bluuebunny/crossref_metadata_2025 huggingface dataset:
Materials Failure Logic Models—A Procedure for Systematic Identification of Material Failure Modes in Mechanical Components
Authors: Marriott D. L. , Miller N. R.
Published: January 2010

This paper addresses the problem of improvement of mechanical component reliability by the systematic identification of material failure mechanisms. Experience shows that, in many cases of service failure, failure was caused by a known mechanism which was overlooked, either by design, or elsewhere in the planning process. This paper describes one approach to designing mechanical components against failure by material deterioration, but may have application to other fields. It is based on a finding from the examination of case studies which shows that material failures follow logic structures which can be described by Boolean algebra expressions. These structures are defined as Material Failure Logic Models (MFLM’s), and can be used as a means of systematically identifying potential failure mechanisms in a complex process. The identification technique is based on the observation that MFLM’s are insensitive to the precise causes of the individual events. The paper deals primarily with problems of defining MFLM’s. Some examples of MFLM’s are given. A brief discussion is presented of a CAD system under development at the University of Illinois at Urbana-Champaign.
Mechanical Energy Absorbers and Aluminum Honeycomb
Authors: Kirk J. A.
Published: January 2010

In this paper general equations for a replaceable element energy absorber are presented. For long stroke application (1 m or more) a metal cutting energy absorber is preferred. For shorter stroke applications crushing of aluminum honeycomb material is suggested. To evaluate the usefulness of aluminum honeycomb, as an energy absorber, a drop test apparatus was designed and built. Results suggest two effects, a geometry (“size”) effect and an impact velocity effect, cause the dynamic crush strength of the honeycomb to be different than static crush strength values. Experimentally the net effect causes less then 20 percent difference between static and dynamic crush strengths at extrapolated impact velocities of 50–100 m/s (164–328 ft/s).
Heat Propagation in Rotating Shafts Due to Damping
Authors: Panteliou S. , Dimarogonas A.
Published: January 2010

Static loading of rotating shafts can yield substantial temperatures in the shaft due to heat generated from material damping. It has been recently observed that such a situation in electric generators can lead to insulation failures and machine outages. The hysteretic model for material damping was used to yield the heat generation in the elastic deformation range. The heat conduction equation was solved in the cylindrical shaft with surface cooling. Analytical solutions were obtained and expressions for the maximum temperatures and the maximum surface temperatures were computed and tabulated for design purposes. It is shown that substantial temperatures can develop in shafts at high speeds of rotation even at moderate static loads.
Optimal Tooth Numbers for Compact Standard Spur Gear Sets
Authors: Savage M. , Coy J. J. , Townsend D. P.
Published: January 2010

The design of a standard gear mesh is treated with the objective of minimizing the gear size for a given ratio, pinion torque, and allowable tooth strength. Scoring, pitting fatigue, bending fatigue, and the kinematic limits of contact ratio and interference are considered. A design space is defined in terms of the number of teeth on the pinion and the diametral pitch. This space is then combined with the objective function of minimum center distance to obtain an optimal design region. This region defines the number of pinion teeth for the most compact design. The number is a function of the gear ratio only. A design example illustrating this procedure is also given.
A Method of Selecting Grid Size to Account for Hertz Deformation in Finite Element Analysis of Spur Gears
Authors: Coy J. J. , Chao C. Hu-Chih
Published: January 2010

A method of selecting grid size for the finite element analysis of gear tooth deflection is presented. The method is based on a finite element study of two cylinders in line contact, where the criterion for establishing element size was that there be agreement with the classic Hertzian solution for deflection. Many previous finite element studies of gear tooth deflection have not included the full effect of the Hertzian deflection. The present results are applied to calculate deflection for the gear specimen used in the NASA spur gear test rig. Comparisons are made between the present results and the results of two other methods of calculation. The results have application in design of gear tooth profile modifications to reduce noise and dynamic loads.
Design Optimization of Hydraulic Networks Using Mixed Integer Linear Programming
Authors: Conry T. F. , Werhane J. A.
Published: January 2010

The optimum design problem is formulated for the selection of pipe sizes in a hydraulic network such as a power plant service water or bearing cooling water system. The flows in each branch of the network are taken to be known, which makes the design problem linear in the variables. The optimization problem is formulated as a mixed integer linear programming problem. A design example is given. The role of this problem formulation and solution method in an interactive computer aided design (CAD) system is discussed.
Optimum Phasor Tolerances for Machines With Designed Unbalance
Authors: Nivi H. , Seth B. B. , Field N. L.
Published: January 2010

This paper describes the development of a procedure to determine optimum tolerances for the balancing of machines with inherent unbalance, such as, 90 degree V-6 engines. The conventional circular tolerances were found not to be the optimum ones. The optimum tolerances result in increased feasible area for the random unbalance vector, without exceeding the vibration levels encountered with conventional tolerances. The development is based on the fact that the absolute unbalance vectors are the controlling factors of the vibration levels. Experimental results have been presented to show the feasibility of the optimum tolerances concept. The application of optimum tolerances in the manufacturing facility, where thousands of nearly identical machines need to be balanced, will result in increased productivity, and a reduction in procurement, repair and operation costs of balancing machines.
A New Approach to Probability in Engineering Design and Optimization
Authors: Siddall J. N.
Published: January 2010

The anomalous position of probability and statistics in both mathematics and engineering is discussed, showing that there is little consensus on concepts and methods. For application in engineering design, probability is defined as strictly subjective in nature. It is argued that the use of classical methods of statistics to generate probability density functions by estimating parameters for assumed theoretical distributions should be used with caution, and that the use of confidence limits is not really meaningful in a design context. Preferred methods are described, and a new evolutionary technique for developing probability distributions of new random variables is proposed. Although Bayesian methods are commonly considered to be subjective, it is argued that, in the engineering sense, they are really not. A general formulation of the probabilistic optimization problem is described, including the role of subjective probability density functions.
A Case for a Knowledge-Based Active Set Strategy
Authors: Azarm S. , Papalambros P.
Published: January 2010

A strategy for selecting active constraints in a design optimization program is proposed. The strategy differs from previous ones in that it suggests a combination of local and global knowledge. This knowledge may be analytical in nature, such as the one provided by monotonicity analysis. But it may also be provided by an expert. The strategy is proposed as a first attempt toward development of knowledge-based iteration procedures for optimization.
A Multi-Objective Optimal Design of Thermal Distribution Systems
Authors: Ito K. , Akagi S. , Ohta M.
Published: January 2010

A multi-objective nonlinear optimal planning method is proposed to design thermal distribution systems used for district heating. The following three objective functions are considered which are conflicting mutually and noncommensurable with one another; that is, 1) to minimize the total size of piping system, 2) to minimize the pump power, and 3) to minimize the total size of heat exchangers. Adopting the weighting method in multi-objective optimization, the abovementioned multi-objective functions are optimized by using the generalized reduced gradient algorithm. A man-machine interactive optimal planning system is developed to determine the optimally preferred solution from the set of Pareto optimal solutions derived by the method mentioned above. The validity and effectiveness of the design method proposed here are ascertained through a numerical study for a thermal distribution system, and it is certified that much worthwhile information can be obtained by the optimal planning system developed in this study.
Design Sensitivity Analysis of Large-Scale Constrained Dynamic Mechanical Systems
Authors: Haug E. J. , Wehage R. A. , Mani N. K.
Published: January 2010

A method for computer-aided design sensitivity analysis of large-scale constrained dynamic systems is presented. A generalized coordinate partitioning method is used for assembling and solving sets of mixed differential-algebraic equations of motion and adjoint equations required for calculation of derivatives of dynamic response measures with respect to design variables. The reduction in dimension of the equations of motion and associated adjoint equations obtained through use of generalized coordinate partitioning significantly reduces the computational burden, as compared to methods previously employed. Use of predictor-corrector numerical integration algorithms, rather than an implicit integration algorithm used in the past is shown to greatly simplify the equations that must be formulated and solved. Two examples are presented to illustrate accuracy of the design sensitivity analysis method developed.
Spatial Transient Analysis of Inertia-Variant Flexible Mechanical Systems
Authors: Shabana A. A. , Wehage R. A.
Published: January 2010

An analytical method for transient dynamic simulation of large-scale inertia-variant spatial mechanical and structural systems is presented. Multibody systems consisting of interconnected rigid and flexible substructures which may undergo large angular rotations are analyzed. A finite element technique is used to characterize the elastic properties of deformable substructures. A component mode technique is then employed to eliminate insignificant substructure modes. Nonlinear holonomic constraint equations are used to define joints between different substructures. The system equations of motion are written in terms of a mixed set of modal and physical coordinates. A generalized coordinate partitioning technique is then employed to eliminate redundant differential equations. An implicit-explicit numerical integration algorithm solves the remaining set of differential equations and the approximate physical system state is recovered. The transient analysis of a spatial vehicle with flexible chassis is presented to demonstrate the method.
Optimal Design of Electric Overhead Crane Girders
Authors: Cho S. W. , Kwak B. M.
Published: January 2010

An optimal design for minimum weight bridge girders of electric overhead traveling cranes is presented. The welded box-type girder is modeled as a simply supported beam. A generalized steepest descent algorithm is adopted for mathematical programming, which includes constraints on stress, displacement, buckling, and sizes. A computer program capable of designing girders according to CMAA, DIN, BS, and JIS specifications is developed. Numerical comparisons with existing girders for those four specifications are given. A sensitivity analysis of the optimum design with respect to parameters affecting the design is studied for each specification.
Optimum Balancing of Combined Shaking Force, Shaking Moment, and Torque Fluctuations in High-Speed Linkages
Authors: Lee T. W. , Cheng C.
Published: January 2010

This paper presents an analytical and computer-aided procedure on the balancing of high-speed linkages. The method allows for the trade-offs necessary to achieve optimum dynamic response of the linkage in the design stage. These trade-offs involve a balance among the shaking force, the shaking moment, bearing reactions, and input-torque fluctuations by mass distribution of the links or counterweighting the linkage. Analytical mechanics and heuristic optimization techniques have been demonstrated to be useful tools in developing such a trade-off. The first part of this paper concerns the development of an optimality criterion in which an integrated approach is presented using both the Lagrangian and the Newtonian formulations, and consequently, a higher computational efficiency is achieved. Based on this theoretical development, the remainder of the paper focuses on the formulation of an optimization problem for linkage balancing and the solution of the problem by the Heuristic Optimization Technique of Lee and Freudenstein. The theory and computation are illustrated by numerical examples in the case of four-bar linkages.
A New Matrix Method for the Kinematic Analysis and Motion Simulation of Planar Mechanisms With Lower Pairs
Authors: Sparis P. D. , Mouroutsos S. G.
Published: January 2010

This paper presents a new matrix method for the kinematic analysis and the determination of the velocities, accelerations and jerks for planar mechanisms incorporating rolling, sliding, and pivoting members with a single or multiple degrees of freedom. It also presents a motion simulation procedure that uses the results of the kinematic analysis to estimate the successive positions of the members during the cycle of operation of the mechanism, with third order accuracy in time. Due to the improved accuracy, the proposed motion simulation procedure presents minimal member distortion caused by the accumulation of numerical errors, and does not require iterations for its convergence.
Some Extensions to an Algorithm for the Identification of Single-Degree-of-Freedom Machines
Authors: Nitao J. J. , Wiederrich J. L.
Published: January 2010

In a previous work the second author presented a theory for the identification of a single-degree-of-freedom machine from its forced periodic operating characteristics. In this work that concept is extended by presenting two new methods of solution which, unlike the previous work, do not use Fourier series. The first method is a deterministic method of solution which is not restricted to using periodic data. This deterministic method is used to establish necessary and sufficient conditions for the existence of a unique solution. In particular, it is shown that three observations of the instantaneous drive shaft speed and torque characteristics under different operating conditions are necessary and that the observed speeds must satisfy two conditions. These conditions assure that the observations are independent of each other and that the observations uniquely define three periodic functions which characterize a machine belonging to the specified class of machines. The second method of solution is a least squares formulation which is derived from the first method; however, the derivation of this second method requires that the data be periodic.
Calculation of Spur Gear Tooth Flexibility by the Complex Potential Method
Authors: Cardou A. , Tordion G. V.
Published: January 2010

Complex potentials have already been used to calculate analytically spur gear stresses. However, their application to the calculation of tooth flexibility is not so straightforward since displacements of interest are at the tooth contact point, which is a singular point for the equations being used. A method has been devised to circumvent this difficulty and to obtain the value of the displacement at each point of the line of action, and thus, the flexibility of a given pair of spur gears.
Closed-Form Approximations to the Solution of V-Belt Force and Slip Equations
Authors: Dolan J. P. , Worley W. S.
Published: January 2010

A method for generating accurate numerical solutions of the exact differential equations describing tension distribution and radial penetration of a flexible V-belt on driveN and driveR sheaves is presented and results are compared with approximate solutions reported in the literature. Analytical approximations for these solutions of higher accuracy than any previously published have been found and are presented. They suggest important modifications of current design practice for belt tensioning and life appraisal.
Optimization of Electromagnetic Actuator Performance for High-Speed Valves
Authors: Karidis J. P. , Turns S. R.
Published: January 2010

The dynamic performance of electromagnetic actuators driving on-off control valves is optimized numerically by combining hybrid lumped-parameter/distributed-parameter actuator models with an efficient constrained optimization technique. Two examples of constrained actuator optimization are presented where up to eight design parameters are optimized. One example problem involves minimizing variations in the response time of a fuel injection control valve caused by manufacturing and assembly tolerances, while the other example deals with minimizing the response time of a high-speed gas sampling valve.
Dynamics of Inertia-Variant Flexible Systems Using Experimentally Identified Parameters
Authors: Shabana A.
Published: January 2010

In this investigation modal parameters (frequency, damping, and mode shapes) which are determined experimentally using parameter estimation techniques are employed to simulate and predict the dynamic behavior of flexible multibody systems which consist of interconnected rigid and flexible components. The system differential equations of motion and algebraic constraint equations describing mechanical joints in the system are first identified using analytical techniques. Dynamic parameters such as mass, damping, and stiffness coefficients that appear in the system differential equations are then identified using a set of experimentally measured data. Mode shapes which are the result of the experimental identification are used to write the physical elastic coordinates of selected nodal points on the flexible body in terms of a reduced set of modal coordinates. The nonlinear differential and algebraic constraint equations are then written in terms of mixed sets of coupled reference and modal coordinates. These equations are integrated numerically using a direct numerical integration technique coupled with Newton–Raphson type iterations in order to check on constraint violations. The formulation developed is numerically exemplified using a three-dimensional dune buggy vehicle model.
Design of a Three-Degree-of-Freedom Robotic Worktable With Prescribed Entire-Motion Characteristics
Authors: Chen Jau-Jung , DiBenedetto A. , Pennestri E. , Lee Ting W.
Published: January 2010

This paper presents the analysis and design of a robotic worktable with a structure based on two platforms connected by three four-bar linkages. The worktable has three rotational degrees-of-freedom and is designed for special motion generators, such as gyroscope calibration instruments and flight simulators. Of primary interest is the influence of the characteristics of a single four-bar linkage on the entire-motion characteristics of the worktable. This involves an investigation of the effects of limit positions, rotatability of cranks, transmission-angle characteristics and the variation of design parameters of the four-bar linkages on the characteristics of the compound platform mechanism. Based on the analytical results, some physical insights are interpreted and general guidelines can be drawn on the design of this robotic worktable with prescribed motion characteristics.
An Application of Dual Graphs to the Automatic Generation of the Kinematic Structures of Mechanisms
Authors: Sohn Wayne J. , Freudenstein Ferdinand
Published: January 2010

Through the use of dual graphs, a powerful new representation of the kinematic structure of mechanisms has been developed. This permits the development of a highly efficient completely automatic procedure for the computer-generated enumeration of the kinematic structures of mechanisms. As an example, the kinematic structures of one, two and three-degree-of-freedom plane bar linkages with up to four independent loops have been enumerated on a personal computer.
Ultimate Strength Design of Racks for Jack-Up Units
Authors: Honda Hiroshi
Published: January 2010

The subject of paper discusses an approach taken in evaluating the load acting on racks for jack-up units (the jack load) together with its computed results. The fracture test of a full-scale rack for a jack-up unit and a finite-element elastic stress analysis for this rack were also conducted. These results led to new design criteria for the ultimate strength design method of racks for jack-up units, when exposed to a combination of loads including stormy conditions. Typically, the ultimate strength of the racks was evaluated on the assumption that the cross section of the rack tooth plastically collapses at its root. During this investigation, it was shown, however, that the ultimate strength of the racks needs to be evaluated also on the premise that the rack tooth is subject to shear fracture caused by its mating pinion tooth.
A Computer-Aided-Design Technique for the Optimum Synthesis of RRSS Path Generating Spatial Mechanisms With Prescribed Input Timing
Authors: Premkumar P. , Kramer S. N.
Published: January 2010

With the current emphasis on automation, the need for single actuator mechanical devices that can perform simple repetitive tasks much more economically, energy-efficiently and accurately than multiple-degree-of-freedom, multiple-actuator robotic manipulators is greatly felt. This paper presents an optimum synthesis technique for the RRSS path generating spatial mechanism with prescribed input timing. The selective precision synthesis technique is used to formulate the nonlinear constraint equations involving accuracy neighborhoods and corresponding error envelopes and these are then solved using the generalized reduced gradient method of optimization. The mathematical formulation and derivation as well as numerical examples are presented in this paper.
Instantaneous Properties of Multi-Degrees-of-Freedom Motions—Point Trajectories
Authors: Ghosal Ashitava , Roth Bernard
Published: January 2010

A general framework is presented for the study of the properties of trajectories generated by points embedded in rigid bodies undergoing multi-degrees-of-freedom motions. Quantities are developed to characterize point trajectories generated by different mechanisms and to distinguish between different positions along the same trajectory. Point trajectories are classified into three types according to whether the number of degrees of freedom is less than, equal to, or greater than the dimension of the space in which the motion takes place. Local and global motion properties are developed for each of these three cases. A new way of using the redundant degrees of freedom in (redundant) mechanisms is presented. These analysis techniques are applied to two- and three-degrees-of-freedom mechanisms containing rotary and prismatic joints.
Description and Optimum Design of Fuzzy Mechanical Systems
Authors: Rao S. S.
Published: January 2010

Much of the decision-making in the real world takes place in an environment in which the goals, the constraints and the consequences of possible actions are not known precisely. To deal quantitatively with imprecision, the tools of fuzzy set theory can be used. This paper deals with the description and optimization of mechanical systems containing fuzzy information. The fuzzy constraints define a fuzzy feasible domain in the design space and hence the fuzzy optimum solution will be defined by a fuzzy set of points. In this work, two methods are presented for solving a fuzzy optimization problem using ordinary optimization techniques. The optimum design of a four-bar function generating mechanism with fuzzy objective function and fuzzy constraint set is considered to illustrate the procedures.
A Theory for the Articulation of Planar Robots: Part II—Motion Planning Procedure for Interference Avoidance
Authors: Young L. , Duffy J.
Published: January 2010

This paper presents a motion planning procedure for planar robots which provides the robots with abilities to change flexure (i.e., to articulate) and hence to avoid interference with other robots or with obstacles. The angular displacement for each of the joints will be determined using those motion planning procedures.
Robot Workspace of a Tool Plane: Part 1—A Ruled Surface and Other Geometry
Authors: Davidson J. K. , Hunt K. H.
Published: January 2010

The sweeping process is used for conceptually describing plane-workspaces and for distinguishing certain forms of these workspaces for robots. The tangent point to the plane-workspace of a tool plane σ is identified as the intersection point of σ with that extreme-distance line which is also normal to σ. The quartic ruled surface, which is a new property of the dual torus, is identified and described. It contains information that uniquely identifies the 2-R manipulator which generates the dual torus. these geometric features are then used in developing the equations for computer generation of plane-workspace envelopes and boundaries for an n-R robot.
Dynamic Model of a Fluctuating Rocker-Arm Ratio Cam System
Authors: Chan Chingyao , Pisano Albert P.
Published: January 2010

This study is focused upon one example from a class of cam systems with a fluctuating rocker-arm ratio, known as “finger follower” cam systems. This class of cam systems is typically built in practice with a hydraulic tappet as the pivot-end support for the finger-follower, and the rocker-arm ratio varies as much as 34 percent from the baseline value during the cam cycle. A six-degree-of-freedom dynamic model is formulated to predict the forces as well as the motions of the cam system components. Successful dynamic modeling of such a system requires an accurate model for the hydraulic tappet as well as for the cam system, and so, six separate dynamic phenomena are identified in the tappet and the resulting nonlinear dynamics included in the cam system model. Lateral and rotational motions, as well as the customary longitudinal displacement, are admitted for the valve, and it is found that although the extra degrees of freedom change the cam contact force but little, they strongly influence where in the cam system toss and impact occur.
Synthesis of Path-Generating Mechanisms and Tolerance Allocation Using Information Theory
Authors: Sukhija R. P. , Rao A. C.
Published: January 2010

The information theory based on probability concept was developed for application in communication engineering. This theory utilizes the concept of “entropy,” a measure of uncertainty. The errors existing in the output of a path-generating linkage and desired path can be taken as random variables. The entropy function is formulated in terms of design parameters. Minimization of maximum entropy leads to the synthesis of a path-generating mechanism. Optimum allocation of tolerances on link lengths is also carried out.
A Differentiable Null Space Method for Constrained Dynamic Analysis
Authors: Liang C. G. , Lance George M.
Published: January 2010

A geometric approach to the solution of the dynamic response of constrained mechanical systems is proposed. A continuous and differentiable basis of the constraint null space is automatically generated using the Gram-Schmidt process. The independent coordinates are obtained by transforming the physical velocity coordinates to the tangent hyperplane of the constraint surface. As a result the independent coordinates lie on the constraint surface and no constraint violation control is necessary.
Surface Geometry of Straight and Spiral Bevel Gears
Authors: Tsai Y. C. , Chin P. C.
Published: January 2010

The fundamental geometrical characteristics of bevel gears have been discussed in this study. The mathematical modeling of the tooth surface geometry of bevel gears can be developed based on the basic gearing kinematics and involute geometry along with the tangent planes geometry. The parametric representations of the spherical involute and the involute spiraloid, which are the tooth surface geometry of straight bevels and spiral bevels, respectively, have been derived in this paper. This study may provide some fundamentals for computer numerical controlled manufacturing of bevel gears.
An Interior Linear Programming Algorithm Using Local and Global Knowledge
Authors: Li Heng Long , Papalambros Panos
Published: January 2010

A new algorithm for linear programming problems is presented. The algorithm makes interior moves with a special active set strategy that utilizes both local and global knowledge. This knowledge represents primarily monotonicity and dominance information. The article describes the rationale, theory, implementation, and some test examples for the algorithm. The ideas presented form the basis for nonlinear programming extensions in sequel articles.
Multiobjective Hydraulic Cylinder Design
Authors: Michelena Nestor F. , Agogino Alice M.
Published: January 2010

Monotonicity analysis is used to solve a three-objective optimization problem in which a hydraulic cylinder is to be designed. With the additional application of the Karush-Kuhn-Tucker optimality conditions a reduced symbolic design chart is obtained which is then utilized to obtain parametric numerical results. Two- and three-dimensional parametric Pareto-optimal plots are obtained for the three conflicting objectives: (1) cross-sectional area, (2) circumferential stress ratio and (3) pressure ratio. The analysis and design procedure strengthens and extends the results suggested by previous works.
Development of the Tri-Level Variable Rate Trajectory With Discretely Vanishing Shock for Optimum Design
Authors: Kramer Steven N. , Curran Richard L.
Published: January 2010

The tri-level variable rate trajectory is a general motion which can be applied to programmable controllers, robotic manipulators, mechanisms, and mechanical devices where the input crank orientation, velocity, and acceleration vary with time. In the work presented here, the tri-level variable rate trajectory is an extension of the variable-rate trans-symmetric motion developed by the first author in 1984. That motion and the one developed here consist of discrete segments of constant and linearly varying accelerations occurring over specified time intervals, thereby providing versatile programmable trajectories with several advantages over the constant acceleration motion, simple harmonic motion, cycloidal motion, and the popular polynomial trajectories used in robotics. The tri-level variable-rate trajectory allows much more control of the acceleration contour of the motion and as a result, there is a decrease in the power required, a decrease in the operating cost, and a decrease in dynamic responses such as shock, vibration, and shaking force and virtual elimination of the overshoot problem that sometimes accompanies the polynomial segment motions. This is a general method which can be applied to many applications. The results of applying this trajectory to a complex machine controller are presented as an example.
Computation of Euler Parameters From Multipoint Data
Authors: Friberg O.
Published: January 2010

A method for computing Euler parameters using three noncollinear points which have been given coordinates in a dynamic and an inertial frame is presented. One object with the method is to facilitate the establishment of initial conditions for differential equations by the use of multipoint data that can easily be interpreted physically. From these data, the mathematically convenient Euler parameters, which are used in computer programs for mechanical systems, are computed. A FORTRAN program is included.
Design and Mechanics of Multi-Lay Wire Strands
Authors: Velinsky Steven A.
Published: January 2010

Wire strands and ropes have been used extensively for many years. However, the method for designing these elements remains highly dependent on the designer’s experience. In recent years, capabilities for the analysis of wire rope have progressed to a level where a reevaluation of wire rope design is appropriate. Recently, a linearized theory has been developed that allows a relatively simple method for analyzing complex strands and wire ropes. This theory, through substantiation with experiment, is felt to be reasonably accurate for most wire rope behavior. The present paper considers multi-lay wire strands and adds generality to the linearized theory to account for strands with any number and direction of wire lays. The geometry of wire strands is investigated in detail and a design methodology for strand geometry, including sizing the wires, is devised. The theory is then utilized to examine the effects of various design parameters on strand properties.
Cam Motion Synthesis Using Spline Functions
Authors: Tsay D. M. , Huey C. O.
Published: January 2010

The application of spline functions to the general synthesis of cam motion programs is presented. The approach provides a single, systematic, easily automated method of accommodating discrete constraints on follower displacements, velocities, and accelerations, even when the set of constraints becomes large. Yet, it is as easily applied in simple cases as are the more traditional methods of syntheses. It also allows the designer to refine the motion program by locally influencing characteristics of the motion while still satisfying the discrete constraints. A series of examples is presented to illustrate application of the method and to compare it to the more traditional techniques.
Load and Stress Distributions in Spur and Helical Gears
Authors: Simon V.
Published: January 2010

A method for the determination of load and stress distributions along the contact lines of the instantaneously engaged teeth of spur and helical gears is represented in this paper. The calculation includes the tooth profile modifications and crownings, manufacturing and alignment errors of gears, tooth deflections, local contact deformations of teeth, gear body bending and torsion, and deflections of supporting shafts. The influence of gear parameters on load and stress distributions is discussed. On the basis of the obtained results, by regression analysis, equations are derived for the calculation of load and stress distribution factors.
A General Method of Determining and Eliminating Branching in Planar Multiloop Mechanisms
Authors: Krishnamurty S. , Turcic D. A.
Published: January 2010

In most mechanism systems, there exists more than one mode of assembly or configuration, of the mechanism for a given set of input conditions. During the synthesis process, branching occurs when the mechanism changes from one configuration to another. Branching in mechanisms renders them unsuitable because they have to be disassembled and reassembled in order for them to correctly perform the design tasks. In this paper, a comprehensive method for the determination and the elimination of branching problems during synthesis in planar multiloop mechanisms with lower kinematic pairs and with multiple modes of assembly is presented. A general method is developed for the identification of all the branching configurations in a given mechanism. Sub-Jacobian matrices are formed for the sets of constraints associated with each potential branching configuration. The signs of the determinant values of the sub-Jacobian matrices are evaluated. By maintaining the signs of the determinant values to be the same, at all times, during the synthesis process, solutions without the effect of branching are achieved for general planar multiloop mechanisms. Implementation of the method in a general mechanism synthesis package is discussed and applications of the method are illustrated by means of examples. This method of determining branching in mechanisms also is ideally suited for implementation in an optimization process to select the appropriate mechanism configuration that best satisfies the design requirements and for maintaining that configuration throughout the entire cycle of operation.
Design of Mechanisms Via Constrained Least-Squares Method and Its Variants
Authors: Cheng Hui , Gupta K. C.
Published: January 2010

Based on the design equation of mechanism and the least-squares techniques, a rapidly convergent iteration method and simple direct methods for the synthesis of mechanisms are presented. It is proved that the so-called linear superposition method is a special case of the direct methods whose effectiveness depends upon the singular nature of the normal equations of the least-squares method as well as the smallness of the Lagrange multipliers of the compatibility equations for the mechanism. While the significance of the latter has been recognized in the literature, that of the former has not been documented in the literature. By examining the correlation matrix and the condition number for the normal equations, we show that these are near-singular. This property provides a fundamental basis for the direct methods presented in this paper. The sensitivity of solutions to the design specifications and to the precision of floating point computations also is discussed. The theory and associated algorithms can be applied to the synthesis of any planar or spatial mechanism where the use of the least-squares technique is contemplated.
Helical Gears With Involute Shaped Teeth: Geometry, Computer Simulation, Tooth Contact Analysis, and Stress Analysis
Authors: Tsay Chung-Biau
Published: January 2010

The paper covers the solutions to the following problems: (1) Setting up a mathematical model for the involute helical gears; (2) Computer simulation of the conditions of meshing and bearing contact; (3) Investigation of the sensitivity of gears to the errors of manufacturing and assembly; and (4) Stress analysis of the gears. In this paper, the theory of gearing and the concept of differential geometry have been applied to deal with the relations of two mating helical gears and their bearing contact. Computer program for tooth contact analysis (T.C.A.) has been developed for the gears. The T.C.A. computer program makes it possible to simulate gear meshing and bearing contact, and to investigate the influence of gear misalignment on kinematic errors. A method of compensation for the dislocation of bearing contact and for kinematic errors induced by errors of manufacturing and assembly has been proposed. Four numerical examples have also been presented to illustrate the influence of the above-mentioned errors and the method of compensation for the dislocation of bearing contact. Based on the derived mathematical model, an automatic mesh generating computer program—AMG has been developed to define the geometry of the gears and to divide the gear tooth into elements as well as to generate nodal points automatically. The results of T.C.A. provide the locations and directions of the applied loadings for the finite element method (F.E.M.) stress analysis.
Decision Making in the Choosing of New Materials from the Standpoint of Machine Structural Dynamics
Authors: Yoshimura M.
Published: January 2010

The use of a new material is a hopeful strategy for breaking through the barrier of improving the product performance and/or the lowering of the product manufacturing cost. However, if the definite decision making method for selection of materials has not been established, use of a new material may not result in enhancement of the product performance and/or reduction of the product manufacturing cost. This paper proposes a methodology for decision making of a material used in machine structures from the standpoint of structural dynamics. First, purposes for use of new materials and evaluative parameters for decision making of material choice are described, and fundamental knowledge and theorems for decision making are established. Then, general decision making procedures for material choice are constructed. Finally, for model cases of purposes for use of new materials, detailed decision procedures are explained using also some numerical examples.
Optimization With Discrete Variables Via Recursive Quadratic Programming: Part 1—Concepts and Definitions
Authors: Cha J. Z. , Mayne R. W.
Published: January 2010

Although a variety of algorithms for discrete nonlinear programming have been proposed, the solution of discrete optimization problems is far from mature compared to continuous optimization techniques. This paper focuses on the recursive quadratic programming strategy which has proven to be efficient and robust for continuous optimization. The procedure is adapted to consider a class of mixed discrete nonlinear programming problems and utilizes the analytical properties of functions and constraints. This first part of the paper considers definitions, concepts, and possible convergence criteria. Part II includes the development and testing of the algorithm.
A General Method for Computing Worm Gear Conjugate Mesh Property: Part 2—The Mathematic Model of Worm Gear Manufacturing and Working Processes
Authors: Zheng Changqi , Lei Jirong
Published: January 2010

Part 2 of this article is devoted to building a generalized mathematic model of worm gear manufacturing and working processes which can be used for calculating the contact line, the profile, the normal curvature, the conjugate boundary and the angle between the directions of contact line and relative velocity vector for any kind of worm gear tooth surface.
The Effect of Geometry Imperfections on the Performance of Multiple V-Belt Drives
Authors: Massouros G.
Published: January 2010

It has been observed in practice, that the lifetime of a multiple V-belt drive is always less than the corresponding life of a single V-belt drive. This is due to an uneven contribution of all belts of the multiple drive to the power transmission owing to microerrors in the equality of the diameters and profiles of all grooves and of the lengths of all belts. These microerrors cause a distribution of the transmission ratios among the branches of the V-belt around a mean value which in turn results in an uneven loading of the belts and a reduction of their “life.” In the present work, analytical relations are obtained for the influence of the aforementioned errors on the elastic creep of the belts, on the transmitted power, and on the other characteristics of the belt drive. An experiment was made to verify the analytical results.
Position, Velocity, and Acceleration Synthesis of the RRSS Spatial Path-Generating Mechanism Using the Selective Precision Synthesis Method
Authors: Premkumar P. , Kramer S. N.
Published: January 2010

The inclusion of velocity and acceleration constraints is a crucial step in the coupling of the dynamics with the kinematics of spatial mechanisms. In this paper, an optimum synthesis technique is presented which allows an arbitrary combination of positions, velocities, and accelerations to be specified along with appropriate tolerances at one or more of the prescribed path points. The method of Selective Precision Synthesis is used to formulate nonlinear constraint equations which are then solved by the generalized reduced gradient method of optimization. This is significant since it paves the way for the coupling of mechanism dynamics with the kinematics of spatial mechanisms. The technique developed herein is general to all spatial mechanisms and is exemplified by the RRSS path-generating spatial mechanism.
Dynamic Response Optimization of Mechanical Systems With Multiplier Methods
Authors: Paeng J. K. , Arora J. S.
Published: January 2010

A basic hypothesis of this paper is that the multiplier methods can be effective and efficient for dynamic response optimization of large scale systems. The methods have been previously shown to be inefficient compared to the primal methods for static response applications. However, they can be more efficient for dynamic response applications because they collapse all time-dependent constraints and the cost function to one functional. This can result in substantial savings in the computational effort during design sensitivity analysis. To investigate this hypothesis, an augmented functional for the dynamic response optimization problem is defined. Design sensitivity analysis for the functional is developed and three example problems are solved to investigate computational aspects of the multiplier methods. It is concluded that multiplier methods can be effective for dynamic response problems but need numerical refinements to avoid convergence difficulties in unconstrained minimization.
A Dynamic Analysis of a Spatial Mechanism With a Passive Degree of Freedom
Authors: Suh C. H. , Kang H. Y.
Published: January 2010

A method is developed for kinematic and dynamic analysis of a spatial mechanisms that has one or more links with a passive degree of freedom. The Sphere-Sphere (SS) link, the most commonly known link having a passive degree of freedom, is investigated to develop in detail displacement, velocity, and acceleration matrices for complete kinematics. The dynamic analysis of the RSSR mechanism is presented as an example, using the developed kinematic method for SS links and Euler’s equations of motion.
Design and Implementation of a Prototype ‘Intelligent’ CAD System
Authors: Jakiela M. J. , Papalambros P. Y.
Published: January 2010

System requirements and system design for integrating a production rule program and a computer aided design system are presented. An implementation using a commercially available graphics modeling system is described. A “suggestive mode” interface is programmed as an example with application to design for automated assembly. Initial use of the implementation indicates that encoding production rules is more difficult than with conventional text-only knowledge-based system, but that this system is a more effective way to use artificial intelligence techniques in design. The system is intended for use with knowledge domains that are not well represented by usual analytical means.
Displacement Analysis of Two Special Cases of the TTTR Mechanisms
Authors: Lin Wei , Duffy Joseph
Published: January 2010

A pair of quartic polynomials in the tangent of the output angular displacement were derived for two TTTR mechanisms designed in such a way that the serially connected pairs of Hooke joints have their successive transverse axes parallel or mutually perpendicular. These results form the basis for an efficient reverse displacement analysis and for the design of a new group of robots with three serially connected Hooke joints which may prove to be attractive to industry.
An Automated Procedure for Globally Optimal Design
Authors: Hansen P. , Jaumard B. , Lu S. H.
Published: January 2010

An experimental computer system for globally optimal design, called BAGOP, is discussed. This new tool uses the computer algebra system MACSYMA to implement a variety of tests and branching rules in a flexible branch-and-bound framework. Many problems of globally optimal design have been solved by BAGOP, some of them for the first time, and most of them for the first time in an entirely automated way.
On the Design of Wire Rope
Authors: Velinsky S. A.
Published: January 2010

In recent work, a design methodology for multi-lay wire strands has been developed. The current paper expands on this earlier work to study wire ropes in which the strand is a basic component. Wire ropes with the three types of cores, independent-wire-rope-core (IWRC), fiber-core (FC), and wire-strand-core (WSC), are considered. This work further generalizes the previously developed linearized theory which, through substantiation with experiment, is felt to be reasonably accurate for most wire rope behavior. The theory is then utilized to examine various parameters in the design of wire ropes.