relatively small number of parameters are needed in this model to estimate the sensible thermodynamic properties of a wide range of species. The model may also be used to estimate the properties of molecules and their isomers, which have not been measured, and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations.
Heat Exchangers Networks Synthesis and Optimisation Performed by an Exergy-Based Expert Assistant
Authors: Maiorano Massimo , Sciubba Enrico
Published: December 2021

This paper presents a novel method for the design of “optimal” (or quasi-optimal) HEN. The method consists of an Expert System (“ES”) based on a small number of powerful and strongly selective heuristic rules. The important contribution of this study does not lie in the formulation of the rules, that have been adapted from the existing literature, but in their expression as logical propositions, and in their subsequent implementation in a prototype ES that performs interactively with the user.

It is not unusual to find chemical processes with as many as 100 interacting streams, and even simple thermal processes, excluding refineries and chemical plants, contain at least a 10-streams-HEN: hence the high demand for an “automatic” (in some sense) Design Procedure that may conveniently be adapted to design-and-optimisation problems. Pinch Technology (“PT”), at present the almost universally adopted design procedure, is very successful in most types of applications (except in cases where mechanical and thermal power must be optimised concurrently), but it constitutes an operative tool, and does not improve its user’s comprehension of the problem: it assumes, rather, that the user is already familiar with the design of HEN. The approach we present in this paper is entirely different: we do not “mask” the thermodynamic and thermo-economic principles that guide the engineer in the path towards the “optimal” HEN configuration, and do not allow concerns about “user friendliness” to impair the necessary participation of the user to the HEN synthesis procedure. In fact, though our ES (which we prefer to call “Expert Assistant”, to underline its peculiarity of constantly interacting with the user) is still lacking many of the capabilities that a good designer possesses, the underlying procedure is, unlike any of the other existing Design-and-Optimisation Procedures, entirely inspectable by the user for what its decision-making rules are concerned. It can be interrogated about its decision making, so that the logical path followed from the design data to the final solution can be inspected at will, and it can be used to directly compare different alternatives in a logically systematic fashion. The paper begins with a brief review of the HEN design problem, followed by a critical discussion of the heuristic rules that form the basis for the Inference Engine of the Expert System. The formalisation of these rules into logical propositions suitable for Knowledge Based Methods is then presented, and the resulting macrocode developed. As a preliminary validation, two examples of application of the code (named Heat Exchanger Network Expert Assistant, HENEA for short) are presented and discussed: since both cases have published, and their “optimal” solutions are known, the performance of HENEA can be assessed by comparison.
Perfect Heat Recovery From a Partial Oxidation Gas Turbine Engine
Authors: Call Frederick W.
Published: December 2021

This paper shows how to obtain the complete recovery of exhaust heat in the context of a gas turbine power plant. The power plant uses partial combustion of the fuel and yields power and a synthesis gas for further use in a chemical plant or conventional steam power plant. The key is a heat exchanger in conjunction with a Ni/NiO chemical loop that alters the composition of the air stream so that there is nearly a perfect match of the hot and cold streams down to ambient temperature. The chem-loop removes the oxygen for fuel combustion from the air as it raises the temperature of both the water/air and the synthesis gas streams (only the latter is used for power production). Assuming no heat losses from unit operations, no parasitic losses, and a pinch of only 2°C (simultaneous boiling and condensing) the First Law efficiency of the power plant can be over 98% (Second Law is about 45%). There are no acidic stack gases to contend with at this point as the partially combusted fuel is then exported for other uses, its value diminished only by the amount of power produced.
Effect of Circuit Arrangement on the Performance of Plate Finned Tube Heat Exchangers Under Dehumidifying Conditions
Authors: Liu Min-Sheng , Leu Jin-Sheng , Wang Chi-Chuan , Mei Vince C.
Published: December 2021

This study experimentally investigates the effect of circuitry on the performance of plate finned tube evaporators. Experiments were carried out with the heat exchangers having 1-circuit arrangements. A total of six circuitry were examined in this study, including two counter-cross, two parallel-cross, and two z-shape arrangements. The results showed that the counter-cross arrangement gives the best performance. However, heat conduction along the fins may offset the benefits of the counter-cross arrangement. In addition, the pressure drop of refrigerant-side increased with frontal velocities. Among the six 1-circuit arrangements, the parallel-cross flow circuit would produce a larger pressure drop than other arrangements. However, for G = 200 kg/m2·s and parallel flow, the pressure drops decrease with increase of the frontal velocity. The unusual characteristics are likely related to the flow pattern transition subjected to heat addition. The location of refrigerant inlet does not significantly affect the performance of heat exchangers.
Isentropic Expansion and the Three Isentropic Exponents of R152a
Authors: Kouremenos D. A. , Kakatsios X. K. , Floratos O. E. , Fountis G.
Published: December 2021

The isentropic change of an ideal gas is described by the well known relations pvk = const., Tv(k-1) = const. and p(1-k)Tk = const., where the exponent k is defined as the ratio of the constant pressure to the constant volume specific heat, k = Cp/Cv. The same relations can be used for real gases only if the differential isentropic changes under consideration are small. A better examination of the differential isentropic change shows that for p, v, T systems, there are three different isentropic exponents corresponding to each pair formed out of the variables p, v, T. These three exponents noted kT,p, kT,v, kp,v after the corresponding pair of variables used, are interconnected by one relation, and accordingly only two out of the three are independent. The analysis of the present paper shows the numerical values of these exponents as well as the isentropic expansion ratios for R152a in the vapor phase, presented in diagram form. It can be seen that the deviations of the three isentropic exponents relative to the conventional k = Cp/Cv values are considerable and depend upon the initial pressure and the stage of the expansion. Additionally, the effect of the three isentropic exponents on the ideal gas relations describing the isentropic expansion ratios is examined, in order to develop simple yet more accurate relations without having to resort to the complex real gas state equations.
Integrated Systems for Cogeneration and Absorption Chilling: Comparison for Varying Chiller COPs
Authors: Tang R. , Rosen M. A.
Published: December 2021

The thermodynamic effects are demonstrated of integrating steam turbine-based cogeneration systems with absorption chillers. A wide range of realistic extraction steam pressures and coefficient of performance (COP) values of absorption chillers are considered. A simple model of a steam turbine-based cogeneration plant is used for the evaluation of the integrated system. The integrated systems are evaluated based on the ratio of fuel consumption between a base case (one-stage absorption chiller with a COP value of 0.6) and several alternative cases (multi-stage absorption chillers with COP values ranging from 0.6 to 1.5). Two categories of scenarios are considered: (i) cases where the cooling load is fixed; and (ii) cases where the cooling load is fixed and the electrical output for the integrated system is set equal to that for the base case.
Mixed Mode Interface Cracks in a Bi-Material Half Plane and a Bi-Material Strip
Authors: Huang Haiying , Kadomateas George A. , La Saponara Valeria
Published: December 2021

This paper presents a method for determining the dislocation solution in a bi-material half plane and a bi-material infinite strip, which is subsequently used to obtain the mixed-mode stress intensity factors for a corresponding bi-material interface crack. First, the dislocation solution in a bi-material infinite plane is summarized. An array of surface dislocations is then distributed along the free boundary of the half plane and the infinite strip. The dislocation densities of the aforementioned surface dislocations are determined by satisfying the traction-free boundary conditions. After the dislocation solution in the finite domain is achieved, the mixed-mode stress intensity factors for interface cracks are calculated based on the continuous dislocation technique. Results are compared with analytical solution for homogeneous anisotropic media.
Computational Model for Free Abrasive Machining of Brittle Silicon Using a Wiresaw
Authors: Bhagavat Milind , Kao Imin
Published: December 2021

The present paper deals with physics based computational modeling of the wiresaw Free Abrasive Machining (FAM). The wiresaw is used to slice large diameter wafers of predominantly brittle semi-conductors such as silicon. The wiresawing model proposed in the present paper involves cutting action by ‘floating’ abrasives. It is proposed that the abrasive carrying slurry forms a film in the cutting zone by an elasto-hydrodynamic action. Finite Element Analysis shows this film to be in general thicker than the average abrasive size. This signifies a ‘float’ machining condition, wherein there is no direct pressing of abrasives by the wire. Typical rolling and indenting of abrasives under such free body abrasion environment is supported by hydrodynamic shear and pressure respectively. The abrasive is assumed to remove material by typical indentation fracture. Finite element analysis of stresses underneath an indenting abrasive shows that cracks leading to chipping occur only during unloading of indented abrasives (during rolling). The volume of the chip removed in a single indentation is proportional to the volume of plastic zone underneath the indenter. We integrate the elasto-hydrodynamic model and the single abrasive indentation model into a complete representative model of wiresawing.
Acoustic Emission Analysis for Fatigue Prediction of Lap Solder Joints in Mode Two Shear
Authors: Van De Wal Bryan J. , Kendall Gay , Sahay Chittaranjan
Published: December 2021

The traditional methods of fracture mechanics and failure prediction has historically been aimed at isentropic elastic materials that are ductile, i.e. steels, alloys, etc. Little effort until recently has focused on anisotropic compliant materials such as solder and its alloys due to the problems inherent in anisotropics.

The use of acoustic emission as a NDT has also been geared towards the same type of materials, i.e. in situ examinations of steel bridging, pressure vessels, and the like.

Traditional acoustic NDT theory uses the “Ring Down” methodology to characterize the waveforms created during fatigue. More modern techniques include utilizing acoustic emissions for peel testing, crack location, and other techniques. Not much research has been done combining these two basic research disciplines. The current research utilizes both successfully.

In the current research, the methodology used is that of using a signal recovery technique that filters and stores the waveforms. These waveforms are analyzed for energy, area of waveforms, and duration of waveforms via MATLAB© software. Semi-log plots of these energies, areas, and durations will aid in characterizing the different types of signal groups seen from the oscilloscope. SEM and Confocal analysis is concurrently used to facilitate a failure mechanism model of these lap joints. The ultimate goal is to see if a statistical correlation can be drawn between 1) the nature of waveforms seen on the oscilloscope, 2) the nature of the filtered data in the power spectrum, and 3) the modes of failure as seen under the Confocal and SEM. The results should show a clear and definitive empirical field method that can predict which “stage” of fatigue failure a soldered lap joint is undergoing.

The term “stage” refers to the qualitative observation that for each solder joint, regardless of cycle life, there are three characteristic general emission patterns seen as the joint fatigues to failure. Whether these “stages” or patterns correspond to the classical stages of fatigue is to be determined within this paper.
Design and Implementation of a Flexible Intelligent Electronics Remanufacturing System
Authors: Fidan Ismail , Kraft Russell P. , Derby Stephen J.
Published: December 2021

Electronic manufacturing of circuit boards has undergone major changes in the last decade as new technologies have emerged and are perfected to replace older ones. A result of the increased board layout densities and higher levels of integration at the chip level is a dramatic increase in the value of circuit boards. The benefit is much more functionality in smaller boards, but the disadvantage is significant losses when a defective board must be scrapped. The same technology that has increased the density of the board functionality has made manual rework to correct manufacturing defects almost impossible. Higher levels of circuit integration in moving from VLSI to ULSI (Ultra Large Scale Integration) have required more pin-outs on the packages which in turn has resulted in finer lead pitches and a change from through-hole mounting to surface mounting technology (SMT). These two changes, with the decreased interchip spacing, have necessitated the use of automation to perform reliable component replacement on defective boards. This paper discusses the complexities of integrating several automation technologies into a single robotic electronic remanufacturing workcell. Involved are vision guidance, control software development, and multiple special end-effector designs for the several required steps, including defective component removal, board cleaning, solder paste dispensing, component placement, and laser soldering [1].
Impact of On-Die Discrete Heating on Thermal Performance Characteristics of Silicon Based IC Electronic Packages
Authors: Adams V. H. , Ramakrishna K.
Published: December 2021

Simulations for thermal characterization of electronic packages for silicon-based integrated circuit (IC) components typically assume one of the two uniform heat generation conditions. They are: (1) an isoflux condition in which heat generation is uniformly distributed over the active surface of the die, or (2) a uniform heat generation over the entire (or active) volume of the die. The use of these models may be justified due to high thermal conductivity of silicon, size of the devices on the die, and their relatively uniform spatial distribution over the entire surface of the die in the traditional silicon technologies. However, the current and future technologies are migrating towards embedded systems solutions, such as system-on-chip, and in traditional applications devices are brought in close proximity to each other for improved on-chip electrical performance. These trends result in localized regions of power dissipation on the die that would invalidate the use of traditional uniform generation models in the thermal characterization.

The present study examines the effect of discrete heat sources (as opposed to uniformly distributed sources) on the die on thermal performance and characterization of the electronic packages. For this purpose, a conjugate heat transfer problem of a memory chip in a 119 I/O flip chip ceramic and plastic ball grid array (FC-C & PBGA) package under natural and forced convection conditions. First the model is validated against experimentally measured thermal data on a 119 I/O FC-C & P BGA daisy-chain test packages with a thermal test die with uniformly distributed resistive heat source. Junction-to-ambient temperature difference predictions from the simulations are within 10% of the measurements for the uniform heating case. The validated model is then suitably modified to account for discrete heat sources and actual substrates. Results from the discrete heat sources study show a 15–20% increase in predicted junction-to-ambient temperature difference and a larger (a 10–15 °C) temperature variation across the active face of the die than for with a uniform heat source. These results call for the use of discrete heat sources in the thermal characterization of new generation of embedded silicon technologies. They also point to the need for development of test die and characterization methodologies for these technologies with discrete heat sources.
Curvature of a Film-Substrate System in the Nonlinear Deformation Range
Authors: Freund L. B. , Rosakis A. J. , Lee H. S.
Published: December 2021

The physical system considered is a thin film bonded to the surface of an initially flat circular substrate, in the case when a residual stress exists due to an incompatible mismatch strain in the film. The magnitude of the mismatch strain is often inferred from a measurement of the curvature it induces in the substrate. This discussion is focused on the limit of the linear range of the relationship between the mismatch strain and the substrate curvature, on the degree to which the substrate curvature becomes spatially nonuniform in the range of geometrically nonlinear deformation, and on the bifurcation of deformation mode from axial symmetry to asymmetry with increasing mismatch strain. Results are obtained on the basis of both simple models and more detailed finite element simulations. Preliminary full-field observations are reported on deformation of a 6 μm thick Al film deposited onto a 100 μm thick Si substrate subjected to thermal cycling.
Elastic Response of Rubber Double Networks
Authors: Roland C. M. , Santangelo P. G. , Mott P. H.
Published: December 2021

Double network elastomers are formed by twice-curing rubber, the second time while the material is deformed. When measured parallel to the curing deformation, the equilibrium modulus of a double network exceeds that of an isotropic elastomer of equal crosslink density. This difference increases with increasing strain. Despite the higher modulus, the mechanical fatigue lifetimes of double networks of natural rubber were found to be as much as a factor of ten higher than for the conventionally crosslinked rubber. The double network’s tensile strength, on the other hand, was slightly lower. Such results suggest that the conventional compromise between modulus and failure properties can be circumvented using double network rubbers. Their utilization can yield elastomers of better mechanical properties.
Strain-Temperature and Strain-Entropy Internal Constraints in Finite Thermoelasticity
Authors: Casey James
Published: December 2021

Starting out with the set of unconstrained thermoelastic materials, appropriate equivalence relations are introduced as a means towards defining internally constrained materials. The construction is first carried out in strain-temperature space, and subsequently in strain-entropy space. The question of the interrelationships between the two types of constraints is examined.
On the Determination of Entropy From a Scalar Potential for Special Inelastic Materials
Authors: Johnson George C. , Imam Ali
Published: December 2021

A known version of the second law of thermodynamics embodying the notion of dissipation is employed to obtain restrictions among constitutive response functions for two classes of inelastic bodies. It is shown that for such bodies the entropy function can be determined once the constitutive relation for the Helmholtz free energy function is specified. In addition the internal energy function is shown to depend exclusively on the temperature and the deformation gradient.
Methodology Development for Simulating Full Frontal and Offset Frontal Impacts Using Full Vehicle MADYMO Models
Authors: Deshpande Bala , TJ Gunasekar , Morris Russell , Parida Sudhanshu , Rashidy Mostafa , Summers Stephen
Published: December 2021

MADYMO articulated full vehicle models of the 1992 Ford Taurus, 1995 Chevrolet Lumina and the 1994 Dodge Intrepid for frontal and side impact modes have been developed and validated against test data. MADYMO (Mathematical Dynamic Model) is typically used to model occupants in the environment of the vehicle interior and thus finds application mainly in assessing occupant injuries. In this study however, MADYMO has been employed not only to model the occupants but also to represent the major load bearing structures in the vehicles. Input for the MADYMO models consisting of rigid body joint stiffness was obtained from corresponding full vehicle Finite Element (FE) models. Model validation was done by comparing the vehicle and dummy numbers with the New Car Assessment Program (NCAP) test results. Models correlated very well with both test and FE data. This modeling approach demonstrates the utility of rigid body based full car models for crashworthiness analysis. Such models result in significant saving in computational time and resources.

In this paper, we describe the simulation of two different crash modes: full frontal and offset frontal impacts using the full vehicle MADYMO models. These simulations were validated with the corresponding test results in full frontal mode and IIHS offset mode. The models are useful for simulating a variety of impact situations, for example, with different occupant sizes, occupant positions, impact velocities, and in car to car impacts for performing compatibility studies.
Development of a Finite Element Model of the Human Shoulder
Authors: Iwamoto Masami , Miki Kazuo , Sambamoorthy Babushankar , Yang King H. , King Albert I.
Published: December 2021

During an automotive side impact, the shoulder is likely to be the first body part that is directly impacted either by the internal structures of the vehicle or by the side airbag. Therefore, a good understanding of the injury mechanism and the kinematics of the shoulder is critical for occupant protection in side impact. Existing side impact crash dummies do not have structures that are capable of reproducing the kinematics and kinetics of a human occupant. Over the past several years, many numerical models have been developed from head to foot in an attempt to overcome the shortcomings of these crash dummies. However, relatively few attempts have been made to include the shoulder. The purpose of this study is to develop a finite element model of the human shoulder in order to achieve a deeper understanding of the injury mechanism and the kinematics of the shoulder in side impacts.

Basic anthropometric data used to develop the skeletal portion of the shoulder model were taken from a commercial data package of the human shoulder geometry (Viewpoint Datalabs). This geometry was scaled to fit a 50th percentile male occupant according to the data reported by Schneider et al. (1983). The shoulder model included the three bones of the shoulder, namely the humerus, scapula and clavicle. Each bone was modeled in two parts. The spongy bone was modeled using crushable solids and the cortical bone was modeled using damageable shell elements. The model also includes major ligaments, which form the acromioclavicular and sternoclavicular articulations. The deltoid muscle, which was modeled by crushable solids in order to absorb part of the impact energy, was added to this model for lateral impact simulations. This shoulder model was then integrated with a human thorax model developed by Wang (1995), along with other preexisting models of other parts of the human anatomy. Material properties for the model were taken from the literature. Experimental data obtained from lateral impact sled tests of 17 cadavers conducted at Wayne State University were used to validate the model. Impact forces in four regions, specifically, the shoulder, thorax, abdomen and pelvis, were calculated by the model and were compared with forces obtained experimentally from rigid wall impacts at 6.7m/s and padded wall impacts at 8.9m/s.
Analytical Modeling of Forced Convection in Slotted Plate Fin Heat Sinks
Authors: Teertstra P. , Culham J. R. , Yovanovich M. M.
Published: December 2021

Analytical models are developed for the average heat transfer rate in forced convection-cooled, slotted fin heat sinks. These models for the upper and lower bounds can be used to investigate the effects of slot size and placement on heat sink performance. Experimental measurements are performed for a variety of slot configurations over a range of Reynolds numbers, and these data are compared with the proposed analytical models. An approximate model is proposed that predicts the experimental results for the average heat transfer rate to within a 12% RMS difference.