bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Inlet Flow Parameters on Confined Turbulent Swirling Flow
Authors: Dong Mingchun , Lilley David G. 
Published: March 2021

Abstract
The development of a primitive-variable finite difference computer code is discussed, with application to a turbulent swirling nonreacting flow in a typical combustor. Primary air enters through the main inlet, and a secondary annular inlet in the outer wall is permitted through which secondary air flows. Parameters of special interest include the secondary to primary velocity ratio, primary swirl and contraction angles, and secondary swirl and upstream angles. Combustor flowfield predictions are given to illustrate the effects of these parameters on the flowfield (velocities and turbulence levels), and the dramatic effects are illustrated via velocity profiles and streamline patterns.
New Algorithm for Solution of the Non-Linear Equation Systems Occurring in the Design of Thermal Systems
Authors: Saraç Halil Ibrahim , Güven Hasan Riza , Sözbir Nedim , Uysal Ünal 
Published: March 2021

Abstract
Models used for the design of thermal systems often lead to non-linear equations which can be converted to linear systems. In this paper, a new algorithm is described for the solution of linear equation systems which have normal or ill-conditioned form A new algorithm and the Gauss-Seidel method were used for two-stage air compression with an inter-cooler. The solutions obtained by using two different methods are compared.
Implementation of the Hartley-Transform-Based Block LMS Algorithm
Authors: Ogunfunmi Tokunbo 
Published: March 2021

Abstract
This paper presents a cost-effective The Frequency-domain Least-Mean-Square (FLMS) adaptive algorithm (or more generally the Transform-domain LMS adaptive algorithm) [12], [13] has mainly two advantages over the conventional LMS algorithm [19]. The first is that it overcomes the slow convergence of the LMS algorithm by orthogonalizing the input (thereby performing better than the LMS for correlated input signals) and the second advantage is that it can be used for implementing the time-domain Block LMS (BLMS) algorithms as well [18].
The Hartley transform is a newly introduced real-to-real transform that is a suitable replacement for the complex Fourier transform [1] and [2] in several adaptive filtering applications such as adaptive interference cancellation that has wide applicability to problems in telecommunications, biomedical engineering, etc.
The realization of the Transform-domain BLMS adaptive algorithm based on the Discrete Hartley Transforms (DHT) and its implementation on the TMS320C30 digital signal processor chip is described.
A Representation Language for Mechanical Behavior
Authors: Neville Dorothy , Joskowicz Leo 
Published: March 2021

Abstract
Automating mechanism design requires developing a representation language for describing mechanism behavior. The language is necessary to specify design requirements, to describe existing mechanisms, and to catalog them for design reuse. This paper presents a simple and expressive language for describing the behavior of fixed-axes mechanisms. The language uses predicates and algebraic relations to describe the positions and motions of each part of the mechanism and the relationships between them. It allows both accurate and complete descriptions and partial, abstract, and under-specified descriptions. We show that the language is computationally viable by describing how to automatically derive behavioral descriptions stated in the language from the mechanism structure. To test its usefulness, we describe a design validation algorithm that determines if a given mechanism structure can produce desired behaviors stated in the language.
Development of a Machine Understandable Language for Design Process Representation
Authors: Shah Jami J. , Bliznakov Plamen I. , Urban Susan D. 
Published: March 2021

Abstract
This paper describes the work in progress at Arizona State University to develop a design process description language. The intent is to go beyond decision making level in recording design activities, thus providing a basis for broad application of the proposed representation. At the same time the granularity is limited to a feasible level. The design language proposed in this paper currently is Prolog-based. It is able to relate the sequence of actions to attributes of the design artifacts, thus, providing reference to the product data. Specifics of the design process which are reflected in a natural way include iterations of the activities, versioning of the designs, as well as reasons, purpose, constraints, and method / knowledge / technique used for design decisions (although the latter is currently done in a somewhat unstructured manner). The association between rationale, actions, and artifacts is captured, so explanation of previous designs is adequately supported.
The Synthesis of Planar Linkages to Satisfy an Approximate Motion Specification
Authors: Mirth John A. 
Published: March 2021

Abstract
This paper introduces the method of quasi-precision position synthesis for planar linkages. A quasi-precision position is defined by an approximate region that the mechanism must pass through. The quasi-precision position problem specification generates an increased design region by not requiring the accurate position specification that is characteristic of optimization and precision position methods. The design space is generated by intersecting the individual design regions of different four position sets. Each four position set consists of three exact positions plus one quasi-precision position. The method allows for the use of any number of quasi-precision positions. The result of using quasi-precision positions is an increase in the available design space without violating the basic problem constraints. The increased solution region gives the designer a greater variety of choices while reducing the number of required design iterations. The complete process of quasi-precision position synthesis is presented through the use of an example.
Testing of a Relative Comparison Method for Evaluating Design Concept Alternatives
Authors: Diteman Michele L. , Stauffer Larry A. 
Published: March 2021

Abstract
Two methods for assessing conceptual alternatives for the solution of a design problem are compared in the areas of reliability, sensitivity, and validity. The method utilizing relative comparisons has been shown in previous analysis to be more usable than the method utilizing absolute ratings, but the current analysis shows that the relative comparison method does not produce results as well as the absolute rating method in the areas of reliability and validity.
An Exploration of Engineering Learning
Authors: Brereton Margot F. , Leifer Larry J. , Greeno James , Lewis Jason , Linde Charlotte 
Published: March 2021

Abstract
This paper explores how students learn engineering, paying particular attention to development of engineering intuition.
Examination of traditional engineering curricula reveals that design and analysis are taught in separate classes. In contrast, learning theory and engineering design practice suggest engineering is best learned through integrated experiences. “Synalysis exercises”, which integrate activities in problem formulation, analysis and synthesis, have been developed to study integrated learning. Video analysis of the exercises reveals how students use formal knowledge in practice, the processes by which they learn and the social context in which learning occurs. The integration of dissimilar activities in synalysis exercises is found to evoke questioning behavior and to provide resources for answering questions. The exercises are explored as a tool for educational assessment.
Development of Design Skills Through Employment of Open-Ended Problems
Authors: Brock Harvey R. , Condoor Sridhar S. , Burger Christian P. 
Published: March 2021

Abstract
With the recent increased concern about the design and problem solving needs of U.S. industry, and academia’s inability to address them, there has arisen a desire to incorporate open-ended problems in engineering education. In the initial stages most, if not all, real-world engineering problems are ill-defined, and have several acceptable solutions, i.e. they are open ended. Yet, our students get very little practice in finding solutions for this type of problem. Correcting this weakness in engineering curricula is hampered by misconceptions about, and inexperience with, these types of problems. As a consequence, educators often attempt to modify typical well defined example problems by expanding their scope, but still taking care to insure that the solution domains are closely circumscribed and well defined. The goal of this paper is to illustrate the main features of open-ended problems and their utility in design education. Such problems are characterized by incomplete or inconsistent information, no evident solution strategy, non-unique solutions, and often poorly understood goals. A real-world open ended design problem will be contrasted with its’ typical engineering education counterpart. This paper attempts to provide the necessary insights to aid in the formulation and selection of effective open ended problems for use in engineering education.
Experimental and Analytical Study of X-Ray Tube Rotor Dynamics
Authors: Nickel D. A. , Krousgrill Charles M. 
Published: March 2021

Abstract
An X-ray tube rotor has been analyzed, using experimental and numerical methods, as a part of an effort to diagnose an intermittent acoustic noise problem. The type of rotor studied is supported by two solid-lubricated angular contact bearings, and operates in a vacuum.
Experimental studies of rotor vibration were performed using a test fixture with radio frequency proximity sensors. Coast-down studies indicated the presence of both synchronous and sub-harmonic whirl, along with a tendency for the nature of response to change rapidly during operation.
Two ODE (ordinary differential equation) models: a three-dimensional four-degree-of-freedom model and a one-dimensional one-degree-of-freedom model were derived. Large bearing clearances were a significant source of stiffness nonlinearity in both. Direct ODE solution was used to analyze both models. Parametric continuation was also used to find periodic solutions to the one-degree-of-freedom model for different sets of parameter values. The simulations were performed with geometric and stiffness properties representative of the X-ray tube rotor. Small damping was assumed because of the solid lubricant.
Direct ODE solutions showed a variety of synchronous and subharmonic periodic motions. Multi-branch frequency response curves were computed using continuation. Qualitative agreement between experimental and numerical results was obtained in terms of tendency to jump, frequency at which multivaluedness was first observed, and existence of subharmonic solutions.
Dynamics Response of a Hysteretic Structure Under Random Excitations
Authors: Orabi Ismail I. 
Published: March 2021

Abstract
The response of a hysteretic structure under horizontal and vertical random excitations is considered. The excitations are modeled by segments of stationary and nonstationary Gaussian white noise and filtered white noise processes. The linearization technique is used and the moments equations of the responses are evaluated. The transition probability density of the response is described and the associated second moment equations are derived. The transient and nonstationary response statistics for a range of values of parameters are obtained. A Monte-Carlo digital simulation study is performed. The results are compared with the theoretical findings and good agreements is observed. Particular attention is given to the amplification effects of the vertical acceleration. It is shown that the effect of the vertical excitation is usually insignificant, unless the load coefficient is quite large.
On-Line Identification and Location of Rotor Cracks
Authors: Ratan Santosh , Baruh Haim , Rodriguez Jorge 
Published: March 2021

Abstract
A new method is proposed to detect and locate a crack in a rotor system. A vector quantity ‘Residue’ is defined using the measured vibration response of the rotor system and the modeled system matrices. It is shown that the non-zero elements of ‘Residue’ correspond to the nodes encompassing the element carrying the crack. Although, the derivation of ‘Residue’ is based on the linear model of the rotor system, the response due to the non-linearity caused by the breathing of the crack causes only a small amount of contamination. To investigate the robustness of the proposed method, a sensitivity analysis is conducted. It is found that the method could detect a crack of as small depth as 4% of the shaft diameter. The effects of light damping and the order of finite element discretization on the detection result are also investigated, and are found to be small.
Parametrically Excited Nonlinear Two-Degree-of-Freedom Systems With Repeated Natural Frequencies
Authors: Nayfeh A. H. , Chin C. , Mook D. T. 
Published: March 2021

Abstract
The method of normal forms is used to study the nonlinear response of two-degree-of-freedom systems with repeated natural frequencies and cubic nonlinearity to a principal parametric excitation. The linear part of the system has a nonsemisimple one-to-one resonance. The character of the stability and various types of bifurcation are analyzed. The results are applied to the flutter of a simply-supported panel in a supersonic airstream.
Extended Decision Tables for Multistate Fault Tree Synthesis
Authors: Wang J. D. , Liu T. S. 
Published: March 2021

Abstract
This study presents component modeling based on extended decision tables for multistate fault tree synthesis. Events are defined by both qualitative and quantitative forms. Compound functions of subsystems, such as redundancy, are described by virtual transfer components. Editing procedures are implemented to expedite the synthesizing process and prune the generated fault trees. A pressure tank system is employed as an example to demonstrate the proposed mothed.
An Efficient Reliability Technique to Study the Performance of Rocket Motors
Authors: Janajreh Ibrahim M. , Heller Robert A. 
Published: March 2021

Abstract
An efficient reliability technique is developed based on Response Surface Methodology (RSM) in conjunction with the First Order Second Moment (FOSM) reliability method. The technique is applied when the limit state function cannot be obtained explicitly in terms of the design variables, i.e. when the analysis is performed using Finite Element Codes. When compared with exact analysis, results have shown an excellent agreement. Therefore, this technique allows the extension of most Finite Element Codes to account for probabilistic analysis, where statistical variations can be added to the design variables.
An explicit solution for rocket motors consisting of propellant and steel case under environmental temperature variations is compared to the RSM technique. The method is then used for the analysis of rocket motors subjected to two opposite line loads for which the stress analysis is performed using finite element method. Results have shown that the reliability of the motor decreases as the applied load increases or the storage time increases.
Fatigue Analysis of Induction Hardened Pins
Authors: Lindner Mark J. , Elbella Abdalla 
Published: March 2021

Abstract
A generalized procedure was developed to predict fatigue failure in the design of induction hardened pins. Finite element analysis was used to determine the elastic and inelastic strain response at subsurface locations. The finite element mesh was arranged in a layered fashion in which each layer had a unique cyclic stress-strain curve. The procedure incorporated the effects of residual stresses due to induction hardening and used the strain-life approach to determine fatigue life and damage. The areas of predicted failure agreed with those observed in the field.
Crack-Tip Fields of Short Cracks in Bending As Characterized by Two Parameter Criterion
Authors: Zarzour J. F. , Dah-Wei Y. , Kleinosky M. J. 
Published: March 2021

Abstract
Single edge notched bars (SENB), in the bending mode, with a/W ratios ranging from 0.05 to 0.5 were examined for fracture toughness in terms of the J-integral approach. The results indicate that for a/W ratios less than 0.3, there is a significant loss of J-dominance. This loss is attributed to the effect of plastic deformation on the cracked face. For a/W ratios greater than 0.3, J-dominance is maintained into the large scale yielding regime. According to the recently developed two-parameter criterion (J,Q), compressive Q-stress was interpreted as an indication of low crack-tip stress triaxiality for shallow cracks, while positive Q-stress was associated with high crack-tip stress triaxiality for deep cracks. For the material properties and specimen geometries considered herein, a fracture toughness locus was constructed in terms of the (J,Q) parameters for each of the a/W ratios. The overall fracture data are in agreement with those predicted by other approaches and provide a rigorous framework for interpreting the effect of loss of crack-tip constraint in elastic-plastic fracture analyses.
Member Stiffness and Contact Pressure Distribution of Bolted Joints
Authors: Lehnhoff Terry F. , Ko Kwang-Il , McKay Matthew L. 
Published: March 2021

Abstract
Member stiffnesses and the stress distributions in the bolts and members of bolted joints have been calculated for various bolt sizes, as well as thicknesses and materials of the members. The finite element method has been used to calculate the displacements and the stress distributions in the components of the bolted joint. Using axisymmetric elements, the bolted joint was analyzed as a two-dimensional problem. Member stiffness ratios were calculated from the finite element results and compared with those calculated by a commonly used theory. The differences in values were significant (16–30 percent difference) for the assumptions under which the theory was applied. Formulas and dimensionless curves which can be used to estimate the member stiffness ratios for several kinds of bolted joints are presented.
Analysis and Results of an SCS-6/Ti-15-3 MMC Reinforced Ring Structure Under Internal Radial Loading
Authors: Gravett Phillip W. , deLaneuville Robert E. 
Published: March 2021

Abstract
This paper presents a stress analysis method and test results of a ring structure reinforced with SCS-6/Ti-15-3 MMC under an applied internal radial load. To assess the structural integrity of an MMC reinforced component, the state of stress within the component must be determined. Two major factors complicating the state of stress in the given MMC reinforced rings are the stress concentrations caused by the load fixture and the thermal residual stresses induced during processing. To model the stress concentrations, the ring and its load fixture were modeled as a 3-d solid finite element model. To calculate the processing residual stresses, a 2-d axisymetric finite element thermal stress analysis was completed. Plasticity was modeled with the 2-d axisymetric finite element model accounting for the nonlinear response of the MMC core and monolithic sheath. Testing of the rings at room and high temperature showed good correlation to load-deflection calculations while ultimate strength was far less than predicted. Subsequent post failure analysis revealed preexisting damage within the MMC which was not detected by pretest NDE inspections. This damage did not significantly affect the measured stiffness of the ring, but diminished the ultimate strength by reducing the capability of the MMC in a localized area.
Long Duration, High Temperature Creep/Relaxation Data for Near Eutectic Pb-Sn Solder
Authors: Mason Jerry , Caroselli Rom , Russell Stan 
Published: March 2021

Abstract
A model for solder behavior based on nonlinear dynamics has been developed by the authors (1990–1992). Supporting this study, data have been collected for near eutectic Pb-Sn solder joints using a ring and plug geometry which has been subjected to isothermal (80°C, 120°C) creep/relaxation loading ranging over a period of time up to 260 hours. Four types of relaxation data were observed: (1) smooth, low rate of unloading, (2) smooth, high rate of unloading, (3) onset of unstable racheting, and (4) onset of unstable, irregular unloading. Types (1) and (2) appear to be related to grain boundary and matrix creep, respectively. These are two creep mechanisms which have been reported in the literature. As far as we are aware, types (3) and (4) have not been previously reported by other investigators in terms related to solder instability. Therefore, our purpose is to document, in some detail, conditions under which unstable behavior has been observed. A detailed discussion is made of variables which control and measure instability including loading, fixture load cell stiffness and material type, and checks of instrumentation accuracy. This paper reports details of the experimental study regarding test specimens, test fixture, instrumentation and calibration, and environmental control. This paper provides a summary of data collection.
Microstructurally Based Thermomechanical Fatigue Lifetime Model of Solder Joints for Electronic Applications
Authors: Frear D. R. , Rashid M. M. , Burchett S. N. 
Published: March 2021

Abstract
We present a new methodology for predicting the fatigue life of solder joints for electronics applications. This approach involves the integration of experimental and computational techniques. The first stage involves correlating the manufacturing and processing parameters with the starting microstructure of the solder joint. The second stage involves a series of experiments that characterize the evolution of the microstructure during thermal cycling. The third stage consists of a computer modeling and simulation effort that utilizes the starting microstructure and experimental data to produce a reliability prediction of the solder joint. This approach is an improvement over current methodologies because it incorporates the micro-structure and properties of the solder directly into the model and allows these properties to evolve as the microstructure changes during fatigue.
MMC Ring Fatigue and Fracture Life Prediction: An Engineering Model
Authors: Halford Gary R. 
Published: March 2021

Abstract
The framework of an engineering creep-fatigue durability model has been adapted for use in estimating the radial static burst pressure and cyclic low-cycle fatigue macro-crack initiation resistance of continuous fiber reinforced (CFR) metal matrix composite (MMC) rings for application at 800 °F. Rings of circumfrentially wrapped SCS6/Ti-15-3 were manufactured by Textron Specialty Metals and burst tested by Pratt & Whitney as a part of a cooperative program with the NASA Lewis Research Center. Fatigue tests have as yet to be performed. The engineering model is based on a 3-D elasto-plastic micromechanics analysis of the tensile-loaded composite architecture. Use is made of the rule of mixtures, strain compatibility, equilibrium, and the stress-strain relationships of the constituents. Knowledge is required of the mechanical and fatigue properties of the matrix and fibers and how the presence of each affects the sharing of imposed stresses and strains. The model addresses specific issues such as residual fabrication stresses, inelastic deformation within the ductile matrix, multiaxial constraint imposed on the matrix, cyclic relaxation of both residual and applied mean stresses in the matrix, fatigue micro-crack initiation and propagation in the matrix, and tensile fracture of both the ductile matrix and the brittle fibers. In the current application of the model, the specific issues were empirically calibrated through use of tensile and tension-tension fatigue coupons that had been subjected to essentially identical loading as the rings.