bluuebunny/crossref_metadata_2025_split huggingface dataset:
Worst Case and Statistical Tolerance Analysis of the Daughter Card Assembly
Authors: Guilford James , Sethi M. , Turner Joshua 
Published: March 2021

Abstract
Designers are increasingly finding the need for an automated tolerance analysis package which interprets tolerances according to established tolerancing standards. Unfortunately, most of the commercial packages available make simplifying assumptions for the conventional plus-minus tolerances and do not support geometric tolerancing at all. Construction of a tolerance analysis models with these packages can be time consuming.
GEOS is an automated tolerance analysis package which overcomes these shortcomings. It is based on variational modeling and feasibility space approaches. This report presents the results for a worst case amd statistical tolerance analysis done on an industrial assembly using GEOS. For this analysis, no special models had to be created as GEOS can accept the 3-D CAD model directly. The models used both conventional plus-minus tolerances as well as geometric tolerances. A GEOS graphical front-end, integrated with a commercial CAD system, was used to define the assembly relations, design function, and analysis parameters.
On the Effects of Parallelism on Computer-Aided Process Planning
Authors: Levin Jordan B. , Dutta Debasish 
Published: March 2021

Abstract
Computer-aided process planning is a critical function in the overall scheme of computer-integrated manufacturing (CIM). Progress in CIM is key to increased productivity. Furthermore, as new CIM systems evolve, the latest advancements from the constituent areas must be incorporated. Toward that end, our ongoing research deals with the development of methodologies to enable the inclusion of a new class of machine tools characterized by their ability to carry out machining operations in parallel. In this paper, we identify and elaborate on the effects of parallelism on computer-aided process planning, which are brought about by these new machine tools.
Numerical Design Method to Obtain Minimum Pressure Losses in Duct Elbows
Authors: Paul James C. , Noles David R. 
Published: March 2021

Abstract
A numerical procedure has been developed for the design of duct elbows that exhibit minimum pressure loss. A two-dimensional potential flow modeling method is used to determine the ideal static pressure distribution for a given elbow geometry. A turbulent boundary layer separation criterion is then used to determine whether the ideal distribution can be obtained. Those elbow designs for which flow does not separate are shown to produce minimum pressure loss. The procedure is also shown to be effective in the design of turning vanes. The design method is confirmed by experiments with a 90 degree elbow within a square duct.
The Use of Von Karman’S Similarity Hypothesis in Turbulent Fluid Flow Computation
Authors: Foster David J. 
Published: March 2021

Abstract
Von Karman’s similarity hypothesis for the turbulent mixing length in boundary layer type flow is extrapolated to a plausable two dimensional expression. The corresponding incompressible turbulent flow equations are developed in terms of the transient vorticity transfer and stream function equations. Numerical solutions for the separated flow behind a step and in a rectangular cavity were obtained and the results are presented pictorally. The streamlines computed for the step flow solution compare favorably with those calculated from experimental measurements at a similar Reynolds Number.
Development of Finite Element Analysis Support System Based on the Hybrid Knowledge Model
Authors: Nagasawa S. , Sakuta H. , Goto M. 
Published: March 2021

Abstract
This paper deals with conceptual orientation and system development of intelligent support system for general purpose FEA (finite element analysis) programs.
An integrated support system called “InhierTalk” (Integrated interactive environment for hierarchical representation for FEA) has been developed in Smalltalk, an object oriented language, in order to confirm effectivity of hierarchical representation and to establish an optimum method of the system development.
Two object-oriented knowledge models which consist of macro visual data representation and micro regularized data representation are proposed. In the development, it is found to be clear that active and passive evaluation methods are effective for construction of support system.
A Blackboard Based Approach to Intelligent Finite Element Modeling and Analysis
Authors: Grosse Ian R. , Corkill Daniel D. 
Published: March 2021

Abstract
In this paper a methodology and associated system architecture is proposed for the development of an intelligent finite element modeling assistant. The technique is ideally suited for specific application domains in which the physical system to be modeled can be constructed from a limited and well defined set of features. The development of knowledges sources needed to support automatic finite element modeling and analysis is discussed. A computational framework is proposed for interfacing the various knowledge sources and controlling the execution of the knowledge sources in an opportunistic manner based on the multiple expert blackboard paradigm. An example application in the domain of finite element modeling and analysis of multichip module microelectronic devices is presented and discussed.
A Domain Decomposition Study for a Parallel Finite Element Code
Authors: Rodriguez J. , Sun J. 
Published: March 2021

Abstract
The primary objective of this study was the implementation and comparison of domain decomposition algorithms for a parallel Finite Element Method (FEM) used in the area of Computational Structural Mechanics (CSM). A parallelized FEM code exploits the concurrency inherent in the method to improve its computational efficiency. In order to use a larger size granularity in the parallel computation, the parallel FEM needs to partition its domain into subdomains in a proper manner. It is therefore necessary to search for domain decomposition algorithms to satisfy the special requirements of a parallel FEM.
The domain decomposition algorithms investigated in this study physically decompose a meshed domain into a desired number of subdomains. Addressing the requirements of the parallel FEM, these algorithms are able to handle any type of two- and three-dimensional domains, balance the workloads across the multiple processors, minimize the communication overhead among the processors, maintain the integrity of each subdomain, minimize the overall bandwidth of the resulting system matrix, and require only a small amount of CPU time for the decomposition.
Modifications to existing decomposition algorithms, such as the single wave propagating method and the bisecting method using vertical/horizontal cuts, are investigated. A new algorithm, based on the proposed multiple wave propagating method and the bisecting method using middle cuts, is formulated. These algorithms are compared with each other using performance criteria based on the overall FEM code and the algorithms themselves. An optimal combination algorithm is proposed. This algorithm combination is flexible and intelligent in some sense since several judgements are suggested to guide and organize different decompositions based on the general geometry of the meshes. The combination algorithm possesses both the desirable features of wave propagating and bisecting methods.
As an application, the present algorithm is included in an existing parallel FEM code and some improvements in this code are made. The overall efficiency of the FEM code was increased.
Error Estimation and Mesh Optimization for Finite Element Analysis of Short Fiber Reinforced Composite Materials
Authors: Kim H. G. , Grosse Ian R. , Nair S. V. 
Published: March 2021

Abstract
Knowledge of internal stress fields in fiber or whisker reinforced composites is crucial to the design, manufacturing and applications of composites. Finite element analysis (FEA) presents the only rigorous approach to a solution of this problem. However, the application of FEA to composites requires careful attention to the geometry of the optimum mesh used in the analysis. Standard energy analysis and mesh refinement procedures have yet to be generalized or extended to the special case of fiber or whisker reinforced non-homogeneous composites. Current automatic mesh generation codes do not provide the optimum mesh for composites.
This paper is concerned with the development of a generalized approach for optimal mesh refinement in a short fiber reinforced composite. Optimization procedures are based on the calculation of the error in energy norm for global convergence and the traction differential approach at the fiber/matrix interface for local convergence whereas the mesh refinement strategy is based on the use of elongated elements at the fiber/matrix interface. An isoparametric finite element model that has a periodic hexagonal array of elastic fibers surrounded by an elastic matrix was used in the investigation. It is shown that this approach provides the optimum mesh with a much more rapid convergence than conventional meshes. In this manner converged local solutions can be obtained with significantly lower degrees of freedom than by conventional mesh refinement methods.
Response of a Cylindrical Section to an Internal Blast
Authors: Gupta Aaron Das 
Published: March 2021

Abstract
Transient response analysis of a hollow cylindrical section subjected to an internal explosive blast has been conducted from a structural integrity standpoint. The reflected blast overpressure upon the internal surface of the cylinder was estimated based on a cube root scaling law and the modified Friedlander exponential decay. A closed form solution of the governing equation of motion for the internally pressurized cylinder was obtained subject to initial conditions. The solution was optimized by a trial and error approach to yield an optimum time which was employed to predict the peak response.
Matrix Solution of Digitized Planar Human Body Dynamics for Biomechanics Laboratory Instruction
Authors: Alciatore David G. , Abraham Lawrence D. , Barr Ronald E. 
Published: March 2021

Abstract
The dynamics of planar human body motion, solved with a non-iterative matrix formulation, is presented. The approach is based on applying Newton-Euler equations of motion to an assumed 15 body segment model resulting in a system of 48 equations. The system of equations was carefully ordered to result in a banded system (bandwidth = 10) which is solved efficiently. The method is more favorable than a traditional iterative solution because it is more easily coded, reaction forces are more easily dealt with, and multiple solutions for a given body position can be readily obtained. The results described are limited to planar body motion but the method is easily extendible to general three-dimensional motion. A computer program was developed to process digitized body point coordinate data and calculate resultant joint forces and moments for each frame of data.
This method of human body dynamics analysis was developed to support laboratory instruction for an Engineering Biomechanics course. Athletic activities are captured with a three-dimensional video digitizing system and the data is processed resulting in time histories of force and moment distributions throughout the body during the captured event. Computer software performs the analyses and provides real-time graphical illustrations of the kinematics and dynamics results. The dynamics results for the leg of a runner are presented here as an example of the application of the method.
Comparison of Web Stress Concentration Factors and Safety Margins for a Thin Webbed Spur Gear Subjected to Static and Cyclic Loading Conditions
Authors: Clerici Paolo , Girotti Ambrogio , Perazzolo Alessandro 
Published: March 2021

Abstract
The stress distribution in the holed web of a gear was studied in order to evaluate the effects of overstress caused by a reduction in weight in comparison with a gear without lightening holes. The analysed gear is a component of a helicopter principal transmission: geometry and dimensions (web with eight circular holes) are usually employed.
A 3-D mesh of the gears was made using PATRAN and a FEM analysis was carried out using NASTRAN 65a2.
Moreover the principal stress history in one revolution of the gear was reconstructed at the critical points of the web. Thus it was possible to evaluate the actual fatigue cycle and the consequent safety margin for the different load conditions under which helicopter transmissions are generally checked.
It was found that the stress variations in one revolution of the gear are significant even in constant power conditions and that the stresses at each point on the border of the holes always have the same sign in a complete revolution.
Safety margins in the web were evaluated and compared using different formulas.
A Study on the Hourglass Worm Gearing Manufactured by a Pinion Cutter
Authors: Maki Minoru , Nagashima Sakae , Horiuchi Akiyo 
Published: March 2021

Abstract
A method to obtain the higher productivity of hourglass worm gearing with high performance is developed. For this purpose, a method for manufacturing the worm by a pinion cutter is developed, along with a method for analyzing how the cutting blades generate the worm tooth surface.
A method to calculate the true profiles of the worm tooth surface generated by the pinion cutter blades is discused. These calculating method are available for any kind of the gearing manufactured by any type of cutting tool.
Characteristics of a Modified Double Enveloping Worm Gear Drive
Authors: Simon Vilmos 
Published: March 2021

Abstract
A modified new type of double enveloping worm gearing is developed. The gear tooth surface is generated by a flying tool whose cutting edge has the modified profile of the entering edge of the worm, and the worm surface has a straight-lined axial profile and circular lead changed to the established rule. The same rule governs the motion of the flying tool in processing the gear teeth.
To compare the performance characteristics of the classical and the modified new type of double enveloping worm gearings, the load distributions are calculated and the elastohydrodynamic analysis of lubrication is carried out for both types of worm gearings. The obtained results show the advantages of the new type of double enveloping worm gear drive.
A Study on Hourglass-Worm Gearings Designed to Concentrate Surface Normals: Design for Worm Gearings With a Large Lead Angle
Authors: Gunbara Hiroshi , Shimachi Shigeyuki , Kobayashi Tohru , Kawada Hiroshi 
Published: March 2021

Abstract
For moderating the edge contact of gear tooth surfaces on load, a new concept has been proposed on designing worm gearing. As a first step of research, restricting a field of application of the designing concept, a few methods for generating tooth surface of hourglass worm gearing having a small lead angle have been devised.
This paper tries to apply this designing concept to wider general use — an hourglass worm gearings with a large lead angle. First, the worm axis displacement relative to the wheel axis is roughly calculated by means of elastic deformation theory. And, this idea is applied to the gear designs using two kinds of hourglass worm gearings. As a result, validity of this design concept is substantiated also in the case of large lead angle of worm gearing.
Laser Holographic Measurement of Tooth Flank Form of Cylindrical Involute Gear: Part 1 — Principle and Measurement of Spur Gear
Authors: Kubo A. , Fujio H. , Tochimoto S. , Honda T. , Saitoh S. , Suzuki M. 
Published: March 2021

Abstract
Form deviation of tooth flank of spur gear is measured by laser holographic interferometer. To get the reflected ray from the objective tooth flank, laser beam is irradiated with large incident angle to the objective tooth flank which has considerably rough surface finish in comparison with that of optical parts. Some tooth flanks with various kinds of form deviation were measured, and image patterns of interference fringe were obtained. The conversion of the coordinates of the image figure of the gear tooth flank on CRT to the coordinate system of the gear is worked out by fitting the contour form of simulated figure to that of observed images. The algorithm of transformation from interference fringe pattern to tooth flank form deviation is shown: The brightness of the interference fringe image on the CRT is converted to the amplitude of form deviation defined on the plane of action of the gear via phase difference of light beam which is obtained by phase stepping method. The form deviations of tooth flanks of spur gear obtained by this interference method were compared with the results of conventional measuring method using contacting stylus.
Computer-Aided Optimal Gear Design
Authors: Andrews G. C. , Argent J. D. 
Published: March 2021

Abstract
Gear-sets designed using standard tooth profiles are rarely optimum strength designs, where “optimum strength” is defined as the maximum tooth bending strength for minimum tooth numbers and tooth size. However, standard tooth profiles are widely used because of the difficulty of determining the amount of hob (or rack) “offset” necessary to cut optimum strength non-standard gears. Also, stresses are not easily calculated for non-standard tooth profiles since geometry factors (I and J) are not tabulated. This paper describes a computer-aided method for obtaining optimum strength designs of spur gears, through iterative strength calculations. Two common cases are considered in which a non-standard gear-set is to replace a standard gear-set with the same center distance. When the speed ratio must be rigidly maintained, the “long and short addendum method” can be used; when minor variations in speed ratio are permissible, the “non-standard center distance” method can be used and much larger increases in strength can be achieved. The methods are illustrated by a numerical example. Increases of strength in the range of 10 to 20 percent are typical when standard gears-sets are replaced by non-standard gears with the same center distance, assuming material properties remain constant. The procedure for estimating the hob offsets which yield optimum design is simple and novel, and has proved efficient in obtaining convergence in a few iterations of the optimization process.
Analysis of an Eight Speed Gear Train Using a Narrowing Iterative Step Algorithm
Authors: Osman M. O. M. , Dukkipati R. V. , Siva Prasad V. 
Published: March 2021

Abstract
Analysis of double composite gear trains using the algebraic equations method involves a great deal of manual manipulations. Though the tedium of the process is reduced to some extent by the use of the General Theory, it will not lead to realization of computer algorithm generalized for all kinematic versions of a drive. The present algorithm based on the Unified Theory provides an efficient method to find values of the largest gear at a design optimization point Sop. The narrowing iterative step technique facilitates rapid convergence to the pivotal point. Six kinematic versions of open type having uniform group structure are analysed using the algorithm.
The Linear Approximated Equation of Vibration for a Pair of Spur Gears: Theory and Experiment
Authors: Cai Yurong , Hayashi Teru 
Published: March 2021

Abstract
The nonlinear equation for the rotational vibration of a pair of spur gears has a restriction that the analytical solution of the equation cannot be obtained. In this paper, the linear equation of vibration is derived theoretically and its physical model, i.e. the linear model of vibration is presented. The analytical solution of the linear equation, which is derived by analytical method, agrees well with the numerically calculated result by the nonlinear equation. By analyzing the analytical solution of the linear equation in detail, we clarified the relation between the waveforms of the vibration and the profile error of gear pairs, and also found that the effect of the contact ratio to the vibration is large and complex. The equivalent error, accounting for effects of the static load, the time-varying stiffness and the profile error of gear pairs, is proposed in this paper. It can be considered as promising for evaluating the profile error, because the vibration of gear pairs is excited mainly by the equivalent error. Finally, for confirming the above results, the vibration of two tested gear pairs has been measured by an experimental set-up for this purpose.
Recursive Determination of Conjugate Profiles in Planar Motion With Application to Gear Design
Authors: Innocenti Carlo 
Published: March 2021

Abstract
A general procedure for determining the envelope of the outline of planar rigid figures is presented which allows both local and finite undercutting to be taken into account. A suitable parametrization of the enveloped curves, together with the insertion of cusps wherever undercutting occurs, enables the procedure to be applied recursively while maintaining high accuracy in describing the resulting envelopes. The proposed procedure provides the basis for an original validation method regarding parallel-axis spur and helical gears. The method takes into account possible undercutting during hobbing or shaping, considers the desired amount of meshing clearance over the entire tooth profile, and is able to detect meshing interference. Further, it provides a criterion in choosing the proper cutter profile. A numerical example showing the application of the method is discussed at the end of the paper.
A Few Aspects on Lubricant Selection for Stepless Chain Coverters: Efficiency and Service Life
Authors: Schönnenbeck G. 
Published: March 2021

Abstract
Stepless vehicle drives will assume their place next to automatic switching units throughout the world if they meet their expected fuel-saving potential. This necessitates optimizing the individual components of the CVT as regards their efficiency. The main source of losses are the hydraulic supply units and the losses which result specifically from non-positive transmission. In the case of stepless chain conveners, these result mainly from friction disk deformation. These losses account for 50 to 70 % of total CVT losses. Both loss components are influenced by the lubricant to a significantly greater extent than it would appear at first sight: In the case of fully-hydraulic clamping and control systems, the viscosity and its long-term stability determines the degree of leakage losses and therefore the size of the pump or pump combinations. This applies to pressure levels between 20 and 40 bar. This in turn is directly proportional to the hydraulic losses on the CVT. The friction coefficient of the lubricant determines the level of the necessary clamping forces. These are responsible for friction-disk deformation. Also of importance as far as the selection of lubricant is concerned is its influence on the CVT service life. The critical service life limits for chain converters are chain breakage (not the subject of this report) and evidence of wear, i.e. grey staining, sheave-grooving, pitting, scoring and rocker pin wear. Standardized test methods exist at P.I.V. for both wear manifestations and for the friction coefficient, these tests allowing a targeted selection of lubricants.