bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method for Selecting Electronic Manufacturing Processes Based on Cost Factors
Authors: Shina Sammy G. , Saigal Anil
Published: July 2023

The implementation of electronic circuits into products involves several complex steps in design and manufacturing. One of the most common implementations is in Printed Circuit Boards (PCB’s), which presents a low cost alternative in tooling and manufacturing over integrated circuits. In addition, PCB’s can be altered to accommodate design changes after the product has been manufactured.

This paper addresses the different factors involved in the choice of design and manufacturing parameters to accommodate the lowest cost electronic implementation in PCB’s by focusing on fabrication and assembly issues. It suggests an algorithm based on these factors which is collected from the different steps for design, layout and fabrication of PCB’s. The factors are analyzed in terms of expected quality, chosen technology and their effect on completing the total design and manufacturing process in the shortest time to market.
Order Accumulation and Sorting Using an Automated Storage and Retrieval System
Authors: Xie Xiaodong , Sharp Gunter P. , Dickerson Steve
Published: July 2023

A pick-and-sort (PAS) system consists of a picking system (PS) and an accumulation/sorting system (A/SS). In a PAS, picking and order accumulation are highly interdependent. In general, the more orders that are being processed simultaneously, the greater the potential efficiency of picking as the motion required to move between successive storage locations can be decreased. Conversely, a larger number of orders being processed simultaneously increases the order accumulation cost. An automated storage/retrieval system (AS/RS) may be used for accumulating and sorting a large number of orders. In terms of the total cost of a PAS system, an AS/RS is a potentially low cost alternative to a conveyor system for order accumulation/Sorting. An approximate analytical performance model for rotary rack A/SS has been developed, as well as a cost model for a PS, in terms of the number of orders in process. A numerical example for a warehouse is presented.
Three-Dimensionai Finite Element Analysis of Stress Response in Adhesive Butt Joints Subjected to Impact Tensile Loads
Authors: Sawa Toshiyuki , Okuno Hirohisa , Higuchi Izumi
Published: July 2023

The stress wave propagation and the stress distribution in adhesive butt joints of similar adherends subjected to impact loads are analyzed using three-dimensional finite-element method (FEM). The code employed is DYNA3D. An impact load is applied to a joint by dropping a weight. An adherend of a joint is fixed and the other adherend to which a bar is connected is impacted by the weight. The height of the weight is changed. The effect of the ratio of the adherends’ the adhesive’s Young’s modulus, the adhesive thickness and the geometry of T-shape adherends on the stress wave propagation at the interface are examined. It is found that the maximum stress is caused at the interface of the adherend subjected to an impact load. In the case of T-shape adherend, it is seen that the maximum stress is caused near the center of the interface and that it increases as Young’s modulus of the adherends increases. In the special case where the web length of T-shape adherends equals to the interface length, it is seen that the singular stress occurs at the edge of the interfaces and it increases as Young’s modulus of adherends decreases. The maximum principal stress increases as the adherends’ thickness increases. In addition, strain response of adhesive butt joints subjected to impact loads was measured using strain gauges. Fairly good agreement is found between the numerical and the measured results.
Stress Analysis and Strength of Joints Combining Adhesives With Bolts Subjected to Torsions
Authors: Yoneno Masahiro , Sawa Toshiyuki , Nishijima Hidekazu , Matsuo Motohiro
Published: July 2023

The stress distributions in joints combining adhesives with bolts are analyzed by using axisymmetrical theory of elasticity as a three-body contact problem when torsion is applied to the joints. The joints consist of two hollow cylinders and they are fastened by a bolt and nut after being joined with an adhesive. When an external torsion is applied to combination joints, an increment / decrement of torsion occurs in the bolt. A method for estimating the variation of torsion in the bolt is proposed. In addition, using the interface stress distribution, a method for predicting strength of the combination joint is proposed. The torsional load produced in the bolt was measured using strain gauges. Strength of the combination joint was also measured. A fairly good agreement was seen between the analytical and the experimental results. It is shown that the increment of torsional load occurs in the bolt is small. It is found that the strength of the combination joints is greater than that of adhesive joints. It is also seen that the combination joint strength increases as the initial clamping force increases and that it is greater than that of bolted joints without adhesives.
Contact Pressure Distribution in a Key Joint
Authors: Váradi Károly , Verghese D. M. , Engelbrecht S.
Published: July 2023

This paper contains an investigation of the contact pressure distribution in a key joint using the Finite Element Method. The key is mounted using an interference fit, and the torque transmission is increased in steps from 0 to 25, 50, 75, and 100 % of the maximum torque. The obtained pressure distributions show a very pronounced transition of the stress distribution from pure interference fit to almost pure torque transmission. It is also found that the pressure distribution and the number of contact surfaces depends heavily on the initial fit between the shaft and the key.
Engineering Systems: An Industry and Product View Point
Authors: Tran K.-C.
Published: July 2023

The engineering discipline has evolved in the last decade in response to market pressure and technological changes.
Applications of Active Noise and Vibration Control in Automotive Vehicles
Authors: Shoureshi Rahmat A. , Gasser Robert , Knurek Thomas , Wheeler Matthew
Published: July 2023

Competitive pressure in improving automotive fuel economy has forced manufacturers to design smaller and lighter vehicles with more and more non-metallic (composite) components. This manufacturing trend has resulted in vehicles with increased levels of noise and vibrations. In parallel, there have been efforts in using different noise control techniques quieting small aircraft. Today, noise and vibration control have become a prime consideration in the general manufacturing industry, and more specifically the aircraft and automotive industries. Increased attention to product quality has brought the issue of “psycho-acoustics” to the transportation industry. Automotive manufacturers believe that noise and vibration levels in a vehicle are measures of quality used by the consumer. Thus within recent years, there has been a major increase of effort in the design of noise and vibration characteristics of vehicles that would better appeal to the occupants. This paper presents some results from our research and development in the area of active/adaptive noise control in transportation systems with specific results from our activities related to aircraft and to automotive vehicles.
Application of Active Noise Control in Corporate Aircraft
Authors: Jackson Philip J. B. , Ross Colin F.
Published: July 2023

Following the successful introduction of Active Noise Control (ANC) systems as standard production fits on commuter aircraft (Saab2000, Saab340B and Dash8Q series 100, 200 & 300), recent efforts have focused on developing low-cost, low-weight systems for smaller corporate aircraft.

This paper describes the approach taken by Ultra to the new technical challenges and the resulting improvements to the design methodology. A review of system performance on corporate (King Air & Twin Commander) turboprop aircraft shows repeatable global Tonal Noise Reductions (TNR’s) of > 8 dBA throughout the whole cabin, achieving reductions > 20 dB in some locations at the blade-pass frequency (BPF), and major comfort benefits throughout the flight envelope with a weight penalty of less than 20 kg.
A “New” Approach to Active Noise Control in Ducts
Authors: Mehta Prashant , Zheng Yuan , Chait Yossi , Hollot C. V.
Published: July 2023

In this paper we consider the fixed-filter design approach for active noise control (ANC) in ducts. Based on a large body of literature during the past decade that deals strictly with adaptive filter solutions (see [1] and references contained therein) the fixed-filter approach appears to be all but discarded for this application. The ANC system under consideration has a similar configuration to those used in most adaptive implementations; i.e., a duct equipped with both feedforward and feedback sensors and a control speaker. Our design of a linear, time-invariant controller involves three steps: (1) system identification from the experimental duct frequency response, (2) H∞ synthesis using the identified plant and model errors, and (3) use of Quantitative Feedback Theory (QFT) to further improve performance by sequential tuning of the feedback and feedforward filters using the experimental data. Preliminary experiments indicate that attenuation levels of 10–30 dB are achievable over a 400 Hz band without amplification in the immediate range. An important consequence of LTI designs is that performance is guaranteed for wideband noise as well as pure tone disturbances — in adaptive schemes stability and performance may be very difficult (if impossible) to guarantee beforehand. This paper focuses on the third step of our three-step approach — the QFT design aspect — (the other two steps are described in [2]).
Experimental Active Vibration Control of Automotive Chain Drive Systems
Authors: Dishan Huang , Fan Q. , Tan C. A.
Published: July 2023

Impact between chain links and sprockets during their engagements is generally considered to be the major source of noise in power transmission chains. To reduce the noise, one approach is to reduce the tension in the chain. However, this would lead to excessive chain vibrations and subsequently reduce the life span and durability of the chain. This paper presents an experimental approach to reduce vibrations of a chain drive system. Experiments were conducted on a test stand which consists of an automotive chain running between two fixed sprockets. The experiment results show that the amplitude of vibration of the chain can be reduced by as much as 90% in the speed range under consideration.
The Impulse Response of Panels
Authors: Reynolds Robert R.
Published: July 2023

The impulse response of a thin, elastic panel is predicted using classical modal analysis and a new asymptotic modal approximation. The asymptotic solution requires much less solution effort than the classical solution. It is shown that the latter also provides a good estimate of the local panel response near the excitation and of the average response away from the excitation for short to moderate times after the input pulse. The method yields excellent predictions of the most important features of the response; the maximum amplitude of the response and its decay behavior. It is expected that this method will provide engineers with a very efficient, method for estimating structural behavior for vibration isolation and control purposes.
On the Energy Dissipation Characterisctics of Active Constrained Layer Damping
Authors: Baz A.
Published: July 2023

The shear strains in the visco-elastic cores of beams controlled by Active Constrained Layer Damping (ACLD) treatments are determined and compared with those of beams controlled by Active Control (AC) and conventional Passive Constrained Layer Damping (PCLD) treatments. Such comparison is essential in quantifying the individual contribution of the active and passive damping components, to the overall damping characteristics, when each operates separately and when both are combined to interact in unison as in the ACLD treatments. The comparisons are based on distributed-parameter models which describe the behavior of beams controlled by ACLD as well as beams treated by AC and PCLD treatments. The distributed-parameter models give closed-form expressions for the energy dissipation characteristics of the ACLD treatments in comparison with those of the AC/PCLD treatments. The results obtained indicate that the ACLD treatments are capable of developing shear deformations, in the visco-elastic cores, higher than those generated by the AC/PCLD treatments when the ratio of the longitudinal rigidity of the constraining layer to that of the base beam is less than 1. With such enhanced shear deformation capabilities, the ACLD treatments can develop high damping and effective attenuation of the vibration of critical structural systems.
On Optimal Placement of Piezoelectric Actuators in Vibration Control of Adaptive Structures
Authors: Gabbert Ulrich , Schulz Ingolf
Published: July 2023

The paper presents an optimality criterion for the placement of actuators in adaptive mechanical structures, which can be formulated independently of the control algorithm and the actuator type. The basic idea is an energetically approach of a dynamic system. Treating a vibration as a periodically transformation between different energy forms, damping demands that the vibration energy must be deleted. In vibration control a part of this energy is transmitted to active or passive damping elements and changed into other energy forms, which do not contribute to the movement of the system. A maximum input of energy into the actuators during the considered time range is expected for optimal vibration control of the system. To ensure the time invariance of the criterion, the results of the simulation (finite element method, Newmark integration scheme) are transformed from the time domain into the frequency domain using the discrete Fourier transformation. The proposed technique of actuator placement is demonstrated at an excited beam structure.
Design of a Piezoelectric Actuator for Active Vibration Control
Authors: Brennan M. J. , Garcia-Bonito J. , Elliott S. J. , David A. , Pinnington R. J.
Published: July 2023

In an active vibration control system there is a requirement for actuators, sensors and an electronic controller. Although there have been significant advances in controller design, in terms of software, hardware and control algorithms, this has not been matched in the design of the transducers. This paper is concerned with the area of actuator design. Novel transducers are described that use piezoelectric devices as the active elements, and are designed to be used as a large displacement vibration actuators over a broad range of frequencies. Because piezoelectric elements are high impedance devices, the designs of the actuators have to incorporate impedance transformers so that the displacement output from the piezoelectric element is amplified significantly and two different ways of achieving this are described.
Uniform Damping and Stiffness Control of Structures With Distributed Actuators
Authors: Washington Gregory , Silverberg Larry
Published: July 2023

The research in this paper introduces an algorithm for uniformly damping and stiffening structures using distributed actuators. Inherent in this algorithm is the ability to eliminate structural biases, which can cause steady state error. The method involves the utilization of modal techniques to calculate the proportional, integral, and derivative gains in a feedback control law. The gains are calculated by first converting the system into the modal domain, second by employing the principles of uniform damping and stiffening to the system in the modal domain, and finally by converting that system back into the physical domain. The beauty of this technique lies in the fact that even though the principles of modal control are used in gain setting, no modal information is needed in the final control law. The theory is validated by simulations and is illustrated in an example. Since a modal approach and distributed actuation is utilized, the benefit to active control and adaptive structures is discussed.
Neural-Network-Based Control of Vibration in the Presence of Uncertainties in System Parameters and Excitation Frequencies
Authors: Wang T.-C. , Sinha A.
Published: July 2023

A neural-network-based algorithm has been developed to control steady state vibration in a flexible structure. The main feature of this algorithm is that neural networks are trained to compensate for uncertainties in system parameters and excitation frequencies. Numerical results are presented to corroborate the validity of this algorithm.
An Optimization Based Technique for Determining Nonlinear Normal Modes
Authors: Slater Joseph C.
Published: July 2023

This paper examines a new approach for determining the nonlinear normal modes of undamped non-gyroscopic multiple degree of freedom systems. The method presented here can be called an optimized Poincare section technique. Algebraic solutions generally assume a solution for nonlinear modes in the form of polynomial expansions. This method makes only the assumption of repetitive motion in numerically determining the mode shapes. The advantage of this approach is that the accuracy obtained in the mode shape identification is a function only of the accuracy of the numerical integration and optimization used and not of the number of terms in the power series representation of the nonlinear mode shape. However, invariance of the modal manifolds cannot be proven using this technique, and mode bifurcations can be easily overlooked.
On-Line Prediction and Optimization of a CVD Barrel Reactor: An Experimental Study
Authors: Mahajan R. L. , Walker K. J.
Published: July 2023

Neural networks offer an attractive technique for process modeling and optimization. Once trained, these models tend to be very fast and can be easily updated. In this paper, we exploit these desirable properties of neural networks and demonstrate that these models can be incorporated, on-line, into a process to provide real-time analysis as well as estimate settings for process optimization. The process selected is a mock-up chemical vapor deposition barrel (CVD) reactor. The temperature distribution on the facets of the susceptor is influenced by the flow imbalance through the two inlet nozzles and their orientations. A statistical design of experiments (DOE) is conducted to relate the input parameters to the output (average temperature and temperature variation) and a neural network model is trained using the DOE points. The model is then embedded in a PC which is also used to control the flow meters monitoring flow entering the barrel reactor through the two nozzles. The temperature readings are fed into a data acquisition system which is interfaced with the PC. It is shown that for given input settings the neural network model predicts the average temperature over the surface of the susceptor facet in less than a fraction of a second. A side by side comparison with the experimental average temperature shows excellent agreement for a wide range of input parameters. A deviation model exhibits similar agreement. The deviation model, in conjunction with a steepest descent algorithm, provided an estimate of optimum settings for minimum deviation.
Liquid Slug Motion in Compliant Piping
Authors: Wiggert D. C. , Hatfield F. J.
Published: July 2023

An approximate method of estimating the displacements and stresses in piping caused by a liquid slug moving in a voided line is presented. The event is caused when the slug experiences a change in momentum and transfers a force at a discrete location in the pipe. The most significant mode of the piping response is treated as a single-degree-of-freedom system that responds to the transient hydrodynamic excitation. Impact factors are generated for several representative hydrodynamic waveforms. An example is presented to demonstrate the methodology.
Three-Dimensional Numerical Analysis of Low Reynolds Number Precessing Jets
Authors: Manohar Shailesh S. , Pauley Laura L. , Kulkarni Anil K.
Published: July 2023

Experimental observations have shown that precessing jets have two distinct flow regimes. At “subcritical” Strouhal numbers, the jet continues to move away from the axis of precession. At “supercritical” Strouhal numbers, the jet bends back towards the axis of precession and eventually appears axisymmetric downstream. The objective of this study is to numerically determine the critical Strouhal number for the transition between the two flow regimes and to observe the nature of a precessing jet. A three-dimensional Navier Stokes solver employing the artificial compressibility method and a four-stage Runge-Kutta scheme has been used. Two Reynolds numbers, 125 and 250 were considered. The precessing jet was found to have a pressure gradient acting across it which caused it to spiral and bend back towards the axis of precession. The critical Strouhal number was independent of the Reynolds number and determined to be ∼ 5 × 10−3. This conclusion compared favorably with experimental observations at high Reynolds numbers.
Parametric Study of Pin Length and Reynolds Number Effects on Heat Transfer in a Cast Pin Fin Coldwall for Electronic Systems
Authors: Short Byron Elliott , Raad Peter E. , Price Donald C.
Published: July 2023

At low to moderate Reynolds numbers, cast pin fin coldwalls provide an excellent combination of performance and low unit cost for air-cooled electronic systems. The purpose of the paper is to study the details of the fluid dynamics in order to better understand the heat transfer performance within the flow regime appropriate for cast pin fin coldwalls.

A parametric study is presented examining the variation in the Nusselt number over a range of pin lengths and Reynolds numbers. The numerical study uses a five-pin cell to simulate an embedded flow pattern within a large array of staggered pin fins. The modeling technique was previously validated using experimental data.

Performance comparisons are made for pin length-to-pin diameter ratios of 2 ≤ L/d ≤ 6 and for 200 ≤ Red ≤ 2000. Conclusions are drawn assessing the effects of the fluid dynamics, such as the horseshoe vortices formed at the pin-wall interface, on the local heat transfer mechanisms. Effects of the pin spacing were addressed by a previous experimental study.
On the Routinization of Analysis for Physical Design
Authors: Peak Russell S. , Scholand Andrew J. , Fulton Robert E.
Published: July 2023

While it is generally agreed physical designers would like to benefit more from analysis, methodologies are lacking for identifying appropriate analysis models and transforming them into readily usable tools. This paper identifies physical designer needs with respect to analysis, and introduces the term “routinization” to describe the process of creating routine analysis modules — automated analysis models that can be regularly used in product design.

A routinization methodology is presented with electronic packaging examples. Based on the multi-representation architecture (MRA), a design-analysis integration strategy, this methodology creates catalogs of product model-based analysis models (PBAMs) — analysis modules that associate design data with specific analysis models to obtain results in a highly automated manner.

The methodology is illustrated using a simple PBAM for PWB warpage analysis. Applications to solder joint fatigue and plated through hole deformation are also highlighted, with solution methods ranging from encoded formulae to multi-vendor 3D finite element analysis. Observations are given, including how routinization aides both electronic packaging researchers and physical designers. While it enables researchers to more readily benefit designers, it also acts as a catalyst for identifying needed research extensions.
Prevention of Overheating and Frequent Thermal Cycling of Outdoor Electronic Cabinets Cooled by Forced Air Convection in Cold Climates
Authors: Zimmerman Eric B. , Hegab Hisham , Colwell Gene T.
Published: July 2023

Telephone companies use electronics to route calls between customers. These electronics are generally packaged together and placed in steel containers located outdoors. When a significant amount of electronics are packaged together the cooling capacity of natural convection is exceeded and supplementary cooling systems are needed. Forced air cooling is generally the system of choice given the relative low cost and simplicity when compared to alternative cooling methods. Simple axial flow fans are typically turned on and off by a thermostat located inside the cabinet to keep the inside air temperature below a predetermined maximum. While the behavior of an electronics cabinet with this type of cooling system may be acceptable under conditions of a summer day in the desert southwest, it may overheat or have unacceptable thermal cycling during the cold days of winter. Numerical simulation using a system of lumped thermal capacitances is used to predict the air-flow rate which would prevent thermal cycling and reduce operating temperatures to well below that found in the summer months.
Dynamic Analysis of the Lightweight Mission Specialist Seats for the Space Shuttle Orbiter
Authors: Jermstad Wayne A.
Published: July 2023

The Orbiter Lightweight Seat - Mission Specialist (LWS-MS) is designed to replace the existing mission specialist seats in the space shuttle orbiter. The goal of the LWS-MS project is to reduce the weight of each seat by 50%, while increasing crashworthiness. The development of typical aircraft seats relies heavily on dynamic crash testing. The LWS-MS team at the NASA Johnson Space Center (JSC) reduced the amount of dynamic testing required by performing dynamic analysis of the seat and occupant.

The analysis uses the Dynamic Analysis and Design Software (DADS) package by Computer Aided Design Software, Inc. Custom code was added to model the seat restraint system, and to model contact between the occupant and the seat. The occupant is modeled as a group of rigid bodies. The seat is represented by its mass and stiffness matrices and by its normal modes. The DADS model shows good correlation with test data for both low and high level input tests.
Linear Visco-Elastic Material Model for Headform Skin With Applications to Interior Head Impact Protection
Authors: Faruque M. O. , Liu N. , Chou C. C.
Published: July 2023

Vinyl rubber dummy skin used in the deformable featureless head form exhibits rate sensitivity. This rate sensitivity seems to play a significant role in the interior head impact evaluation. In order to characterize the rate dependency of dummy skin, a linear visco-elastic material law is developed in FCRASH. To validate this model, a number of hcadform drop tests and interior head impact events are simulated using FCRASH and results are compared with the test data. Evidently excellent agreement is achieved between the analyses and the test data.
Radiative Transfer Between the Pulsed Laser and the Target in the Presence of Laser-Induced Plasma
Authors: Xu Xianfan , Song Kevin H.
Published: July 2023

When high power, pulsed laser interacts with materials, a condensed plasma layer is generated above the target surface. The laser-induced plasma changes the energy coupling mechanisms between the laser beam and the target. This work investigates the radiative heat transfer process in the plasma layer generated by laser irradiation. Novel diagnostic techniques are developed to measure the transient transmission and scattering of the thin plasma layer within the duration of the laser pulse. Based on the measurements radiative heat transfer analysis is performed to evaluate the radiative properties of the plasma layer, including the optical depth, the absorption coefficient, the single scattering phase function, and the scattering size parameters. Knowledge on these radiative properties help to understand the energy transfer process during laser materials interaction. Further this work demonstrates the feasibility of using the transient scattering measurement for in-situ monitoring of the diameter of the laser ejected particles.
Projection Micromachining of Polyimide Thin Films by an Excimer Laser
Authors: Zhang X. , Grigoropoulos C. P. , Krajnovich D. J. , Tam A. C.
Published: July 2023

A KrF excimer laser projection micromachining tool has been designed and implemented aiming to accomplish one-step etching with micron resolution for applications such as chip module packaging and polyimide technology in semiconductor manufacturing. Two polyimide thin films spun on the silicon wafers are annealed at 100 °C and 400 °C, respectively, in order to investigate the effect of the annealing temperature on the laser micromachining process. The micromachined polyimide surface morphology is studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and a surface profilometer for determination of the etch rate at different laser fluences. Micromachining with micron resolution is achieved by this excimer laser projection tool. Measured on a 25 μm line, the etch rate dependence on laser fluence both below and above the ablation threshold is investigated over the fluence range from 10 to 1000 mJ/cm2. The polyimide thin film optical properties, n and k at λ = 248 nm are measured by a spectroscopic ellipsometer for both films. The etch rate above the ablation threshold for the film annealed at 100 °C is found 60% higher than that for the film annealed at 400 °C. This behavior originates from the correspondingly higher by 82% absorption coefficient, α in the 100 °C film. The ablation thresholds for both films are found the same at about 100 mJ/cm2. Calculated etch rates agree with experimental values within 15%. Etch rates of the order of nanometer can be achieved near the ablation threshold of 100 mJ/cm2 for both films.
Surface Contaminant Removal Using Short-Pulse Lasers
Authors: Phinney Leslie M. , Tien Chang-Lin
Published: July 2023

New methods of removing surface contaminants from micro-electronic and microelectromechanical system (MEMS) devices are needed since the decreasing size of their components and structures is reducing the allowable contamination levels. If the pulse duration and fluence are chosen to optimize electronic rather than thermal desorption in short-pulse laser processing, surface species can be removed without exceeding maximum temperature constraints. A two-temperature model for short-pulse laser heating of, and subsequent desorption from, metal surfaces is presented. A scaling analysis indicates that the ratio of electronic to thermal desorption depends on three ratios: the electron and lattice specific heats, the laser pulse duration and electron-lattice thermalization time, and the radiation penetration depth and film thickness. Regimes of predominantly electronic and thermal desorption are identified, and predicted desorption yields from gold films show that electronic desorption is the primary desorption mechanism in certain short-pulse laser processes.
Microelectronic Chip Attach With Silver Filled Epoxies: An Analytical and Experimental Study
Authors: Zwick K. J. , Ayyaswamy P. S. , Cohen I. M.
Published: July 2023

In microelectronic chip packages, a mechanical bond between the chip and the leadframe is formed by depositing a pattern of epoxy drops on the lead frame, and then placing the chip on top of the epoxy. A small force is applied to the top of the chip which causes the epoxy to squeeze out under the chip and form a complete, void-free bond between the chip and the lead frame. In this paper, we analyze the squeezing flow of the bonding epoxy, and demonstrate that the bonding time is longer for large chips than for small chips. We also present the results of some related experiments on the squeezing flow of the epoxy. We find that the squeezing behavior predicted by our analysis agrees very well with the measured behavior under typical bonding conditions. Finally, we discuss two methods of reducing the bonding time, and the advantages and disadvantages associated with each of these methods.
Temperature Distributions in Rods Within an Optical Fiber Draw Tower Furnace
Authors: Mungekar H. P. , Polymeropoulos C. E.
Published: July 2023

The present work is motivated by the current need of increasing the yield of optical fiber drawing by using high draw speeds. For such conditions the preform feed rate through the draw tower furnace can affect the heat transfer to the preform rod and as a consequence the formation of the neckdown. In the present work temperature distributions along the axis of stationary as well as moving graphite and fused silica rods inserted in a fiber optic draw tower furnace was found experimentally. Experimental data clearly showed that the thermal lag increased at higher draw speeds. Implications of this to high speed fiber drawing are highlighted. Measured temperatures were compared with numerically computed temperature distributions in moving rods. Excellent agreement was found between the temperature recorded in moving graphite rod experiments and the computed temperatures which validated the furnace temperature profile found in the previous work. However, for glass rods the computed temperature lag was greater than the measured temperature lag. The difference between computed glass temperatures and those measured using a thermocouple was explained using a simplified modeling taking into account spectrally selective radiation properties of glass.
Flow Behavior and Heat Transfer of Atomizing Gas and Metal Droplets in Spray Forming Process
Authors: Cui Chengsong , Shen Jun , Xu Daming , Li Qingchun
Published: July 2023

The dynamics for the fluid flow and heat transfer in spray forming process is theoretically analyzed and the controlling equations of the flow and heat transfer are derived. The shape/geometry and the solidification profiles such as temperature and remained liquid in the preform are calculated by the simulation of the controlling equations. The predicted cooling rates at different positions can reach 102−103 °C /s at the beginning of deposition and decrease to 100∼101 °C/s in the subsequent cooling process. The characteristics of rapid solidification structures with spray forming are mainly due to the high cooling rate of droplets during spray process (>104 °C /s) and breaking mechanism of dendrite on deposition.
Simulation of Micro-Pore Formation in Spray Deposition Processes
Authors: Delplanque J.-P. , Lavernia E. J. , Rangel R. H.
Published: July 2023

The present work investigates porosity formation in spray deposition processes. The emphasis is on one possible mechanism of micro-pore formation during droplet spreading and solidification: liquid-jet overflow. To this end, the Navier-Stokes equations are solved numerically using finite differences and the free surface is tracked using the Volume Of Fluid method. A previously developed multi-directional solidification algorithm is adapted and implemented in the Navier-Stokes solver to perform numerical simulations of liquid-metal droplet impact, spreading, and solidification. The results obtained allow a detailed description of the liquid-jet overflow mechanism and of the resulting solidified disk morphology. The influence of the Weber and Reynolds numbers, the solidification constant, and the contact angle is investigated.
Simulation of Phase Change and Convective Heat Transfer in Float Zone Processing
Authors: Rao Madhukar M. , Shyy Wei
Published: July 2023

A computational capability has been developed to predict the free surface shape, heat transfer and melt-crystal interface shapes in float zone processing. A moving boundary, second order, finite volume, incompressible Navier-Stokes solver has been developed for the fluid flow and heat transfer calculations. The salient features of the approach include solving the dynamic form of the Young-Laplace equation for the free surface shape, dynamic remeshing to fit the free boundary, a flexible, multi-block, grid generation procedure and the enthalpy method to capture the melt-crystal and the melt-feed interfaces without the need for explicit interface tracking. Important convective heat transfer modes; natural convection and thermocapillary convection have been computed. It is shown that, whereas the overall heat transfer is not substantially affected by convection, the melt-crystal interface shape acquires significant distortion due to the redistribution of the temperature field by the thermocapillary and buoyancy-induced convective mechanisms. It is also demonstrated that the interaction of natural and thermocapillary convection can reduce the melt-crystal interface distortion if they act in opposing directions.
Numerical Simulation of Temperature Field of Copper and Copper Alloy in Horizontal Continuous Casting
Authors: Wenhua Xie , Shuisheng Xie , Shenghong Huang
Published: July 2023

To investigate the temperature distribution and solidification shell profile in a continuous casting process for round bars, transient mathematical models, describing the thermal process, have been developed. Then Finite Element Method (FEM) has been applied to simulate the solidification proceess.

Parameters included casting speed, casting temperature and cooling conditions, have been analysized. It is shown that different parameters have different influence on the thermal process and must be carefully controlled in continuous casting process. Finally, the simulated results are compared with the experimental results.
Simultaneous Three-Wavelength Interferometry for Head/Tape Spacing Measurement
Authors: Baugh Eric , Talke Frank E. , Swenson James
Published: July 2023

Instrumentation for the simultaneous acquisition of three monochromatic interference patterns is described. An algorithm to process the three images using a weighted average method into a map of the head/tape spacing and an estimated contact pressure map is presented. Both experimental evidence and Monte-Carlo simulation indicate that the three-wavelength technique is an improvement over standard monochromatic techniques. Sample one- and two-dimensional measurements are given.
Quantification of Standing Wave Patterns in Rotating Flexible Disks Using Optical Reflection Techniques
Authors: Ma Yiping , Thomas Fred C.
Published: July 2023

This paper is a follow-on to a paper previously presented to ASME on an experimental instrument designed to enable the observation of standing wave modes for flexible media. In that earlier paper qualitative results showing changes in the disk standing waves were obtained using the experimental setup. The current paper presents the same experimental system from the perspective of looking at the system as an optical instrument, and, based on optical ray trace methodology, quantifies the results seen in the previous paper on a more absolute basis. Based on this analysis, the authors also describe design changes from both an instrument setup perspective and the application of other electro-optic sensor technologies which will improve the system’s static and dynamic resolution.
Frequency Domain Characterization of Take-Up Reel Air-Entrainment in Low-Tension and High-Speed Tape Transport
Authors: Mathur Priyadarshee D. , Messner William C.
Published: July 2023

Air entrainment in tape spooling is important in determining tape stacking quality and in modeling the transport system for control purposes. Accurate estimates are difficult to obtain by direct measurement. In this paper, the length of the entrained air film is estimated by determining the spring constant of the unsupported tape span. Using multi-input single-output (MISO) frequency based system identification, the resonant frequency of the system associated with the longitudinal mode of the tape is derived. This data is compared to predictions from the well known nip equation. The utility of these equations is discussed.
Effects of Inserting Arm Blockage on Heat Transfer in a Corotating Disk Assembly
Authors: Chyu M. K. , Hsing Y. C.
Published: July 2023

To advance disk drive design for increased performance and reliability, a thorough understanding of flow and thermal transport in the disk file is essential. The primary objective of this study is to examine the effects of slider arm blockage on the convective characteristics in a 3.5-inch corotating disk stack. Using an analogous mass transfer system based on naphthalene sublimation, the detailed distribution of local mass transfer coefficient over the disk surface is determined by an automated micropositioning system. By analogy, the mass transfer coefficient can be transformed to the corresponding heat transfer coefficient and friction coefficient. All the transport coefficients reveal strong variation with the arm blockage in the radial direction. However, overall average transfer coefficient obtained by integrating their corresponding local values are rather insensitive to the extent of arm protrusion.
A Parametric Study Addressing the Three-Dimensional Components of Spinal Loading During Complex Dynamic Lifting Tasks
Authors: Fathallah F. A. , Marras W. S. , Parnianpour M.
Published: July 2023

Increasing evidence indicates that spinal shear forces are important risk factors in occupationally-related low back disorders (OLBDs). This paper demonstrated how ignoring these forces and focusing only on compressive loading could severely under-represent the complete mechanical exposure to the spine. A parametric scheme is proposed to consider the combined 3-D forces during dynamic lifting tasks. As more complete tolerance data become available, loading limits that reflect such information may be determined. This would help in finding the best means to assess the effects of spinal loading and would thereby be useful in reducing back disorders in industry.
Dynamic Response of an L2-L3 Motion Segment to Compressive Cyclic Loading Using a Nonlinear Viscoelastic Finite Element Model
Authors: Wang J. L. , Shirazi-Adl A. , Parnianpour M. , Engin A. E.
Published: July 2023

The axial compressive cyclic loading was applied to a nonlinear viscoelastic finite element model of an L2-L3 motion segment to investigate its dynamic response. In this validated model, the material properties of the anulus matrix, anulus fibers and nucleus pulposus (NP) have been represented by the viscoelastic constitutive laws. The detailed stress-strain analysis of the motion segment under cyclic loading was performed to quantify the load sharing amongst passive elements. The cyclic loading encountered due to exposure of vibration or during driving has been implicated as a risk factor for occupational low back disorders (OLBD). The cyclic axial compressive loading was controlled, peak to peak, from 600 N to 1000 N at 0.5 Hz for 15 cycles (30 seconds). The results indicated that the axial stiffness of the motion segment decreased, while intradiscal pressure (IDP) and the strain of the anulus fiber increased.
Realistic Virtual Reality Simulation of Touching Hard Tumors Beneath Soft Tissue
Authors: Dinsmore Michael , Langrana Noshir , Burdea Grigore
Published: July 2023

Touch has always been central to many aspects of medical practice. The surgeon working deep inside the abdominal cavity will feel and squeeze the liver to determine which, if any, nodule to biopsy. Palpation of a female breast is a sensitive means for detecting malignancies. Surgeons and pathologists routinely take advantage of the fact that cancers feel different than normal tissue.
Cervical Spine Laminectomy and Facet Wiring
Authors: Yoganandan Narayan , Cusick Joseph F. , Pintar Frank A.
Published: July 2023

Using physiologic compression-flexion loading, eight human cadaver cervical spinal columns (C2-T1) were tested under intact, laminectomy, and facet wiring conditions. Forces, displacements, and the overall and local kinematics of the spinal components at every level of the column were obtained. Laminectomy decreased the stiffness and increased the overall local spinal motions (p < 0.05). Individual facet wiring to bone graft and through the spinous process inferior to laminectomy did not restore the stiffness and overall sagittal rotations. In contrast, the Luque rectangle induced stiffness changes to levels exceeding the intact preparations and reduced the sagittal rotations. The significant increases in the total column flexibility and the segmental flexion rotations secondary to laminectomy were most effectively corrected by the cross-linking of the facet wire fixation above and below the laminectomized segments and not by the individual facet wires secured to an overlying structure.
Finite Element Analysis of Cervical Laminectomy With Graded Facetectomy
Authors: Kumaresan Srirangam C. , Pintar Frank A. , Yoganandan Narayan
Published: July 2023

This study was undertaken to investigate the biomechanical effects of the human cervical spine under intact, and laminectomy with and without graded facetectomy conditions. An anatomically accurate finite element (FE) model of a three-segment (C4-C6) spine unit was developed. The FE model was validated under physiologic flexion, extension, lateral bending, and axial torsion loading modes. The model response matched well with the experimental data. The gross external (angular rotation) and the internal responses (e.g., superior and inferior intervertebral disc stress) were delineated under these physiological loading modes. Laminectomy markedly altered the cervical angular motion and the disc stress under flexion loading compared to the other loading modes. Laminectomy with facetectomy increased the angular motion and the inferior disc stress notably under flexion without affecting the adjacent superior disc. Facet resection of more than 50 percent caused pronounced increase of angular rotation and intervertebral disc stress.
Development, Validation and Clinical Relevance of a C5-C6 Motion Segment Finite Element Model
Authors: Clausen John D. , Goel Vijay K.
Published: July 2023

A fully three-dimensional finite element (FE) model of a C5-C6 human cervical spine motion segment has been developed and validated. This model is the first to incorporate many of the important biomechanical aspects of the cervical spine not represented in previous models. To demonstrate the models’ predictive power we have addressed a variety of clinical issues including injury and stabilization. Additionally, the loading paths from one vertebra to another are fully described in multiple modes of loading. Knowledge of loading paths will allow injury and stabilization to be characterized in a manner previously not possible.

Our model represents significant and essential advancements over previous FE models of the cervical spine making it possible to address a broad spectrum of clinically relevant issues which could not be investigated in the past.
A Viscoelastic Model for the Natural History of Adolescent Idiopathic Scoliosis
Authors: Meade K. P. , Patwardhan A. G. , Gavin T.
Published: July 2023

Early detection of scoliosis through school screening programs sends a large number of young patients with mild curves to scoliosis clinics for evaluation. Only about 20 percent of the curves progress if not treated. Uncertainty in the prognosis for progression can result in unnecessary bracing of benign curves. In this paper, a new approach is described for modeling the natural history of idiopathic scoliosis, which could change this situation by predicting which curves progress and which do not.