bluuebunny/crossref_metadata_2025 huggingface dataset:
Noninteracting Weight, Moisture, and Opacity Control
Authors: aL-Shaikh A. , Shigemura M. S.
Published: November 2010

For the control of a multi-input, multi-output process with time delays, algorithms for noninteractive control with time delay compensation are developed. These are then applied to a 3 input, 3 output process, to obtain the 3×3 noninteracting algorithms. To test and study the behavior of such a control system, simulation techniques are found to be very useful not only in designing and testing the control system but also in investigating and correcting for its limitations. Simulation results are presented and discussed. Although these algorithms are general and have been used in various industry applications, the major contribution of this paper is the application of the developed theory in the paper industry. For a fine paper machine, the major quality variables are basis weight, moisture and opacity. Control of these variables is effected by adjustment of stock flow, steam pressure and TiO2 flow. Mathematically this process includes time delay and dynamics in addition to cross-coupling effects. The control algorithms developed here are implemented using a digital process control computer. Field results are presented and discussed in detail.
Heave Mode Dynamics of a Tracked Air Cushion Vehicle With Semiactive Airbag Secondary Suspension
Authors: Margolis D. L. , Tylee J. L. , Hrovat D.
Published: November 2010

Bond graph modeling techniques are used to develop a fully nonlinear heave mode model of a tracked air cushion vehicle incorporating a semiactive airbag secondary suspension. The governing state space equations were simulated for various deterministic guideway inputs and comparisons were made with the exact solution of the linearized equations. An experimental test stand is described which provides experimental corroboration of the mathematical models for the case of totally passive secondary suspension elements. Theoretical results are presented which demonstrate the superior vehicle ride characteristics with respect to passenger-guideway isolation provided by the combination of soft airbag springs and semiactive dampers.
Optimal Dynamic Absorbers for Plate Vibration Control
Authors: Van De Vegte J.
Published: November 2010

Modern optimal control theory is used to design passive dynamic absorbers to minimize the transient vibrations of thin plates. In addition to spring and damping constants, the absorber locations on the plate are optimized. If dynamic plate loads excite certain modes of vibration, the technique can be used to select parameters such that damping of these modes will be emphasized. The numerical example used to discuss the characteristics of the optimal designs concerns a uniform rectangular plate which is simply supported at its edges, but the technique applies in all cases where the vibration can be expressed as a sum of terms in orthogonal modes of vibration.
On Optimal Control Laws for a Class of Constrained Dynamical Systems (With Application to Control of Bipedal Locomotion)
Authors: Townsend M. A. , Tsai T. C.
Published: November 2010

The physical and dynamical constraints of a constrained dynamical system are related to system controllability and stability. Proper formulation of these inequality constraints and treatment of the active ones leads to stabilizing controls with relatively smooth control efforts—in all cases, control laws. These approaches were useful in a study of the biomechanics of climbing and descending gaits by mathematical synthesis techniques, necessitated by the increased importance of terrain and lower extremity kinematics and incomplete specification of the tasks. The general criteria entail no uniqueness requirements on system motions and controls, although for the most common (and probably most desirable) condition of the constraints (fewer active constraints than system degrees of freedom) an “optimal” control law can be derived. Two examples are presented, and some general discussion is given relating mainly to the control of biped locomotion.
On the Improvement of Deconvolution With Digitized Data Using a Runge-Kutta Integration Scheme
Authors: Houghton J. R. , Townsend M. A. , Packman P. F.
Published: November 2010

A relatively simple change in the treatment of the input function in numerical integration of high-order differential equations by Runge-Kutta methods provides substantial improvements in accuracy, particularly when the forcing function is in digitized form. The Runge-Kutta-Gill coefficients are modified to incorporate the changes; with pulse-type excitations, improvements on the order of 2 to 50 times greater accuracy are demonstrated.
Single-Axis Gyroscopic Motion With Uncertain Angular Velocity About Spin Axis
Authors: Singh S. N.
Published: November 2010

A differential game approach is presented for studying the response of a gyro by treating the controlled angular velocity about the input axis as the evader, and the bounded but uncertain angular velocity about the spin axis as the pursuer. When the uncertain angular velocity about the spin axis desires to force the gyro to saturation a differential game problem with two terminal surfaces results, whereas when the evader desires to attain the equilibrium state the usual game with single terminal manifold arises. A barrier, delineating the capture zone (CZ) in which the gyro can attain saturation and the escape zone (EZ) in which the evader avoids saturation, is obtained. The CZ is further delineated into two subregions such that the states in each subregion can be forced on a definite target manifold. The application of the game theoretic approach to Control Moment Gyro is briefly discussed.
Effect of Surface Slope on Shear Angle in Metal Cutting
Authors: Boothroyd G.
Published: November 2010

The effect of the work surface slope, or the rate of change of undeformed chip thickness, on the shear angle in metal cutting is studied experimentally. It is shown that the results of previous analyses only apply to one specific cutting condition and cannot generally be used in studies of machine tool chatter.
Fracture Initiation in Low Strength Steel Pressure Vessels
Authors: Cowan A. , Kirby N.
Published: November 2010

Tests to failure have been made on 5 ft dia × 1 in. thickness steel pressure vessels containing longitudinal slits through wall thickness representing natural defects. Steels of from 33,000 to 70,000 psi yield strength have been tested over a range of temperatures with defects of 6, 12 and 24 in. length. When the toughness exceeds 20/30 ft lb Charpy V-notch energy, failure occurs by plastic collapse, and failure conditions can be predicted from the tensile properties of the steel. At lower levels of toughness the concept of a constant crack opening displacement (COD) at fracture initiation of defects in pressure vessels and in notched bend specimens can be used to predict vessel failure conditions. Recognition must be made of the variables found in COD notched bend testing, and tests are necessary to determine the most embrittled area of a pressure vessel. Examples are given of the method of application of COD and the degree of embrittlement possible in a low alloy steel.
An Analysis of Drill Geometry for Optimum Drill Design by Computer. Part I—Drill Geometry Analysis
Authors: Fujii S. , DeVries M. F. , Wu S. M.
Published: November 2010

A comprehensive analysis of the twist drill point geometry is made in order that the high-speed digital computer can be used as an aid in the design of a drill. This subject is treated in two parts. In Part I, the drill geometry is analyzed with respect to the drill flute and flank contours by considering cross sections of the drill cut by planes perpendicular to its axis. Since several important drill angles are defined in planes inclined to the drill axis, the analysis is extended to cover the general case where the drill is cut by any plane inclined to its axis.
An Analysis of Drill Geometry for Optimum Drill Design by Computer. Part II—Computer-Aided Design
Authors: Fujii S. , DeVries M. F. , Wu S. M.
Published: November 2010

In Part II, a computer program that aids in the design of a twist drill is described, based on the analysis presented in Part I. A true drill and a “computer-designed” drill having identical design and grinding parameters are compared in orthogonal cutting planes. The effects of the design parameters on drill geometry are investigated utilizing the computer program.
Plastic Collapse of ASME Ellipsoidal Head Pressure Vessels
Authors: Gerdeen J. C. , Hutula D. N.
Published: November 2010

Plastic collapse of ellipsoidal head pressure vessels is considered. The heads have an inside semimajor axis to semiminor axis ratio of 2:1. Diameter to thickness ratios (D/t) vary from 20–2000. Calculations are performed based upon the von Mises yield criterion. Previous results based upon the Tresca yield criterion are included for comparison. The combined results give reasonably close bounds on the plastic collapse pressure (limit pressure) over the large range of D/t.
A Strong Relationship Between New and Old Inversion Mechanisms
Authors: Dijksman E. A.
Published: November 2010

Application of the theory on cognate six-bars of Watt’s type makes it possible to link the well-known inversion mechanisms through mechanical cognation. It is proved that the inversors of Peaucellier, Hart, and Sylvester are cognates, though they do not all have the same number of links and turning-joints. As side-lines, two new inversion linkages and two other straight-line mechanisms are found. All of them are each other’s cognate and produce the same straight line. The presented cognates cover a wide range in sizes.
Physical Distribution—A New Dimension of Management Control
Authors: Spencer John F.
Published: November 2010

This paper describes how physical distribution management systems have the inherent property of improving top management’s control of performance and costs in typical business organizations. It suggests some of the shortcomings of segmented types of control and of incentives related to segmental controls; it explains how the introduction of an integrative principle in management structure can correct these shortcomings, while relieving top management of certain tasks which can be delegated, and in some instances even computerized.
Spiral Power Springs. Part 1—Theory
Authors: Queener C. A. , Wood G. E.
Published: November 2010

This paper is the first of a series of two dealing with spiral power springs (i.e., motor springs or clock springs). A new theoretical treatment is presented which, neglecting friction, predicts the entire torque-turn curve. A key assumption in the model is that the uncaged spring has the shape of a logarithmic spiral, and wide plate theory instead of narrow beam theory is applied to the bending process. The torque-turn curve is divided into two stages. In the first stage, the material in the unpacked inner zone is treated as a hairspring of ever increasing length with the increase in length coming from “peeling away” material from the packed region. In the second stage, it is assumed the packed region of the spring has ceased to exist and the entire length of the spring is “active” with the spring behaving as a hairspring of constant length. Theory is compared against experiment for five commercially manufactured springs. It is shown that the assumption of a logarithmic spiral for the free shape is justified and the theoretical torque-turn curves are in good agreement with those generated experimentally.
On Half Harmonics
Authors: Fazekas G. A.
Published: November 2010

A study of the pulsations in hydraulic pumps and motors has led to some theorems concerning the nature of half-harmonics, and to certain aspects of design wherein such properties may be exploited.
Photoelastic Study and Fatigue Tests of a Contoured, Integrally Reinforced Branch Connection
Authors: Schneider R. W. , Jackson W. M. , Nicolls W. R.
Published: November 2010

The paper describes the results of an extensive study of a contoured, integrally reinforced branch connection in a cylindrical pressure vessel (or run pipe). Three epoxy models were tested by means of three-dimensional photoelasticity using the stress-freezing and slicing technique. Loads applied were internal pressure, a longitudinal moment on the branch, and a transverse bending moment on the branch; one model was required for each mode of loading. Stress distribution curves are given. In addition, thirteen geometrically similar steel headers were fatigue tested by longitudinal and transverse forces cyclically applied to the branch pipes. Tests were conducted over a range of nominal stress in the branch. Stress concentration factors or stress indices from the photoelastic tests for bending and stress intensification factors from the bending fatigue tests are compared. Stress concentration factors for internal pressure loading, as derived from the photoelastic tests, are presented. Since stress intensification factors are not used to describe fatigue behavior under pulsating pressure, a similar comparison is not possible. Owing to the amount of data accumulated, only the most pertinent are presented; in every instance this includes the area of maximum stress.
Modification of Drill Point for Reducing Thrust
Authors: Bhattacharyya A. , Bhattacharyya Ajit , Chatterjee A. B. , Ham Inyong
Published: November 2010

A considerable amount of thrust force during drilling is due to the cutting action at the chisel edge of drills. This is in turn due to large values of negative rake angle along with a very small cutting velocity in the zone of chisel edge. The authors have developed a grinding technique for modifying the chisel edge into a pair of auxiliary cutting edges with positive rake angle by generating two slots at the chisel point in a manner similar to Zhirov-point drills. Analytical expressions have been developed for analyzing the geometry of modified chisel edge. Experimental investigations have indicated that during drilling of cast iron such modifications result in the reduction of thrust force by about 50 percent. However, there is an optimum orientation angle and setting angle which should be chosen during grinding of drills in order to get the maximum benefit in regards to the reduction of thrust force.
The Forces on a Cylinder Oscillating Sinusoidally in Water
Authors: Hamann F. H. , Dalton C.
Published: November 2010

This investigation deals with the experimental modeling of wave forces on offshore structures. The model chosen is a sinusoidally oscillating cylinder in a body of water otherwise at rest. This model represents a sinusoidal progressive wave moving past a single, fixed leg of a platform. The dynamic force generated by the water-cylinder interaction was measured by means of strain gages. Oscillations of amplitudes ranging from 0.67 to 9.6 cylinder diameters and frequencies from 10 to 60 cpm were covered in the investigation. Results are presented in the form of diagrams of force versus velocity with acceleration as a parameter and of maximum force versus the amplitude parameter, A/d.
Normal Mode Solution for the Vibrational Motions of Long Flexible Booms on the RAE Satellite
Authors: England F. E. , Cunniff P. F.
Published: November 2010

A normal mode analysis is applied to the Radio Astronomy Explorer satellite which uses four 750 ft booms arranged in an “X” configuration. The state variables consist of three Euler angles of the central body, a damper boom angle and “8n” generalized coordinate for the four booms, in two orthogonal directions each, for each of the “n” normal modes selected. The following information is obtained from a computer solution: (a) the static deflection of the antenna booms, (b) the natural frequencies of the configuration, and (c) the steady-state dynamic deflections of the booms due to thermal bending. Results are compared with other approaches found in the literature.
The Autoparametric Vibration Absorber
Authors: Haxton R. S. , Barr A. D. S.
Published: November 2010

The paper presents the basic features of the steady-state performance of a two-degree of freedom system consisting of a main linear spring mass system under periodic forcing, the motion of which acts parametrically on the motion of an attached absorber system. Terms, nonlinear in the absorber motion, act back on the main mass and with appropriate choice of tuning parameters, “absorption” of the main mass response can be obtained. Experimental results for this type of device are compared with a theoretical solution obtained from a first order asymptotic approximation. Comparison is also made with the performance of a linear tuned and damped absorber.
Harmonic Response of Masses on an Elastic Half Space
Authors: Warburton G. B. , Richardson J. D. , Webster J. J.
Published: November 2010

A number of elastic half-space problems which are related to the response and interaction between foundations subjected to harmonic excitation are considered. Results are given for the amplitudes of vibration and resonant frequencies for a number of two-mass problems. The effect of Poisson’s ratio for the half-space and the distance between the masses on the half-space is examined and the relationship of the authors’ solutions to some other work is discussed.
Particle Motion on Oscillating Conveyors—Part 1. The Equations of Motion and the Rules for Predicting Motion Form Transitions
Authors: Gaberson H. A.
Published: November 2010

This analysis concerns the important class of conveyors that may be idealized as a nearly horizontal plane oscillating sinusoidally in a straight line with direction inclined to the plane and amplitude great enough to cause particle flights. In Part 1 of this paper it is shown that particle motion perpendicular to the plane becomes a function of a single generalized amplitude, while motion along the plane takes any of four forms. The various equations of motion are derived as well as rules and conditions which predict and establish transitions between the separate motion forms. Part 2 continues this analysis and presents the solutions.
Vortex Excitation of Metal Bellows
Authors: Gerlach C. R.
Published: November 2010

The present paper extends the results presented in an earlier paper, and pertains to the prediction of vibratory amplitudes and stress levels resulting from flow-induced vibrations of metal bellows. Included is visual verification of the vortex shedding-bellows convolution coupling phenomena. Two methods for predicting flow excitation amplitudes are described. One method, called a “Stress Indicator” method is a simplification of the other, and allows rapid estimates of bellows dynamic stress values. This simplified method is complemented by a plot of “Stress Indicator” versus number of cycles to failure, obtained from experimental data for actual bellows failures. The influences of bellows damping and acoustical resonances are discussed.
Optimum Design of a Linear Multi-Degree-of-Freedom Shock Isolation System
Authors: Willmert K. D. , Fox R. L.
Published: November 2010

A technique is presented, using mathematical programming methods, of determining the optimum values of the masses, spring and damping coefficients of a linear multi-degree-of-freedom shock isolation system. The problem posed is the one dimensional isolation of a mass from a shock of finite duration imposed by a supporting base. The work deals with the minimization of the maximum acceleration of the isolated mass subject to a constraint on the relative displcement between the mass and the base. In addition to the optimization of the M, C, and K coefficients, the problem of determing the optimum number of elements in the system (i.e., its topology) is also investigated. Discussion concerning this topic includes the question of uniqueness and absolute optimality of the solution.
On the Dynamic Response of Axially Coupled Turborotors
Authors: Lemke D. G. , Trumpler P. R.
Published: November 2010

An analytical investigation of the effect of coupling characteristics on the response of axially coupled sets of turborotors is presented. The results of this investigation are based on transfer matrix techniques which utilize a generalized machine element matrix and coupling fixity matrix. Disc inertia, gyroscopic effects, and both shaft as well as coupling orthotropy are included in this study. An illustrative example, utilizing two axially coupled modified Prohl rotors, demonstrates that the nature of the coupling has a significant effect on the response characteristics of the rotor set. This is accomplished by varying coupling fixity from zero to infinity in an isotropic as well as orthotropic manner. As a consequence, this result implies that the coupling must be taken into account throughout the entire mechanical design effort devoted to the rotor system. In particular, the coupling must be considered when writing balancing specifications and during actual balancing of the rotor set. Finally, it is shown that the axial coupling of turborotors can result in the unloading of particular bearings of the turborotor set at discrete speeds. Such unloading may initiate journal instabilities that are known to be associated with light loading conditions.
Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 3—Lift Forces in Tube Bundles
Authors: Chen Y. N.
Published: November 2010

The trend of the fluctuating lift coefficient CL and the dimensionless shedding frequency S (Strouhal number) of the vortex in tube bundles at higher Reynolds numbers R will be predicted by the course of the steady pressure drag coefficient CD at the corresponding R ranges. Furthermore, some measurements of the vortex lift forces in tube bundles will be given. It reveals that the lift force for certain small transverse tube spacings possesses a strong second harmonic. The tubes and, therefore, the transverse gas column in the tube bundle channel can be excited to vibrate in resonance either at the critical flow velocity or at its half value. Finally, the coupled vibration between the vortex shedding and the transverse gas column will be covered with some experiments.
Dynamic Characteristics of a Vibrating Plate Compactor
Authors: Fu C. C. , Paul B.
Published: November 2010

Vibrating plate soil compactors are widely used in building and road construction, yet no adequate dynamic theory exists to predict vital performance characteristics such as frequency of impacts, speed of forward travel, power delivered to the soil, etc. In this paper, a model is defined which takes into account the intrinsically nonlinear features of the process. Two modes of investigation are used. First, it is shown that for certain values of system parameters, it is possible to have periodic behavior of the system where the period of the motion is an integer multiple of the period of the exciting force. The dynamic stability of these “simple” nonsyn-chronous steady-state solutions is investigated, and the stability boundaries in parameter space are found. Next, it is shown how the problem may be investigated via a digital computer. This mode of investigation allows us to explore a wide variety of possible motions, and enables us to predict the performance for any given set of system parameters. In general, it is found that the forward speed and power delivered to the soil are sensitive functions of the ratio of exciting force to dead weight. The power delivered to the soil tends to be a maximum when the exciting force is approximately twice the dead weight.
Effect of Corner Shape on Elastic Stress and Strain Concentration in Plates With an Oblique Hole
Authors: Ellyin F. , Izmiroglu U. M.
Published: November 2010

The effect of the corner cut on the elastic stress and strain concentration in plates containing an oblique hole is studied. Fourteen steel plates with different corner break configurations and varying angles of inclinations are tested. This study has resulted in the determination of the effective range of the controlling variables for a “radius tip” or a “vertical cut”. An investigation of this nature is of interest in the design of oblique nozzle connections in pressure vessel heads and shells. It provides an insight into the nature of stresses in skewed holes and nozzle attachments. Previous works [3, 8] have shown the applicability of the plate model to the oblique nozzle connection, and present study fills the gap with regards to the effect of acute corner cut on the stress and strain distribution.
Rigid-Plastic Collapse of Cylindrical Shells
Authors: Haydl H. M. , Sherbourne A. N.
Published: November 2010

This paper suggests a simple numerical approach to the limit analysis of cantilever cylindrical shells. The loads considered are external pressure and external pressure combined with a moment at the free shell end. It is shown that the collapse loads are within 4.5 percent on the safe side of the exact von Mises limit loads. The extension of the method of analysis to more complex problems is suggested.
Analysis of Center to Edge Foundation Settlement of Atmospheric Storage Tanks
Authors: Hayashi K. , Kraus H.
Published: November 2010

Modern large capacity atmospheric steel storage tanks incur differential settlement of the soil foundations upon which they rest due to the Boussinesq effect [1, 2]. The difference in settlement between the center of such a tank and its edge generates membrane forces in the bottom plates. For good design, these forces should be limited below the bottom plate strength, and their radial component at the edge should be limited below the critical shell buckling shear force. To meet these requirements tank site improvement to reduce the anticipated differential settlement may occasionally be requied prior to the tank erection. An analysis for determining the membrane forces in the bottom plates based on the large deflection theory and the critical shell buckling forces as functions of tank properties and the foundation modulus is presented.
On the Limits to Energy Release and Implications for Present Policy
Authors: Barus C.
Published: November 2010

Technology has been a provider of benefits directly improving man’s lot. These benefits have usually gone first to those already at the top of society, but increased production has gradually spread them to those lower down. Today much of our technology is serving affluence rather than basic needs, yet worldwide poverty remains a dominant human problem. Perpetual technological growth is still seen by many as the solution to this problem. But we no longer operate in a world of infinite reservoirs—infinite sources and sinks. Though energy sources may prove to be virtually infinite, energy sinks and pollutant sinks are finite. Engineers have a responsibility to plan for such limitations. The capacity of the atmosphere as a heat sink remains an ultimate geophysical limit to energy release by man. Various writers have estimated the order of magnitude of this limit. Some of these estimates are discussed. Possible modes of approach to a limit are considered in the light of current trends, published predictions, and the problem of meeting human needs. It is found that U. S. planning for an orderly and equitable transition to a fixed-energy-rate economy is already overdue.
Kinematic Synthesis of Adjustable Mechanisms—Part 2: Path Generation
Authors: McGovern Joseph F. , Sandor George N.
Published: November 2010

A method utilizing complex numbers similar to that used in Part 1 for adjustable function generator synthesis is applied to the synthesis of adjustable path generators. Finitely separated path points with prescribed timing as well as higher order approximations (infinitesimally separated path points) are treated, by way of analytical and closed form solutions. Adjustment of the path generator mechanism is accomplished by moving a fixed pivot. Mechanisms adjustable for different approximate straight line motions, for various path curvatures, and path tangents as well as several arbitrary paths can be synthesized. Four-bar and geared five-bar mechanisms are considered. Examples are included describing synthesized mechanisms.
Direct Analytic Synthesis of Four-Bar Function Generators With Optimal Structural Error
Authors: Rose Richard S. , Sandor George N.
Published: November 2010

This paper is a departure from the usual procedure for obtaining the optimal dimensions of a four bar function generator by iteration. In the usual procedure, the accuracy points are first chosen by means of Chebishev spacing or some other means. Using these accuracy points, a four bar linkage is synthesized and the error calculated. Freudenstein’s respacing formula may then be used to respace the accuracy points so as to minimize the errors. After the respacing of the accuracy points is calculated, a new mechanism is synthesized. The process is repeated until the magnitudes of the extreme errors occurring between accuracy points are equalized. The procedure adopted in this paper is to immediately force the extreme errors between accuracy points to be equal in magnitude by imposing additional constraints upon the problem. These constraints eliminate the arbitrary choice of the first set of accuracy points. This procedure results in a more extensive set of equations to be solved than the conventional method. However, once the equations are solved, they lead directly to equalized (and thus minimized) extrema of the magnitude of structural errors between the precision points. Thus there is no need to perform the iterative steps of conventional optimization. The proposed method is illustrated with an example.
Decelerative Cutting of 6061-T9 Aluminum, 65-35 Brass, and TPE Copper With Constant Impact Energy
Authors: Pleck M. H. , Von Turkovich B. F.
Published: November 2010

The chip formation process during metal cutting in which the cutting velocity is permitted to decrease freely is examined from an experimental standpoint. Metal cutting data are obtained from a specially constructed decelerative cutting apparatus for 6061-T9 aluminum, 65-35 brass, and TPE copper under the test conditions of constant energy input and variable initial momentum, velocity, and rake angle. The overall mechanics of chip formation are found to be essentially identical to that for the steady state, including a similarity of the dynamic velocity dependence of cutting forces to their velocity dependence in steady state tests. A complex velocity dependence is noted for 6061-T9 Aluminum. Further evidence of the constancy of the dynamic shear stress is presented. Kinetic energy and momentum are found to have no significant effects upon the chip formation process.
Modification of Nonlinear Equality Constraints in Nonlinear Problems
Authors: Polo R. J. , Sposito V. A. , Lee T. T.
Published: November 2010

This paper presents a technique for solving nonlinear programming problems with nonconvex feasible regions. The procedure expands the feasible region by replacing nonlinear equality constraints by appropriate inequality constraints. The expansion is used to solve two structural optimization problems using the sequential unconstrained-minimization technique of Fiacco and McCormick. The solutions are compared with solutions obtained by classical mathematical methods.
The Laboratory Simulation of Vehicle Service Stress
Authors: Dodds C. J.
Published: November 2010

A simulation technique which will enable the response of vehicle components or complete vehicles to be reproduced in the laboratory is presented. For the case of a complete four wheeled vehicle it is shown how synthesized random displacements, based on a knowledge of the road surface undulations, can be derived; it is demonstrated that the information necessary to derive these four signals can be obtained from the spectral density evaluated from a single traverse along the road. Comparison is made between vehicle response measured on the test track, and the response on the simulator under synthesized random displacements and point-by-point profile excitation.
Response Spectra of Strain Hardening Structural Systems to Earthquake Motions
Authors: Hongladaromp T. , Srimahachota D. , Lee S. L.
Published: November 2010

The effect of strain hardening in limiting the forces developed in structures subjected to earthquake motions below those of the elastic behavior is investigated by treating a single degree of freedom system. Response spectra for El Centro earthquake, May 1940 are generated from an idealized bilinear strain hardening resisting force-displacement relation for different values of the strain hardening coefficient and ductility factor. Optimum response spectra are presented in terms of the yield displacements and the maximum displacements. For a system with the optimum yield displacement, the maximum displacement response is always less than that of the elastic system, and thus the optimum response spectra may be used as a guide in selecting members for a displacement constrained design.
Nonlinear Vibration Analysis of Elastic Four-Bar Linkages
Authors: Sadler J. P. , Sandor G. N.
Published: November 2010

A method of kineto-elastodynamic analysis is developed employing lumped parameter models for simulating moving mechanism components subject to elastic bending vibrations. The mechanism analyzed is the general planar four-bar linkage and the analytical model includes the response coupling associated with both the transmission of forces at the pin joints and the dependence of the undeformed motion of a link on the elastic motion of other links. Nonlinear equations of motion are derived by way of Euler-Bernoulli beam theory, and numerical solution of these equations is illustrated for specific examples. The model is suitable for the analysis of mechanisms with non-periodic motion and with nonuniform cross-section members.
Analytical and Experimental Studies of a Mechanical Pulse Generator
Authors: Safford F. B. , Masri S. F.
Published: November 2010

A simple, low-cost mechanical pulse generator has numerous applications in laboratory investigations and field tests of structures. Applications may include shock tests, transient load simulations, and impedance measurements. By drawing a metal bar or mandrel having a variable cross-sectional area through a cutting tool (or vice versa) with suitable motive power, a waveform directly related to the configuration of the profile of the bar may be developed. The force time history generated would be dependent in part upon the velocity of the cutting tool. Reaction at the attachment points of the device transmits a force output to the driven load or structure. Initial experiments with a laboratory device show considerable promise by generating forces and waveforms comparable to predictions.
Optimization of the Response of Frictionally Damped Beam Type Structures With Reference to Gas Turbine Compressor Blading
Authors: Williams E. J. , Earles S. W. E.
Published: November 2010

A simplified experimental model of a compressor blade with “clapper” attachments is examined and the existence is established of optimum clamping loads across the clapper interfaces in order to minimize separately the displacement and stress responses. A theoretical prediction of the optimum conditions, assuming a linearized frictional force interaction dependent on the slip amplitude, is shown to compare favorably with the experimental results. For each response parameter, a simultaneous optimization of the clamping load and position for the clapper ring is carried out. It is found that the optimum positions differ by less than 10 percent from the value currently used in some design practice.
Diffractographic Techniques for Vibration Measurement
Authors: Pastorius W. J. , Pryor T. R.
Published: November 2010

The single slit diffraction phenomenon is shown to be useful as a noncontacting vibration measurement technique. The diffracting slit is formed between the vibrating object and stationary reference point. Little or no mass need be added to the object. Several readout techniques are described as well as a method for determining vibratory data along a line, in which case vibratory amplitude may be determined at all points in one coordinate direction.
A Rotor-Fixed Modal Simulation Model for Flexible Rotating Equipment
Authors: Childs D. W.
Published: November 2010

A transient, flexible rotor formulation is derived on the basis of a representation previously employed to simulate the motion of flexible spinning spacecraft. The distributed parameter characteristics of the rotor are approximated by modeling the rotor as an elastically connected group of n rigid bodies. The elastic rotor deflections of the component rigid bodies are defined in terms of a rotor-fixed frame of reference; hence, during constant synchronous whirling the elastic deflections appear to be constant. The model is initially simplified by the traditional small deflection assumptions of the theory of elasticity, and is additionally simplified by the use of modal coordinates. Modal coordinates dramatically reduce the dimensionality of the model, and significantly clarify the dynamic analysis of the problem. Required data input to the model, and typical model output are demonstrated for the Mark 15-F turbopump of the Rocketdyne J-2 engine system. The model is shown to correctly demonstrate the form of unstable rotor whirling associated with internal hysteresis damping when operating above the first bending-mode critical speed.
Nonlinear Stability Analysis of Chatter in Metal Cutting
Authors: Saravanja-Fabris N. , D’Souza A. F.
Published: November 2010

The occurrence of machine-tool chatter is usually undesirable as it gives rise to severe production problems. The existing theoretical and experimental studies on dynamic cutting indicate that the chip thickness and forces in cutting are related by a nonlinear equation. But the existing studies on chatter stability employ a linear relationship between these variables. In this paper, a relationship is developed between the chip thickness and forces in cutting under dynamic conditions. This relationship is based on existing experimental results and it exhibits active hysteresis. Hence, the oscillations in chip thickness lead the oscillations in cutting forces for all frequencies. A nonlinear theory is developed based on the describing function approach. An example is given of computing a stability chart giving the width of cut, frequency of chatter, and critical cutting speeds for regenerative chatter. In contrast to the linear stability analysis, the nonlinear theory can better explain the experimentally observed phenomena as well as give better correlation with the theoretical analysis of dynamic cutting.
The Design of Complex, Circular, Safety-Rupture Diaphragms
Authors: Beese J. G. , Peters R. M.
Published: November 2010

Equations are developed which predict the maximum hydrostatic pressures and the corresponding bulge heights of circular safety diaphragms comprising two thin disks of dissimilar materials. Diagrams which are based on the equations facilitate the selection of materials, and dimensions and general design.
Stability of High Speed Rotors With Internal Friction
Authors: Vance J. M. , Lee J.
Published: November 2010

The problem of nonsynchronous whirl induced by internal friction is shown to be important when rotating machinery is designed for operation at supercritical speeds. Mathematical methods are used to determine the stability speed threshold of nonsyncronous whirl instability for an unbalanced flexible rotor on a rigid foundation. This threshold of instability is shown to be the same as the threshold for balanced rotors established by previous investigations. The location of the external damping (foundation or rotor) is shown to be important in determining stability when the foundation is made very rigid. The effect of shaft stiffness orthotropy on nonsynchronous whirl induced by internal friction is also investigated. Results from the stability analyses are verified by numerical solution of the differential equations. It is concluded that rotors can be safely operated up to speeds about eighty percent above the significant critical speed if the external damping is larger than the internal friction, and that shaft stiffness orthotropy has an insignificant effect on friction-induced whirl.
Equipment for Measuring Complex Moduli of Thin Coatings at Elevated Temperatures
Authors: Sridharan P. , Plunkett R.
Published: November 2010

Porcelain enamels are thin, inorganic, glassy coatings, extensively used to protect metal surfaces exposed to the corrosive and erosive effects of hot gases. They are known to increase the fatigue life and vibratory damping of the coated member in some cases but the amount of improvement and the governing parameters are not known. Three pieces of equipment for measuring the damping and complex moduli of porcelain enamel coatings as a function of temperature, strain level and state of stress have been developed as part of a program now underway to determine these properties. All three are designed to cover the temperature range from room temperature to 2000 deg F. The first is an adaptation of the low frequency torsional pendulum equipment useful from about 1 to 20 Hz. The second uses a flat beam in bending to cover the frequency range from 10 Hz to 200 Hz and the third uses a hollow torsional specimen to cover the range from 150 Hz to 600 Hz. This paper describes the design details, advantages and disadvantages and error analysis of each of the three pieces of equipment.
Propagation of Elasto-Plastic Stress Waves in Cylindrical High-Pressure Sections
Authors: Baumgarten J. R. , Dewitt J. R. , Cable A. J.
Published: November 2010

An analysis is made of the axisymmetric elastic and plastic stresses and deformations in thick-wall cylindrical shells subjected to internal dynamic pressures. The study utilizes a direct numerical approach called the discontinuous-step analysis. This analysis is based on the direct use of the boundary conditions and the applicable physical laws to propagate dynamic changes in the cylinder by finite steps. Reflection of stress waves from both inner and outer boundaries is automatically generated. The validity of the method is checked by comparison of numerical results in the elastic range with published results for thick-wall cylinders. Comparison is made with experimentally measured strains from the high-pressure section of a hypervelocity launcher. This analysis assumes that the work hardening of the material is independent of the strain rate and is constant for a large variation of plastic strain. Stress-strain relationships are derived for the condition of plane strain in the cylinder which is held to be representative of the actual conditions in the launcher high-pressure section. The digital computer program developed from this study predicts the distribution of dynamic stress and strain throughout the cylinder, the internal radial growth, the distribution of particle displacement, the distribution of yield stress in an autofrettaged cylinder, and the residual stress.
Responses of Submerged, Inclined Pipelines Conveying Mass
Authors: Wilson J. F. , Biggers S. B.
Published: November 2010

The inclined pipeline is modeled as a Bernoulli-Euler beam with an initial static deflection due to self-weight, end loads, and external drag forces. Pipeline stability and transient responses are determined for a constant flow rate suddenly imposed on the contained fluid mass. Effects of the following dimensionless system parameters are studied: ratio of pipe mass to contained mass; ratio of flow frequency to a reference pipeline frequency; axial loads including line pressure, self-weight and added weight; external drag and linear, viscous damping. Results can be used in the design of oil-conveying pipelines and of dredge pipes used to convey mineral deposits to ships from the ocean floor.
Recovery of Modal Information From a Beam Undergoing Random Vibration
Authors: Parmenter W. W. , Christiansen R. G.
Published: November 2010

An organized approach for implementing the techniques of random process theory in the recovery of structural information from random vibration data is presented. The boundaries of various configured Bernoulli-Euler like beams are subjected to random vibrations and the acceleration response of these beams is measured and recorded. The Fast Fourier Transform (FFT) makes the use of random process theory both a feasible and economical tool for experimental structural analysis.
Design of Springs of Rectangular Wire Coiled Edgewise
Authors: Dore´ R. , Deslauriers S. , Hung N. T.
Published: November 2010

A technique is presented for the analysis of deflection and stresses in helical compression or tension springs of rectangular cross-section. The technique consists in analysing a cylinder cut radially. Using theory of elasticity, a stress system is determined which gives as the resultant over any terminal cross-section, a single force parallel to the axis of the cylinder. In addition, the case where a resulting couple exists on the ends of the cylinder is analysed. If the pitch angle of the spring is neglected, the stresses in a helical spring are obtained. The deflection and stresses are evaluated in terms of the dimensions of the spring and compared with the results of other theories.
An Improved Least-Squares Method for Designing Function-Generating Mechanisms
Authors: Sutherland G. H. , Roth B.
Published: November 2010

An improved general theory for the least-squares synthesis of function-generating mechanisms is developed. This theory leads to a rapidly converging iterative-type algorithm, the use of which is illustrated by two planar four-bar examples. The theory and associated algorithms may be applied to the synthesis of any planar or spatial function-generating linkage.
Synthesis of Multi-Variable Function-Generator Linkages Using Point Position Reduction
Authors: Mruthyunjaya T. S.
Published: November 2010

A graphical method based on point position reduction is presented for synthesis of multivariable function-generator linkages to satisfy a set of arbitrarily selected precision positions. The method is illustrated for 10-link, three-variable and 13-link, four-variable function-generator linkages. The maximum number of precision positions satisfied in these cases are, respectively, six and eight for linkages with rotary inputs and output, five and seven for linkages with sliding inputs and output. The number of positions satisfied can be increased by combining point position reduction with, for example, the theory of finitely separated positions. The method is also applicable for synthesis of multidegree-of-freedom linkages for point-path generation or rigid body guidance as a function of several independent inputs.
Shaking Force Optimization of Four-Bar Linkage With Adjustable Constraints on Ground Bearing Forces
Authors: Tepper F. R. , Lowen G. G.
Published: November 2010

A method for partial force balancing of four-bar linkages, which allows control over the increase in ground bearing forces, is presented. A novel adaptation of the Lagrange Multiplier method makes it possible to obtain design equations for appropriate counterweights.
Dynamics of a Current Collector for a High-Speed Railway
Authors: Yoshida Kazuo , Manabe Katsushi , Shimogo Taro
Published: November 2010

In this paper, a mathematical model of a collecting rail and collector system with sliding contactors is proposed for a current collector system of a very-high-speed railway. Its dynamic characteristics, especially the variation of contact force and the probability of contact break, are investigated by means of linear analysis. In order to prove the appropriateness of the linear model, the computer simulation and theoretical analysis are performed using a nonlinear model. Experimental investigations are also performed in order to examine the dynamic characteristics of the model. From these results, it is concluded that the probability of contact break can be kept to less than about 10 percent for a train speed of 500 km/hr by choosing the proper values of natural frequencies and damping ratios under constraints.