bluuebunny/crossref_metadata_2025 huggingface dataset:
A Feedback Vibration Controller for Circular Saws
Authors: Ellis R. W. , Mote C. D.
Published: November 2010

Transverse vibration of circular saws is detrimental to their cutting performance. A feedback controller which increases the transverse stiffness and damping of a circular saw is analyzed, designed and tested. The proportional-derivative controller suppresses saw vibration with electromagnetically induced forces. Laboratory tests confirm theoretical predictions and demonstrate stiffness and damping increases greater than 400 percent with control. Production tests on the controller support the laboratory findings.
Optimal Control of Turbine Engines
Authors: DeHoff R. L. , Hall W. Earl
Published: November 2010

Multivariable control design for turbine engines has been studied for over 20 years. In the last 10 years, the application of linear, optimal design techniques has produced a number of turbine engine controllers. A group of these design procedures is described and a discussion of the procedures’ performance, complexity and implementation is presented. The design of a full-envelope controller for the F100 turbofan engine based on linear, optimal synthesis and locally linear modeling techniques is discussed. A perspective of optimal control design for turbine engines is presented and the future is examined.
On the Optimal Digital State Vector Feedback Controller With Integral and Preview Actions
Authors: Tomizuka Masayoshi , Rosenthal Dan E.
Published: November 2010

A digital state vector feedback controller with integral and preview actions, which can be called a proportional plus integral plus derivative plus preview (PIDP) controller, is derived based on linear quadratic optimal control theory. The preview action is a generalization of the feedforward concept which has been exercised in many process control situations. Preview of future system disturbance inputs is shown to be effective to improve the performance of the control system.
Some Connections Between Modern and Classical Control Concepts
Authors: Bryson A. E.
Published: November 2010

This is a tutorial paper that discusses the synthesis of optimum constant-gain feedback controllers for stationary linear systems. These controllers minimize the mean value of a weighted sum of squared output error and squared input in the presence of stationary random gaussian disturbances. Symmetric root locus is shown to be a useful graphical technique for visualizing closed loop pole locations as functions of the performance index weighting parameters and the disturbance spectral densities. The main component of the optimal controller is a minimum variance observer that estimates the system state variables using a measurement of the output and a set of observer gains. These estimated states are fed back to the input with a set of optimal regulator gains. This optimal controller is interpreted here as a classical compensator. A fourth order example is used throughout the paper to help clarify the concepts.
Influence of Vehicle and Distributed Guideway Parameters on High Speed Vehicle-Guideway Dynamic Interactions
Authors: Chiu W. S. , Smith R. G. , Wormley D. N.
Published: November 2010

Modal analysis techniques are used to study the dynamic interactions between a one-dimensional high speed ground transport vehicle model and a guideway consisting of multiple independent spans resting freely on rigid discrete supports. The study includes an evaluation of the effects of variations in the fundamental vehicle and guideway parameters on span maximum dynamic deflections and vehicle heave accelerations. Results of the study indicate that vehicle-guideway dynamic interactions strongly influence both vehicle suspension and guideway span design. For the range of parameters of interest in high speed systems (200–300 mph), guideway span dynamic to static deflection and stress ratios, or impact factors, may approach values of 2.0 for a single vehicle passage, and vehicle heave accelerations may exceed the levels of 0.05g desired for good ride quality unless very strong constraints are placed upon vehicle suspension requirements and guideway stiffness, weight, and span length specifications. System design guidelines are presented in the form of parametric plots in which the values of vehicle and guideway parameters required to limit maximum vehicle heave accelerations and guideway dynamic deflections are specified.
Nonlinear Filtering in Distributed Parameter Systems
Authors: Seinfeld J. H. , Gavalas G. R. , Hwang M.
Published: November 2010

A general nonlinear filter is derived for systems described by partial differential equations which contain random disturbances in initial and boundary conditions, as dynamical inputs and measurement errors. Observations are assumed to be made continuously in time at an arbitrary number of discrete spatial locations. As an example, the filter is used to estimate the state in a nonlinear hyperbolic system describing a tubular flow chemical reactor.
The Near-Minimum-Time Control Of Open-Loop Articulated Kinematic Chains
Authors: Kahn M. E. , Roth B.
Published: November 2010

The time-optimal control of a system of rigid bodies connected in series by single-degree-of-freedom joints is studied. The dynamical equations of the system are highly nonlinear, and a closed-form representation of the minimum-time feedback control is not possible. However, a suboptimal feedback control, which provides a close approximation to the optimal control, is developed. The suboptimal control is expressed in terms of switching curves for each of the system controls. These curves are obtained from the linearized equations of motion for the system. Approximations are made for the effects of gravity loads and angular velocity terms in the nonlinear equations of motion. Digital simulation is used to obtain a comparison of response times of the optimal and suboptimal controls. The speed of response of the suboptimal control is found to compare quite favorably with the response speed of the optimal control.
Lateral Dynamics of a Real Moving Web
Authors: Shelton J. J. , Reid K. N.
Published: November 2010

A second-order method is presented which uses the results of static mechanics analysis for the systematic derivation of ordinary differential equations describing the lateral dynamic behavior of massless, moving webs. The theory relates the lateral dynamics of a web at a downstream roller to the longitudinal web velocity, the angle between the web and the roller, the induced web curvature, and the roller dynamics. Transfer functions are derived for several fundamental elements which are found in practical web guide control systems. A comparison of these results with those of a first-order analysis presented in a companion paper, is presented to illustrate the inadequacy of the latter for certain frequency ranges and operating conditions. Experimental verification of two transfer functions is presented.
Lateral Dynamics of an Idealized Moving Web
Authors: Shelton J. J. , Reid K. N.
Published: November 2010

A simplified dynamic analysis of a moving web which neglects materials properties is presented, and the transfer functions of several fundamental elements of lateral web behavior are derived. The transfer functions facilitate analysis of a wide variety of web guide control systems, and examples of two practical systems are given. The idealized analysis is useful for a qualitative understanding, and in most situations is sufficiently accurate for current needs of engineering analysis.
Linear Optimal Control of a Linear System With State and Control Dependent Noise
Authors: McLane P. J.
Published: November 2010

A quadratic minimization problem for a linear stochastic system is solved in this paper. Both the finite and infinite terminal time cases are considered. Also two precise representations of the controlled stochastic process are considered. In one representation we include the correction term [6] for the state and control-dependent noise and in the other we do not. For the case with no correction terms, the optimal control is shown to be a linear feedback of the system state variables. Uniqueness and stability conditions are presented for this problem. The case with correction term is much harder to solve and we only determine the linear optimal control. An example is included which illustrates many results of the paper.
Avoidance Control
Authors: Aggarwal R. , Leitmann G.
Published: November 2010

An avoidance control is an admissible control which permits avoidance of a givenset of state space Rn. Existence theorems for avoidance controls are given for control processes governed by ordinary differential equations.
Optimum Boundaries for Elliptic Systems
Authors: Hari Y.
Published: November 2010

In this paper a modification of the Ritz method is presented for finding optimum boundaries in which the Laplace or the Poisson equation is known to hold. The method developed utilized the classical calculus of variations to determine candidates for optimum boundaries. The method is applied to obtain the optimum tooth shape for maximum torque of a magnetic exciter used on a resonant stepping mechanism.
A Large-Scale Model of the Human Cardiovascular System and its Application to Ballistocardiography
Authors: Auslander D. M. , Lobdell T. E. , Chong D.
Published: November 2010

Bond graphs have been used to construct a distributed-parameter model of the human cardiovascular system. The model includes the heart and arterial, capillary, and venous segments of both the pulmonary and systemic circulations. Anatomical and physiological data were utilized in implementing the model on a large digital computer. Comparisons of simulated output and measured responses are shown. Because a general-purpose bond graph simulation language for distributed-parameter systems was used, this cardiovascular simulation retains considerable flexibility and can be modified to suit the application. One such application that has been investigated in detail is the simulation of the body motions caused by blood flow in a subject mechanically isolated from the earth. This measurement, the ballistocardiogram (BCG) holds the possibility of a noninvasive means of determining heart output.
The Memristor: A New Bond Graph Element
Authors: Oster G. F. , Auslander D. M.
Published: November 2010

The “memristor”, first defined by L. Chua for electrical circuits, is proposed as a new bond graph element, on an equal footing with R, L, & C, and having some unique modelling capabilities for nonlinear systems.
The Mathematics of Coordinated Control of Prosthetic Arms and Manipulators
Authors: Whitney D. E.
Published: November 2010

The problems of coordinated rate control and position control of multidegree-of-freedom arms are treated together in this paper. A mathematical formulation is presented which allows real time computer-assisted rate control under a variety of external coordinate systems. A new solution to the endpoint position control problem is given, allowing the arm to be driven to a final position specified in meaningful external coordinates without the corresponding final joint angles being known. Attention is given to redundant arms, to the possibility of singularities, and to the relation between this work and dynamic control of arms.
Analysis of the Nonlinear Dynamics of a Railway Vehicle Wheelset
Authors: Law E. Harry , Brand R. S.
Published: November 2010

The nonlinear equations of motion for a railway vehicle wheelset having curved wheel profiles and wheel-flange/rail contact are presented. The dependence of axle roll and vertical displacement on lateral displacement and yaw is formulated by two holonomic constraint equations. The method of Krylov-Bogoliubov is used to derive expressions for the amplitudes of stationary oscillations. A perturbation analysis is then used to derive conditions for the stability characteristics of the stationary oscillations. The expressions for the amplitude and the stability conditions are shown to have a simple geometrical interpretation which facilitates the evaluation of the effects of design parameters on the motion. It is shown that flange clearance and the nonlinear variation of axle roll with lateral displacement significantly influence the motion of the wheelset. Stationary oscillations may occur at forward speeds both below and above the critical speed at which a linear analysis predicts the onset of instability.
Use of State Observers in the Optimal Feedback Control of Automated Transit Vehicles
Authors: Garrard W. L. , Kornhauser A. L.
Published: November 2010

The theory of optimal control and the theory of observers is applied to the design of feedback systems for longitudinal control of vehicles in automated, high-capacity transit systems. The resulting controllers require only measurement of position and velocity errors and excellent dynamic response is achieved for mainline operation, for merging and demerging from stations, for maneuvering at intersections, and for emergency stopping.
A Survey of Railway Vehicle Dynamics Research
Authors: Law E. H. , Cooperrider N. K.
Published: November 2010

This paper presents a survey of the research concerned with the dynamics of single, conventional railway vehicles. Attention is concentrated on analytical research and only that experimental research that has been performed in conjunction with analytical efforts. The often conflicting objectives for railway vehicle suspension design and the research done to understand the design implications of these objectives are discussed.
Transit Time Correlation—A Survey on Its Applications to Measuring Transport Phenomena
Authors: Mesch F. , Fritsche R. , Kipphan H.
Published: November 2010

A survey is given on different types of correlation methods and their application to measuring velocity of moving surfaces, flow rates, and to ranging. The different methods are unified by regarding them as special cases of classical identification methods for dynamical systems. Special difficulties occurring in flow rate measurement are discussed in some detail, and some problems yet to be solved are indicated.
The Application of Active Control to Improve Boring Bar Performance
Authors: Klein R. G. , Nachtigal C. L.
Published: November 2010

A previously established theoretical basis for controlling both the static stiffness as well as dynamic vibrations and regenerative chatter in particular was implemented in the work described by this paper. It was found that the experimental boring bar setup did exhibit two principal modes but that the controller could be synthesized largely independent of these modes. Cutting tests were performed using Delrin acetal plastic on a lathe equipped with a pivoted boring bar which was controlled by an electro-hydraulic servo system. It was found that the theory established earlier did in fact predict qualitatively the new stability borderline. Width of cut was improved by a factor of twelve and equivalent static stiffness was increased without bound.
On the Time-Weighted Quadratic Sum of Linear Discrete Systems
Authors: Jury E. I. , Gutman S.
Published: November 2010

In this paper the weighted quadratic sum J=∑k=0∞xk1Qkxk of a stable linear discrete system xk+1 = Axk is discussed. The formula of J is obtained from matrix z-transform formulation. Alternatively, it is shown that the weighted sum index J can be calculated recursively from a matrix equation. Finally, a combinatorial rule is obtained for calculating this matrix equation.
Controllability Index Based on Conditioning Number
Authors: Friedland B.
Published: November 2010

Use of the conditioning number k(F) = ∥ F ∥ • ∥ F−1 ∥ where F is a symmetric matrix related to the controllability (observability) matrix is suggested as basis for index of controllability (observability). This index has advantages of being independent of scaling of state variables and being a continuous function of parameters of process.
Force Feedback Control of Manipulator Fine Motions
Authors: Whitney Daniel E.
Published: November 2010

The automation of mechanical assembly requires analysis of both force and position information in order to monitor, guide, and guarantee the success of assembly tasks. This information may be obtained by force and position sensors on the assembly device, and used to make small corrections in the paths of parts while they are in contact and coming together. Two issues are involved: what path corrections to make, and how to make them in a stable dynamic fashion, given that such motions will alter the subsequent information. This paper presents a formal representation of vector force feedback strategies and shows that they must be expressed as control problems. Stability bounds are derived based on simple linear actuator models and sampled data control. These bounds are verified using computer simulation and laboratory test apparatus.
Optimal Control of a Partially Time Lagged River Aeration System Subject to Random Disturbances
Authors: O¨zgo¨ren M. K. , Cooper C. A. , Longman R. W.
Published: November 2010

Pollution abatement by means of artificial aeration is considered for rivers which are contaminated by distributed effluent sources. The system model includes plant and observation noises to account for the poor reproducibility of water quality measurements and for the poor accuracy with which plant driving terms are known. An optimal feedback aeration policy is developed which operates upon those water quality measurements which are available at scattered measurement stations along the river. Because some types of water quality measurements are more time consuming and more difficult to make than others, a state estimator is developed for use in the feedback structure using partially delayed and intermittent data.
Periodic Motion of Vehicles on Flexible Guideways
Authors: Doran A. L. , Mingori D. L.
Published: November 2010

Periodic motions of vehicles on flexible guideways are explored as candidate “test” motions for optimization studies where it is necessary to compare large numbers of designs under equivalent conditions. Exact and approximate methods are developed for identifying initial conditions that lead to periodic motions of single vehicles or many equally spaced vehicles. Using exact equations, fundamental questions regarding the nature of these motions are addressed (existence, uniqueness, stability, etc.). Approximate equations are developed to reduce the computational burden of examining large numbers of designs. It is shown that the assumptions inherent in the approximate equations are valid provided that vertical accelerations of the vehicles are sufficiently small. This restriction is not considered serious because small vertical accelerations are required to satisfy ride comfort criteria. Two standard test motions are proposed for design evaluation, one for the single vehicle case and one for the multi-vehicle case. Numerical results showing peak vehicle acceleration and guideway response are presented for the single vehicle case.
Deterministic Disturbance Rejection in Linear Identification
Authors: Tomizuka M. , Takahashi Y.
Published: November 2010

Adverse effects of deterministic disturbances in linear identification are pointed out. The deterministic disturbance rejector (DDR) is introduced to remove such effects in discrete-time series-parallel and parallel identification schemes for single-input, single-output systems. The method works for a class of disturbances such as a constant disturbance that can be regarded as the outputs of free systems with known dynamics.
Optimal Offset on Translating Follower Plate Cams
Authors: Mischke C.
Published: November 2010

The size of a plate cam moving a translating, offset roller or knife-edged follower is sensitive to the magnitude of the offset. The designer should not omit the opportunity to reduce size and cost by establishing optimal offset. A suboptimization procedure is presented which will permit determination of minimum pitch circle radius rapidly, routinely, and without use of the digital computer.
A Comparison Between Measured Pressure Waves in Water Arising From Electrical Discharges and Detonation of Small Amounts of Chemical Explosives
Authors: Bjorno Leif
Published: November 2010

The question of the choice between electrical discharges and chemical explosives as a source for shockwaves in water is replied to by comparing the form of the pressure-time curves, their peak pressure, impulse and energy as a function of the electrical and chemical characteristics together with the distance from the pressure source. Based on the latter, empirical formulas have been established. The investigation shows the existence of a scaling-law for shock waves from electrical discharges analogous with that previously known from chemical explosives. Smaller deviations at the front and on the exponential part of the shock wave are stated. By means of a Fourier analysis differences in the energy spectre for both types of waves appear. The acoustical efficiency of the two types of waves has seen examined. It is concluded that electrical discharges can be an advantageous substitute for chemical explosives in a number of fields.
Effect of Mean Stress and of Mean Strain in Low-Cycle Fatigue of A-517 and A-201 Steels
Authors: Dubuc J. , Vanasse J. R. , Biron A. , Bazergui A.
Published: November 2010

A number of low-cycle fatigue tests has been carried out at room temperature on two materials commonly used in pressure vessel fabrication. For strain-controlled tests, the influence of different mean strains is studied; similarly, the effect of varying the mean stress is analyzed for stress-controlled tests. Relations involving elastic and plastic strain ranges, and the variations of strains or stresses during the fatigue tests are discussed.
The Synthesis of Tooth Profile Shapes and Spur Gears of High Load Capacity
Authors: Lebeck A. O. , Radzimovsky E. I.
Published: November 2010

In this work a method is presented for the synthesis of high capacity noninvolute spur gears and tooth profiles. Two gear capacity criteria are used in the synthesis: (1) the capacity based on maximum allowable Hertz stress and (2) the capacity based on the bending strength of the tooth. These capacity criteria are related to a generalized noninvolute gear geometry which includes the factors number of teeth and contact ratio. It was found that there are certain optimal relationships which exist among the noninvolute parameters which lead to a solution, for a maximum capacity noninvolute gear pair. For a speed ratio of one to five it was found that a significant capacity advantage exists for the synthesized noninvolute gear pair (compared to a 20-deg involute spur gear pair) for moderate as well as high hardness values. For a speed ratio of one to one a capacity advantage was found for moderate hardness but the advantage decreased significantly for high hardness.
On the Theory of the Hydraulic Gyroscope
Authors: Fazekas G. A. , Grubbs T. M.
Published: November 2010

Any continuous or quasi-continuous system of particles, moving through an arbitrary closed path, generates a gyroscopic torque when precessed. Such systems can be a belt or chain drive, continuous flow hydraulic systems, or the like. In the apparent absence of any published analytical work, the present treatment offers a first-order analytical approximation, together with some quantitative experimental evidence.
Earth Orbital Mission Requirements for Secondary Propulsion Systems and Their Impact on Colloid Systems
Authors: Benson Ralph A.
Published: November 2010

This paper develops the earth synchronous orbital mission requirements for secondary propulsion subsystems (SPS) involving positioning of satellites in orbit and station keeping when in position. It also discusses the orbital requirements associated with attitude control and touches on the requirements for SPS pulsing, thrust vector alignment, and thrust vector control. After developing the earth-orbital mission requirements for SPS, the implications of using low-thrust colloid SPS are discussed. Conclusions are then presented regarding use of colloid, SPS for synchronous earth-orbital operations.
Tolerancing the Components of an Assembly for Minimum Cost
Authors: Peters J.
Published: November 2010

Based on the contributions of the work of A. Gladman and of R. Cave´, a comprehensive study is made of the different possibilities of distributing the tolerances between the components of an assembly in order to achieve the minimum cost requirement, taking into account the process variability and the costs of the components. Sample tables and graphs of practical value are presented.
A Technique for Accelerated Life Testing
Authors: Rabinowicz E. , McEntire R. H. , Shiralkar B.
Published: November 2010

If it is assumed that test specimens fail as soon as the damage accumulated in them reaches some definite amount, then a simple accelerated testing technique can be devised. Some specimens are failed under uniform accelerated conditions, while others are foiled partly under normal conditions and partly under accelerated conditions, and a graphical procedure then gives the life under normal conditions. Experimental tests with light bulbs, electric hand drills, electric motors, and bearing balls gave results which were consistant with the cumulative damage criterion, even though the modes of failure of the test specimens varied widely.
The Effect of Biaxial Stresses on Fatigue and Fracture
Authors: Kibler John J. , Roberts Richard
Published: November 2010

The results are presented of an analytical and experimental program which was conducted to determine if a biaxial stress field produces a significant effect on the fatigue and fracture behavior of thin plates. The materials tested were 6061-T4 and 6061-T6 aluminum sheets and plexiglas sheets. The experimental program included fracture tests with various magnitudes of biaxial load at fracture and fatigue tests with sinusoidal loading normal to the crack and either constant or sinusoidal stresses applied parallel to the crack. The effect of nonsingular stresses on the behavior of a crack is examined from both a linear elastic and an elastic-plastic viewpoint. The experimental study indicates that a biaxial stress field does affect the behavior of a crack in a thin sheet. An increase in the apparent fracture toughness with increasing biaxial load was observed experimentally but as yet cannot be adequately explained using linear fracture mechanics theory. Biaxial stresses were found to produce a shift in the fatigue crack growth rate data, and it is shown that this shift can be predicted using several empirical fatigue crack propagation models.
High-Velocity Gas Flow in Reduced Port Valves
Authors: Bake Earl A.
Published: November 2010

A semiempirical method has been developed to treat the flow capacity and pressure drop of reduced port, straight-through flow valves handling compressible fluids. Calculations can be based on familiar incompressible flow equations. Correction factors produce results which apply to all gas flow rates up to the critical flow rate of the valve. These corrections will prevent the serious errors which can result from using standard incompressible flow equations alone.
Differential Displacement Matrices and the Generation of Screw Axis Surfaces in Kinematics
Authors: Suh C. H.
Published: November 2010

A generalized matrix for the description of differential displacement in three dimension is developed with constraint equations for both synthesis and analysis of mechanisms. Application of the matrix is shown in generating the fixed and moving screw axes surfaces of the motion of various space mechanisms.
Education and Training for the Profession of Management 1960–1970
Authors: Urwick L. F.
Published: November 2010

Upon the definition of the term “progress” depends the conclusions that can be reached in regard to the title of this paper. If used in the objective sense, i.e., “goings on”, there were an immense volume of goings on in the decade of 1960–1970—more millions of words written and spoken on the subject of management than in any previous decade in human history. Involved are the two processes of education and training. The former is determined by academic persons, the latter is undertaken by employers, many of whom have little contact with the “theory” to which their recruits have been submitted—this is an historical accident. The result and danger is that the thinking of the two sets of institutions will be out of phase with each other. What is needed is cooperation between the two institutions. Retired executives and consultants who have a genuine taste for and ability in teaching should not be barred from the university campus by the PhD requirement of preparing a thesis merely to qualify for an academic trade union ticket. The developing use of the computer during 1960–1970 has made a great contribution to the management process of more rational decision-making. However, we need to be wary of extravagant claims as to the effect of the computer on human groups, for the most complex part of the manager’s task is securing spontaneous co-operation of people without whose work whatever is decided cannot be done. There appears to be some evidence at the moment that the computer’s influence on people, on the climate of management, may well be reactionary rather than progressive. The most hopeful development in management thinking during 1960–1970 has been the growing recognition of the fact that while competition compels nations and businesses to try to keep ahead of each other in applying technical innovations, the changes thus brought about on ways of living impose great strains on social cohesion.
Nitric-Oxide Generation in a Simulated Spark-Ignition Engine
Authors: Hodges J. L. , McAlevy R. F. , Potter J. H.
Published: November 2010

Nitric oxide emitted from the exhaust of spark-ignition automotive engines has long been recognized as a contributor to air pollution. A mechanical analog for the spark-ignition engine was designed, instrumented, and tested. Product gas concentrations of nitric oxide were monitored in the analog, using an ultraviolet absorption technique. Nitric oxide concentrations were found to be independent of the rate at which product gases were expanded.
Automatic Planning of Optimal Metal-Cutting Operations and Its Effect on Machine-Tool Design
Authors: Barash M. M. , Berra P. B.
Published: November 2010

Increasing complexity of components and cost of manufacturing make it necessary to employ computer techniques for process planning in metal working. The paper describes an automatic, computerized system for the planning of optimal machining operations, exemplified in complex machine shafts. Certain aspects of the design of the machine tool are discussed; namely, those which render the machine easily compatible with automatic process planning.
A Study of Plunge (or Form) Machining of Low-Carbon Resulfurized Steel on a Multispindle Automatic Screw Machine: Part 1—Influence of Speed, Feed, and Ingot Variation on Diameter Increase and Surface Finish in Prolonged Machining
Authors: Tipnis V. A. , Joseph R. A.
Published: November 2010

The objective of this investigation was to study the effect of operating variables such as cutting speed, feed, and coolant on surface finish, tool wear, dimensional control, and productivity in prolonged plunge machining on a multispindle automatic screw machine. Low carbon resulfurized and low carbon resulfurized leaded steels were chosen as the workpiece material since these steels account for the bulk of the tonnage used on screw machines. The results show that (a) finer feeds give poorer surface finish than coarser feeds; (b) within the range of feed (0.00049–0.0042 ipr) and speed (86-353 sfpm) investigated, surface finish in plunge machining was found to be more sensitive to changes in feed than to changes in speed; (c) the surface roughness as well as wearland grow rapidly within the first few minutes of the life of a tool, and then attains a much lower rate of deterioration during the remainder of the run until just before the tool failure when the deterioration rate rises progressively; (d) the surface-finish variation is higher in bars obtained from various locations within a single ingot than in bars obtained from similar locations in adjoining ingots; (e) there exists a strong radial variation which gives poorer surface finish and larger diameter increase as the cutting moves from the center of the bar to the outside; and (f) leaded resulfurized steel gives poorer surface finish and greater diameter increase with straight oil than with water soluble oil; the reverse is true for nonleaded resulfurized steel.
Vibration Isolation With Nonlinear Damping
Authors: Ruzicka Jerome E. , Derby Thomas F.
Published: November 2010

This paper discusses the performance characteristics of single degree-of-freedom vibration isolation systems in which the isolator damping force is proportional to the relative velocity across the isolator raised to an arbitrary power. The concept of equivalent viscous damping is employed to develop a general equation for the equivalent viscous damping ratio which is used to determine approximate isolation system response parameters. A range of isolator damping nonlinearity is studied by varying the relative velocity exponent between 0.5 and 5 for a fixed value of damping. Detailed results for parametric variations in damping are presented for specific values of the relative velocity exponent that correspond to Coulomb, viscous, quadratic, and cubic damping mechanisms.
Bending of Cylindrical Shells by Initial Parameter Method
Authors: Haydl H. M.
Published: November 2010

The initial parameter method, in the form proposed by V. Z. Vlasov, is presented and extended to the case of symmetric bending of cylindrical shells. It is shown that the method can be used efficiently for the solution of shells with and without intermediate supports. The loads applied to the shell can be arbitrarily distributed and discontinuous in the axial direction of the shell. The problem formulation has the distinct advantage that the complete solution contains at most two unknown “initial parameters.” These unknown parameters are determined from the boundary conditions. For shells on many supports the solution contains additional unknowns which can be determined from the support conditions. In any case, the solution consists of solving only two sets of algebraic equations. Tables of influence coefficients and loading functions for some common load cases are given in the paper. Some examples are worked out to illustrate the application of the method of initial parameters.
Oxide Treatment of Tungsten Carbide Tools and Its Influence on Mass Diffusion and Tool Life
Authors: Suh Nam P. , Naik Subhash K.
Published: November 2010

The role of oxide layers on tungsten carbide tools in metal cutting was investigated using oxide-treated tools. It is shown that the structural change of the subsurface of the tool takes place due to mass diffusion between the oxide and the substrate, which enhances the metal cutting properties of tungsten carbide tools. The tools were coated with titanium dioxide and heated in a vacuum of 10−4 torr. These oxide-treated tools and the untreated tools were diffusion-bonded to steel in a vacuum so as to determine the influence of the oxide treatment on mass diffusion. The changes in the hardness of these bonded specimens were measured after maintaining them at high temperatures for various durations. The hardness across the interface of the bonding changed sharply in the case of the untreated tools, the hardness of steel increasing and that of tungsten carbide decreasing. In the case of the oxide-treated tools, the hardness did not change appreciably. Cutting experiments showed that the cutting force and the crater wear decreased by about 12 to 20 percent after the oxide treatment.
Effects of Tension-Compression Cycling on Fatigue Crack Growth in High Strength Alloys
Authors: Crooker T. W.
Published: November 2010

Crack growth by low-cycle fatigue is a potential failure mechanism for welded pressure vessels. Residual stresses remaining from fabrication or caused by localized plastic deformation incurred in shakedown can result in operating stress cycles approaching fully-reversed tension-compression. However, virtually all of the fatigue crack propagation data reported in the literature for structural alloys are generated under simple, zero-tension cycling, and their direct application to such problems is questionable. This paper presents the results of a study which shows that the compression portion of fully-reversed tension-compression cycling can contribute substantially to fatigue crack growth rates in plate thickness medium-to-high strength alloys. Data from several alloys show a 50 percent increase in fatigue crack growth rates due to tension-compression cycling. The implications of these findings and methods for applying the results of this study are discussed.
Thermal Stresses in Thick-Walled Circular Cylinders Under Axisymmetric Temperature Distribution
Authors: Yang K. W. , Lee C. W.
Published: November 2010

A series solution is obtained for thick-walled cylinders subjected to a temperature distribution which varies both radially and axially. The solution is based on three-dimensional linear theory of thermoelasticity, with appropriate approximations by neglecting small terms and using St. Venant’s principle. The internal and external curved surfaces are assumed traction-free. In each series of the solution the first term is identical to the thin shell theory and the subsequent correcting terms are expressed in increasing powers of the thickness-to-radius ratio. An illustrative example problem is solved by using the present solution, and the numerical results are compared with those based on the thin shell theory.
Free-Surface Vibrations of a Magnetic Liquid
Authors: Dodge F. T. , Garza L. R.
Published: November 2010

A theory of magnetic fluid sloshing in a solenoidal magnetic field is developed herein. It shows that (a) the free-surface waves on a magnetic fluid are dynamically similar to the waves on an ordinary liquid in a reduced gravity field, and (b) the apparent reduction in gravity depends on the strength of the applied magnetic field. But, a deviation from true low-gravity behavior occurs whenever the Bond number (ratio of effective gravitational force to surface tension force) is much smaller than 1.0. The deviation is caused by a magnetic interaction that induces a jump in pressure across the free surface. To verify the conclusions of the theory and to evaluate the usefulness of magnetic sloshing as a low-gravity sloshing simulation, an exploratory series of tests was conducted using a magnetic-colloid liquid and a large solenoidal electromagnet. Measured slosh natural frequencies agreed well with theory, but the measured slosh damping was larger than predicted by existing correlation equations.
A Finite Element Model for Distributed Parameter Turborotor Systems
Authors: Ruhl R. L. , Booker J. F.
Published: November 2010

A specific numerical calculation procedure is outlined for a general turborotor-bearing system in which distributed inertia and elasticity are consistently represented. Bearings are represented by up to sixteen linear cross coupled coefficients each for stiffness and for damping. Discrete (as well as distributed) masses are allowed. As an example, for stability analysis (free response) a non-dimensional parameter study is made for the special case of a simple rotor supported on two short (Ocvirk) fluid film bearings. A comparison of discrete and distributed parameter rotor representations shows that the discrete parameter model predicts onset of instability at a lower speed ratio and is, therefore, more conservative. For unbalanced response (forced response), comparison is made to Prohl’s method, which represents mass discretely. A considerable reduction in the number of degrees of freedom necessary for accurate system representation is observed with the finite element formulation.
Notch-Ductility Transition of Structural Steels of Various Yield Strengths
Authors: Shoemaker A. K.
Published: November 2010

The notch-ductility transition of six structural steels, A36, ABS-Class C, A302-Grade B, HY-80, A517-Grade F, and HY-130, ranging in yield strength from 36 to 137 ksi, was studied with the use of 5/8 and 1 in. dynamic-tear (DT) test specimens. The results were compared with previously published data for V-notch and fatigue-cracked Charpy tests and dynamic fracture-toughness (KID) tests. Energy, lateral-contraction, and fracture-toughness values were compared. The results of this study showed that the full-shear upper energy shelves in the Charpy V-notch and DT specimens are the products of constant average plastic energy densities for each steel and the plastic volume estimates for the fracture of the different specimens. The transition from ductile to brittle fracture behavior is essentially the same in the fatigue-cracked Charpy and DT specimens since, for each steel, the same lateral contraction was measured in each specimen broken at a given temperature. This lateral contraction increased exponentially with temperature until a full-thickness shear fracture developed. However, the maximum lateral contraction increased with increased test-specimen thickness, suggesting that the Kc values corresponding to full-shear fracture should also increase with thickness. Using the proportionality found between the lateral contraction and the values of KID2/σYDE for the brittle-fracture behavior of these steels, the Kc values are estimated to be as much as 4.5 times greater than the KIc values at the same temperatures. In general, the notch-ductility transition can best be quantitatively characterized by the lateral contraction through KID and Kc values, whereas upper shelf energies are related by constant plastic energy densities and plastic volumes which develop during fracture.
Simulation of the Dynamics of Machinery
Authors: Dix R. C. , Lehman T. J.
Published: November 2010

The dynamics of motion of general, two-dimensional machine systems incorporating linkage elements is studied by a procedure which eliminates equation writing. The method is similar to chemical engineering process analysis procedures utilizing an interconnection matrix to describe attachments between components of a system. A digital computer program based on the procedure, termed the Machine Dynamics-Universal System Analyzer (MEDUSA), has been written and tested. This program contains subroutines for simulating the behavior of the following standard components: rigid links, torsional and linear springs, torsional and linear dashpots, force sources, motion generators, and flexible beams. Gears, chain drives, hydraulic transmissions, electric motors, and other components may be added to the simulation without difficulty. To use the program, the engineer follows a standard method to develop a special subroutine calling various component subroutines in proper order. The program computes the accelerations at the centers of mass of the various rigid elements and the interconnection forces simultaneously. Numerical integration alternating with the acceleration computation determines the position and force history of the machine. Experience shows that the engineering effort needed to develop a dynamic simulation of a general machine system using MEDUSA is greatly reduced compared to deriving the equations of motion.
Calculation of Tolerance Based on a Minimum Cost Approach
Authors: Speckhart F. H.
Published: November 2010

This paper presents a workable analytical method for finding the optimum set of dimension tolerances for a mechanical device that will minimize manufacturing costs and meet the imposed restraint conditions. The restraint conditions represent physical requirements that critical parts must fit relative to each other with a given precision. Using the mathematical description of the restraints and information on the cost of manufacturing each dimension as a function of the tolerance, the method utilizes Lagrange multipliers to minimize nonlinear cost functions subject to nonlinear restraint conditions. For all but the simplest problems the use of the method requires computer programming. The method is presented in sufficient detail to allow the reader to develop a computer code. A Fortran computer program that will handle essentially any mechanism and calculate tolerances on a sure fit or statistical-fit basis has proven that the method will give useful results.
Torsional Response of a Gear Train System
Authors: Wang S. M. , Morse I. E.
Published: November 2010

A gear train system can be represented by a spring-mass system having many degrees of freedom. The transfer matrix technique [1, 2] has been applied to give the static and dynamic torsional response of a general gear train system. The method develops, directly from drawings, all equations necessary for the solution of the problem. Effects that can be included in the formulation are the gear tooth stiffnesses, gear web stiffness, nonuniform cross section of shafts, external torques, special types of joints, general boundary conditions, and multi-geared branched systems. A general computer program has been written to obtain numerical solutions. The experimental evaluation of a gear train system has been conducted using an electrohydraulic exciter and an Automatic Mechanical Impedance Transfer Function Analyzer System (TFA). The spindle shaft of a non-rotating, preloaded gear train system is excited by applied forces in the bending and torsional directions. The computed torsional natural frequencies and mode shapes correlate at low frequencies. At higher frequencies, there is a coupling effect between the motion in torsion and transverse motions. The presented analytical and experimental technique may be a practical method to evaluate the torsional response of a gear train system.
Review of Materials Processing Literature—1966–1968: 1—Metal Cutting Analysis
Authors: Ramalingam S. , Von Turkovich B. F.
Published: November 2010

The primary purpose of this series is to provide a review of significant technical literature published about materials processing up to the end of 1968. On the Fiftieth Anniversary of the ASME Production Engineering Division, this review publication has been revived after a five-year absence and is presented through the Society as a contribution to the improvement of materials processing practice throughout industry. A review covering the period from 1968 to 1970 will be published at a later date. The section of the review concerned with Lubrication in Materials Processing will be discontinued. Readers are referred to the Journal of Lubrication Technology, Trans. ASME, Series F, for reviews in this area. To promote awareness of publications in languages other than English, a section reviewing German language publications is included in this paper. An additional section reviewing publications in Japanese will be included in the next review publication.
Viscoelastic Transition
Authors: Hoffman E. J.
Published: November 2010

The viscoelastic region is characterized as a transition between elastic and viscous behavior. The transition may depend upon both the state of the system and the rheological domain. The former is related to temperature (and other state variables); the latter to the force-time-distance variation. In this connection, the concepts of shear and elongational viscosity are discussed and compared.
Impact Extrusion—Upper Bound Analysis of the Early Stage
Authors: Avitzur B. , Bishop E. D. , Hahn W. C.
Published: November 2010

The upper bound approach is used to analyze the early stage of impact extrusion of a thin or thick-walled cup. It is shown that during the early stage of extrusion with a flat ram the ram pressure increases linearly with increasing penetration of the ram, increased area of contact between the tool and the workpiece, and poorer lubrication. With the same friction and process geometry the early stage of extrusion is made easier by using a nosed ram instead of a flat one. The optimum nose contour can be determined by a minimization technique.