bluuebunny/crossref_metadata_2025 huggingface dataset:
Defence Acquisition Decision Support Through Design Systems Modelling and Exploration
Authors: Smith Warren F. , Hoadley Stephen R. , Moyle Nicholas J.
Published: December 2020

In this paper, two case studies are highlighted that relate to hypothetical decision support in the acquisition of major defence systems through design systems modelling and exploration. With defence acquisition processes becoming more global, the professional experiences of the “detailed systems designer” and the “client specifier / evaluator” are diverging. However, the notion of the client being an informed customer pervades and making right judgements in writing specifications and evaluating tenders relies on reliable design decision modelling and exploration. In providing design decision support to the acquisition organisation, we subscribe to and have applied the paradigm of “decision-based design” using the constructs of the Decision Support Problem Technique (DSPT). The technique offers a holistic systems approach that is flexible, adaptable and able to cope with change.
Modified Sequential Programming for Feasibility Robustness of Constrained Design Optimization
Authors: Yu Jyh-Cheng , Ho Wen-Chung
Published: December 2020

Design parameters are subject to variations of manufactures, environments, and applications, which result in output deviations and constraint uncertainties. Quality products must perform to specifications despite these variations. Conventional constrained optimum may not be statistically feasible due to design variations. This paper addresses design variation characteristics and proposes a design procedure to ensure feasibility robustness in design optimization. Product life cycles often affect design variables with characteristic patterns. The Design Variation Hyper Sphere (DVHS) is presented using the concept of statistical joint confidence regions and decoupling techniques to characterize the coupled variations of design variables. The pattern represents the possible design dispersions at a specified probability, which is a hyper sphere for normal variables. The radius of the hyper sphere is determined by the feasibility requirement. The proposed robust optimization algorithm, SROP, introduces DVHS to the sequential quadratic programming, and modifies the feasible region to accommodate the activity uncertainty. The procedure ensures the design feasibility without over sacrificing the performance optimality. The design of a helical spring serves as an illustrative example of the proposed procedure.
A New Method for Cutting Tools Design
Authors: Oancea Nicolae , Oancea Victor G. , Alexandru Epureanu
Published: December 2020

Most of the existing methods for determining the profiles of cutting tools that work by wrapping are based on the envelope theory. This theory requires cumbersome analytical formulations resulting in sets of equations not always easy to solve. This work presents a new alternative method for studying conjugated surfaces associated with rolling axodes by using a discrete representation of the tool. The new method is based on studying the trajectories of points on the tool relative to the workpiece in order to define the tool’s profile. Several examples are shown for rack, shaper and rotational cutters.
Qualitative Geometric Reasoning for Thermal Design Evaluation of Die Casting
Authors: Ma Yuming , Ragab Adham , Kabiri Khalil , Miller R. Allen
Published: December 2020

This paper discusses a qualitative geometric reasoning method which approximately evaluates the equilibrium thermal characteristics of die-castings and dies at the conceptual design stage. The main idea is to apply circuit analog of heat flow on a voxel model and build the heat flow network for the die. An approximate temperature distribution on the die is then obtained by geometric reasoning and thermal resistance computation on voxel model. The resulting temperature field of the die is visualized using volume visualization techniques, and heat converging regions (hot spots) can be identified from the pattern. Thermal control features can then be placed according to the location of the heat converging regions and part thickness. A prototype system has been implemented on Microsoft Windows-NT platform.
Machining: Quality, Cost and Environmental Estimation and Tradeoffs
Authors: Nicolaou Panicos A. , Thurston Deborah L.
Published: December 2020

The machining process affects manufacturing cost, product quality and the environment. This paper presents a method for formulating a mathematical model for first estimating quality, cost and environmental impacts of two machining operations (end milling and drilling), and then for tradeoff decision making. The milling quality estimation model is developed through virtual experimentation on a simulation model and the drilling quality estimation model through physical experimentation. Cost is estimated through an activity based costing approach. Environmental BOD and FOG impacts are estimated through stoichiometric analysis of cutting fluids. Inputs include material choice, feed rate, speed and cutting fluids. A case study of an automotive steering knuckle is presented.
Bayesian Analysis in Engineering Model Assessment
Authors: Doraiswamy Srikanth , Krishnamurty Sundar
Published: December 2020

Engineering design decisions often need to be made when complete knowledge of the system is not available. Getting such complete deterministic information may be impossible or impractical as the resources required to get the information may be unaffordable. The challenge then is to identify and construct an information-gathering strategy, one that can be expected to yield most reliable results in an efficient manner during design. In this context, an engineering model can be viewed as an information-gathering strategy, using which predictive information regarding the performance of a design can be acquired by means of mathematical simulation studies. Focusing on this issue, this paper presents the development of a Bayesian analysis based model selection strategy to understand and deal with the uncertainty inherent in engineering models. Specifically, this work offers a basis for assessing engineering models under conditions of uncertainty through a methodical generation of the required probabilities in a Bayesian tree format, and subsequently using it in the selection of the best analysis model from a design decision perspective. The selection of the best model is made under conditions of uncertainty by considering the models’ performance on each design attribute, and based on the payoffs resulting from the design outcomes. The modeling of a windshield-wiper arm is used to illustrate the application of the proposed methodology.
Model-Based Abduction for Synthesis
Authors: Yoshioka Masaharu , Tomiyama Tetsuo
Published: December 2020

Synthesis plays a major role in design and abduction is regarded a critical element within a creative synthesis process. While there are many research efforts for formalizing abduction within design, most of them can only deal with limited problems and highly depend on designers’ creative thinking. In this paper as a part of an on-going project to model synthesis, we propose model-based abduction that is a new reasoning method within a multiple model-based reasoning system. We also propose an algorithm of this model-based abduction.
Theoretical Underpinnings of Functional Modeling: Preliminary Experimental Studies
Authors: Kurfman Mark A. , Stone Robert B. , Van Wie Mike , Wood Kristin L. , Otto Kevin N.
Published: December 2020

A model of how a product should function to satisfy customers is an essential element in clarifying, identifying, and establishing product architectures. Such functional models greatly enhance the generation of creative form solutions to a chosen architecture. A wider breadth of solutions is generally possible, implementing new and stable technologies. In turn, using the recent concepts of design repositories, the possibilities exist to archive, retrieve, compute, reconfigure, and reason with the product forms. To realize these benefits to the fullest extent possible, functional modeling needs further theoretical development. A formalism of function classes, vocabulary, topologies, and methodology is a first step towards this goal. Recent research efforts have focused on each of these elements, where great strides toward repeatable formalisms have been made. Yet, across the engineering design field, very little active experimentation has been pursued to test the veracity of these elements, individually and as a whole. We address this issue here through a preliminary set of experiments conducted at three separate universities. Design teams and individuals are asked to create functional models, in the context of product development, with and without the formalisms. The outcomes of the modeling effort are analyzed to determine the repeatability of the process. Early results are quite encouraging. Very repeatable results are obtained for three product evolutions, including a toaster, a power screwdriver, and a toy dart gun. In addition, weaknesses in current formalisms are uncovered, pointing to new directions for advancing the field and for carrying out more advanced experimentation.
Towards a Generic Systematic Problem Solving and Innovative Design Methodology
Authors: Mann Darrell
Published: December 2020

Constructed around the findings of over 1500 person years of research, and the systematic extraction of knowledge from nearly 3 million of the world’s strongest patents, the Russian Theory of Inventive Problem Solving, TRIZ, is the most comprehensive systematic innovation and creativity methodology available to mankind. Powerful as it is, however, the method is not as yet comprehensive enough to permit successful use on all types of problem. The paper discusses pioneering work to integrate an upgraded version of TRIZ with other existing and newly derived problem definition and problem solving tools and strategies to create a uniquely powerful, generically applicable methodology. The paper goes on to describe how the new methodology has been successfully validated over a period of several years against a wide variety of real industry-based case study problems.
A 2-Phase Aspiration-Level and Utility Theory Approach to Large Scale Design
Authors: Callaghan Alison R. , Lewis Kemper E.
Published: December 2020

The ability to make rational decisions is one of mankind’s unique attributes. A characteristic of the formal techniques that have been used for decision making is the selection of the best alternative with respect to a certain figure of merit. One of the most critical problems in engineering design is making early decisions on a sound basis. However, the early stages of design are also the most uncertain, and obtaining precise information upon which to base design decisions is usually impossible. The need for a methodology to represent and manipulate imprecision is greatest in the early, preliminary stages of engineering design, where the designer is most unsure of the final dimensions and shape, material properties, and performance of the completed design. Utility Theory provides an analytical way to aid the decisions in engineering design. By exchanging from objective to attribute and expressing these attitudes mathematically, a utility based attribute function (Utility Function) can be set up to describe the attitude of a decision-maker with regard to his/her preference. In this work, the Aspiration-level Interactive Method (AIM), a goal-seeking method based on identifying non-dominated solutions, is used along with Utility Theory to compensate for the limitations of utility theory in forming a meaningful group preference. This work is an initial attempt to integrate two methodologies from the field of decision theory in order to provide rational decision support for design problems where a hierarchy of decision making is required. The hierarchy, in this paper, is characterized by multiple designers at the lower level who report to one manager. The designers each have different preferences and values, while the manager is driven by project goals and specifications. The approach presented generates feasible and preferred design combinations for further analysis in the detailed design phase.
Grammar-Based Designer Assistance Tool for Epicyclic Gear Trains
Authors: Li Xin , Schmidt Linda
Published: December 2020

This paper presents a grammar-based designer assistance tool for Epicyclic Gear Trains (EGTs) that helps designers generate concepts of EGT structures. The tool is comprised of three parts. The first is a grammar-based graph generation engine, the second is a functional schematic sketching module and the third is a concept selection module. Here we highlight the implementation of the first two modules. This is an initial exploration of using grammar-based design to build a practical designer assistance tool (DAT).
Quantifying Design Freedom in Decision-Based Conceptual Design
Authors: Wood William H.
Published: December 2020

Formal methods for conceptual design must embrace the uncertainty that pervades the earliest parts of the design process. Operating over this uncertainty, decision-based design measures the value of restricting the design space as well as the impact of refining design evaluation or analysis models. Missing from this framework is the cost in terms of design freedom of restricting the design space. We propose a measure of design freedom based on probabilistic entropy and demonstrate its application to two example conceptual design problems.
A New Isomorphism Index and its Applications to Kinematic Chains and Mechanisms
Authors: Vijayananda K. , Mruthyunjaya T. S.
Published: December 2020

In this paper a novel method for the identification of the structure of a kinematic chain has been proposed. By expressing in discrete steps the process that usually goes with the visual comparison of two kinematic chains, a reliable and fast computational test for the detection of isomorphism is developed and successfully implemented on a digital computer. No counterexamples for the test have been encountered among kinematic chains and graphs. Also the new isomorphism index directly detects distinct mechanisms that can be derived from the chain. With slight modifications to the method multiple jointed kinematic chains and the driving mechanisms are also identified.
Kinematics of 3-DOF Pyramid Manipulator by Principal Screws
Authors: Huang Zhen , Wang Jing
Published: December 2020

This paper discusses kinematics of a 3-RPS parallel pyramid manipulator using the principal screws. Firstly, the principal screws are identified by quadric degeneration. The planar conies representing the relations between the pitches and the three linear inputs are described, and the three-dimensional distribution of the axes of all the twists is illustrated. Finally, a numerical example is given successfully.
Synthesis of Reconfigurable Machine Tools With Screw Theory
Authors: Moon Yong-Mo , Kota Sridhar
Published: December 2020

In this paper, we present a systematic methodology for designing Reconfigurable Machine Tools (RMTs). The synthesis methodology takes as input a set of functional requirements — a set of process plans and outputs a set of kinematically-viable reconfigurable machine tools that meet the given design specifications. We present a mathematical framework for synthesis of machine tools using a library of building blocks. The framework is rooted in (a) graph theoretic methods of enumeration of alternate structural configurations and (b) screw theory that enables us to manipulate matrix representations of motions to identify appropriate kinematic building blocks. The methodology described in this paper provides a mathematical framework to address dynamic stiffness, and accuracy prediction of the kinematically-viable designs that are generated by the synthesis procedure. This methodology has been implemented in a program, called PREMADE (PRogram for REconfigurable MAchine tool DEsign), and the results are validated against commercial machine tool designs.
Dimensional Synthesis of Bennett Linkages
Authors: Perez Alba , McCarthy J. M.
Published: December 2020

This paper presents a synthesis procedure for a spatial 4R linkage, known as Bennett’s linkage. It is known that the two solutions of the RR chain synthesis equations form a Bennett linkage. While analytical solutions to these equations have been developed previously, this paper uses the cylindroid that is known to exist for a Bennett linkage to simplify the solution process. It is interesting that geometric constraint associated with the spatial 4R chain simplifies the solution of the RR chain design equations. An example design is presented.
A New Approach for the Reduction of Vibrational Excitation in Kinematics Synthesis of High Speed Linkages
Authors: Yuan L. , Rastegar J.
Published: December 2020

A new method is presented for the modification of the output motion of linkage mechanisms with closed-loop chains using cams positioned at one or more of its joints. In particular, the method is applied to a four-bar linkage mechanism that is synthesized for function generation for the purpose of eliminating the high harmonic component of the output link motion. By eliminating the high harmonic component of the output motion of a mechanism, the potential vibrational excitation that the mechanism can impart on the overall system, including its own structure, is greatly reduced. The resulting system should therefore be capable of operating at higher speeds with increased precision. For mechanisms with rigid links, the primary source of high harmonic motions is the nonlinearity of the kinematics of closed-loop chains. With the present method, the higher harmonic motions generated due to such nonlinearities are eliminated by the integration of appropriately designed cams that are used to vary the effective link lengths. A numerical example is provided together with a discussion of the related topics of interest.
The Ray Optimization Method for the Determination of Workspaces of Planar Parallel Manipulators of General Design
Authors: Hay A. M. , Snyman J. A.
Published: December 2020

An extension to a novel optimization approach for the determination of workspaces of planar manipulators is presented. This approach provides a general method for the determination of manipulator workspaces and has the advantage that it may easily be automated. The method consists of finding a suitable initial radiating point interior to the accessible output set of the manipulator, and then determining the points of intersection of a representative pencil of rays, emanating from this point, with the boundary of the accessible set. The points of intersection are determined by means of an optimization approach in which a dynamic constrained optimization algorithm is used. If any section of the workspace boundary cannot be determined due to non-convexity, then the missing section is mapped using a suitably chosen new radiating point. The method is illustrated by its application to a generally constrained planar parallel manipulator. The method has been implemented in a practical, interactive computer code that has been used to determine convex and non-convex workspaces of different parallel manipulators of arbitrary geometry.
Joint Rotation Space, Workspace, and Singularity-Free Workspace of Parallel Five-Bar Manipulators
Authors: Ting Kwun-Lon , Zhang Yi
Published: December 2020

Closed-loop manipulators, while offering some advantages over the open-loop manipulators, also introduce new topics of study such as their joint rotation space (JRS) and workspace. In the previous studies, the concept of JRS was very effective in the study of the allowable inputs of five-bar linkages[11], and the concepts of sheet and side[7] were later introduced for the purpose of clearly describing all of the joint rotation spaces associated to a parallel manipulator with two degrees of freedom. However, of the two types of singularity of parallel manipulators, only the uncertainty singularity was considered in the aforementioned studies. The stationarity singularity was not indicated in the JRS of the manipulators, which would not be sufficient in the design and trajectory planning of parallel manipulators where the one-to-one correspondence between the JRS and the wrist point workspace would be required. This paper reports an extensive study on the JRS and singularity-free workspace of the parallel five-bar manipulators. The objective of the study is to establish a one-to-one corresponding relationship between the JRS and singularity-free workspace. A concise and sufficient way is proposed to thoroughly recognize the JRS and workspace of the parallel five-bar manipulators. The result can be applied in the design and trajectory planning of parallel five-bar manipulators, and the concepts can be extended to other parallel manipulators.
Modeling Gait Transitions of Quadruped and Their Generalization With CMAC Neural Networks
Authors: Lin Jian-Nan , Song Shin-Min
Published: December 2020

The gait transition models of a quadruped are studied based on gait kinematics and CMAC neural networks are applied to learn and generalize these gait transition models. Three gait transition cases are studied: from wave gait to continuous follow-the-leader gait, from walk to trot, and from trot to gallop. Four solution methods are proposed for solving the gait transition models. Computer simulations are conducted to evaluate and display the gait transition models. The good transition gaits are then selected to train CMAC neural network gait transition models. The performance of the CMAC gait transition models are evaluated and found to be satisfactory.
A Mechanical Design of One D.O.F. Anthropomorphic Finger Based on a Human Finger Motion
Authors: Figliolini Giorgio , Ceccarelli Marco
Published: December 2020

In this paper we propose an analytical formulation for simulation and design of one d.o.f. articulated finger mechanism with three phalanges. The formulation is based on a study of design and operation of index human finger. In particular, we propose a suitable mechanical design for an anthropomorphic finger as both an approximation of human architecture and an easy practical design. Kinematic characteristics are illustrated with numerical examples.
On the Structural Synthesis of Multi-Fingered Hands
Authors: Lee Jyh-Jone , Chen Chun-Po
Published: December 2020

Compared to the serial type of six-freedom robot arm attached with an end-effector, the multi-fingered hand system can provide more dexterity and versatility in the field of autonomous manipulation tasks. Designs of multi-fingered hands can be found in the literature, to name a few, Mechanical Hand by Skinner [13], Multi-jointed Finger System by Okada [6], Stanford/JPL Hand (or Salisbury Hand) [11], Utah-MIT Hand [3], and NTU-1 Hand [5]. Generally, these mechanical hand systems have been designed to simulate a subset function of human hands. The structures of these systems basically resemble the skeleton of human hand and are constructed by designers’ intuition. Not much literature addressed about the structural synthesis of multi-fingered hands.

This paper presents a new approach for the structural synthesis of multi-fingered hands. It takes into account both the total mobility and the force closure criterion of the system. Based upon the Grübler’s mobility equation, relations regarding the numbers of fingers, contact geometry, and object freedoms are established. Subsequently, by applying the force closure criterion, the total number of possible multi-fingered hands with given mobility are synthesized.
Simulating Cervical Vertebrae Motion Using Elementary Contact Pairs
Authors: Kecskeméthy Andrés , Lange Christian , Grabner Gerald
Published: December 2020

Described in the paper is the mathematical modeling of a vertebrae pair using multibody methods and impact analysis techniques with elementary contact geometry for the facet joints. The results are compared with existing approaches and with experimental data, showing a good agreement with the latter and an efficiency boost compared to existing approaches by a factor of 350. The investigations are focused on the vertebrae pair C5-C6 but can be easily extended to other vertebrae.
Modeling of Planar Flexible Link Manipulators: Parameter Identification Using Genetic Algorithm
Authors: Megahed S. M. , Hamza K. T.
Published: December 2020

In this paper, a model for simulation of planar flexible link manipulators is presented. Identification of the model parameters is done based on experimental results obtained from separate experiments performed on every link in the manipulator. A simple experimental procedure is used to determine the first three natural frequencies and damping ratios corresponding to them. The experimental data provides guidance in selecting an appropriate number of elements per link for modeling, mass and stiffness parameters and an initial value of damping parameters. Further enhancement of the model is performed through Genetic Algorithm optimization of the damping parameters with the objective function to be minimized defined as the sum of squares of errors between the experimental response and the simulated one. After optimization, the simulated response and the experimental one are closely matching.
The Kinematics of Redundant Tetrahedron Based Variable Geometry Truss Manipulators Based on Neural Network
Authors: Xu Li-Ju , Wu Jiang
Published: December 2020

The forward displacement analysis of redundant tetrahedron based variable geometry truss manipulators is obtained based on BP neural network, and then a solution to inverse displacement analysis problem is obtained. According to the above network model, the first- and second-order influence coefficients are derived, and the pseudo-inverse of Jacobian matrix is obtained by using a neural network. Finally the simulation calculation of kinematics for a seven celled tetrahedron-tetrahedron variable geometry truss manipulator is given for illustration.
Effect of Sintering Process and Rolling on Surface Durability of Sintered Metal Gears
Authors: Koide Takao , Oda Satoshi , Nakamura Hitoshi , Onishi Michinari
Published: December 2020

This paper presents a study on the surface durability of sintered metal gears. Gear blanks made of partially prealloyed steel powders were compacted and sintered under various processes, then they were hobbed and case-hardened. Some gears were surface-rolled under various amount of rolling before case-hardening. The contact fatigue tests were carried out for these gears using the power-circulating-type gear test machine. The effects of sintering processes and rolling on the surface durability and wear of sintered metal gears were determined. Furthermore, the surface durability of the above-mentioned sintered metal gears was compared with that of the wrought steel gears. The density of sintered metal gears increases by adopting a double-press-double-sinter (2P2S) process as the sintering process. The surface density of the sintered metal gears tends to increase with rolling for the case of gears with relatively lower density. The surface durability of sintered metal gears tends to increase with an increasing surface density. The surface durability of sintered metal gears may approach that of the wrought steel gears by adopting the appropriate sintering and rolling processes.
An Experimental Investigation of Bending Fatigue Initiation and Propagation Lives
Authors: Singh Avinash
Published: December 2020

It has long been recognized that the fatigue life of a component can be divided into a crack initiation phase and a crack propagation phase, but researchers have typically ignored one phase or the other in their analytical models. Even in the stress-life method of life prediction, which implicitly includes both phases, no distinction is made between the initiation and propagation phases. In this paper a methodology for generating initiation and propagation S-N curves will be outlined. It will be shown that for components like gears, both phases represent significant portions of total life. It will also be shown that gear bending fatigue lives for variable amplitude load tests are better predicted by a two-stage linear damage theory compared to the commonly used Miner’s total life linear damage theory.
Optimization for the Dynamic Behavior of High Speed Spiral Bevel Gears
Authors: Fang Zongde , Yang Hongbin , Zhou Yanwei , Deng Xiaozhong
Published: December 2020

A new approach for optimizing the dynamic behavior of spiral bevel gear drives has been developed. The local synthesis, tooth contact analysis (TCA) and loaded tooth contact analysis (LTCA) techniques were used to constitute the design process with feedback, by which a contact ratio being near 2.0 or 3.0 would be achieved. An improved dynamic behavior of the spiral bevel gear drives under certain operating load or a wide range of load could be obtained.
Effects of Tooth Profiles and Addendum Modification on Efficiency of Cylindrical Worm Gears
Authors: Yoshino Hidehiro , Ohshima Fumihiro
Published: December 2020

Power transmission efficiencies of five cylindrical worm gear pairs with different profiles and different addendum modifications were measured. The convex, concave or trapezoid profile and also the positive, negative or zero addendum modification was given to each gear pair. The efficiency of worm gears does not change if only the tooth profile is changed. However, it changes (increases) when the change in the profile and the addendum modification were combined. For example, the efficiency of worm gears with the convex tooth and the negative addendum modification increased by 3% to 91% and that of with the concave tooth and the positive modification increased by 4% to 91.5%. The reason why the efficiency increases is investigated and discussed by analyzing the meshing and lubricating conditions between the meshing teeth. As a result, it will be shown that the efficiency of worm gears is strongly influenced by the condition of oil film formation between the teeth.
Tooth Contact Analysis of Double Enveloping Hourglass Worm Gearing on the Condition That Errors Mixed With Deformation
Authors: Qin Datong , Qin Dongxing , Yang Yalian , Hu Jianjun
Published: December 2020

An accurate geometry and contact finite element model of double enveloping hourglass worm gearing with manufacturing errors are constructed. The hybrid method of finite element method and penalty function method is employed to investigate the contact pattern and contact pressure on tooth surface as well as the load share among contacting tooth pairs with the coexistence of manufacturing error and load. The influences of different values of load and different types of errors on contact pattern and contact pressure as well as load share are studied. The mutual influences of the load and the error on tooth contact and load share are also analyzed. Some results useful for production and application of the worm gearing are presented.
A Study on Noise in Synchronous Belt Drives: Experimental and Theoretical Analysis of Impact Sound
Authors: Zhang Weiming , Koyama Tomio
Published: December 2020

There are two kinds of noise in synchronous belt drives. One is steady sound caused by transverse vibration of belt, and another is impact sound radiating from meshing point of belt and pulley. Recently, it has been reported that the impact sound is due to the sound occurring in an air pipe built up between pulley groove and belt because the frequency of impact sound coincides with the fundamental natural frequency of an open ended pipe whose length equals width of the belt. However, this conclusion is obtained experimentally, there has no theoretical analysis provided. In this study, an analysis of the impact sound is provided to prove its generation mechanism and discuss factors that influence the level of sound theoretically. Sound field in an open ended pipe subjected to an impulsive sound source is analyzed. Comparison between experimental and analytical results is carried out. It is concluded that the level of impact sound is in proportion to the width of belt, and the acoustic energy of impact sound is in proportion to the cube of the width of belt.
Prediction of Automotive Gearboxes Dynamic Behavior: Part A — Experimental Validation of a Global Numerical Model
Authors: Yakhou Karim , Bourdon Adeline , Play Daniel
Published: December 2020

Numerical models have been developed to simulate the overall dynamic behavior of automotive gearboxes. They are based upon Finite Element Methods and their main originality is to integrate all the couplings between the various mechanical components of the gearboxes. The purpose of this study is to qualify these numerical models, and then, use them in order to determine gearboxes new design trends. In this first part of two companion papers, an experimental validation procedure has been implemented in two main stages. The first one is devoted to the study of mechanical systems under load but not-rotating. It is organized according to a “step by step” procedure. Starting with the shafts, the other components are gradually mounted and integrated into the mechanical system being considered. Thus, the modeling of the various parts has been validated and the existence of significant couplings has been confirmed. In the second stage of the procedure, the whole gearbox is studied under operating conditions. Preliminary tests at low rotational speeds allow the determination of the quasi-static transmission error under load. The results are used as input data for numerical simulations. Then tests are conducted at higher speeds with various resistant torques. Dynamic transmission error and dynamic loads transmitted by bearings are recorded. A good correlation between experiments and computations ensures the validity of the main a-priori modeling assumptions.
Experimental and Numerical Investigations on the Influence of Tooth Friction in Spur and Helical Gear Dynamics
Authors: Velex Philippe , Cahouet Violaine
Published: December 2020

An original model based upon a finite element procedure is introduced for analyzing the influence of tooth friction on spur and helical gear dynamics. The equations of motion are solved by combining a time-step integration method with several iterative algorithms aimed at satisfying normal and tangential contact conditions. Comparisons between simulated and measured quasi-static bearing forces are satisfactory and largely validate the theoretical developments. Results also reveal the potentially significant contribution of tooth friction to gear vibration and noise. Simulations are then extended to high speeds and the interest of considering both transmission error and tooth friction excitations to achieve silent gears is discussed.
Modeling and Analysis of Sliding Friction in Gear Dynamics
Authors: Vaishya Manish , Houser Donald R.
Published: December 2020

Sliding resistance on gear teeth can have a dominant effect on housing vibration and noise, due to fluctuating excitation and high force transmissibility in the off-line of action direction. Hence reliable modeling of friction from tribological considerations, supported by experimental data, is of utmost importance. This paper examines some lubrication theories and validates them with 2-disk tests and quasi-static loaded gear tests. From the knowledge of friction characteristics, a lumped parameter system is synthesized for a pair of spur gears. This model includes sliding friction, mounting compliances and lateral-torsional vibration coupling. A different formulation has been applied, which unlike most current models, accounts for energy dissipation in the system due to friction. The influence of various excitations like transmission error, friction and parametric variations, on dynamic response of gears is investigated. Finally, the model is evaluated with dynamic tests carried out on a spur gear set, under varying conditions of torque, speed and lubricant.
Natural Frequency Veering Patterns of Planetary Gears Under Design Parameter Variation
Authors: Lin Jian , Parker Robert G.
Published: December 2020

Noise and vibration reduction is a critical concern in planetary gear applications. During the design process, system parameters are varied to evaluate alternative design choices, avoid resonances, optimize load distribution, and reduce weight. It is important to characterize the effects of parameter variations on the natural frequencies and vibration modes for effective vibration tuning. In planetary gear dynamic models (Figure 1), the key design parameters include the mesh stiffness, support/bearing stiffness, component mass, and moment of inertia. Some plots of natural frequencies versus planetary gear parameters are presented by Cunliffe et al. (1974), Botman (1976), Kahraman (1994), and Saada and Velex (1995). Lin and Parker (1999a) analytically characterized the unique, highly-structured properties of planetary gear natural frequency spectra and vibration modes. They also derived simple, closed-form expressions for the sensitivities of natural frequencies and vibration modes to these parameters (Lin and Parker, 1999b). The natural frequency plots in the above literature show natural frequency veering phenomena where two eigenvalue loci approach each other as a parameter is varied but then abruptly veer away like two similar charges repelling (Figure 2a). The phenomenon has been extensively studied (Leissa, 1974; Perkins and Mote, 1986; Pierre, 1988; Chen and Ginsberg, 1992; Happawana et al., 1998). The vibration modes of the veering eigenvalues are strongly coupled and undergo dramatic changes in the veering neighborhood. Eigenvalue veering is also related to mode localization that can occur when disorder is introduced into nominally symmetric systems like turbine blades, space antennae, multi-span beams and other structures (Pierre, 1988). In the case of especially sharp veering, it is sometimes difficult to distinguish between intersection and veering just by observing eigenvalue plots. Curve veering/crossing complexity obstructs the tracing of eigenvalue loci under parameter changes. Also, when multiple curves veer or intersect close together (Figure 3), strong modal coupling (and associated operating condition response changes) occurs that is not identifiable from frequency loci plots. The objective of this work is to analytically characterize the rules of eigenvalue veering in planetary gear vibration. The special veering patterns derived here help to trace natural frequencies and examine impacts of design parameters on vibration. These veering patterns, combined with the unique modal properties (Lin and Parker, 1999a) and the eigensensitivies analysis (Lin and Parker, 1999b), provide designers considerable insight into planetary gear free vibration.
Analyzing Transmission Rattle: Object-Oriented Simulating and Testing the Dynamic Interaction Among Driveline Components
Authors: Bellomo Pietro , De Vito Nicola , Lang Claus-Hermann
Published: December 2020

In the global market of the 21st century the time-to-market reduction is an imperative statement for every automotive company. Automobile manufacturers must continue their efforts in order to exceed the customers’ expectations for improved quality during the engineering phase of new vehicles. Two available technological methods to meet that goal are simulation and bench testing. These enable advanced engineering and testing departments of the automotive industry to reduce development time and costs, identify weak spots of components or systems before volume parts are ever produced.

This paper presents an integrated approach described as object-oriented simulation and testing for vehicle driveline vibrations. It is also aimed to investigate transmission rattle, which is a well-known classical noise-vibration-harshness (NVH) phenomenon. It affects the vehicle ride and comfort resulting in customer satisfaction. The target of this combined analysis, simulation and testing, is to investigate the dynamic interaction of all driveline components by exciting them with the angular speed irregularities of a 4-cylinder diesel engine.

A new benefit with this approach is the ability for fine-tuning of the vehicle driveline. They also contribute to reduction of the time-to-market bottleneck during design and the development process. Also highlighting new methods to particularly research the transmission rattle phenomenon.

The application of the previously mentioned tools in a real vehicle rattling case is presented to show the potential of this approach.
Tooth Undercutting of Beveloid Gears
Authors: Liu Chia-Chang , Tsay Chung-Biau
Published: December 2020

A beveloid gear can be viewed as an involute gear of which the profile-shifted coefficient linearly decreases from the heel to the toe. Therefore, tooth undercutting occurs and singular points appear on the tooth surfaces near the toe. When undercutting occurs, the gear tooth is comparatively weak. In this study, the conditions of tooth undercutting of beveloid gears were derived and specific phenomena were also investigated by numerical illustrated examples. In addition, according to the characteristics of tooth undercutting on the beveloid gear tooth surface, a novel type hob cutter with varying cutting depths was designed to avoid tooth undercutting of the beveloid gear.
Vibration Characteristics and Surface Durability of Non-Involute Helical Gears
Authors: Nagamura Kazuteru , Ikejo Kiyotaka
Published: December 2020

This paper describes two non-involute helical gears that have involute-cycloid composite tooth profile and modified cycloid tooth profile. We designed and made involute-cycloid composite tooth profile helical gear and modified cycloid tooth profile helical gear to obtain high performance. Using these non-involute helical gears, the circumferential vibration acceleration of the helical gears, the tooth root stress, and the transmission error were measured on the running test. The experimental results showed that the vibration characteristics of the non-involute helical gears do not differ from that of the involute helical gear. Furthermore, we proved that the surface durability of the non-involute helical gears is superior to that of the involute helical gear from pitting test results.
Mixed Mode Fatigue Fracture Criteria for the Plates With an Inclined Semi-Elliptical Crack
Authors: Bian Lichun , Soh Ai Kah
Published: December 2020

The behaviour of fatigue crack propagation of rectangular steel plates, each consisting of an inclined semi-elliptical crack, subjected to axial loading was investigated both experimentally and theoretically. The inclined angle of the crack with respect to the axis of loading varied between 0° and 90°. In the present investigation, the Von Mises yield criterion was applied to define the core region, instead of a core region with a constant distance r from the crack tip. Based on Von Mises elasto-plastic boundary, the two commonly used fracture criteria, the maximum tensile stress and the minimum strain energy density criteria, were modified. The results obtained using the two improved fracture criteria were compared with those obtained using the commonly used mixed mode fracture criteria and experimental results. A mixed mode fatigue crack criterion has been established based on the experimental data.
Elasto-Plastic Behavior of Thermoplastic Matrix Roller Chain Link Plates Reinforced With Steel Fibers
Authors: Arslan Nurettin , Sancaktar Erol , Celik Mehmet
Published: December 2020

The elastic and elasto-plastic stress analysis of thermoplastic matrix roller chain link plates reinforced with steel fibers is performed by using Finite Elements Analysis (FEA). A two-dimensional finite element computer program is developed for elasto-plastic stress analysis. Isoparametric quadratic element with four nodes is used with Lagrange polynomial as an interpolation function. The results of elastic and elasto-plastic finite element stress analysis by using the computer program prepared, are compared with experimental, (photoelastic) results. The spreads of the plastic zones due to the external load applied on the pin-hole of the plate and variations of the residual stresses are determined in different orientation angles and loads. It is shown that the geometry of the link plates can be designed to decrease the stress concentrations. Furthermore, it is shown that the tensile load limit of the roller chain link plate is extended by the residual stresses.
Ultra-thin Al2O3 capped with SiNx enabling implied open-circuit voltage reaching 720 mV on industrial p-type Cz c-Si wafers for passivated emitter and rear solar cells
Authors: Kökbudak Gamze , Keçeci Ahmet E. , Nasser Hisham , Turan Raşit
Published: December 2020

In this study, we report on the passivation quality of atomic layer deposition grown ultra-thin Al2O3 and Al2O3 capped with plasma-enhanced chemical vapor deposition deposited SiNx on Cz p-type wafers for the rear side of a passivated emitter and rear cell (PERC). Different activation recipes using N2, forming gas (FG), and two-step annealing for different durations are investigated before SiNx deposition. The effect of different Al2O3 thicknesses and corresponding activation processes on the Al2O3/SiNx passivation performance, after a high temperature firing step, is studied to reach a new optimization toward higher efficiency and lower cost. A record high iVoc of 720 mV is obtained after firing step from Al2O3/SiNx stacks with Al2O3 thickness as thin as ∼2 nm with FG annealing. Our results demonstrate that, under well-optimized process conditions, ultra-thin Al2O3 thicknesses provide superior passivation quality as compared to the larger thicknesses which are commonly applied in the PERC industrial line and the potential for further improvement of industrial PERC solar cells in terms of cost reduction and efficiency.
Calculating spin correlations with a quantum computer
Authors: Brody Jed , Guzman Gavin
Published: December 2020

We calculate spin correlation functions using IBM quantum processors, accessed online. We demonstrate the rotational invariance of the singlet state, interesting properties of the triplet states, and surprising features of a state of three entangled qubits. This exercise is ideal for remote learning and generates data with real quantum mechanical systems that are impractical to investigate in the local laboratory. Students learn a wide variety of skills, including calculation of multipartite spin correlation functions, design and analysis of quantum circuits, and remote measurement with real quantum processors.
A demonstration of quantum key distribution with entangled photons for the undergraduate laboratory
Authors: Bista Aayam , Sharma Baibhav , Galvez Enrique J.
Published: December 2020

Now that fundamental quantum principles of indeterminacy and measurement have become the basis of new technologies that provide secrecy between two communicating parties, there is a need to provide teaching laboratories that illustrate how these technologies work. In this article, we describe a laboratory exercise in which students perform quantum key distribution with single photons, and see how the secrecy of the communication is ensured by the principles of quantum superposition and state projection. We used a table-top apparatus, similar to those used in correlated-photon undergraduate laboratories, to implement the Bennett-Brassard-84 protocol with polarization-entangled photons. Our experiment shows how the communication between two parties is disrupted by an eavesdropper. We use a simple quartz plate to mimic how an eavesdropper intercepts, measures, and resends the photons used in the communication, and we analyze the state of the light to show how the eavesdropper changes it.