bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of Multi-Span Rotor Balancing Using Least Squares Method
Authors: Fujisawa F. , Shiohato K. , Sato K. , Imai T. , Shoyama E.
Published: January 2010

The least-squares method which uses influence coefficients was applied to simultaneous balancing of a multibearing rotating shaft system, and an experiment was conducted to demonstrate its effectiveness. The rotor system used in the experiment was a 10-bearing, 5-span rotor system. Vibrations were detected simultaneously in horizontal and vertical directions. Using these data, correction weights were calculated with a computer program based on the above least-squares method. Balancing accuracy was considered with regard to two cases, horizontal and vertical vibrations. The balancing experiments were conducted for the cases where unbalance is distributed in one and in all rotors of the multispan rotor system. In both cases, good balance was achieved in one run.
Techniques for the Evaluation of Loads on the Forearm Prior to Impact in Tennis Strokes
Authors: McLaughlin T. M. , Miller N. R.
Published: January 2010

This paper describes techniques developed to permit the evaluation of loadings on the forearm of a tennis player immediately prior to ball/racket impact. Kinematic data were obtained using high-speed three-dimensional cinematography. A specially instrumented racket permitted the quantification of finger gripping forces. Relative magnitudes of the various sources of forearm loading (inertial effects, gripping forces, etc.) were evaluated. Optimization techniques were used to estimate individual muscle forces in the forearm. The results correlate reasonably well with observed patterns of muscle electromyographic activity. Limitations of the current analytical model and experimental techniques are discussed along with planned improvements.
Conformity Factor In Wildhaber-Novikov Circular-Arc Gears
Authors: Lingaiah K. , Ramachandra K.
Published: January 2010

Conformity factor, which is more rationally defined as the ratio of the area of contact to the active area of the flank of the mating teeth, is theoretically evaluated for Wildhaber-Novikov circular-arc gears, using Hertz’s theory of contact stress, without neglecting the effect of the difference in the profile radii of the pinion and wheel teeth, which is an important factor in fully-hardened gears. The variation of the conformity factor with the helix angle, pressure angle, ratio of the profile radii, module and the number of teeth follows closely the variation of load-carrying capacity per unit face-width of these gears and hence, from this study it is concluded that conformity factor is a more rational index on which the selection of the profile and material parameters should be based. This study of the conformity factor, for the particular profile geometry, indicates 7.5 to 15.0 deg as the suitable helix-angle range for achieving maximum load-carrying capacity per unit face-width.
Elastohydrodynamic Lubrication of Hypoid Gears
Authors: Simon V.
Published: January 2010

The full thermal elastohydrodynamic analysis of the lubrication of hypoid gears is presented. A numerical solution of the coupled Reynolds, elasticity and energy equations for the pressure, temperature and film thickness is obtained. The temperature variations across the oil film and in the pinion and gear teeth are included. The real tooth geometry of the modified hypoid gears is treated. The effect of the operating conditions on the performance characteristics is discussed.
Closure Equations for a Six-Link Coupler-Drive Mechanism
Authors: Zohoor H. , Hall A. S. , Holowenko A. R.
Published: January 2010

A new set of position independent inequalities for the determining of the closure in a six-link coupler-drive mechanism is presented. Comparison is made with two other sets of position dependent inequalities for establishing the closure.
The Development of a Perbury Traction Transmission for Motor Car Applications
Authors: Stubbs P. W. R.
Published: January 2010

The paper states how fuel mileage of a passenger car can be improved by increasing the ratio range of its transmission. It discusses briefly what are the practical ways of doing this and why Perbury was chosen. The features of the BL Perbury unit are detailed, together with the test program to which it was subjected. Performance data for the transmission is presented and the control system strategy is defined and the control hardward described. Problems encountered during the test program are reported, together with the solutions adopted.
An Exact Condensation Procedure for Chain-Like Structures Using a Finite Element-Transfer Matrix Approach
Authors: Mucino V. H. , Pavelic V.
Published: January 2010

The main objective of this study is to describe a new scheme to carry out the static or dynamic analysis of elastic systems using a combined Finite Element-Transfer Matrix Approach. The proposed scheme offers the advantage of automatic matrix size reduction without having to truncate degrees of freedom, and preserving the strain and kinetic energy throughout the condensation. Although limited to chain-like elastic systems, the method is generalized to non-repetitive configurations with substructures having intermediate active degrees of freedom.
Factors Influencing Instability and Resonances in Geared Systems
Authors: Benton M. , Seireg A.
Published: January 2010

The parameters influencing high dynamic magnifications and instabilities in multiple-reduction geared systems are investigated in this study. These factors include the effect of external excitations, system inertia, variation in mesh stiffness, contact ratio and damping in the mesh. Design procedures and data are given to aid the designer in predicting system performance beforehand. The reported procedure and data can be used as a guide for safe design and application of geared systems with minimum calculations.
Compliance and Stress Sensitivity of Spur Gear Teeth
Authors: Cornell R. W.
Published: January 2010

The magnitude and variation of tooth pair compliance with load position affects the dynamics and loading significantly, and the tooth root stressing per load varies significantly with load position. Therefore, the recently developed time history, interactive, closed form solution for the dynamic tooth loads for both low and high contact ratio spur gears [1] was expanded to include improved and simplified methods for calculating the compliance and stress sensitivity for three involute tooth forms as a function of load position. The compliance analysis is based on Weber [2] and O’Donnell [3] but with an improved fillet/foundation compliance analysis. The stress sensitivity analysis is a modified version of the Heywood method [4] but with an improvement in the magnitude and location of the peak stress in the fillet. These improved compliance and stress sensitivity analyses are presented along with their evaluation using test, finite element, and analytic transformation results, which showed good agreement.
Factors Affecting Fatigue Strength of Nylon Gears
Authors: Chen J. H. , Juarbe F. M. , Hanley M. A.
Published: January 2010

The effects of some of the factors which influence fatigue strength of molybdenum disulphide (MoS2) filled cast nylon (type 6) gears such as diametral pitch, pressure angle, pitch line velocity, stress level, and lubrication were investigated. It was found that nylon gears, when properly designed and installed, are subject to minimal wear. Premature failures do occur through tooth interference caused by thermal expansion, tooth deflection and creep of the material. The importance of a proper backlash is discussed. Design capacities of nylon gears using formula and tables are presented.
Engineering Design Education: U.S.—Retrospective and Contemporary
Authors: Mann Robert W.
Published: January 2010

For the Centennial of the American Society of Mechanical Engineers, its Design Education Committee asked the author to discuss the “status of design education in the U.S.” In an attempt to discharge this substantial responsibility in an informed and impartial manner, a Resume´ of the author’s personal retrospective impression of engineering design education was prepared and distributed to ninety persons nationwide known by the author to have been actively involved in engineering design education, together with a Worksheet seeking their assessment of the Resume´ and their opinion on the current state of engineering design education. Global and detailed information from the forty-seven replies was collated, evaluated, presented and discussed at the Century 2 Conference in San Francisco, August, 1980. This paper is comprised of the Resume´ and the Worksheet, with quantitative evaluation of the responses on the state of various aspects of engineering design education supplemented by pertinent and pithy remarks of respondents. The overall sense of the surveyed faculty is that engineering design education is in a “so-so” to “bad” state. The paper concludes with the author’s now updated evaluation of the contemporary status of engineering design education and his prospective prognostications thereupon.
Kinematic Mappings. Part 2: Rational Algebraic Motions in the Plane
Authors: De Sa S. , Roth B.
Published: January 2010

Using the concept of kinematic mappings, a theorem is derived which relates the order and circularity of a rational algebraic planar motion to the order and cirularity of the rotation curve and the order of a rotation function (which depends only on the relative orientation of the fixed and moving planes). It is shown that the equations of the point-paths, centrodes and directrices follow from the image space and its mappings in a straightforward fashion. Several examples are presented showing how to qualitatively synthesize whole cycle motions.
The Curvature Theory of Line Trajectories in Spatial Kinematics
Authors: McCarthy J. M. , Roth B.
Published: January 2010

This paper develops the differential properties of ruled surfaces in a form which is applicable to spatial kinematics. Derivations are presented for the three curvature parameters which define the local shape of a ruled surface. Related parameters are also developed which allow a physical representation of this shape as generated by a cylindric-cylindric crank. These curvature parameters are then used to define all the lines in the moving body which instantaneously generate speciality shaped trajectories. Such lines may be used in the synthesis of spatial motions in the same way that the points on the inflection circle and cubic of stationary curvature are used to synthesize planar motion. As an example of this application several special sets of lines are defined: the locus of all lines which for a general spatial motion instantaneously generate helicoids to the second order and the locus of lines generating right hyperboloids to the third order.
An Extension of Screw Theory
Authors: Ohwovoriole M. S. , Roth B.
Published: January 2010

It is shown that, if one considers the “total freedom” of instantaneous motion, three distinct types of screw systems arise. Of these only the ones which maintain the kinematic constraints—the so-called reciprocal screw systems—have been studied before. This paper introduces and studies the two new types, which we name “repelling” and “contrary” screws. We present a detailed theoretical study of the repelling screw systems, these as well as the other screw systems are useful in the mathematical modelling of the parts assembly process and the study of direct contact mechanisms.
Optimum Design of an Abrasive Disk
Authors: Prasad B. , Haftka R. T. , Bao M. S.
Published: January 2010

The minimum weight design of an axisymmetric rotating abrasive disk in the presence of a side tool load is obtained under the strength and stiffness constraints. The PARS (Programs for Analysis and Resizing of Structures) system which employs an optimization procedure based on a mathematical programming method using the Sequence of Unconstrained Minimization Technique (SUMT) is used. The derivatives of the inertia load vector which depends upon the resized dimension (thickness) of the disk are obtained analytically. They are needed in the computation of the derivatives of stresses and displacements, which are also obtained analytically. Due to symmetry, only half of the abrasive disk is modelled using general plate finite elements having bending and extensional stiffnesses. It is shown that by permitting tapered radial thickness distribution, a lighter and much stronger design can be achieved as compared to disks of uniform thickness.
Quasi-Square Hole With Optimum Shape in an Infinite Plate Subjected to In-Plane Loading
Authors: Durelli A. J. , Rajaiah K.
Published: January 2010

This paper deals with the optimization of the shape of the corners and sides of a square hole, located in a large plate and subjected to in-plane loads, with the object of minimizing stress concentrations. Appreciable disagreement has been found between the results obtained previously by other investigators. In this paper new tests have been conducted and discrepancies have been corrected. Using an optimization technique, the authors have developed a quasi square shape which introduces a stress concentration of only 2.54 in a uniaxial field, the comparable value for the circular hole being 3. The efficiency factor of the proposed optimum shape is 0.90 whereas the efficiency factor of the best shape developed previously was 0.71. The shape also is developed that minimizes the stress concentration in the case of biaxial loading when the ratio of biaxiality is 1:-1.
Optimum Vibration Absorbers for Linear Damped Systems
Authors: Randall S. E. , Halsted D. M. , Taylor D. L.
Published: January 2010

This paper presents computational graphs that determine the optimal linear vibration absorber for linear damped primary systems. Considered as independent parameters are the main system damping ratio and the mass ratio examined over the range 0 to 0.50 and 0.01 to 0.40, respectively. The remaining nondimensional parameters were optimized using numerical methods based on minimum-maximum amplitude criteria. With independent parameters specified the computational graphs can be used to find the response amplitudes as well as the optimal absorber characteristics. This procedure is illustrated in a design example. A qualitative discussion of the sensitivity to parameter errors is presented.
Analysis and Synthesis of Mechanical Error in Cam-Follower Systems
Authors: Rao S. S. , Gavane S. S.
Published: January 2010

A method of evaluating the mechanical error in the kinematic and dynamic response of cam-follower systems is presented based on probability principles. The error is analyzed for the three-sigma band of confidence level. A synthesis procedure, using nonlinear programming techniques, of distributing tolerances on geometrical and other system parameters is discussed. The objective of the synthesis problem is to minimize a measure of the manufacturing cost for specified maximum allowable error in the kinematic or dynamic response of the cam-follower system. The application of analysis and synthesis procedures is demonstrated with reference to a disc cam with translating roller follower.
Analysis and Synthesis of Mechanical Error in Geneva Mechanisms—A Stochastic Approach. Part 1: External Geneva Mechanism
Authors: Rao S. S. , Gavane S. S.
Published: January 2010

Because of error of manufacture and assembly, the output kinematic characteristics of a Geneva mechanism will be different from the desired ones. In this paper an analysis procedure is developed to find the error in acceleration and jerk of external Geneva mechanisms from the view-point of probability theory. A synthesis procedure, using nonlinear programming techniques, of distributing tolerances and clearances in the mechanism for specified maximum allowable errors in acceleration and jerk is discussed. The application of analysis and synthesis procedures is demonstrated by means of numerical examples.
A Simple Numerical Method for the Kinematic Analysis of Spatial Mechanisms
Authors: Garcia de Jalon J. , Serna M. A. , Viadero F. , Flaquer J.
Published: January 2010

In this paper we present a new numerical method for the computer analysis of spatial mechanisms. This study is limited to the analysis of velocities and accelerations. Results are obtained in the form of a set of velocities and accelerations of different points of the mechanism. The position of all points of the mechanism is considered as known. The velocities and accelerations of as many input links as the system has degrees of freedom must also be specified. The result is the velocity and acceleration of points on the remaining links.
A Logical Function Method for Dynamic and Design Sensitivity Analysis of Mechanical Systems With Intermittent Motion
Authors: Ehle P. E. , Haug E. J.
Published: January 2010

Dynamic and design sensitivity analysis of mechanisms and machines with intermittent motion are accomplished through introduction of “logical functions” to approximate discontinuities and special features of system motion. The Heaviside step function and the delta and unit doublet distributions are introduced to represent discontinuities and to determine the values of certain functions of isolated times. These functions and distributions are approximated by smooth functions, and validity of the approximation is argued both mathematically and physically. A numerical method is then presented for analysis of the approximate problem. An elementary and a complex, realistic example are presented to illustrate applications of the method.
A New Method of Modeling Gear Faults
Authors: Randall R. B.
Published: January 2010

Detailed mathematical models of gear vibrations have appeared in recent years, but to utilize them requires a detailed knowledge of the gearbox components and their dynamic properties. This paper presents an alternative approach which is applicable to the monitoring and diagnosis of gearbox faults based on an analysis of changes in the vibration signal, showing how these can be related back to various classes of fault. Most emphasis is placed on the effects of the various types of faults on the spectrum, but the applicability of two other techniques, viz., synchronous signal averaging and cepstrum analysis, is also discussed comparatively, making use of practical examples.
Signature Analysis Applied to Drilling
Authors: Braun S. , Lenz E. , Wu C. L.
Published: January 2010

This paper investigates the relationship between drill life, the sound, and the drift forces produced by the drilling process. Tests were performed while drilling steel with 38 in. twist drills. As a tool life criterion, the wear of the drill lips was monitored. Typical signals are described, and various signal processing techniques presented in view of characterizing them. These include time, frequency, and amplitude domain techniques. It is shown that specific signal patterns that occur with increasing lip wear show definite trends which can be followed by some analysis techniques. A discrete point process, derived from the signal’s spectrum, has been found specifically valuable. Results shown for actual data using these signal analysis techniques seem to support a theory of drill wear mechanism which was reported recently.
Iterative Determination of Squeeze Film Damper Eccentricity for Flexible Rotor Systems
Authors: Greenhill L. M. , Nelson H. D.
Published: January 2010

A method is presented to determine the eccentricity of multiple squeeze film dampers used in multishaft rotor bearing unbalance response analyses. The procedure is iterative and is based upon the secant root finding algorithm. Unbalance response is calculated using the iteratively determined eccentricity in closed form expressions of squeeze film stiffness and damping coefficients, for either long or short bearing theory. Circular centered synchronous operation is assumed. The method is demonstrated by determining the response of a single mass centrally preloaded rotor, a multimass flexible rotor supported by two squeeze films, and a multishaft flexible rotor system employing three squeeze film supports. The results obtained in the flexible rotor analysis are compared to test data, with the correlation found to be good. Due to rapid convergence and multiple squeeze film capability, the procedure is particularly suited to large multishaft flexible rotor-bearing system analysis.
Finite Journal Bearing With Nonlinear Stiffness and Damping. Part 2: Stability Analysis
Authors: Hashish E. , Sankar T. S. , Osman M. O. M.
Published: January 2010

Stability analysis is performed on the linearized as well as the actual nonlinear finite bearing equations using the improved mathematical models for the hydrodynamic forces that are presented in Part I of this investigation. The results of the analysis using the linear equations show a significant trend, different from previous investigation, with respect to different L/d ratios and therefore can be considered as modified stability curves for the finite bearing. The nonlinear analysis, based on numerical integration of the equation of motion, is carried out for the commonly used L/d = 1. Details on the stability behavior of the finite bearing are established, including the orbital stability regions. It is also found that under certain light loading conditions, the supply pressure can introduce a high possibility of orbital stability to the system.
Influence of the Aspect Ratio on the Dynamic Stability and Nonlinear Response of Rectangular Plates
Authors: Ostiguy G. L. , Evan-Iwanowski R. M.
Published: January 2010

The dynamic stability and nonlinear response of simply-supported rectangular plates subjected to parametric excitation are investigated. The large-deflection plate theory used in the analysis is derived in terms of the stress function F and lateral displacement w and is applied to rectangular plates with stress-free supported edges and uniformly stressed loaded edges. General rectangular plates are considered, the aspect ratio of the plate being regarded as an additional parameter of the system. Calculations are carried out for rectangular plates of various aspect ratios, and the relative importance of the principal regions of parametric instability associated with the lower mode shapes is clarified. The stationary response of the system within a principal region of instability is also evaluated. The results obtained indicate that the aspect ratio plays a crucial role in determining the stability of rectangular plates; elongated plates are more susceptible to various parametric resonances than square plates.
Asymmetric Free Vibrations of Layered Conical Shells
Authors: Chandrasekaran K. , Ramamurti V.
Published: January 2010

Asymmetric free vibrations of layered truncated conical shells are studied. Individual layers made of special orthotropic materials and both symmetric and asymmetric stacking with respect to the middle surface are considered. An energy-method based on the Rayleigh-Ritz procedure is employed. The influence of layer arrangements and that of the coupling between bending and stretching on the natural frequencies and mode-shapes are analyzed. Experimental results from tests on two shell models are provided for comparison with theoretical predictions. Numerical results based on extensive parametric studies are presented.
Complete Shaking Force and Shaking Moment Balancing of Link Mechanisms Using Balancing Idler Loops
Authors: Bagci Cemil
Published: January 2010

A method for completely balancing the shaking forces and shaking moments in mechanisms is presented. The method introduces shaking moment balancing idler parallelogram loop (or loops) which transfers the motion of a coupler link to a shaft on the frame of the mechanism, where the rotary balancers balance the shaking moment. The complete balancing of a mechanism is accomplished by maintaining the total center of mass of the mechanism stationary meanwhile achieving that the total angular momentum of the moving links of the mechanism vanishes. Positioning of the idler loops is illustrated for a series of multiloop mechanisms. Theorems on the complete balancing of shaking forces and shaking moments in mechanisms are established. Design equations for completely balancing some single and multiloop mechanisms are given. A numerical example is included.
Displacement Analysis of the General N-Bar, Single-Loop, Spatial Linkage. Part 1: Underlying Mathematics and Useful Tables
Authors: Albala H.
Published: January 2010

In order to carry out the displacement analysis of the general n-bar, single-loop, spatial linkage, it was imperative to introduce a rationalization in the mathematical procedure. This rationalization includes the establishment of special symbology and conventions, as well as the setting up of some novel mathematical tools. Among the latter, we find the definitions and properties of cyclic sums and cyclic products, the presentation of an indicial way of handling trigonometric expressions, called Indicial Trigonometry, the definitions and properties of multiple displacement and linkage functions, and the operations of index underlining, index overlining, and index dotting. Tensor algebra is also used to a great extent. Moreover, a method of separating any selected rotation angle from a displacement function leads—in most cases—to linear expressions in the sine and cosine of the selected angle or to second-degree polynomials in the tangent of half the angle. A set of tables is included setting forth the aforesaid expressions for an important number of displacement functions. These tables are a very valuable aid when performing a kinematic analysis.
A New Method for the Measurement of the Straightness of Machine Tools and Machined Work
Authors: Tozawa Koichi , Sato Hisayoshi , O-hori Masanori
Published: January 2010

A new algorithm to measure the straightness of a machine tool and that of a machined work is proposed. This makes it possible to investigate the correlation of the two. The case of an engine lathe is used as an example. The measurement is performed by sensing the relative displacement between the objective and the tool post which carries two sensors and is fed with steps of distance. The machine tool characteristics have the most important effect on the machined work. The method can be extensively applied to measuring the cylindricity.
A Distribution-Independent Plotting Rule for Ordered Failures
Authors: Mischke C. R.
Published: January 2010

Various plotting rules have been developed for associating a cumulative density, Fi, or a reliability, Ri, with an ordered life measure, xi. These suffer from various biases when rules formulated for one distribution family are used with another. The plotting rationale presented 1) is distribution independent, 2) frees the plotter from tabular information while retaining high precision, 3) easily accommodates to censored data, and 4) suggests the proper regression model.
Failure Prediction Criteria for Fretting Wear
Authors: Lyons H. , Collins J. A.
Published: January 2010

Dynamic excitations in machines and structures may lead to a form of wear caused by the phenomenon of fretting, which may cause premature mechanical or structural failure. Fretting-wear has been evaluated under a variety of conditions, and a linear prediction model is compared to experimental results with good agreement.
Probabilistic Design and Reliability of Silicon Carbide Ceramics
Authors: Srinivasan M. , Seshadri S. G.
Published: January 2010

Ceramic materials generally lack ductility and toughness, and exhibit variability in properties. In order to design with ceramic materials, the variation in material properties, especially strength, has to be statistically analyzed for reliability. Conventional design can be done with calculations utilizing safety factors. However, modern design aspects include proof testing and appropriate nondestructive evaluation methodology. Possible microstructural changes which occur during proof testing may influence subsequent material behavior and must be included in the design methodology. The temperature dependence of flexural strength of two engineering structural ceramics—single-phase sintered alpha silicon carbide and two-phase fine grain reaction-bonded silicon carbide—are examined. Using Weibull statistics, the risk of rupture for various stress levels has been derived from flexural versus tensile strength relationships. Ceramic life prediction considers subcritical crack growth and strength degradation in service environments. The slow crack growth possibilities at elevated temperatures for sintered alpha silicon carbide are examined in dynamic stressing rate and stress rupture experiments. Crack arrest and crack propagation resistance during proof testing and their implications in the probabilistic design with ceramics are analyzed.
Design Considerations for Manipulator Workspace
Authors: Gupta K. C. , Roth B.
Published: January 2010

This paper introduces some basic concepts regarding the workspaces of manipulators. The first part gives a general discussion regarding workspace shapes. Most of the rest of the paper focuses on manipulators with three orthogonal mutually intersecting axes. The structures of the primary and secondary workspaces for such systems are determined and the effects of hand size are examined in detail. Several specific examples are presented to illustrate the basic theory.
Application of Euler Parameters to the Dynamic Analysis of Three-Dimensional Constrained Mechanical Systems
Authors: Nikravesh P. E. , Chung I. S.
Published: January 2010

This paper presents a computer-based method for formulation and efficient solution of nonlinear, constrained differential equations of motion for spatial dynamic analysis of mechanical systems. Nonlinear holonomic constraint equations and differential equations of motion are written in terms of a maximal set of Cartesian generalized coordinates, three translational and four rotational coordinates for each rigid body in the system, where the rotational coordinates are the Euler parameters. Euler parameters, in contrast to Euler angles or any other set of three rotational generalized coordinates, have no critical singular cases. The maximal set of generalized coordinates facilitates the general formulation of constraints and forcing functions. A Gaussian elimination algorithm with full pivoting decomposes the constraint Jacobian matrix, identifies dependent variables, and constructs an influence coefficient matrix relating variations in dependent and indpendent variables. This information is employed to numerically construct a reduced system of differential equations of motion whose solution yields the total system dynamic response. A numerical integration algorithm with positive-error control, employing a predictor-corrector algorithm with variable order and step size, integrates for only the independent variables, yet effectively determines dependent variables.
A State Space Technique for Optimal Design of Mechanisms
Authors: Sohoni V. N. , Haug E. J.
Published: January 2010

Problems of optimal design of mechanisms are formulated in a state space setting that allows treatment of general design objectives and constraints. A constrained multi-element technique is employed for velocity, acceleration, and kineto-static analysis of mechanisms. An adjoint variable technique is employed to compute derivatives with respect to design of general cost and constraint functions involving kinematic, force, and design variables. A generalized steepest descent optimization algorithm is employed, using the design sensitivity analysis methods developed, as the basis for a general purpose kinematic system optimization algorithm. Two optimal design problems are solved to demonstrate effectiveness of the method.
Automated Design for Automotive Structures
Authors: Bennett J. A. , Botkin M. E.
Published: January 2010

The application of mathematical structural optimization methods to automotive structures is discussed. The global structures are typically simultaneously frequency and stress constrained. In addition, bending effects in the components cannot be ignored. Therefore, it is necessary to develop a very general approach while still retaining computational efficiencies. It has been found that approximation techniques coupled with mathematical programming allow the optimization of moderately realistic structures. In addition, there is a class of problems which must be characterized in terms of their boundary shape. This imposes a new set of difficulties primarily of insuring model integrity during the optimization.
Use of Figures of Merit in Computer-Aided Material and Manufacturing Process Selection
Authors: Miaw D. C. , Wilson W. R. D.
Published: January 2010

An interactive computer program to aid a designer in selecting candidate manufacturing process and material combinations for a part is described. The program uses a twelve-digit code to eliminate unsuitable combinations from consideration and to rank the remainder using numerical figures of merit.
Development of the Variable-Rate Transymmetric Motion With Discretely Vanishing Shock
Authors: Kramer S. N.
Published: January 2010

In industry when a link, crank, or other mechanical component is to be rotated from one rest position to another, it is necessary to establish appropriate functional relationships for angular displacement, velocity, and acceleration versus time such that the output motion satisfies certain kinematic and dynamic requirements. In the work presented here, a new type of motion is developed which has distinct advantages over constant velocity motion, constant acceleration motion, simple harmonic motion, cycloidal motion, and polynomial motions. The “variable-rate transymmetric” motion allows a designer to assign specific portions of the motion to be described by a linearly varying acceleration and other portions by a constant acceleration. As a result, the designer can decrease the power required, decrease the operating cost, and decrease dynamic responses such as shock, vibration, and shaking force.
Operating Characteristics of Three-Lobe Bearings
Authors: Flack R. D. , Allaire P. E.
Published: January 2010

Three-lobe bearings were studied for both rigid and flexible rotors from three aspects: instability threshold, load carrying capacity, and unbalance response. Offset factor, preload factor, and load orientation were parametrically varied for the bearings and their influences on the foregoing characteristics were studied both theoretically and experimentally. Results indicate that, in general, all three operating characteristics cannot be optimized for the same bearing parameters. For example, the lowest unbalance response was found for small bearing preload factors, while the highest instability thresholds were found for large preload factors. As a result, when choosing a bearing for a particular application, the designer must consider which operating characteristic is most important and choose the bearing accordingly.
Feasibility Study of a Platform Type of Robotic Manipulators from a Kinematic Viewpoint
Authors: Yang D. C. H. , Lee T. W.
Published: January 2010

This paper presents a theoretical investigation on the feasibility of using a platform mechanism as a robotic manipulator. The existence of this type of closed-loop kinematic chain is first investigated via a kinematic number synthesis. A displacement analysis then follows, which gives inverse control equations in terms of motion and design parameters, using the [4 × 4] matrix method. Basic kinematic characteristics and limitations, such as the extreme ranges of motion and rotatability as well as workspace are investigated.
Optimum Design of I. C. Engine Pistons
Authors: Rao S. S. , Srinivasa Rao S. S.
Published: January 2010

The minimum volume design of I. C. engine pistons is considered with constraints on temperature and stresses developed in the piston. The interior penalty function method, coupled with the Davidon-Fletcher-Powell method of unconstrained minimization and the cubic interpolation method of one-dimensional search, is used for solving the constrained optimization problems. The temperature and stresses developed in the piston are determined by using the classic as well as the finite element methods of analysis. A sensitivity analysis is conducted to find the influence of changes in design variables on the objective function and the response parameters.
Kinematic Analysis of Constant-Breadth Cam-Follower Mechanisms
Authors: Dhande S. G. , Rajaram N.
Published: January 2010

An analytical approach to the kinematic analysis of certain types of constant-breadth cam-follower mechanisms has been presented in this paper. The objective of the kinematic analysis is to provide closed-form parametric equations for the displacement, the velocity, and the acceleration of the follower driven by a constant-breadth cam profile rotating at a uniform angular velocity. The follower surface is considered to be a flat-face and the follower motion may either be translatory or oscillatory, or translatory as well as oscillatory. The proposed approach is general in nature and can be used for the kinematic analysis of any profile-closed higher-pair mechanism. Two different cam profiles of constant-breadth, termed as Type I and Type II, have been considered. Numerical examples have been worked out and results of the computational work have been discussed.
On the Motion Characteristics of Tripode Joints. Part 1: General Case
Authors: Akbil E. , Lee T. W.
Published: January 2010

This paper is concerned with the analytical investigation of the motion characteristics of tripode joints with general proportions and arbitrary position of shafts. It provides a rigorous proof that the tripode joint is not a true constant velocity joint except in ideal cases, and this is due to the inherent orbital motion of the output spider shaft. Algebraic derivations of the input-output equation and explicit relations for motion parameters are presented. From this general analytical study, some insights into the behavior of the tripode joint are observed and interpreted.
An Analytical and Experimental Study of the Prediction of Impacts in Planar Mechanical Systems With Clearances
Authors: Dubowsky S. , Norris M. , Aloni E. , Tamir A.
Published: January 2010

Impacts within the clearances of machines can seriously degrade their performance. Past criteria proposed to predict the system configurations for which impacts will not occur do not consider the connection properties. Here, a simple system with clearance, called an Impact Ring Model, IRM, is studied analytically and experimentally. The results show that connection properties can plan an important role in the occurrences of impacts, and hence should be included in impact prediction criteria. A criterion, the Impact Prediction Number (IPN) which correctly predicts the trends found in this study is discussed.
Dynamic Response of Slider-Crank Machines During Startup
Authors: Myklebust A. , Fernandez E. F. , Choy T. S.
Published: January 2010

An analysis of the dynamic response of slider-crank machines is formulated by the principles of variational mechanics. Velocity ratio constraints rather than loop equation constraints are used resulting in first-order differential equations in the undetermined multipliers. The method is applied to a Kohler K91 engine and experimental verification is presented.
The Development of an Atlas of the Kinematic Structures of Mechanisms
Authors: Mayourian M. , Freudenstein F.
Published: January 2010

Based on the restrictions governing the admissible graphs of the kinematic chains of mechanisms, an atlas or listing of 35 graphs has been developed which defines the kinematic structure of a wide class of plane and three-dimensional mechanisms with up to six links. Such an atlas can serve as the basis for the creation of mechanisms in the conceptual stage of mechanical design and permits the partial automation of this process. The same procedure would also be applicable to the development of a similar atlas for mechanisms with more than six links and a greater variety of joints.
Mechanical Advantage of Single-Input and Multiple-Output Ports Mechanical Device
Authors: Midha A. , Hall A. S. , Her I. , Bubel G. M.
Published: January 2010

The mechanical advantage concept has long been used as a measure of design efficiency of mechanical systems, whose function it is to respond by exerting a certain amount of force at the output for a corresponding input force. The mechanical advantage of a device is characterized by a ratio of the output force to the input force, for the instant in consideration. Traditionally, only single-input and single-output port devices have been analyzed for mechanical advantage. The simplicity of such a configuration makes for tractable analysis by one or more methods available. This paper enunciates a more general mechanical device problem containing single-input and multiple-output ports. In particular, emphasis is placed on a single-input and functionally related multiple-output ports device. Its treatment facilitates efficient design of such a device, as exemplified in this paper.
Coulomb Friction in High-Speed Cam Systems
Authors: Pisano A. P.
Published: January 2010

Coulomb friction in the rocker arm pivot of a high-speed cam system was quantified and its effect on high-speed response was examined. Experimental dynamic data from an automotive valve train was used to determine the static and dynamic coefficients. A lumped-parameter dynamic model was used to determine the role of Coulomb damping in actuation forces and valve toss.
Minimum Weight Design Problems of Fiber-Reinforced Beam Subjected to Uniform Bending
Authors: Oda Juhachi
Published: January 2010

Problems considered here are that of minimizing the weight of beams, which are subjected to a uniform bending moment and reinforced by the fibers distributed in the direction of beam axis. The beam is simplified as a multilaminate structure, of which the fiber volume percent Vfi of each lamina is considered as the design variables. To formulate this design problem the bending theory of multilaminate beam and the law of mixture for the composite material strength are applied. Furthermore, the sequential linear programming and the sequential unconstrianed minimization techniques are used to obtain the design solutions numerically.
NEWSUMT-A: A General Purpose Program for Constrained Optimization Using Constraint Approximations
Authors: Grandhi R. V. , Thareja R. , Haftka R. T.
Published: January 2010

The solution of complex constrained optimization problems is often prohibitively expensive because of the computational expense of evaluating the constraints. Under these circumstances the only viable solution is to employ inexpensive constraint approximations accompanied by move-limits that guard against large errors in the approximated constraints. The NEWSUMT-A program is a general purpose optimization program which automates the process of selecting constraint approximations and move-limits to ensure smooth convergence. The present paper describes the theoretical basis and the implementation of the optimization procedure. Examples from the field of structural optimization are presented. These involve stress and displacement constraints which require a costly finite element analysis. Additionally, the performance of two first-order constraint approximations is compared.
Principles on the Development of Mechanical Hands Which Can Manipulate Objects by Means of Active Control
Authors: Datseris P. , Palm W.
Published: January 2010

A methodology based on kinematic structure concepts is described in this paper for development of mechanical hands which can manipulate objects in a controlled fashion. Although articulated mechanical hands were considered, emphasis was placed on nonanthropomorphic novel concepts (reference [19]) with decoupled output motions. Appropriate classes of objects can be manipulated in five degrees of freedom—three translations and two rotations. This emphasis on designs with decoupled degrees of freedom has resulted in a controllable hand design with maximum manipulative capabilities. Since the motions are decoupled, they can be chosen as to obtain any subset of desired motions. Kinematics and dynamics of these mechanical hands can be studied [33] by homogeneous transformation matrices (4×4), methods similar to those employed for robot arm kinematics and dynamics, thus, unifying methods of analysis and simplifying the arm–hand interface.
Configurations of Robot’s Manipulators and Their Identification, and the Execution of Prescribed Trajectories. Part 1: Basic Concepts
Authors: Litvin F. L. , Parenti Castelli V.
Published: January 2010

The authors have proposed a new method for the determination of all potential configurations which may be formed by the manipulator links, the identification of these configurations, and execution of prescribed trajectories. The key to the solution of these problems is the determination of special link positions and the representation of the Jacobian for these positions as a product of sub-Jacobians. The special link positions are considered separately for the two cases when the special link positions occur: (a) by the execution of the prescribed trajectory and (b) by the execution of the trajectory and the orientation of the gripper. Using the information on the special link positions of the manipulator it is possible to determine all versions of assembly of the manipulator (all of its configurations), identify them, and compose six independent equations for the execution of the prescribed trajectories. The structure of the equation system depends on the structure of the determinant for the special link positions. The proposed method was applied for the Unimation Puma manipulator (Part 1) and for other manipulators with various numbers of degrees of freedom (see Part 2).
Solving the Kinematics of the Most General Six- and Five-Degree-of-Freedom Manipulators by Continuation Methods
Authors: Tsai L.-W. , Morgan A. P.
Published: January 2010

This paper presents a unique approach to the kinematic analysis of the most general six-degree-of-freedom, six-revolute-joint manipulators. Previously, the problem of computing all possible configurations of a manipulator corresponding to a given hand position was approached by reducing the problem to that of solving a high degree polynomial equation in one variable. In this paper it is shown that the problem can be reduced to that of solving a system of eight second-degree equations in eight unknowns. It is further demonstrated that this second-degree system can be routinely solved using a continuation algorithm. To complete the general analysis, a second numerical method—a continuation heuristic—is shown to generate partial solution sets quickly. Finally, in some special cases, closed form solutions were obtained for some commonly used industrial manipulators. The results can be applied to the analysis of both six and five-degree-of-freedom manipulators composed of mixed revolute and prismatic joints. The numerical stability of continuation on small second-degree systems opens the way for routine use in offline robot programming applications.
Workspace Analysis of Regional Structures of Manipulators
Authors: Spanos J. , Kohli D.
Published: January 2010

The fundamental equations for conducting workspace analysis of a class of manipulators having the last three revolute joint axes intersect orthogonally at a point are provided in this paper. These equations are intended for application of the basic theory given in [1] and are concisely arranged in tables. Several examples are included illustrating the use of the tables and equations for determining (a) the boundary surfaces, (b) the surfaces separating the regions of different order of accessibility, and (c) the boundaries due to joint motion limitation.