bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial-Multiblock Procedure for Radiation Heat Transfer
Authors: Chai John C. , Moder Jeffrey P.
Published: July 2023

A spatial-multiblock procedure for radiation heat transfer is presented in this article. The proposed procedure is applicable to isothermal or nonisothermal, absorbing, emitting and scattering or transparent media with black or reflecting walls. Although not shown in this article, the procedure is also applicable to nongray conditions. The proposed procedure can be used with the discrete ordinates method and the finite volume method. The heat transfer rate, net radiant power and other full-range and half-range moments are conserved between spatial blocks by the proposed procedure. The utilities of the proposed procedure are shown using four sample problems. The solutions indicate that the multiblock procedure can reproduce the results of a single-block procedure even when very coarse spatial grids are used in the multiblock procedure.
Conjugate Mixed Convective Heat Transfer in Electronic Equipment
Authors: Gadepalli Prashant , Rahman Muhammad M.
Published: July 2023

The cooling of electronic components on a circuit board by cross-flow mixed convection was analyzed in the present study. In this class of flow, the orthogonal free and forced convection result in a three-dimensional boundary layer flow. It was attempted to identify and analyze the significance of the factors that influence the local heat transfer rate and the surface temperatures of these components. A simple two-dimensional model of a thin plate with stripwise heat sources on it was considered first and it was found that having an external cross-flow results in lower surface temperatures than having an aiding flow. Next, a more practical three-dimensional model of a conducting board of finite thickness with four heat sources mounted on the surface was analyzed. Heat transfer from both sides of the board was taken into account. The conservation equations for mass, momentum, and energy were solved. The important factors that influenced the heat transfer mechanism were the distance of the heat sources from the natural as well as the forced convective leading edges, spacing between the sources, the Richardson number, Reynolds number, board thickness, and the properties of the board material.
Natural Convection in Symmetrically Heated Vertical Parallel Plates With Discrete Heat Sources
Authors: Manca Oronzio , Nardini Sergio , Naso Vincenzo
Published: July 2023

Laminar air natural convection in a symmetrically heated vertical channel with uniform flush-mounted discrete heat sources has been experimentally investigated. The effects of heated strips location and of their number are pointed out in terms of the maximum wall temperatures. A flow visualization in the entrance region of the channel was carried out and air temperatures and velocities in two cross sections have been measured. Dimensionless local heat transfer coefficients have been evaluated and monomial correlations among relevant parameters have been derived in the local Rayleigh number range 10 – 106. Channel Nusselt number has been correlated in a polynomial form in terms of channel Rayleigh number.
Modeling of Transient Turbulent Natural Convection in a Melt Layer With Solidification
Authors: Fan T. H. , Cheung F. B.
Published: July 2023

The phenomenon of turbulent natural convection in a horizontal heat-generating melt layer with solidification taking place at the cooled upper and lower boundaries is investigated theoretically. The objective is to determine the transient behavior of the crust at the upper and lower surfaces and the effect of crust formation on the turbulent natural convection process in the melt layer. Various surface temperatures, latent heats, and the heat source strengths are considered along with the effects of the Stefan number and Rayleigh number. Special attention is given to the interaction between the melt pool heat transfer and the crust dynamics. Numerical results are presented for the transient crust thickness, transient temperature distribution, eddy heat transport, and the heat transfer characteristics at the solid-liquid interface during the freezing process. The present study provides basic information needed to predict the transient behavior of a melt pool in a reactor lower head following a severe core-meltdown accident.
Measurement of Wavelength, Dynamic Contact Angles, Front Velocity and Shape of Rivulets on an Inclined Plate by Fluorescent Imaging
Authors: Johnson M. F. G. , Schluter R. A. , Miksis M. J. , Bankoff S. G.
Published: July 2023

Fluorescent imaging is used to measure the fluid characteristics in the neighborhood of moving contact lines. The rivulets formed owing to the instability of the film front advancing down an inclined glass-plate are thus examined in detail, including lateral wavelength or spacing between rivulets, tip velocity, three-dimensional shape and dynamic contact line. The extensions of this technique to a large region (∼ 1 m2) and to a small thicknesses with the necessary precision required extensive calibration and independent measurements.
Effects of Acoustic Atomization on Combustion Emissions
Authors: Cook Charles A. , Charagundla S. Rao , Presser Cary , Dressler John L. , Gupta Ashwani K.
Published: July 2023

Measurements of droplet characteristics and gas-phase chemical composition are reported for spray flames produced by a velocity-modulated, pressure-jet atomizer. A piezoelectric driver was used to modulate the velocity of kerosene fuel through a commercially available pressure-jet nozzle. Phase Doppler interferometry was used to measure droplet size and velocity in the spray flames. Gas samples were extracted from the spray flames, and concentrations of chemical species were determined using FTIR spectroscopy and a chemiluminescent NO/NOx analyzer. Experiments were performed at two different piezoelectric driving frequencies and compared to a base case without velocity modulation. The effect of velocity modulation on both the spray characteristics and chemical product formation were studied. The results show that velocity modulation decreases overall droplet size and increases mean droplet velocity and number density near the spray. These characteristics increase the flame standoff distance and flame length. However, the spray characteristics resulting from velocity modulation decreases the number of droplets escaping the spray flame unburned.
An Automotive Seat Cushion Vibration Model
Authors: Patten William N. , Pang Jian
Published: July 2023

A low order lumped parameter model is proposed to describe the vertical vibration compliance of an automotive seat. The model includes linear stiffness and damping effects and a nonlinear dissipation term to account for the colomb damping exhibited by open cell fluid or gas filled foams that are commonly used in the construction of an automotive seat cushion. A shaped sand bag was positioned on the seat cushion and vibrated to obtain test data. A white noise acceleration with an amplitude ranging from .05 g rms to .45 g rms in increments of .05 g rms was used to excite the seat track. A sports car seat was tested and a nonlinear model was identified that predicts the actual test data with fidelity.
Study of the Apparent Viscosity of Fluidized Sand
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A. , Reddy Shashikiran
Published: July 2023

The present work is concerned with an experimental study of the apparent viscosity of sand used in typical foundries. The viscosity of fluidized foundry sand was measured at both Poiseuille (capillary viscometer) and Couette (rotational viscometer) flows. Capillary tube viscometers are obviously to be preferred when the data are to be used for pipe flow problems, and rotational viscometers, which subject the material under test to a precise and uniform rate of shear, have definite advantages in the analysis of complex system, such as in sand molding processes. Data obtained with the Brookfield viscometer show that as either the shear rate or the bed voidage factor (air flow rate) increases, the apparent viscosity decreases. In addition, the measured viscosities are only slightly affected by changes in particle diameter for the diameters investigated. The capillary viscometer data show that the apparent viscosity does not depend on the overall pressure drop at given capillary tube. However the apparent viscosity measurements were significantly affected by the tube length to inner diameter ratio due to the dominant influence of entrance region energy losses.
An Experimental Evaluation of Capillary Tube-Suction Line Heat Exchanger Performance With Refrigerant HFC-134a
Authors: Bittle Robert R. , Pate Michael B.
Published: July 2023

Capillary tube-suction line heat exchanger performance with refrigerant HFC-134a was experimentally evaluated for a range of heat exchanger geometries and operating conditions typically found in household refrigerators. Due to the number of variables that could potentially influence heat exchanger performance, statistical methods were employed in designing the experimental test plan and in reducing the data. Key variables and their respective ranges tested included; capillary tube inner diameter (0.66 to 0.79 mm), capillary tube length (2440 to 3300 mm), heat exchanger length (1000 mm to 1780 mm), condensing temperature (29.4 to 55.6°C, which corresponds to a condensing pressure of 758 kPa and 1516 kPa), evaporator pressure (131 to 165 kPa), capillary tube inlet condition (2.8 to 5.6°C subcool), and oil concentration level (0 to 3%).

For these experiments, the measured HFC-134a mass flow rates ranged between 2.7 and 9.5 kg/hr, and measured effective subcooling level ranged between 13 and 33°C. Based on the resulting performance database, design correlations predicting mass flow rate and the heat exchanger effectiveness were developed and verified. The HFC-134a results were also compared to measured heat exchanger performance with refrigerants HFC-152a and CFC-12.
Kissing Heat Transfer Between the Wraps of a Scroll Pump
Authors: Sunder Sankar , Smith Joseph L.
Published: July 2023

Conductances associated with the various modes of internal heat transfer in a scroll pump are estimated. Heat transfer through transient contact between scroll wraps (kissing heat transfer) is found to be a dominant mode of heat transfer between discharge and suction sides of the pump. Such heat transfer is characterized by significant steady-state heat fluxes across the wraps of a scroll pump. Experiments on a specially instrumented scroll compressor provide evidence of significant heat fluxes across the wraps of the scroll pump. Estimation of the contact angle between wraps based on Hertzian stresses, as well as an oil film demonstrate that kissing heat transfer is a plausible mechanism of heat transfer in these pumps. Contact angles inferred from experimental data are also shown to be of the same order of magnitude as those predicted by hertzian stress calculations. It is shown that the heat fluxes observed in the kissing heat transfer experiment are too large to be explained by convection between gas and wall in the scroll pump.
Turbulent Flow Through Reed Type Valves of Reciprocating Compressors
Authors: Deschamps C. J. , Prata A. T. , Ferreira R. T. S.
Published: July 2023

The present work considers the modeling of turbulent flow in reed type valves of reciprocating compressors and is based on a simplified geometry of the actual valve, that is, a radial diffuser with axial feeding. The refrigerant gas flow through the valve system is characterized by the Reynolds number Re based on the feeding orifice diameter d. Due to its claimed capability to predict flow including features such as recirculation region, curvature and adverse pressure gradient (all of them present in the flow considered here), the RNG k-ε model of Orzag et al (1993) has been applied in the present numerical analysis. The governing equations are numerically solved using the finite volume methodology, and the approximation of convective transport was performed using the higher-order accurate QUICK scheme. Experiments were conducted to assess the turbulence model. Results of pressure distribution along the front disc and effective flow and force areas for three values of valve lifts s (s/d = 0.05, 0.07 and 0.1) and three Reynolds numbers (Re = 10,000, 20,000 and 40,000) when compared to the experimental data, showed that the RNG k-ε model can provide a good prediction of the important parameters required for valve design and analysis.
Three-Dimensional Simulation of a Molten Carbonate Fuel Cell Stack Under Transient Conditions
Authors: He W. , Chen Q.
Published: July 2023

The three-dimensional distributions of the crucial parameters in a molten carbonate fuel cell (MCFC) stack under transient conditions have been investigated by using dynamic simulation. The major processes with regard to an MCFC’s safe and efficient operation in power-generation systems, such as the mass and heat transport, chemical reactions and electrical power generation, are formulated in a three-dimensional, time-dependent form using the computational-fluid-dynamics (CFD) technique. In this paper, the model performance is demonstrated by applying it to calculate the distributions of current density and temperature under a step change. The simulation results at steady state are consistent with the experimental data and the analytical results from the literature.
Heat Exchanger Network Optimization Strategy Based on Reducing the Number of Heat Exchangers
Authors: Sama Dominick A.
Published: July 2023

The characteristics of good process design methods are discussed. A skill-based design optimization strategy to reduce the number of heat exchangers in a heat exchanger network (HEN) is proposed, and is compared with the pinch technology approach. It is shown that the Hohmann (or Euler) equation can correctly predict the existence of loops in maximum energy recovery (MER) heat exchanger networks, but cannot accurately predict the minimum number of heat exchangers. It is also found that breaking loops, or creating independent subsets of streams does not always reduce the number of exchangers. The importance of using enthalpy vs. temperature plots of individual process streams as well as those of hot and cold composites is demonstrated. In the absence of other overriding criteria, it is recommended that HEN designs should be selected on the basis of reduced number of heat exchangers.
Preview Control of Active Suspension for Railway Vehicles
Authors: Fujioka Takehiko , Yamada Haruo
Published: July 2023

In this paper preview control of active suspension for railway vehicles is studied. Railway vehicles are usually used in a train, and are exposed to the same irregularity of rails. Preview information of disturbance can be gotten easier in rail vehicles than in other vehicles. Preview Control is one kind of feedforward control. When preview control is applied to railway vehicle suspension, fail-safe system should be added in case of failure in preview control system including sensing system. In order to compensate this problem, a combined control by preview and H infinity feedback control is considered in this paper. Numerical simulations and bench tests are performed to verify the effect. Simulations and bench tests confirm the following: (l)The combined control reduces vibration; (2)The reduction of vibration is about the superposition of the effect of each control separately; (3)The amount of control moment does not increase to get the effect above. It is also confirmed in simulations that the feedback loop can compensate the failure in preview control system.
Real-Time CMAC Neural Network Control of a Piezo-Electric Actuated Toolpost With Disturbance Decoupled Observer
Authors: Pinsopon Unnat , Larsen Gary , Cetinkunt Sabri , Nakajima Shin-ichi
Published: July 2023

The design and fabrication of a cerebellar model articulation controller (CMAC) controlled piezo-electric actuated fast tool servo has been reported [Pinsopon et al]. A capacitance type gap sensor with less than 1 nm resolution was used for position feedback. Cerebellar model articulation controller (CMAC) neural network control algorithm has been implemented parallel to the PID controller as the control scheme, and its performance was compared with the standard PID control. The CMAC control algorithm improves the tracking accuracy compared to the PID algorithm. However, the CMAC control system had a poor disturbance rejection capability as compared to the PID control system. In this research, state feedback with disturbance observer is implemented as the control scheme replacing PID controller to improve the disturbance rejection capability. CMAC control algorithm is also used in the feedforward loop to improve the tracking capability of the closed loop system.
Micro-Actuation in Precision Grinding
Authors: Wang Y. , Moon K. S. , Miller M. H.
Published: July 2023

This paper presents an approach to improve the productivity and surface quality of the grinding process. It describes the development and implementation of a high-frequency micro-actuation system for vibratory modulation in the grinding process. The approach is based on the fact that ground surface texture has dominant roughness in the cross feed direction of the surface grinding process. High-frequency vibratory movement of the workpiece in the cross feed direction can reduce the surface roughness in this direction and therefore the overall surface roughness. A three dimensional model for the surface texture generated by a surface grinding process is developed based on the kinematics of the process. A simulation procedure is developed to check the effectiveness of this approach. A prototype workpiece actuator that incorporates magnetostrictive actuation has been developed. It has been tested and implemented on a conventional surface grinding machine. A series of experiments have been conducted to demonstrate the viability of this method. The results show that it offers an effective means of improving the quality of the ground surface texture and improving the grinding process efficiency.
Automatic Identification of Remote Environments
Authors: Schulteis Timothy M. , Dupont Pierre E. , Millman Paul A. , Howe Robert D.
Published: July 2023

A system that can process sensory information collected during telemanipulation tasks in order to automatically identify properties of the remote environment has many potential applications. These include generating model-based simulations for training operators in critical procedures and improving real-time performance when time delays are large. The research issues involved in developing such an identification system are explored, focusing on properties that can be identified from remote manipulator motion and force data. As a case study, a simple block-stacking task performed with a teleoperated two-fingered planar hand is considered. An algorithm is presented which automatically segments the data collected during the task, given only a general description of the temporal sequence of task events. Using the segmented data, the algorithm then successfully estimates the weight, width, height, and coefficient of friction of the two blocks handled during the task. This case study highlights the broader research issues which must be addressed in automatic property identification.
Minimum Surface-Effect Microgripper Design for Force-Reflective Telemanipulation of a Microscopic Environment
Authors: Goldfarb Michael , Celanovic Nikola
Published: July 2023

This paper describes the fundamental physical motivations for minimum surface effect design, and presents a microgripper that incorporates a piezoelectric ceramic actuator and a flexure-based structure and transmission. The microgripper serves effectively as a one degree-of-freedom prototype of minimum surface effect micromanipulator design. Data is presented that characterizes the microgripper performance under both pure position and pure force control, followed by a discussion of the attributes and limitations of flexure-based design. The microgripper is interfaced with a force-reflective macrogripper, and the pair controlled with a hybrid position/force scheme. Data is presented that illustrates the effective operation of the telerobotic pair.
Reactive Path Shaping: Local Path Planning for Autonomous Mobile Robots
Authors: Schmitt Paul R. , Book Wayne J.
Published: July 2023

This paper introduces a path generator for autonomous nonholonomic mobile robots in partially known aisle environments. Reactive Path Shaping (RPS) is designed for autonomous vehicle obstacle avoidance and utilizes information about its environment through ultrasonic sensors. A path is constructed one piece at a time, based upon local environmental information. Each piece is initially considered to be rough and needs to be appropriately “shaped,” or smoothed, to meet mobile robot nonholonomic kinematic constraints. Experiments on a simulated vehicle with ultrasonic sensors are briefly discussed.
Boundary Control of a Nonlinear String
Authors: Shahruz S. M. , Krishna L. G.
Published: July 2023

In this paper, an undamped nonlinear string is considered. It is proved that the nonlinear string can be stabilized by the linear boundary control, which is the negative feedback of the velocity of the string at one end.
Three-Dimensional Dynamic Modeling of the Human Knee Joint: Formulation and Solution Technique
Authors: Hefzy Mohamed Samir , Abdel-Rahman Eihab M.
Published: July 2023

In this paper, a general three-dimensional anatomically based dynamic model of the knee joint that includes both tibio-femoral and patello-femoral joints is presented. This model can predict knee response under internal and/or external sudden impulsive loadings. It is found that all models that were developed in the literature to predict the two-dimensional and three-dimensional dynamic response of the knee joint are special cases of this general model. In all these models, the governing system of equations reduces to a system of nonlinear Differential Algebraic Equations (DAE) whose solution continues to represent major challenges. An improved algorithm that was developed to obtain a solution to this complex system of DAE’s is then discussed. A special case that includes only the tibio-femoral joint is then investigated to determine the three-dimensional knee response under sinusoidal impacting loads acting on the tibia. Solution was obtained using a DAE solver, namely the Differential / Algebraic System Solver (DASSL).
Effects of High Heat on the Strength and Fatigue Life of Unidirectional Polymer-Matrix Composites
Authors: McLaughlin Philip V. D. , McShane Henry A. , Cochran Roland , Armstrong-Carroll Eileen
Published: July 2023

An analysis of local fiber/matrix interface damage growth in unidirectional composites under tension-tension loading is modified to include thermal residual stresses and subsequent temperature histories with the goal of estimating the loss of strength and fatigue life occurring when a graphite/epoxy composite structure is subjected to flame or hot exhaust gasses. Tests show that epoxy thermomechanical and strength properties degrade rapidly from 200 to 300°C, and that time-at-temperature is important. Using properties estimated from these tests, two mechanisms of static strength and fatigue life reduction are studied: thermal-stress-induced interface cracking parallel to fibers, and degradation of room-temperature interface properties. The effects of heat on static strength and constant-amplitude fatigue life of a particular graphite/epoxy material system are then analytically determined for two heat exposure scenarios: one, a relatively short-time exposure of five minutes; and two, a long-time exposure of more than an hour. Strength and life loss are found to be dependent on temperature, time-at-temperature, and length of damage zone, with severe reductions in static and fatigue strengths at temperatures above 200°C.
Dirichlet to Neumann Maps for the Representation of Equipment With Weak Nonlinearities
Authors: Goldman Daniel , Barbone Paul E.
Published: July 2023

We consider modeling the presence of a substructure in a dynamical simulation in terms of the force the substructure exerts on the main structure of interest. The reaction force is given in terms of the displacement of the attachment points. We call the map between the displacement of the attachment points and the force at the attachment a Dirichlet to Neumann, or DtN, map. We use a regular perturbation expansion to derive an approximate DtN for the case when the substructure exhibits weakly nonlinear behavior. The representation is accurate to O(ϵ2t2) + O(t2/N2), where ϵ is a measure of the strength of the nonlinearity, N is the number of modes of the subsystem and t is the simulation time. We note that the representation is particularly suited to the situation when ϵ = O(N−1).
Modelling, Simulation and Experimental Studies on a Variable Displacement Radial Piston Pump Prototype for Automotive Applications
Authors: Caretto R. , Mancò S. , Nervegna N. , Rundo M.
Published: July 2023

Aim of the present study is the development of the mathematical model, the time domain simulation and preliminary experimental analyses of a radial piston pump envisaged for low pressure automotive applications. The pump is a prototype under test at the Fluid Power Laboratory, Dipartimento di Energetica, Politecnico di Torino.
Computer Simulation of the Performance of Digital-Displacement Pump-Motors
Authors: Ehsan Md. , Rampen W. H. S. , Salter S. H.
Published: July 2023

The digital-displacement pump-motor is a hybrid device, which combines reciprocating hydraulics with micro-processor control, creating a highly integrated machine capable of producing variable flow and power. It is based on the conventional hydraulic piston pump but with actively controlled poppet valves for each cylinder. This allows enabling or disabling on a stroke-by-stroke basis in any desired sequence. Time-domain modelling of the pump-motor system predicts the performance under variable-demand, variable-speed as well as different control-modes. The advantages of this approach over conventional variable-swash hydraulic machines lie with both the response speed and the inherent energy efficiency.
Numerical Implementation of a Brittle Damage Model and its Application to Concrete Slab Perforation
Authors: Chen E. P.
Published: July 2023

Numerical simulation of dynamic fracture of concrete slabs, impacted by steel projectiles, was carried out in this study. The concrete response was described by a continuum damage model. This continuum damage model was originally developed to study rock fragmentation and was modified in the present study with an emphasis on the post-limit structural response. The model was implemented into a transient dynamic explicit finite element code LS-DYNA2D and the code was then used for the numerical simulations. The specific impact configuration of this study follows the experiment series conducted by Hanchak et al. (1992). Comparisons between calculated results and measured data were made. Good agreements were found.
A New Detection Technique to Identify Defective Railroad Bearings
Authors: Anderson Gerald B. , Cline James E. , Stone Daniel H. , Smith R. L.
Published: July 2023

New signal detection and processing techniques that may allow production of a new generation acoustic wayside bearing defect inspection system have been developed recently at the Transportation Technology Center (TTC), Pueblo, Colorado.

The ability to detect bearings in early stages of failure, with a high degree of confidence, is the main goal of the bearing research program at the Association of American Railroads (AAR).

This report briefly demonstrates the effectiveness of the new techniques developed at TTC and used to analyze acoustic data, namely: (1) demodulation envelope detection, (2) three-dimensional time-frequency analysis, and (3) neural network used in bearing defect pattern recognition.

These new signal processing schemes have been applied to analyze the bearing burn off test data collected at TTC’s bearing test facility. [1]

Train derailments caused by bearing burnoff failure have remained at a relatively constant rate over the past several years and are a major concern within the industry. For instance, when a bearing fails due to a spun cone defect, the operating temperature can rapidly exceed 2,700 degrees Fahrenheit causing a derailment in minutes.

Solutions to these problems require the identification of a defective bearing in the earliest stages of deterioration, preferably in advance of an overheated condition forcing a train stop. Early detection would provide a railroad with the opportunity to repair or replace the defective bearing at a convenient time and location.
The Hopf Bifurcation in a Rail Wheelset With Nonlinear Damping
Authors: Yang Shaopu , Ahmadian Mehdi
Published: July 2023

This paper presents the analytical investigation of Hopf bifurcation in a rail wheelset system. The nonlinearity taken into account is nonlinear damping force in a longitudinal yaw damper. The bifurcation can be subcritical or supercritical, depending on the system parameters. It is found that softening nonlinear damping will lead to a subcritical Hopf bifurcation, which means that even below the linear critical speed, an unstable limit cycle may occur and lead the wheelset to unstable hunting. Furthermore, our investigation shows that hardening nonlinear damping will introduce a supercritical Hopf bifurcation. The stability of the bifurcated limit cycle is determined. It is found that increasing damping will decrease the amplitude of the hunting vibration and increase the linear critical speed. Based on the results, a method to control the bifurcation mode is suggested.
Adaptive Composites for Active Flight Control Surfaces
Authors: Barrett Ron , Stutts James
Published: July 2023

Important design issues related to structural layout, substrate material selection and bonding methods of adaptive composites are presented in this paper. Several new post-processing techniques are shown which help lend a high degree of fracture toughness, tensile strength and resistance to depoling of active structural elements and lamina. By taking advantage of the inherent mismatch in coefficient of thermal expansion between adaptive materials like piezoceramics and select substrate materials, it is shown that otherwise fragile actuators may be pre-compressed. Several experiments were performed on monomorph lamina of PZT-5H actuator strips which were bonded to a number of different substrate materials. Cure temperatures ranged from 100 to 250°C. An estimate of laminate strain characteristics by using laminated plate theory compared well with experimental results up to 150°C cure temperatures. However, above 150°C, significant deviations from theory were noticed as the resin system cured prior to complete heat soak. A comparison of substrate materials showed that aluminum provides the highest degree of precompression which resulted in a jump in tensile yield strength by 89% and an increase in depoling stress by 185% while maintaining 80% of the active strain generation capability.
Design of a Piezoelectric Caterpillar Motor
Authors: Pandell Tracy , Garcia Ephrahim
Published: July 2023

The development of a piezoelectric caterpillar motor is presented. The design is similar to an inchworm motor except that multiple clamping mechanisms are used instead of two. It is believed that additional clamping mechanisms will reduce slip and glitch in the motor and make for a more accurate and precise device.

Simulations were run using MATLAB SIMULINK to model both inchworm and caterpillar operation. A flexure mechanism was designed to amplify the displacement output of the three clamping piezoelectric stacks. The motor was built to experimentally determine if the caterpillar motor did decrease the amount of slip. Both theoretical and experimental results are presented and discussed that prove that the caterpillar motor did indeed decrease the amount of slip.
Thermal Behavior Study of Power Plastic Package by High Temperature Moire Interferometry and FEA Modeling
Authors: Zhu Jiansen , Zou Daqing , Liu Sheng , Benson Jim
Published: July 2023

In the current study, 1200 l/mm gratings are replicated at either 80°C or 160°C onto the top surfaces or cross sections of power plastic packages. The specimens are measured at room temperature for thermal deformation induced by cooling process. The finite element models are used to simulate the cooling process and the results are compared with the moire interferometry results. The finite element models with different delaminations between die and die attach are also studied.
Minimization of Pressure Drop for EHD-Enhanced In-Tube Boiling of R-134A
Authors: Salehi M. , Ohadi M. M. , Dessiatoun S. V.
Published: July 2023

This paper presents an experimental study that addresses the effect of electrohydrodynamic (EHD) heat transfer enhancement on the pressure drop for in-tube boiling of R-134a in an enhanced (microfin type) tube. It is demonstrated that the heat transfer surface and electrode geometry play a dominant role in determining the pressure drop magnitude. Maxwell stress created in a liquid by an electrical field can lead to either an increase or a decrease in pressure drop depending on the geometry and flow conditions. The present study demonstrates that by changing the electrode-tube design, the EHD assisted flow boiling pressure drop can be decreased substantially.
A Literature Survey on Available Correlations for Prediction of Nucleate Pool Boiling Heat Transfer
Authors: Salehi Mohsen , Ohadi Michael M. , Blanford Mike , Dessiatoun Serguei V.
Published: July 2023

The nucleate pool boiling process is inherently a complex phenomenon. This complexity is in part related to the random behavior of the bubbles near the heating surface, strong property related boiling mechanism and other parameters such as the nucleation site density, bubble growth rates, bubble dimensions, and bubble rise velocity. To date no comprehensive model or correlation exists that can collectively represent all the characteristics of nucleate boiling. Most of the efforts for modeling the nucleate pool boiling phenomena invariably necessitate a fundamental knowledge of bubble frequency, bubble departure diameter, and nucleation site density. Due to irreproducibility of the boiling phenomena, it is very difficult to present these aspects by a general equation using parameters such as working fluid property or surface condition. From an engineering point of view, the demands are for practicality of a correlation while providing satisfactory accuracy. The objective of this paper is to provide a critical survey of the available design correlations on nucleate pool boiling heat transfer. The paper is given in two parts. Discussion of the most commonly known general correlations for nucleate pool boiling is given in part I. In part II correlations with special use will be presented and discussed. Results for independent testing of selected correlations are also given in part II.
Entropy Generation in Heat Pipe System
Authors: Khalkhali Hamed , Faghri Amir , Zuo Zhijun
Published: July 2023

A thermodynamic model of conventional cylindrical heat pipes is developed based on the second law of thermodynamics. Entropy generation, an important parameter of heat pipe performance, is caused by the temperature difference between hot and cold reservoirs, the fluid flows, and the vapor temperature/pressure drop along the heat pipe. Ambient temperature in the condenser region and heat transfer coefficient in the transport region can be adjusted to minimize entropy generation in the heat pipe system. A detailed parametric analysis is presented in which the effects of various heat pipe parameters on entropy generation are examined.
Fiber Coupled High Power Laser Diodes for Solid Freeform Fabrication Directly From Metal Powders
Authors: Dong Jian (John) , Manzur Tariq , Roychoudhuri Chandra S.
Published: July 2023

Solid freeform fabrication (SFF) is a technique which aims at manufacturing physical objects directly from CAD models to avoid conventional time consuming and costly manufacturing process. With the aid of CAD models, SFF technologies have been used successfully to produce plastic, wax and nylon polycarbonate prototype parts. However, solid freeform fabrication of metal or ceramic materials is still at the early stage of research.

This paper presents a successful demonstration of solid freeform fabrication from metal powders using high power laser diodes. It describes the design of the compact desktop SFF apparatus, which has four (power system, powder feeder, atmospheric controlled chamber, and laser scan controller) distinct parts. The effects of various control parameters on SFF parts have also been discussed.
Control of Machining Induced Edge Chipping on Glass Ceramics
Authors: Ng Stanley J. , Le Dung T. , Tucker Shelly R. , Zhang Guangming
Published: July 2023

Edge chipping is a phenomenon commonly observed during the machining of ceramic material. Characterization of edge chipping, both in macro and in micro scale, and correlating its formation to machining parameters form a basis for developing new and innovative technologies for controlling machining induced damage. An experimental-based study using glass ceramic material is performed. Three types of edge chipping are identified. The SEM-stereophotography method and the finite element method are used to evaluate the edge chipping effect under a set of machining conditions. Significant findings are obtained and guidelines for controlling edge chipping during machining are suggested.
Grinding of Reaction Bonded Silicon Nitride (RBSN) Ceramic
Authors: Mayer John E. , Fang Gwo-Ping , Edler James P.
Published: July 2023

Experimental research has been conducted into the effect of grit depth of cut on the flexural strength of ground reaction bonded silicon nitride (RBSN) ceramic. Wheel grit size and machine parameters of wheel depth of cut, workspeed, and wheelspeed in surface grinding have been investigated. Results indicate that the primary factors which control the strength of ground RBSN ceramic are grind direction and grit depth of cut. A critical grit depth of cut was established at, and below, which maximum ground strength exists. Results were compared to those for hot pressed silicon nitride (HPSN) ceramic. A relationship between the critical grit depth of cut and the properties of the ceramic material has been suggested. Surface finish results are also reported.
A Framework for Modeling Variation in Vehicle Assembly Processes
Authors: Hsieh Ching C. , Oh Kong Ping
Published: July 2023

A method is described which facilitates the computer simulation of variation in vehicle assembly processes. The method uses data exchange locations, or DXL, to store data needed in the simulation. and coded keywords to manipulate those data. The DXL structure and the keywords may be tailored to the area of interest. Hence, the method is applicable to a wide range of problems. This paper gives some examples from the structural area to show how dimensional variation may be simulated.
Case Based Evaluation of Component Deterioration for Facility Maintenance
Authors: Takata Shozo , Shiono Hiroshi , Hiraoka Hiroyuki , Asama Hajime
Published: July 2023

With the advances of automation and integration, manufacturing becomes increasingly dependent upon facilities. Providing appropriate maintenance is, therefore, essential to achieve effective production. For planning maintenance strategy, it is necessary to know potential deterioration of the facility which may leads to various problems. In this paper, we propose a case based approach to the prediction of potential deterioration. Occurrences of deterioration are represented in terms of deterioration processes which are combinations of basic mechanisms. The evaluation is carried out by extracting subsets of deterioration cases which could occur at the specified area of the facility, and combining them to form the potential deterioration process. Effectiveness of the method is demonstrated by an experimental system.
Axisymmetrical Thermal Stress Analysis of Laminated Composite Finite Hollow Cylinders Restricted at Both Ends in Steady State
Authors: Katsuo Masahide , Sawa Toshiyuki , Kawaguchi Koji , Kawamura Hiroshi
Published: July 2023

The thermal stress distributions of laminated composite finite hollow cylinders restricted at both ends and at one end of the cylinders are analyzed using the thermoelastic displacement potential and Michell’s stress functions based on the axisymmetrical theory of elasticity. In the numerical calculations, the thermal stress distributions in the laminated composite finite hollow cylinders are examined. The effects of restrictions at the end of the cylinders on the thermal stress distributions are clarified. The analytical results are compared with the results obtained from the plain strain the ory. It can be seen that the differences in the stresses between the inner cylinder and the outer cylinder increase near the restricted end. The hoop and the axial stresses distribute discontinuously at the interface of the cylinders. The difference in the hoop stress at the interface is minimal in the case of the plain strain theory. For verification, the strains were measured and the analytical results were in fairly good agreement with the experimental results.
Systems Engineering: A New Framework for Engineering Design
Authors: Hazelrigg George A.
Published: July 2023

There is a widespread tendency to frame engineering design as a problem-solving activity. In this framework, the goal of a design is to satisfy functional requirements, subject to constraints, at minimum cost. It is shown below that this approach can lead to seriously non-optimal designs, and it further denies the use of a broad spectrum of fruitful tools that open up to the design engineer if only design is viewed instead as a decision-making process. In this context, a definition is given for systems engineering. Then, this definition is built upon to create a new framework for engineering design that has at its base the assertion that design is a process of decision making that is amenable to treatment using classical decision theory.
A Thermal Fatigue Model for Surface Mount Leadless Chip Resistor (LCR) Solder Joints
Authors: Pao Y.-H. , Jih E. , Siddapureddy V. , Song X. , Liu R. , McMillan R. , Hu J. M.
Published: July 2023

The reliability of surface mount leadless solder joints, e.g., LCCC (leadless ceramic chip carrier), LCR (leadless chip resistor), and LCC (leadless chip capacitor), has been a long-term research topic due to the concern of thermal fatigue failure resulting from significant stresses and strains induced in the joint. Numerous studies of failure analysis of leadless solder joints exist in the literature, and a number of life prediction models based on different failure characterizing parameters, e.g., total strain, plastic strain, strain energy density, etc., have been developed for particular loading conditions, such as isothermal or thermal cyclic fatigue tests. To name a few, e.g., one can refer to Engelmaier (1984), Cltterbaugh and Charles (1985), Hall and Sherry (1986), Clech and Augis (1987), Wong et al. (1988), Bae et al. (1989), Solomon (1990), Frear et al. (1991), Satoh et al. (1991), Lee and Stone 91991), Lau (1991), Govila et al. (1994), Schroeder and Mitchell (1994), JPL (1994), Syed (1995), Wen and Ross (1995), Jih and Pao (1995), Zhang et al. (1996), Kawai et al. (1996), Hu (1996), Guo and Conrad (1996), Lin et al. (1996), and Lau and Pao (1996).
Flow Modeling of Wire Sweep in Transfer Molding
Authors: Chen Xiao Hong , Lee K. S. , Yuen M. M. F. , Tong Pin
Published: July 2023

Transfer molding is one of the most widely used process for encapsulating integrated circuits. Wire sweep is becoming a critical process defect in the era of miniaturization of electronic products. This is because wire sweep can cause electrical short as integrated circuit lead count increases which leads to reducing wire pitches. Common practices in predicting wire sweeps in encapsulation calculate first the flow in the cavity without wires. The drag force on the wires is then calculated based on the local velocity using the flow drag relationship of flow in an infinite medium. Recent experimental result has shown that wire density had a strong influence on wire sweep. This paper describes both an empirical prediction and a stokes flow analysis of flow wire interaction on wire sweep. The analysis determined the flow induced loads on the wires for different wire shapes, spacing, and locations from the wall.
Computer Modeling of Steady and Transient Flows Within a Gasoline Fuel Injector
Authors: Ren Wei-Min , Nally John F.
Published: July 2023

The steady and transient internal flows within an automotive fuel injector are studied by solving ensemble-averaged, three-dimensional mass and momentum conservation equations. In the analysis, the effects of operating pressure, orifice size, and needle lift on the static flow rate, and the effect of opening rate on the dynamic flow rate have been parametricly investigated. Pressure drop was varied from 100 kPa to 500 kPa; the orifice diameter and needle lift ranged between 400 μm to 700 μm and 60 μm to 120 μm, respectively. A multiblock moving mesh method was used to simulate the needle motion.

Predicted static flow rates provide good agreements with the experimental measurements. Static flow increases as the orifice diameter increases. For a constant orifice diameter, static flow rate is found sensitive to the changes of the needle lift for a large nozzle while relatively insensitive for the smaller one. Dynamic flows under various needle opening rates are calculated and results are presented.
The LVEL Turbulence Model for Conjugate Heat Transfer at Low Reynolds Numbers
Authors: Agonafer Dereje , Gan-Li Liao , Spalding D. Brian
Published: July 2023

A simple method is described for calculating distances from walls in circumstances of complex geometry. This is then used as the basis of a comparative study of conjugate heat transfer, involving two previously published and one new low-Reynolds-number turbulence models. It is argued that the new model, called LVEL, performs as well as the older Lam-Bremhorst-Yap and Two-Layer-κ-ε models. Since it is computationally less expensive, and easily applied to three-dimensional problems, it is recommended for practical use, especially for electronics-cooling applications.
The Determination and Utilization of AuSn Solder Creep Properties to Bond GaAs Dice to Diamond Substrates
Authors: Chandran B. , Schmidt W. F. , Gordon M. H. , Djkaria R.
Published: July 2023

The stress in gallium arsenide dice larger than 2mm × 2mm conventionally bonded to diamond substrates using eutectic gold-tin solder is larger than the dice’s fracture strength leading to fracture during bonding. This paper discusses a novel bonding technique to reliably bond large gallium arsenide devices to diamond substrates using eutectic gold tin solder. In this technique, the cooling process after bonding is controlled to induce creep in the solder layer. Creep deformation in the solder layer relieves part of the stress in the die and thereby prevents die cracking. An analytical model describing the stress relaxation in the die due to solder creep deformation was developed. Due to the lack of published creep properties of AuSn solder, they were experimentally determined. Optimal cooling curves were generated using the relaxation model to reliably bond different sizes and thicknesses of GaAs dice to diamond substrates. Bonding experiments indicate that all the bonded dice cooled using conventional techniques cracked after bonding and that those cooled using the generated cooling schemes survived. Previously, these creep properties were boot-strapped from the published values for other solders. The experimentally obtained properties deviate substantially from those previously boot-strapped. However, it is interesting to note that the implied cooling schemes were similar.