bluuebunny/crossref_metadata_2025 huggingface dataset:
A Learning Shell for Iterative Design (L’SID): Concepts and Applications
Authors: Jamalabad V. R. , Langrana N. A.
Published: February 2008

A software shell called “Learning Shell for Iterative Design,” L’SID, has been developed in conjunction with a simple data matrix, the “learn table.” Histories of design are utilized in aiding the acceleration of routine design problems. The class of problems addressed are non-convex, noninvertible and with multiple performance criteria. The design parameters can be of any definable type; continuous, integer or nonordered feature based. L’SID is domain independent and highly modular. The ability of L’SID to aid deterministic methods is shown statistically with two example problems (extrusion die and airfoil). Results also show the ability of the technique to surmount nonconvexity in design space and computational noise related to roundoff.
Simultaneous Engineering of Quality Through Integrated Modeling
Authors: Soyucayli S. , Otto K. N.
Published: February 2008

Simultaneous engineering has become the means to ensure quality through incorporation of manufacturing. This proves difficult without quantitative support tools. We present here a modeling-based approach to simultaneously design a product and its production process. We demonstrate an approach of examining sensitivities of output to all inputs of a system, from product design specifications, process variables, and material specifications. We further develop mathematics of estimating the effects of in-line process control changes to improve quality. We demonstrate a method to choose noise sources to measure and process variables to control in-line based upon these measurements, and estimate the error reduction that such process control changes will provide. The tool allows simultaneous engineering of the product and process to improve quality.
Discretely Actuated Manipulator Workspace Generation by Closed Form Convolution
Authors: Ebert-Uphoff Imme , Chirikjian Gregory S.
Published: February 2008

We determine workspaces of discretely actuated manipulators using convolution of real-valued functions on the Special Euclidean Group. Each workspace is described in terms of a density function that provides the number of reachable frames inside any unit volume of the workspace. A manipulator consisting of n discrete actuators each with K states can reach Kn frames in space. Given this exponential growth, brute force representation of discrete manipulator workspaces is not feasible in the highly actuated case. However, if the manipulator is of macroscopically-serial architecture, the workspace can be generated by the following procedure: (1) partition the manipulator into B kinematically independent segments; (2) approximate the workspace of each segment as a continuous density function on a compact subset of the Special Euclidean Group; (3) approximate the whole workspace as a B-fold convolution of these densities. We represent density functions as finite Hermite-Fourier Series and show for the planar case how the B-fold convolution can be performed in closed form. If all segments are identical only O(log B) convolutions are necessary.
On the Determination of the Workspace of Complex Planar Robotic Manipulators
Authors: Ricard Re´mi , Gosselin Cle´ment M.
Published: February 2008

A new method for the determination of the workspace of complex planar robotic manipulators is described in this paper. The method is based on the use of joint limits to obtain equations describing limiting curves. These limiting curves are then segmented at their mutual intersections and validated. The resulting sets of portions of curves form the envelope of the workspace. The algorithm is completely general and can be applied to any three-degree-of-freedom planar manipulator—serial, parallel or hybrid—with or without joint limits. Examples of the application of the method to a serial three-degree-of-freedom manipulator, to a hybrid three-degree-of-freedom manipulator and to a parallel three-degree-of-freedom manipulator are given.
NTU Hand: A New Design of Dexterous Hands
Authors: Lin Li-Ren , Huang Han-Pang
Published: February 2008

A new five-finger robot hand (NTU hand) with seventeen degrees of freedom (DOF) is developed in this paper. In contrast to traditional tendon-driven robots, the NTU hand has an uncoupled configuration that each finger and joint are all individually driven. Since all actuators, mechanical parts and sensors are packed on the hand, the size of NTU hand is almost the same as a human hand. Such compact design makes the hand easily adapt to the industrial robot arm and the prosthetic applications. Based on the mechanical structure of the NTU hand, the direct and inverse kinematics are developed. In addition, computer simulation with three-dimension graphics is built to evaluate the manipulable range of the NTU hand. From the simulation, the relationship between the hand and the grasped object in a specific point of view can be obtained.
Closed-Form Determination of the Location of a Rigid Body by Seven In-Parallel Linear Transducers
Authors: Innocenti C.
Published: February 2008

The paper presents an original analytic procedure for unambiguously determining the relative position and orientation (location) of two rigid bodies based on the readings from seven linear transducers. Each transducer connects two points arbitrarily chosen on the two bodies. The sought-for rigid-body location simply results by solving linear equations. The proposed procedure is suitable for implementation in control of fully-parallel manipulators with general geometry. A numerical example shows application of the reported results to a case study.
Using Chaos to Obtain Global Solutions in Computational Kinematics
Authors: Jovanovic V. T. , Kazerounian K.
Published: February 2008

In this paper we examine the sensitive dependence on the initial conditions of the Newton-Raphson search technique. It is demonstrated that this sensitivity has a fractal nature which can be effectively utilized to find all solutions to a nonlinear equation. The developed technique uses an important feature of fractals to preserve shape of basins of attraction on infinitely small scales.
Classification of 3R Positioning Manipulators
Authors: Wenger P.
Published: February 2008

In this paper, the complete categorization of all generic 3-revolute jointed (3R) positioning manipulators is established using a homotopy based classification scheme. It is shown that there exists exactly eight subsets of homotopic generic manipulators which have similar global kinematic properties. The classification of generic manipulators serves as an efficient tool for the categorization of cuspidal and non cuspidal manipulators, i.e., manipulators which can or cannot change posture without meeting a singularity, respectively. As a result of this classification, it appears that, in contrast with common belief most 3R manipulators are cuspidal.
Maximizing Kinematic Motion for a 3-DOF VGT Module
Authors: Williams R. L , Hexter E. R.
Published: February 2008

This article presents design results for maximizing kinematic motion range in three-degree-of-freedom (DOF) double-octahedral variable-geometry-truss (VGT) modules modeled as extensible gimbals. Design curves are presented to describe motion and results are summarized.
An Object Shape Dependent Kinematic Manipulability Measure for Path and Trajectory Synthesis and Shape Optimization
Authors: Rastegar J. , Zhang S. Z. , Kazerounian K.
Published: February 2008

The manipulability of robot manipulators has been studied with respect to the ability to position the end-effector in its workspace. However, since manipulators have to manipulate objects with finite dimensions, the ability of a manipulator to position and orient an object is quite different from its end-effector manipulability. Object shape dependent kinematic manipulability measures are essential for the formulation of optimal path planning and trajectory synthesis algorithms used for moving objects in operations such as mating parts and for formulating related object shape optimization problems. The optimality criterion may be related to part positioning accuracy, mating accuracy, kinematics performance of the manipulator for applying force (torque) to the object at some stage of the assembly, or a number of other accuracy, force or control measures. In the present study, a class of shape dependent kinematics measures is developed for the object manipulability. The measures can be used to evaluate the manipulability of objects with various shapes, for path and trajectory synthesis, and for designing object shapes. No rigid body constraint is imposed and the object considered may be deforming, stretching or shrinking during its manipulation. A number of examples are presented.
Stress Analysis of Cylindrical Webbed Spur Gears: Parametric Study
Authors: Kim H. C. , de Vaujany J. P. , Guingand M. , Play D.
Published: February 2008

In this paper, a numerical computer software based on the Finite Prism Method, is proposed in order to design external cylindrical spur gears with a web. It enables computing load sharing, pressure distribution, meshing stiffness and 3D tooth fillet stresses. The software is generally used during the detailed design for optimizing gear meshing. The software is also used to quantify the influences of web design parameters. The process is based on a statistical method: experimental design, that permits studying the influence of parameters. Thus, a simple formula was found in order to estimate the maximum principal stress in the tooth root. The results of the formula were compared with those found in the bibliography. The formula can be useful during the preliminary design for predimensioning webbed spur gears in design department.
The Design of Quasi-Ellipsoidal Gear Ratio and Pitch Curved Surfaces
Authors: Qimi Jiang , Zhouji  , Huamin Li
Published: February 2008

The design of the gear ratio and pitch curved surfaces of a new type of gear called as quasi-ellipsoidal gear is presented in this paper. The quasi-ellipsoidal gear can be applied to the flexible wrist of a robot and will make the wrist light and nimble, so the transmission precision will be greatly improved.
EHD Lubrication Characteristics of a New Type of Ground Cylindrical Worm Gearing
Authors: Simon V.
Published: February 2008

A full thermal elastohydrodynamic analysis of lubrication of a new type of cylindrical worm gearing with concave worm profile, ground by a grinding wheel whose profile consists of two circular arcs, is presented. The EHD lubrication analysis is based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace’s equations. The oil viscosity variation with respect to pressure and temperature and the density variation with respect to pressure are included. The finite difference method and numerical integration have been used to get the solution of the highly nonlinear integrodifferential system of governing equations. By using a computer program, the influence of design and operating parameters of the new type of worm gearing on EHD lubrication characteristics has been investigated. Also, the comparison of the EHD load carrying capacity and of the power losses in the oil film of the new type and of the commonly used cylindrical worm gearings has been carried out.
A General Mathematical Model for Gears Cut by CNC Hobbing Machines
Authors: Chang Shinn-Liang , Tsay Chung-Biau , Nagata Shigeyoshi
Published: February 2008

A hobbing machine’s cutting mechanism is a mechanism with multi-degree of freedom during the cutting process. In this paper, we propose a general gear mathematical model simulating the generation process of a 6-axis CNC hobbing machine based on the cutting mechanism of CNC hobbing machine and worm-type hob cutter. The proposed gear mathematical model can be applied to simulate different types of gear cutting. Some examples are included to verify the mathematical model. Also, a novel type of gear named “Helipoid” which can be used in crossed axes transmission is proposed. The proposed general gear mathematical model can facilitate a more thorough understanding of generation processes and toward the development of novel types of gears.
Offset Face Gear Drives: Tooth Geometry and Contact Analysis
Authors: Zhang Y. , Wu Z.
Published: February 2008

This paper presents a detailed investigation on the manufacturing, tooth geometry and contact characteristics of face gear drives with offset axes. In the paper, the tooth geometry of offset face gears is analytically determined by simulating the conjugate motion between the gear and the cutting tool in the generation process. Design criteria are established for the optimal tooth element proportions of offset face gears that avoid tooth undercutting and pointing. The tooth surface geometry of the gear member of the drive is modified by using a shaper that resembles the pinion in profile but has a few more teeth than the pinion to localize the tooth contact. The contact characteristics of the offset face gears are analyzed by a tooth contact analysis (TCA) program that simulates the meshing process of the gear drive assembled under misalignment. An example of offset face gear design and contact analysis is included in the paper.
Classification of Sketch Strokes and Corner Detection Using Conic Sections and Adaptive Clustering
Authors: Shpitalni M. , Lipson H.
Published: February 2008

This paper presents a method for classifying pen strokes in an on-line sketching system. The method, based on linear least squares fitting to a conic section equation, proposes using the conic equation’s natural classification property to help classify sketch strokes and identify lines, elliptic arcs, and corners composed of two lines with an optional fillet. The hyperbola form of the conic equation is used for corner detection. The proposed method has proven to be fast, suitable for real-time classification, and capable of tolerating noisy input, including cusps and spikes. The classification is obtained in o(n) time in a single path, where n is the number of sampled points. In addition, an improved adaptive method for clustering disconnected end-points is proposed. The notion of in-context analysis is discussed, and examples from a working implementation are given.
A New Criterion for Positive Mean Stress Fatigue Design
Authors: Wang Shyh-Jen , Dixon Marvin W.
Published: February 2008

The modified Findley line is proposed by using ultimate strength and endurance limit as parameters to obtain a good initial approximation of an acceptable design. Comparing with experimental data, the modified Findley line could be a strong candidate for fatigue design criterion for parts made of a nonferrous materials, and be conservative for ferrous material parts.
Electromechanical Ski Release Binding With Mechanical Backup
Authors: Hull M. L. , Swanstrom M. , Wade B.
Published: February 2008

To better protect Alpine skiers against injuries to both the lower leg and the knee, the objective of this work was to design a binding which: (1) maintained a consistent release level in twist in the presence of combined loads; (2) released the heelpiece based on the anterior/posterior (A/P) bending moment transmitted by the leg; and (3) modulated the release level in twist depending on the degree of contraction in muscles crossing the knee. To fulfill the objective, a conventional ski binding was modified. Modifications included integrating dynamometers into the toepiece, anti-friction device (AFD), and heelpiece. The toepiece sensor indicates the twisting moment while the AFD and heelpiece sensors indicate the anterior bending moment transmitted by the leg. To gain electronic control of binding release, a solenoid actuated mechanism was added which translated the heelpiece rearward along the ski to decouple the boot from the binding. Otherwise, the binding allowed normal mechanical function. Prototype testing confirmed the ability of the dynamometers to accurately measure desired loads in the presence of extraneous loads and the reliability of the solenoid actuated mechanism in releasing the hoot under loads typical of skiing. Thus, this work demonstrated the feasibility of hybrid electromechanical/mechanical releasable bindings. Such a demonstration should encourage the development of designs for commercial use.
Analytical and Experimental Identification of Nonlinearities in a Single-Nut, Preloaded Ball Screw
Authors: Cuttino J. F. , Dow T. A. , Knight B. F.
Published: February 2008

The nonlinear performance of a single-nut, preloaded ball screw actuator is analyzed in this paper. The study identifies the source of nonlinear torque in the ball screw and subsequently maps that torque into the nonlinear displacement response due to windup in the shaft. The study is complemented with an experimental verification using a small angle rotation fixture (ARC) to input very small amplitude angular displacements to the screw while measuring induced torque and displacements. The experimental results are obtained from a Precision Linear Optimization Testbed (PLOT) which was developed to study the ability of different actuator systems to provide long range motion with nanometer accuracy. The analysis is conducted for the case of no axial loading. The study shows that the nonlinearities in the ball screw originate in the rolling friction between the balls and the races which induces torque in the nut and subsequently windup in the shaft. It also shows that the torque can be deduced from a relationship of the torque between a ball spinning in a race.
Generalized Abbe Principle: Position Error Propagation in Machine Elements
Authors: Pegna Joseph
Published: February 2008

In the quest for ever finer levels of technology integration, mechanical linkages reach their precision limits at about 5 micrometers per meter of workspace. Beyond this physical limit, all six dimensional degrees of freedom need to be precisely ascertained to account for mechanical imperfections. This paper substantiates Wu’s vision of “precision machines without precision machinery.” A formulation and statistical characterization of position and orientation error propagation in rigid bodies are presented for two extreme models of measurement. It is shown that error distribution is uniquely dependent upon the design of the measurement plan. The theoretical foundations presented were evolved in the course of designing precision machinery. Other potential applications include: fixture design, metrology, and geometric tolerance verification.
Modeling and Design of an Inertial Vibration Reflector
Authors: Longoria R. G. , Narayanan V. A.
Published: February 2008

This paper presents the modeling and analysis of a novel vibration suppression device. This reflector system exerts inertial forces, induced by tuned pendular motion, to control translational vibration of a primary system. Tuning of the reflector critically depends on the parameters of the pendula and on the rotational speed at which they are spun about an axis oriented parallel to the undesired motion. Consequently, one of its most appealing attributes is this devices’s ability to be tuned to, and thus actively track, the dominant frequency of disturbance forces. The paper describes how governing equations from an integrated physical model are developed using a bond graph approach and then used to derive relations applicable in design of an inertial reflector system. It is shown how the model supports component selection and tradeoff studies as well as simulation. Experimental results from testing of a laboratory realization of a prototype system are used to verify the design and to compare with simulation of a mathematical model. The results from the laboratory demonstrate the ability of the inertial reflector to control steady and transient vibration, and the favorable results suggest extended investigation for active vibration control situations. In particular, applications in low frequency vibration mitigation are promising.
Constrained Three-Dimensional Component Layout Using Simulated Annealing
Authors: Szykman S. , Cagan J.
Published: February 2008

This research introduces a computational algorithm that uses simulated annealing to optimize three-dimensional component layouts. General component layout problems are characterized by three objectives: achieving high packing density, fitting components into a given container and satisfying spatial constraints on components. This paper focuses on the extension of a simulated annealing packing algorithm to a general layout algorithm through the implementation of a language of spatial constraints that are characteristic of layout problems. These constraints allow the designer to specify desired component proximities or to restrict translation or rotation of components based on a global origin or set of coordinate axes, or relative to other component locations or orientations. The layout of components from a cordless power drill illustrates the algorithm.
A Designer’s Spreadsheet
Authors: Ramaswamy R. , Ulrich Karl
Published: February 2008

We have observed that many designers use spreadsheet programs for preliminary parametric design calculations. The primary reason for this appears to be the flexibility and ease of use of spreadsheets as compared to more advanced analysis tools. However, current commercially available spreadsheets were originally designed for finance and accounting and do not naturally support the analytical techniques used in design and engineering. In this paper, we propose a fundamentally different kind of spreadsheet for use in preliminary parametric design. We describe the features of this spreadsheet that make it especially suitable for preliminary parametric design, discuss the theoretical basis for implementing it and present the results of preliminary user tests.
Effect of Rim Thickness on Gear Crack Propagation Path
Authors: Lewicki D. G. , Ballarini R.
Published: February 2008

Analytical and experimental studies were performed to investigate the effect of rim thickness on gear tooth crack propagation. The goal was to determine whether cracks grew through gear teeth or through gear rims for various rim thicknesses. A finite element based computer program (FRANC, FRacture ANalysis Code) simulated gear tooth crack propagation. The analysis used principles of linear elastic fracture mechanics. Quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically using an automated re-meshing scheme. Crack tip stress intensity factors were estimated to determine crack propagation direction. Gears with various backup ratios (rim thickness divided by tooth height) were tested to validate crack path predictions. Gear bending fatigue tests were performed in a spur gear fatigue rig. From both predictions and tests, gears with backup ratios of 3.3 and 1.0 produced tooth fractures while a backup ratio of 0.3 produced rim fractures. For a backup ratio of 0.5, the experiments produced rim fractures and the predictions produced both rim and tooth fractures, depending on the initial geometry of the crack.
Computerized Design, Generation and Simulation of Meshing of Modified Involute Spur Gears With Localized Bearing Contact and Reduced Level of Transmission Errors
Authors: Litvin F. L. , Kim D. H.
Published: February 2008

The authors propose modification of geometry of spur gears that enable to localize the bearing contact and reduce the level of transmission errors. Methods for generation of spur gears with the modified geometry are proposed as well. Computer programs for simulation of meshing and contact of misaligned spur gears with the modified geometry have been developed. The developed theory is illustrated with numerical examples.
On the Matrix Realization of the Theory of Biquaternions
Authors: Ge Q. J.
Published: February 2008

This paper describes a matrix algebra realization of Clifford’s theory of biquaternions. By examining 4 × 4 skew-symmetric matrices, the paper shows the connection between infinitesimal screws in elliptic three-space and vector quaternions. By studying the matrix exponential of the skew-symmetric matrices, the paper also shows how finite screws in elliptic three-space lead to matrix realization of quaternions. Finally, it is shown that line transformations in elliptic three-space lead to double quaternions and that a dual quaternion is a limiting case of a double quaternion.
Modeling of the Backlash Hysteresis Nonlinearity
Authors: Ge P. , Jouaneh M.
Published: February 2008

In this paper, the backlash hysteresis nonlinearity is examined, and a mathematical model based on the particular behavior of the backlash is developed. A geometrical interpretation of this model using switching operators is provided to facilitate an understanding of it. Simulation of output prediction of the backlash mechanism using an arbitrary input signal is performed to verify the correctness of the developed model. A linearization scheme based on the model is also developed to compensate for the backlash nonlinearity. The scheme was applied for tracking an arbitrary signal similar to that used in the modeling. The results show that our model-based linearization scheme although running in an open loop fashion, provides a simpler way to perform tracking control for structures with backlash hysteresis nonlinearity.
Domains of Mobility for a Planar Body Moving Among Obstacles
Authors: Haug E. J. , Adkins F. A. , Coroian D.
Published: February 2008

A formulation is presented for defining domains of mobility for a planar convex body moving with three degrees-of-freedom among convex planar obstacles. Applications included are determination of areas of a factory floor or material storage facility in which objects can he manipulated without impacting fixed obstacles. Mobility of the moving body is defined to encompass (1) dexterous mobility of the body; i.e., points that can be reached by a reference point on the body and at which the body can be rotated through a specified range of admissible orientations without penetrating any stationary obstacle, and (2) limited mobility of the body; i.e., points that can be reached by the reference point and at which the body does not penetrate any stationary obstacle, for some admissible orientation. Analytical criteria for points on boundaries of domains of mobility are derived and numerical methods suitable for mapping these boundaries are summarized. An elementary example involving a moving and a stationary ellipse, with and without orientation restrictions, is solved analytically to illustrate the method. A more general application with one moving body and three stationary obstacles is solved numerically.
Classifying Functions for Mechanical Design
Authors: Kirschman C. F. , Fadel G. M.
Published: February 2008

As design methods are studied, the usefulness of function-based methodologies becomes clear. However, for these methodologies to be fully utilized, there must be some standardization of the functions used to provide a common language. This paper presents a taxonomy of elemental mechanical functions which can be used with many decomposition techniques. The taxonomy can be used as a pedagogical tool or as a basis for the derivation of a complete taxonomy. Also discussed are generic forms and how they interact with the taxonomy.
Implications of Modularity on Product Design for the Life Cycle
Authors: Newcomb P. J. , Bras B. , Rosen D. W.
Published: February 2008

Growing concern for the environment has spurred interest in product Design for the Life Cycle (DFLC) which encompasses all aspects of a product’s life cycle from initial conceptual design, through normal product use, to the eventual disposal of the product. A product’s architecture, determined during the configuration design stage, plays a large role in determining its life cycle characteristics. In this paper, modularity of product architectures with respect to life cycle concerns, not just functionality and structure, is defined and applied in the analysis of architecture characteristics. An architecture decomposition algorithm from the literature is adopted for partitioning architectures into modules from each life cycle viewpoint. Two measures of modularity are proposed: one that measures module correspondence between several viewpoints, and another that measures coupling between modules. The algorithm and measures are applied to the analysis and redesign of an automotive center console. Results of applying the algorithm and measures accurately reflected our intuitive understanding of the original center console design and predicted the results of our redesign. Furthermore, these measures incorporate only configuration information of the product, hence, can be used before detailed design stages.
Shape Design Optimization of Thermoelastic Structures for Durability
Authors: Grindeanu I. , Choi K. K. , Chang K.-H.
Published: February 2008

Shape design sensitivity analysis (DSA) and optimization methods for the fatigue life of thermoelastic structural components are presented in this paper. A multiaxial fatigue life prediction method is used for crack initiation. The crack initiation life prediction is modeled using constant amplitude strain-life data and cyclic stress-strain curves. A hybrid DSA method is used for the fatigue life. The design sensitivities of the dynamic stress and the temperature field are obtained using analytical approaches. The design sensitivity is used to predict the dynamic stress and temperature of the perturbed design. Using predicted stress and temperature, the fatigue life of the perturbed structural design component is predicted. The predicted fatigue life is then used to obtain the design sensitivity of the fatigue life by utilizing the finite difference method. The proposed DSA method is applied to design optimization of an automotive exhaust manifold of an automotive vehicle, considering crack initiation lives as design constraints.
Designing for Material Separation: Lessons From Automotive Recycling
Authors: Coulter S. , Bras B. , Winslow G. , Yester S.
Published: February 2008

Virtually all of the material in today’s automobiles can technically be recycled. The challenge facing engineers is making this recycling process economical, especially for materials in such components as seats and instrument panels. Recycling these components requires the different materials to be separated so that each can be recycled individually. This separation can be accomplished either manually, where workers disassembly and sort the vehicle components by hand, or mechanically, where the vehicle is shredded and the materials sorted by properties such as conductivity and density. In this paper, the usefulness of including likely separation techniques in DFR guidelines is discussed. Three vehicles were dismantled at the VRDC as part of an effort to establish a baseline of current vehicle recyclability. Concurrently, this allowed examination of the effectiveness of the early design for recycling (DFR) efforts. The applicability of common design guidelines to the two types of separation is discussed, and a simple method for determining the appropriate separation process in the early stages of design is presented.
An Integrated Approach to Optimal Three Dimensional Layout and Routing
Authors: Szykman S. , Cagan J. , Weisser P.
Published: February 2008

This paper integrates simulated annealing-based component packing, layout and routing algorithms into a concurrent approach to product layout optimization. The design of a heat pump is presented to compare the integrated method to the previous sequential layout-then-route approach; results show a substantial improvement in route design with more organized component placements. The example is given in detail to provide a test case for future research in this area.
The Selection of a Most Efficient Clutching Sequence Associated With Automatic Transmission Mechanisms
Authors: Hsieh H.-I. , Tsai L.-W.
Published: February 2008

This paper presents a methodology for the identification of a most promising clutching sequence associated with an epicyclic-type automatic transmission mechanism. First, a methodology for the analysis of torque distribution on the links of an epicyclic gear mechanism is described. Then, the power loss relations associated with various clutching sequences of an epicyclic gear mechanism are derived. Finally, a procedure for the selection of a most efficient clutching sequence associated with a transmission mechanism is developed.
Manipulability of Closed Kinematic Chains
Authors: Park F. C. , Kim J. W.
Published: February 2008

This paper presents a coordinate-invariant differential geometric analysis of manipulability for closed kinematic chains containing active and passive joints. The formulation treats both redundant and nonredundant mechanisms, as well as over-actuated and exactly actuated ones, in a uniform manner. Dynamic characteristics of the mechanism and manipulated object can also be naturally included by an appropriate choice of Riemannian metric. We illustrate the methodology with several closed chain examples, and provide a practical algorithm for manipulability analysis of general chains.
Real-Time Computation of the Actual Posture of the General Geometry 6-6 Fully-Parallel Mechanism Using Two Extra Rotary Sensors
Authors: Parenti-Castelli V. , Di Gregorio R.
Published: February 2008

The paper presents three algorithms for the determination of the actual configuration of the general geometry 6-6 fully-parallel mechanism by using two extra rotary sensors in addition to the six ones that are normally implemented in the servosystems of the six actuated legs. The three proposed algorithms provide a one-to-one correspondence between the sensor measurements and the configuration of the mechanism. Comparison of the three algorithms, that are all for real-time computation, is presented and one of them is shown to be a good compromise between precision and computation time.
Stabilization Method for Numerical Integration of Multibody Mechanical Systems
Authors: Lin Shih-Tin , Hong Ming-Chong
Published: February 2008

The object of this study is to solve the stability problem for the numerical integration of constrained multibody mechanical systems. The dynamic equations of motion of the constrained multibody mechanical system are mixed differential-algebraic equations (DAE). In applying numerical integration methods to this equation, constrained equations and their first and second derivatives must be satisfied simultaneously. That is, the generalized coordinates and their derivatives are dependent. Direct integration methods do not consider this dependency and constraint violation occurs. To solve this problem, Baumgarte proposed a constraint stabilization method in which a position and velocity terms were added in the second derivative of the constraint equation. The disadvantage of this method is that there is no reliable method for selecting the coefficients of the position and velocity terms. Improper selection of these coefficients can lead to erroneous results. In this study, stability analysis methods in digital control theory are used to solve this problem. Correct choice of the coefficients for the Adams method are found for both fixed and variable integration step size.
Dynamic Effects of Pressure Loads in Three Screw Pump Rotors
Authors: Mimmi G. C. , Pennacchi P. E.
Published: February 2008

In a previous paper the authors have dealt with the calculation of the pressure loads on the rotors of a three screw pump. The pressure loads can be modelled as a force and a moment. In particular, starting from the knowledge of rotor geometry, the loads can be calculated and subdivided into their components along the screw axes. In this paper the simulation results obtained by using the proposed model are presented. The results show that the satellite screws are thrust towards the case in a specified direction. This fact can be verified in practice, since the cases actually present a wear zone in a particular position.
Reliability Modeling in Design for Remanufacture
Authors: Shu L. H. , Flowers W. C.
Published: February 2008

Remanufacture involves the disassembly, cleaning, and replacement or refurbishment of worn parts of products at the end of life. Since the essential goal of remanufacture is part reuse, the reliability of components is important. The goal of this work is to consider reliability effects on life-cycle costs to enable design for reuse. A reliability model is developed to better describe systems that undergo repairs performed during remanufacture or maintenance. This model allows replacement components to be of a type different from the original components. The behavior, preliminary experimental validation, and application of the model to an example are presented.
Metrics for Assessing Design Freedom and Information Certainty in the Early Stages of Design
Authors: Simpson T. W. , Rosen D. , Allen J. K. , Mistree F.
Published: February 2008

Our primary focus in this paper is on open engineering systems. Developing ranged sets (as opposed to point sets) of top-level design specifications is a means to enhance openness and system flexibility by increasing design knowledge while maintaining design freedom. Consequently, our secondary focus in this paper is on metrics for assessing the design freedom and information certainty associated with a ranged set of top-level design specifications. As a demonstration, these metrics are applied to an example problem, namely, the conceptual design of a family of aircraft. Our emphasis in this paper is on introducing open engineering systems and metrics for design freedom and information certainty, and not on the example, per se.
An Observational Study of Design Team Process: A Comparison of Student and Professional Engineers
Authors: Smith R. P. , Leong A.
Published: February 2008

Fifteen groups composed of engineering students and professionals were videotaped while performing a simulated design task. Using interaction analysis, it was found that professional teams were more likely to engage in management activities, outline an overall design philosophy, and not overlook detailed specifications. Professional teams also adhered tentatively to the early design artifacts; early design attempts were viewed as experiments for acquiring more information about the design space. Student teams were much more likely to engage in a generate and test pattern throughout their design process, making incremental improvements to their current artifact. Although the number of groups was small, these patterns were strong and the differences were statistically significant. It is suggested that these differences are useful for guiding how engineers are educated and for understanding whether students should be used as experimental subjects in engineering design research.
Collaborative, Sequential, and Isolated Decisions in Design
Authors: Lewis K. , Mistree F.
Published: February 2008

The Massachusetts Institute of Technology (MIT) Commission on Industrial Productivity, in their report Made in America, found that six recurring weaknesses were hampering American manufacturing industries. The two weaknesses most relevant to product development were 1) technological weakness in development and production, and 2) failures in cooperation. The remedies to these weaknesses are considered the essential twin pillars of CE: 1) improved development process, and 2) closer cooperation. In the MIT report, it is recognized that total cooperation among teams in a CE environment is rare in American industry, while the majority of the design research in mathematically modeling CE has assumed total cooperation. In this paper, we present mathematical constructs, based on game theoretic principles, to model degrees of collaboration characterized by full cooperation, approximate cooperation, sequential decision making, and isolated decision making. The design of a pressure vessel is given to illustrate the theory, and the design of a passenger aircraft is given to illustrate the application to a large-scale systems design.
A Framework for Decision-Based Engineering Design
Authors: Hazelrigg G. A.
Published: February 2008

Engineering design is increasingly recognized as a decision-making process. This recognition brings with it the richness of many well-developed theories and methods from economics, operations research, decision sciences, and other disciplines. Done correctly, it forces the process of engineering design into a total systems context, and demands that design decisions account for a product’s total life cycle. It also provides a theory of design that is based on a rigorous set of axioms that underlie value theory. But the rigor of decision-based design also places stringent conditions on the process of engineering design that eliminate popular approaches such as Quality Function Deployment. This paper presents the underlying notions of decision-based design, points to some of the axioms that underlie the theory of decision-based design, and discusses the consequences of the theory on engineering education.
Recognition of Machining Features Based on HSPCE Decomposition, Feature Composition, and Process Centered Classification
Authors: Shen Y. , Shah J. J.
Published: February 2008

A comprehensive set of computational procedures have been developed for transforming a geometric model based on design features to alternative sets of machining features. In the paper we only discuss a sub-set of these procedures; those related to machining feature recognition. There are three phases in the recognition process: 1) orthonormal decomposition of the removal volumes based on half space partitioning at concave edges (HSPCE) to determine regions of interaction and to recover portions of features lost by interaction 2) concatenation of decomposed cells into candidate machining features based on cycles in cell adjacency graphs, 3) classification of these volumes with respect to accessibility and tool motion for subsequent feasible process selection. This strategy is process centered—it recognizes all features that can be produced by common machining operations in a uniform way. It is not restricted to a few predefined features that each require specific, predefined rules. It deals with many types of feature interactions with one general purpose algorithm and produces alternative sets of machining feature sequences. Several measures have been incorporated to reduce computational complexity.
An Interactive Multistage ε-Inequality Constraint Method For Multiple Objectives Decision Making
Authors: Palli N. , Azarm S. , McCluskey P. , Sundararajan R.
Published: February 2008

Multiple objectives decision making (MODM) in engineering design refers to obtaining a preferred optimal solution in the context of conflicting design objectives. Problems with multiple objectives do not have a unique optimal solution but a set of Pareto optimal solutions. This paper presents a new interactive multistage MODM method which captures a decision maker’s preference structure in order to obtain a preferred Pareto solution even for non-convex problems. Representative subsets of an entire Pareto optimal set are generated and expanded based on the decision maker’s preference. The ε-constraint method is used to constrain the multiple objectives problem based on the decision maker’s feedback. In addition, ideas from an interactive weighted Tchebycheff approach are applied to reduce the feasible region at each stage, ensuring that the process eventually converges to a preferred solution. The method is demonstrated with two examples: (i) a simple two-bar truss design, and (ii) a more complicated problem in power electronic module design.
Design Optimization of Valveless DTH Pneumatic Hammers by a Weighted Pseudo-Gradient Search Method
Authors: Chiang L. E. , Stamm E. B.
Published: February 2008

A design methodology for Down-The-Hole (DTH) pneumatic hammers used for rock drilling is proposed which renders an optimal design for a given set of constraints. A generic non-linear dynamic model developed by the authors is used to compute the hammer performance. This model consists of a set of six differential equations plus a set of twenty non-linear polynomial equations. In addition there are parameter range restrictions given by fabrication and operational standard procedures. In any given application, magnitudes such as power, impact energy, frequency, efficiency and mass flow may be sought for optimality. However these magnitudes must be computed by integration after solving the dynamic model over an entire cycle, thus traditional optimization methods for non-linear equations that are based in gradient information are not suitable. Hence a method that uses secant information is used to approximate the gradient of the space of design variables. Several prototypes using this optimization method have been designed and field tested. The results are in agreement with predicted values.
Effect of Involute Contact Ratio on Spur Gear Dynamics
Authors: Kahraman A. , Blankenship G. W.
Published: February 2008

The influence of involute contact ratio on the torsional vibration behavior of a spur gear pair is investigated experimentally by measuring the dynamic transmission error of several gear pairs using a specially designed gear test rig. Measured forced response curves are presented, and harmonic amplitudes of dynamic transmission error are compared above and below gear mesh resonances for both unmodified and modified gears having various involute contact ratio values. The influence of involute contact ratio on dynamic transmission error is quantified and a set of generalized, experimentally validated design guidelines for the proper selection of involute contact ratio to achieve quite gear systems is presented. A simplified analytical model is also proposed which accurately describes the effects of involute contact ratio on dynamic transmission error.
Critical Tolerance Oriented Process Planning in Sheet Metal Bending
Authors: Shpitalni M. , Radin B.
Published: February 2008

Although bending is one of the final processes in sheet metal part manufacture, it is relatively inaccurate compared to the other components of sheet metal processing. Critical tolerances at several locations on the sheet metal part impose limitations on bending operations and sequences. The lack of success up to now in embedding accuracy in process planning for sheet metal products has resulted mainly from the fact that tolerance analysis usually requires simulating the manufacturing process. This paper discusses the issue of automatic determination of the bending sequence in sheet metal products subject to critical tolerance constraints. It proposes conditions for identifying cases where the problem of determining the bending order which results in the best accuracy at specific locations is, in fact, a topological problem. Two explicit rules for achieving the best accuracy in such cases are formulated and then demonstrated by using these rules to construct a precedence graph.