bluuebunny/crossref_metadata_2025 huggingface dataset:
Observer Design for the Minimum-Time State Reconstruction of Linear Discrete-Time Systems
Authors: O’Reilly John
Published: November 2010

The problem of observer design for the minimum-time state reconstruction of a general class of discrete-time linear multivariable systems is considered. Both full-order and minimal-order observers, each specified by a gain matrix in closed form, are presented which reconstruct the system state in a minimum of vo and vo − 1 steps respectively, where vo is the system observability index. The simplicity and generality of the designs are demonstrated by numerical example.
A Logical Procedure for the Construction of Bond Graphs in Systems Modeling
Authors: Martens H. R. , Bell A. C.
Published: November 2010

The problem of deriving a suitable mathematical model for complex devices is discussed. A small vibratory air pump is used as the medium of presentation. The modeling process begins with the basic coupling structure of the device. In a logical step-by-step procedure the initial model is built up to satisfy a number of functional considerations inherent to the device, such as the resonance behavior, input impedance, output impedance, and internal dissipation. At each step in the modeling process the completeness and suitability of the model is examined. Bond graphs drawn for the successively larger and more complex model clearly predict the shortcomings of the partial model and point the way to the next step. It is evident that the principle of causal relations forms a most important guiding element in the modeling process. The final model is in the form of a set of linear state equations, and scaling of the A-matrix indicates the relative importance of parameters when experimental values are substituted for literals.
Simulation of Nonlinear Multiport Systems Using Bond Graphs
Authors: Martens H. R.
Published: November 2010

An approach for the computer simulation of nonlinear multiport systems is presented. Bond graph techniques are utilized in the development. The objective of the formulation is to derive a system of mixed first-order differential/algebraic equations, whose solution is facilitated by approximating the derivatives by a linear combination of the present and several previous solution points. Thus the original system of equations is converted to a system of implicit nonlinear algebraic equations which are solved by a Newton iteration procedure. The formulation procedure lends itself to mechanization similar to ENPORT. Computational results from an illustrative example show the method to be excellent in speed and accuracy relative to other simulation approaches.
A Survey of Automatic Control Teaching and Research in University Mechanical Engineering Departments
Authors: Healey A. J. , Nachtigal C.
Published: November 2010

This article describes the results of a questionnaire survey taken within the last two years of the state of control education in university mechanical engineering departments. The results of the analysis showed in general that control per se is not regarded as a subject of singular importance in engineering curricula. For instance, 13.25 percent of the replies indicated no control courses at the undergraduate level; 42.1 percent of the replies indicated control as an elective, and 42.16 percent as a required undergraduate course; and 44.5 percent replied with no control laboratory. Use of computers, however, was very common (77.1 percent teaching analog and digital computation, 6 percent teaching digital only, and 0 percent teaching analog only). Details of courses and texts were solicited. It was found that most departments do not offer graduate courses in control, most having less than five masters and less than three doctoral students.
An Analytical and Empirical Basis for the Design of Turbulence Amplifiers: Part II: Empirical Relationships and Design Procedure
Authors: Bell A. C.
Published: November 2010

This paper is a direct extension of Part I. The relationships important to turbulence amplifier characteristics but not amenable to direct analysis are empirically determined in this part. These include the output pressure-control flow characteristics, the influence of amplifier geometry on control performance, and data on the location of the free (uncontrolled) transition that always occurs in the main jet. With this information and the results of Part I of this paper, a design procedure is presented and confirmed by an example compared with measured data. The procedure is useful for the design of turbulence amplifiers operating with air as the working fluid.
The Frequency Response of Pneumatic Lines With Branching
Authors: Ravindran V. K. , Manning J. R.
Published: November 2010

Some experimental results are presented for amplitude and phase of small signal frequency response of pneumatic lines in configurations with branching. The recent data of Franke, Malanowski, and Martin [1] is extended in two areas: 1 Phase as well as amplitude measurements were made. 2 Stepped and conical branches were studied as well as constant area branches. Agreement is good with theoretical predictions based on the Iberall-Nichols-Brown model [2, 3, 4] and a simple continuity model for branch junctions. Three-dimensional effects at junctions are apparently not significant for the small amplitudes (less than 0.1 psi) and range of frequencies (100 to 1000 Hz) studied.
Simulation as Applied to the Design of Interactive Control Systems
Authors: Dubowsky S.
Published: November 2010

The design of an interactive control system used in the electromechanical transport of an optical reading system was performed, using both analog and digital simulations. Included are laboratory data and traces taken from an engineering breadboard. The equations of motion are developed and are found to be highly nonlinear which cannot be solved by a closed-form analytical solution, and thus a simulation approach was required. Results of the digital solution are compared with the analog solution with emphasis on the similarities and differences of the two approaches. Simulation plots are compared to traces of the control signals of the actual system. This leads to significant insight into the strength and weaknesses of the simulation approach.
Simulation of Respiratory Regulation of Blood Gases in the Critically Ill Patient
Authors: Farrell Edward J. , Siegel John H.
Published: November 2010

In the regulation of arterial blood gases, the relative importance of metabolic exchange, respiratory capability, and level of ventilatory control sensitivity to blood O2, CO2 and pH was investigated. The study was based on a dynamic computer simulation of a multi-compartment elastic lung and its interactions with the cardiorespiratory system, and the regulation of acid/base balance. The model was evaluated with clinical data from control and critically ill patients. This study suggests that increases in metabolic demand and reduced ventilatory capability are major factors in influencing the regulation of arterial gas tensions and pH in patients with severe sepsis, rather than changes in the level of sensitivity to arterial CO2 and O2.
Instability and Mitotic Patterns in Tissue Growth
Authors: Glass Leon
Published: November 2010

A mathematical model which reproduces several qualitative features of cancerous tumor growth is proposed. The onset of unstable growth is characterized by a dimensionless number, which is defined in terms of the parameters describing the system. Patterns of mitotic activity of the model system are compared with experimentally observed patterns of mitotic activity in cancerous tissues.
The Properties of Bond Graph Junction Structure Matrices
Authors: Ort J. R. , Martens H. R.
Published: November 2010

Some fundamental theorems concerning the relationship between the junction structure of bond graphs and the effort and flow equations, are presented. Necessary and sufficient conditions are stipulated to guarantee the correct number of constraint equations. The structure and rank of the coefficient matrices of the effort and flow equations are examined. An orthogonality relationship between effort and flow equations is established. The development yields the result that the number of effort and flow equations corresponding to a causal assignment are sufficient and their coefficient matrices are of maximum rank.
Solutions of the Singular Stochastic Regulator Problem
Authors: Hutton M. F.
Published: November 2010

The limiting form of the optimum stochastic regulator is determined which minimizes the steady-state expectation, Es{x′Qx + u′Ru}, for the linear process, x˙ = Ax˙ + Bu + Gv, given noisy observations y = Hx + w (with v and w being independent white noise processes) when either the control weighting matrix, R, or the spectral density matrix, W, of the observation noise, w, is singular. It is shown that as R tends from a positive-definite matrix to a non-negative definite matrix, the optimum regulator can be synthesized by a system using at most n − ks integrators, where n is the order of the system and ks equals the rank of B minus the rank of BR. Similarly, when W tends from a positive-definite matrix to a non-negative definite matrix, the optimum regulator can sometimes be synthesized by a system using at most n − rs integrators, where rs equals the rank of H minus the rank of WH. The structure of the regulator is given for each of these cases.
The Optimal Adaptive Sampled-Data Regulator
Authors: Schlueter R. A. , Levis A. H.
Published: November 2010

The optimal control problem for sampled-data processes in which sampling is not triggered by a timer, but occurs when one or more outputs attain preset threshold values is formulated as an adaptive optimal sampled-data regulator problem. Both open loop and closed loop solutions are determined and a comparison of a system’s performance with adaptive and with periodic sampling is presented.
A Theoretical Basis for the Active Control of a Boring Bar Operation
Authors: Klein R. G. , Nachtigal C. L.
Published: November 2010

The properties of low stiffness and low structural damping in boring bars are widely known to be factors resulting in chatter and inaccurate machining. The application of active control offers a new alternative to improving the performance of a boring bar. This paper presents the theoretical basis for such an active control system. The analysis includes the practical consideration of principal modes in the boring bar model and discusses this influence on controller design. Simulation results using data from an experimental system illustrate some important factors of system design.
A New Approach to Manipulator Control: The Cerebellar Model Articulation Controller (CMAC)
Authors: Albus J. S.
Published: November 2010

CM AC is an adaptive system by which control functions for many degrees of freedom operating simultaneously can be computed by referring to a table rather than by mathematical solution of simultaneous equations. CM AC combines input commands and feedback variables into an input vector which is used to address a memory where the appropriate output variables are stored. Each address consists of a set of physical memory locations, the arithmetic sum of whose contents is the value of the stored variable. The CM AC memory addressing algorithm takes advantage of the continuous nature of the control function in a way which promises to make it possible to store the necessary data in a physical memory of practical size.
Computer-Aided Design Procedure for Laminar Fluidic Systems
Authors: Drzewiecki T. M. , Wormley D. N. , Manion F. M.
Published: November 2010

This paper presents a computer aided procedure for the design of laminar proportional fluid amplifiers and gain blocks. The procedure is based upon a fundamental analysis of the flow regimes in an amplifier. With the aid of a computer, amplifier static and dynamic characteristics, required in control system design, may be determined as a function of geometry and fluid properties. The procedure is illustrated and evaluated by comparison of predicted design and experimentally measured performance. The procedure has been applied to individual elements designed by three different organizations, multistage gain blocks, and laminar jet rate sensor preamplifiers. The results of the procedure are shown to be quite accurate over a wide range of amplifier geometries (eleven different amplifiers with aspect ratio from 0.25 to 3 – a range of 12 to 1 – and nozzle sizes from 0.5 to 10 mm) and operating fluids (both air and oil). Experimental measurements were within 10 percent of the design predictions for amplifier gains, operating resistances, and bandwidth for all examples investigated.
Vehicle-Follower Control With Variable-Gains for Short Headway Automated Guideway Transit Systems
Authors: Chiu H. Y. , Stupp G. B. , Brown S. J.
Published: November 2010

The use of the vehicle-follower approach for the longitudinal control of vehicles in an automated transit system is discussed for the short headway (0.4 to 3.0 s) range of operation. It is shown, if one adopts a constant gain approach, that the required bandwidth of such controllers increases rapidly with a decrease in nominal headway if safe operation is to be assured. Initial conditions typically encountered during merge and overtake maneuvers can cause unacceptably large jerk and acceleration levels if applied to such constant gain controllers. A candidate for overcoming these problems is a control technique which first employs gains appropriate to the initial conditions and then varys the gains to achieve the desired values as controller errors are reduced. Under nominal operating conditions, this time-varying gain approach is also demonstrated to satisfy performance requirements based upon the kinematics of ride quality constraints.
Filtered Sequential Regression Parameter Identification Applied to a Gas Turbine Engine Model
Authors: Warner D. E. , Ward E. Dawson
Published: November 2010

In this paper a filtered sequential regression parameter identification technique is developed which is feasible for on-board digital computer implementation on gas turbine engines. When applied to a test second order system, this filtered sequential technique is superior to a nonfiltered sequential technique for noisy data. The practicality of the technique is demonstrated by application to data generated from a twinspool gas turbine engine model. A simplified linear set point model was identified using the two spool speeds as state variables. The model obtained with this filtered sequential regression technique matched the system state response to within 2 percent accuracy.
Mechanics of Gear Hobbing
Authors: Bhattacharyya A. , Deb S. R.
Published: November 2010

The exacting demands for producing accurate gears make it necessary to determine the cutting forces coming on the hob-shaft which is the weakest element subjected to severe bending and torsion. The authors, with the help of a specially designed hobbing dynamometer, have investigated the magnitude and nature of the tangential and radial component of cutting force during the conventional hobbing process.
Dynamic Analysis of Long-Travel, High-Efficiency Shock Absorbers in Freight Cars
Authors: Freudenstein F.
Published: November 2010

A dynamic analysis is presented relating the principal design parameters of a constant force type, dissipative shock absorber to the forces experienced by a resilient lading. The analysis, which correlates the effects of coupler force, lading force, cushion travel, closure time, impact speed, and friction, represents an application of classical mechanics to a dynamical system with sliding friction (Coulomb damping). Although a lumped-parameter analysis forms the basis of the derivation, a procedure is described which takes into account the mass- and compliance distribution within the lading.
Some Applications of State and Parameter Estimation to Machine Tool Problems: I—Applications of Nonsequential Estimation
Authors: Henke Russell F.
Published: November 2010

A general introduction to the area of off-line and on-line identification of systems is given, and applications of these techniques to machine tool problems, especially adaptive or optimal control, are discussed. The problem of identifying the dynamic model of the metal cutting process is given special emphasis. A general formulation of the nonsequential or off-line estimation problem is presented using state variable notation, so that nonlinearities and time varying parameters may be present. Two techniques tailored to the use of the high-speed digital computer are developed to solve this general problem. The first utilizes a direct multivariable search to match the output, of an assumed dynamic model to actual experimental observations in a least squares sense. The second method uses a modified quasilinearization procedure. Controlled digital experiments are used to refine and test the proposed techniques. The two algorithms are then applied to actual experimental cutting process data. Estimates of the cutting stiffness and damping factor in the dynamic model of the cutting process are obtained, thus demonstrating the effectiveness of the developed nonsequential identification schemes, and showing that the assumed linear dynamic model adequately represents the cutting process. A later paper will consider sequential estimation applications.
Marine Pipeline Analysis Based on Newton’s Method With an Arctic Application
Authors: Dareing D. W. , Neathery R. F.
Published: November 2010

Newton’s method is used to solve the nonlinear differential equations of bending for marine pipelines suspended between a lay-barge and the ocean floor. Newton’s method leads to linear differential equations, which are expressed in terms of finite differences and solved numerically. The success of Newton’s method depends on initial trial solutions, which in this paper are catenaries. Iterative solutions converge rapidly toward the exact solution (pipe deflection) even though large bending moments exist in the pipe. Example calculations are given for a 48-in. pipeline suspended in 300 ft of water.
An Application of Boolean Algebra to the Motion of Epicyclic Drives
Authors: Freudenstein F.
Published: November 2010

The kinematic structure of epicyclic drives has been investigated with the aid of Boolean algebra. The correspondence between the graph representation of the structure, the mechanism, and the form of the displacement equations has been derived. A canonical graph representation has been given. A method, believed to be novel, is described for the determination of the algebraic displacement equations by inspection, directly from the kinematic structure. The theory can be applied similarly to dynamic analysis and computer-aided sketching and animation.
Extension of Freudenstein’s Equation to Geared Linkages
Authors: Mohan Rao A. V. , Sandor G. N.
Published: November 2010

Freudenstein’s equation for planar four-bar function generators correlates input and output crank positions implicitly in a scalar expression, with coefficients that are functions of link proportions. Applying this approach to planar geared function generator linkages leads to nonlinear systems of algebraic equations. By the principle of superposition taken from the matrix theory of linear systems and by Sylvester’s dyalitic elimination, closed form solutions are obtained. When the geared linkages are changed into the planar four-bar by setting certain link lengths equal to zero, the generalized equations derived here specialize to Freudenstein’s well-known equation. Results of computer programs for synthesis and analysis based on this theory are tabulated.
Structural Analysis of Two General Constraint Kinematic Chains and Their Practical Application
Authors: Soni A. H.
Published: November 2010

The structural analysis of space linkages with two general constraints has been conducted by using Franke’s condensed notation. Linkages with mobility one and mobility two with up to three loops are considered. Censuses of chains with eight, nine, eleven and twelve links and a case study describing a practical application of these chains are presented.
Stereoscopic Drawings Made by Analog Computer of Three-Dimensional Surfaces Generated by Spatial Mechanism
Authors: Torfason L. E. , Crossley F. R. E.
Published: November 2010

Spatial mechanisms with up to five links and containing at least one ball joint can be solved by considering the intersection of the three dimensional surfaces which can be generated by portions of the mechanism. This paper presents a method whereby stereoscopic pairs of the surfaces can be drawn using an electronic analog computer and the figures viewed as if they were three dimensional. This results in a far better visualization of the surfaces. In many cases it can be seen what the type of intersection between surfaces is. This determines the gross motion of the mechanism, the limits of its motion, and an estimate of its transmission properties.
Dynamic Analysis of Mechanical Systems With Clearances—Part 1: Formation of Dynamic Model
Authors: Dubowsky S. , Freudenstein F.
Published: November 2010

A mathematical model of an elastic mechanical joint with clearances has been formulated and the dynamical equations of motion derived (Part I). The model, which we have called an Impact Pair, is basic to the determination of the dynamical response of mechanical and electromechanical systems with clearances, including determination of dynamic force amplification, frequency response, time-displacement characteristics, and other dynamic characteristics. Whenever possible, the results for the impact pair under various operating conditions are illustrated by graphs, which may also offer some insight into the behavior of clearance-coupled systems.
Theory of Shaking Moment Optimization of Force-Balanced Four-Bar Linkages
Authors: Berkof R. S. , Lowen G. G.
Published: November 2010

A least-square theory for the optimization of the shaking moment of fully force-balanced inline four-bar linkages, running at constant input angular velocity, is presented. It is shown that the optimum conditions of partial moment balance are given by certain link mass distribution ratios. These optimum ratios are found to be functions of link length ratios only.
Kinematic Analysis of Spatial Mechanisms by Means of Screw Coordinates. Part 1—Screw Coordinates
Authors: Yuan M. S. C. , Freudenstein F.
Published: November 2010

The concept of screw coordinates is developed in terms of motor algebra, and applied to the kinematics and statics of rigid bodies, in particular to the computer-aided motion analysis of spatial mechanisms. The laws of the composition and transformation of screw coordinates and their application to the kinematics and statics of rigid bodies are developed. These results form the basis for the development of numerical methods for the kinematic analysis of spatial mechanisms.
The Utilization of Engineers in Industry
Authors: Landis Fred
Published: November 2010

Based on an extensive questionnaire survey and management interviews it is shown that the time and intellectual utilization of most engineers in industry are generally high, although there is a significant minority which remains underchallenged. Except for excessive clerical work, few of the nonengineering related tasks can or should be transferred to nonprofessional personnel. Variations in engineering utilization are defined primarily by local company attitudes and are independent of industry groups. Means of improving utilization are largely related to a better appreciation by management of the motivation factors applicable to its professional engineering staff.
The Engineer’s Responsibility for Product Safety
Authors: Egerer Herbert
Published: November 2010

The most effective way in which the engineer can fulfill his responsibility in the field of product design and product safety is to have a secure command of the engineering fundamentals in general, and to possess the expertise of performance in his specific field of practice. This will enable him to design products which will perform in such a manner that the health and welfare of the user specifically, and society in general, is better protected. Toward this end, it is essential to realize that the engineer’s authority is proportionally limited to his responsibility as a member of the team which introduces a product into the market place. It is important that the engineer’s contribution to product safety be evaluated objectively and possible steps for improvement be taken from a realistic level; there is little use in discussing unachievable, idealistic goals which are built on wishful thinking.
Continuing Management Education in the Universities
Authors: Schultz Andrew
Published: November 2010

In this paper the influence of the 1950’s on the development of continuing management education by the universities is briefly discussed, the need for continuation of the successful executive educational programs so popular is established, and the difficulties faced by management and the universities in arriving at an effective and self-improving means of bringing to bear on continuing management education the much-needed competence of the universities in particular specialized areas is explored.
The Dynamic Behavior of Surface Grinding: Part 1—A Mathematical Treatment of Surface Grinding
Authors: Thompson R. A.
Published: November 2010

A mathematical representation for surface grinding is developed. The main feature of the model is that it takes into account the reversing motion of the workpiece, typical to surface grinding. The most general steady state solution is applied to the governing equations to give insight into the dynamic behavior of surface grinding. The theory predicts that steady state surface grinding vibrations can exist. They occur at a frequency which is always higher than the system’s uncoupled resonant frequency and slightly dependent on the workpiece’s direction of motion. Further, the model predicts the existence of wheel lobes. The lobes precess around the wheel according to their size, the wheel wear coefficient, and the chatter amplitude. The model suggests that the lobes can produce a rough ground surface even in the absence of dynamic grinding forces. As Part 2 of the presentation, some test results are offered in support of the mathematical theory of Part 1.
A Photoelastic Study of Stress Distribution During Orthogonal Cutting—Part 2: Photoplasticity Observations
Authors: Ramalingam S.
Published: November 2010

This paper extends the photoelasticity studies reported in Part 1 of this paper to the plastic regions associated with chip formation during orthogonal cutting. These regions include the deformation zone, the tool-chip interface and the chip itself. Problems connected with quantitative studies involving photoplasticity techniques are discussed. Qualitative interpretation of the photoplasticity observations carried out under dynamic cutting conditions are offered. Some comments regarding the role of the residual stresses in the chip in influencing the types of chips formed during cutting are made.
Grinding Wheel Elasticity
Authors: Nakayama K. , Brecker J. , Shaw M. C.
Published: November 2010

The deflection of individual abrasive grains in the cutting surface of a vitrified grinding wheel has been postulated to explain many fine grinding results; however, the magnitude of the deflection has never been firmly established. Experiments conducted to measure the deflection associated with an individual grain showed it to be of the same order of magnitude as the undeformed chip thickness. A model of a grinding wheel which allows both the deflection of the center of an individual grain and the deformation in the contact zone between the grain and the work material to be evaluated was developed. Contact zone deformation was found to be approximately twice as great as the deflection of the center of the grain.
A Study of the Stresses Around Elliptical Holes in Flat Plates
Authors: Jones Norman , Hozos Demosthenes
Published: November 2010

The theoretical elastic stress distribution is presented for a thin flat plate of finite width which contains an elliptical hole. Various uniaxial and biaxial in-plane loads are applied to the plate and the results are compared with some existing experimental work. The results of a series of photoelastic tests which were arranged to examine the interaction between the stresses around two neighboring elliptical holes in flat plates are also presented.
A Design Oriented Approach to Creep and Plasticity in Finite Element Programs
Authors: Wilson E. A.
Published: November 2010

This paper presents procedures for introducing plasticity and creep into finite element programs. The plasticity method described is intended for the designer who is interested in the stress distribution under prescribed loading conditions. The plasticity method uses a “relaxing approach” with initial strain equations. As a natural extension of the initial strain equations, creep is also presented. With both plasticity and creep available, a finite element program can be used to examine the stresses during the duty cycle of a piece of hardware. Examples of highly stressed turbine disks are shown.
Elastic-Plastic Analysis of Thick-Walled Pressure Vessels With Sharp Discontinuities
Authors: Larsen P. K. , Popov E. P.
Published: November 2010

Application of special isoparametric finite elements is presented for the elastic-plastic analysis of shells of revolution. General isoparametric elements are selected which, in the form of a layered system, are capable of representing a solid of revolution. The customary Kirchhoff-Love hypothesis is not invoked and solutions therefore apply both to thin and thick shells of revolution. Sharp discontinuities in geometry, circumferential ribs and/or grooves, as well as cellular walls may be studied. A special feature is the development of an element permitting sliding at the element interfaces with or without friction. The illustrative examples include a pressure vessel with a circumferential crack in the wall thickness, and a circular plate consisting of two disks which can slide along their interface. The solutions are limited to axially symmetric problems. Flow theory of plasticity is used in the inelastic regions.
Theoretical Model of Crater Wear
Authors: Lee Yong-Son
Published: November 2010

A one dimensional mass diffusion equation including the first derivatives with respect to the coordinates in Fick’s second law is considered. The diffusion coefficient is also considered, as a function of temperature distribution in a semi-infinite media under certain boundary conditions. Since the boundary conditions for both temperature and concentration on the contact surfaces are not a well defined function, the solutions are approximated by dividing the boundary conditions into several well defined functions, such as step functions, and then superimposed. The results obtained by the present analysis are compared with the empirical results of other investigators.
Economical Aspects of Cutting Speed Selection When Turning Stepped Parts
Authors: Kops L.
Published: November 2010

The concept is developed of analytical comparison between two methods of cutting speed selection when cutting stepped parts: the constant rpm method and constant cutting speed method. Formulas for cost and time of machining stepped parts are derived and analyzed for two different examples of stepped parts: short ones with large differences in diameters (turbine disk) and long ones with small differences in diameters (propeller shaft). The results presented in graphical form show the advisable operating regions for the use of one of the two methods considered. The effect of time required to change the rpm on the effectiveness of the constant speed method is examined and the limit of applicability is determined. It is found that a reduction of as much as 1/3 in cost and time may be obtained when the constant speed method is applied in the case of the turbine disk. It is noted also that the minimum-cost speed and minimum-time speed depend on the choice of the method and on the shape of the machined part as well. The conclusions set out the conditions under which the use of the constant cutting speed method is justified.
Upper-Bound Solutions of Some Axisymmetric Cold Forging Problems
Authors: Liu J. Y.
Published: November 2010

A new velocity field for the forging of some cylindrical workpieces is presented taking into account the bulging of the free cylindrical surface during deformation. The velocity field is more realistic than that proposed by Avitzur in that the physical boundary and continuity conditions are satisfied. Numerical results indicate that the current analysis improves upon previous solutions published in the literature.
Design Concepts of Super Insulated Pipes for Superconducting Cryogenic Electric Power Cables
Authors: Eigenbrod L. K. , Long H. M. , Notaro J.
Published: November 2010

Development of superconducting power transmission cables operated at liquid helium temperature requires a cryogenic system with extremely low heat-leak characteristics. A thermal envelope, housing the superconducting cables and having the highest performance superinsidation systems, still exhibits high heat-leak losses in relation to the electrical losses generated by the superconductor. This paper describes a conceptual superconducting transmission line configuration using multiple-layer, vacuum-insulated pipe with intermediate thermal shielding to reduce the helium-level refrigeration load. The intermediate metallic shields, anchored at discrete temperature levels on a vent vapor tube, and sensible refrigeration of the vent vapor stream intercept heat leak to the lower temperature helium compartment, thus upgrading thermal performance of the insulated pipe and bringing heat-leak losses in line with superconducting losses.
Stresses in a Pressurized Ribbed Cylindrical Shell With a Reinforced Circular Hole Interrupting a Rib
Authors: Durelli A. J. , Parks V. J. , Chandrashekhara K. , Norgard J. S.
Published: November 2010

The stresses in a ribbed cylindrical shell with a reinforced circular hole intersecting one of the ribs are analyzed when the shell is subjected to internal pressure. Several experimental methods were used: brittle coatings, electrical strain gages, and the photoelastic freezing technique. The results obtained here were compared with those corresponding to a ribbed shell with a reinforced circular hole between two ribs, a ribbed shell with a nonreinforced circular hole, an unribbed shell with a reinforced circular hole, and an unribbed shell with a nonreinforced circular hole.
Limit Analysis for Combined Edge and Pressure Loading on a Cylindrical Shell
Authors: Ho H. S. , Updike D. P.
Published: November 2010

Equations describing the stress field and velocity field occurring in a circular cylindrical shell at plastic collapse are derived corresponding to stress states lying on each face of a yield surface for a uniform shell of material obeying the Tresca yield condition. They are then applied to the case of a shell under combined axisymmetric loadings (moment, shear force, and axial force) at one end and uniform internal or external pressure on the lateral surface. For a sufficiently long shell, complete solutions are obtained for a fixed far end, and for a certain range of values of axial force and pressure, they are obtained for a free far end. All the solutions are represented by either closed form or by quadratures. It is shown that in many cases the radial velocity field is proportional to the shear force.
The Effect of Stringer Width and Damping on the Response of Skin—Stringer Structures
Authors: Henderson J. P. , Nashif A. D.
Published: November 2010

Analytical and experimental results for a five-span skin-stringer structure are presented. The analysis uses a transfer matrix technique which considers the effects of stringer dimensions including finite stringer width and damping on the computed forced response. Resonant frequencies, frequency response functions, damping and mode shapes for the first group of modes are compared for theoretical and experimental results. This agreement is found to be good.
Multi-Parameter Optimization of Damped Linear Continuous Systems
Authors: Dale O. B. , Cohen R.
Published: November 2010

A method is presented for obtaining and optimizing the frequency response of one-dimensional damped linear continuous systems. The systems considered are assumed to contain unknown constant parameters in the boundary conditions and equations of motion which the designer can vary to obtain a minimum resonant response in some selected frequency interval. The unknown parameters need not be strictly dissipative nor unconstrained. No analytic solutions, either exact or approximate, are required for the system response and only initial value numerical integrations of the state and adjoint differential equations are required to obtain the optimal parameter set. The combinations of state variables comprising the response and the response locations are arbitrary.
Analysis and Experiments on Multi-Plane Balancing of a Flexible Rotor
Authors: Lund J. W. , Tonnesen J.
Published: November 2010

The accuracy of the conventional method of field balancing is investigated. A test rotor is provided with a known set of unbalance weights and is subsequently field-balanced by the trial-weight method, using the same planes in the rotor as those in which the unbalance weights are inserted. Vibration measurements are taken at several locations and speeds, and the results are used to calculate the required correction weights by means of a computer program, based on a least-squares minimizing procedure. A direct comparison between inserted and calculated weights gives a check on the method. Tests are conducted for balancing in two and three planes, and several types of analyzing instrumentation are employed for comparison. The accuracy of the measurements is also investigated.
Particle Motion on Oscillating Conveyors—Part 2. Practical Solutions to the Equations of Motion and the Extension of the Theory to Beds of Granular Material
Authors: Gaberson H. A.
Published: November 2010

This paper is a direct extension of Part 1 [15], and presumes a complete knowledge of the previous material. Here the theory of Part 1 is used to develop the actual solutions. Formulas for several common solution forms are derived, and a general procedure for finding any solution is outlined. Example single particle solutions are given with experimental verification. The important extension of single particle theory to beds of granular material is also presented. It was found that most beds of granular material move as a slug; for these materials the single particle theory is directly applicable. Solutions for beds of granular material are given and experimental verification cited.
The PLP Algorithm
Authors: Charrett D. E. , Rozvany G. I. N.
Published: November 2010

In piece-wise linear programming (PLP), the objective function is convex and piece-wise linear and the constraints are linear. The PLP algorithm is described in detail and the advantages of this technique over linear programming are discussed.
A New Approach for Plate Vibrations: Combination of Transfer Matrix and Finite-Element Technique
Authors: Dokainish M. A.
Published: November 2010

When the finite-element method is used in the vibration analysis of plates and shells, it results in large matrices requiring a large digital computer. A commonly used method of reducing the matrix size is to eliminate certain “slave” displacements by minimizing strain energy. The approach requires good judgement in the selection of the “master” displacements and involves additional approximations and some loss of accuracy. In the present method small matrices are obtained without any further approximations and without reducing the number of degrees of freedom. The transfer matrix technique, generally known as the Holzer-Myklestad method, is well known for beams and shafts. The present method is an extension of this idea to plates. The structure is divided into several strips, with a number of nodes on the left and right sections of each strip. Each strip is subdivided into elements and the stiffness and mass matrices are obtained for individual strips. The nodal equilibrium equations are rearranged to obtain a relation between the section variables of the left and the right sections. The section variables are the forces and the displacements of all the nodes on the section. Requirements of displacement continuity and force equilibrium at the nodes, on common sections of two adjacent strips, gives the transfer matrix relation. Successive matrix multiplication finally relates the variables of the left and right boundary of the structure. Boundary conditions require the determinant of a portion of the overall transfer matrix to vanish at the correct frequency. By calculating the determinant at various assumed values of frequency, the correct frequencies are obtained. The method also gives the corresponding mode shapes. The method as applied to several plate problems gives satisfactory results.
Stress Distribution at the Interface Between Tool and Chip in Machining
Authors: Kato S. , Yamaguchi K. , Yamada M.
Published: November 2010

Stress distribution along a tool rake face were measured directly in the orthogonal machining of various metals. The method of measurement was based on the use of a composite tool which was divided into two parts parallel to a cutting edge in order to measure separately the force acting on one section of the tool. The stress distributions under actual cutting conditions were revealed, and the relationship between the nature of stress distribution and the mechanical properties of work material was clarified. It was ascertained that the nature of stress distribution was closely connected with the strain hardening index of work material and the frictional coefficient between tool and material.
A Treatise on the Streamlines and the Stress, Strain, and Strain Rate Distributions, and on Stability in the Primary Shear Zone in Metal Cutting
Authors: Spaans C.
Published: November 2010

It is shown that both the flow stress and the hydrostatic pressure are constant in the greater part of the shear zone. The increase of the temperature with the strain is balanced by a proper strain rate increase, which provides a basis for a model generating the shape and the size of the shear zone, with the streamlines of material flow and the strain, strain rate and temperature distributions. Quick-stop tests make the streamlines visible. There is no reason for instability in the primary shear zone.
The Effects of Eccentricity in a Clutch
Authors: Fazekas G. A.
Published: November 2010

Eccentricity between clutch plate and its driver can prevent the transmission of substantial torque, at a synchronous speed. This can cause several malfunctions, and may be also converted to useful purposes.
A Study of Temperature Gradients Inside a Horizontal Cylinder With Heated and Recirculated Diving Gas Mixtures
Authors: Linderoth L. S. , Werner D. P. , Bentz R. L.
Published: November 2010

There is little data available in the literature regarding temperature gradients and heat transfer in diving chambers (decompression chambers) with an environment of normal diving mixtures of helium and oxygen at pressures up to 33 atm. This paper reports on a preliminary study that was made to determine the actual behavior of the gas mix-tures in a model chamber as compared to predicted behavior. It was hypothesized that three distinct regions of flow are developed from the circulation of the environmental gas. Equations were developed for the temperature profiles and checked by the model data. Agreement between theory and test data was quite good. The test procedure and instrumentation are described in part. Full details and data are available in reference [18].
Statistical Analysis of Charpy-V Impact Properties SA533 Grade B Class 1 and SA516 Grade 70 Plate Material
Authors: Smith R. E. , Ayres D. J.
Published: November 2010

A statistical analysis of a large quantity of data was made to evaluate the typical Charpy V-notch properties of SA533, grade B, class 1 quenched and tempered, and SA516, grade 70, normalized and tempered materials. The orientation of the specimen, with respect to the rolling direction of the plate under test, was considered in measuring impact properties. Other variables were plate thickness and position within the plate from which the specimens were sampled. The analysis considered both the “RW” and “WR” orientations of 1/4 thickness specimens. The statistical population of the data for SA533 RW orientation was compiled from tests on approximately 670 commercial plates, and includes plate thicknesses up to 12 in. Because of the large population, statistics are good and “typical” values are considered accurate. Charpy V-notch curves are presented to indicate the expected values of impact energy and lateral expansion at a particular temperature for the materials in question. These curves indicate that the impact transition properties of 10 to 12-in. thick SA533, grade B, class 1 quenched and tempered material form an accurate baseline transition curve which gives a conservative estimate for toughness behavior of the three materials investigated. The shift in drop weight nil-ductility temperature (DWNDT) with increasing plate thickness of SA533 quenched and tempered material does not appear to be the same as the shift in Cv transition curves for associated thicknesses.
An Evaluation of the Mechanical Properties of Mn-Mo and Mn-Mo-Ni Steels
Authors: Swift R. A. , Gulya J. A.
Published: November 2010

A study of the effects of normalizing and austenitizing on the mechanical properties of Mn-Mo and Mn-Mo-Ni steels is presented. It is shown that the quenched and tempered condition has superior notch toughness, elevated temperature tensile properties, and creep ductility than the normalized and tempered condition. The basis of comparison used for strength is the percentage of the room temperature strength. The creep strength and rupture resistance of the normalized and tempered condition are better than those of the quenched and tempered condition. Also, a comparison of the properties of the steels is made to evaluate the effects of a 0.5 percent Ni addition. While it improves hardenability, Ni tends to impair the elevated temperature creep strength and rupture resistance. Significant effects of Ni are seen on the elevated temperature tensile properties. The loss in ultimate tensile strength with increasing temperature is greater for the Ni modified grade than for the unmodified Mn-Mo. In the quenched and tempered condition, both yield strength and ultimate tensile strength are less affected by temperature when no Ni is added.
Feeding Calcine Dust With a Belt Feeder at Falconbridge
Authors: Reed G. B. , Johanson J. R.
Published: November 2010

This paper describes a bin for feeding dry calcine dust at a uniform rate of up to 90 TPH directly onto a belt. A small amount of air is injected into the bin to ensure controlled flow. A patent is pending for this system.
Kinematic Geometry Associated With the Least-Square Approximation of a Given Motion
Authors: Sarkisyan Y. L. , Gupta K. C. , Roth B.
Published: November 2010

The problem of finding the locus of points in a moving plane which best approximate a circle in N positions is studied. The approximation is one which minimizes the deviation of the sum of the square of the circle radius. Two ninth order curves, analogous to the circle point curves of the exact theory are derived and studied, and several numerical results are presented. These results can be applied to the synthesis of planar linkages.
Synthesis of Mechanical Threshold Logic Systems With Three Variables
Authors: Dewey G. H. , Soni A. H.
Published: November 2010

Using the approach of threshold logic, a method is presented for the synthesis of linkages to generate each of the 256 functions of three variables. Each function generator is composed of two parts: a separator linkage and a threshold linkage. The work shows that all 256 functions can be generated with different combinations of five basic separator linkages and a limited number of threshold linkages.