bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Analysis of Rail Vehicle Forced Lateral Response and Stability
Authors: Hedrick J. Karl , Arslan A. V.
Published: November 2010

The method of statistical linearization is presented as a design tool for rail vehicles that is capable of including fundamental nonlinearities such as wheel profile geometry and suspension nonlinearities. The method is capable of predicting the response of the vehicle to statistical track irregularities as well as the onset of hunting. The fundamentals of the method, an efficient frequency domain numerical algorithm for stationary response, and a design example are presented. The design example illustrates the influence of wheel profile, gage, track roughness, and suspension variations on vehicle response and stability.
Comparative Study of the Linear and Non-Linear Locomotive Response
Authors: Chang E. H. , Garg V. K. , Goodspeed C. H. , Singh S. P.
Published: November 2010

A mathematical model for a six-axle locomotive is developed to investigate its dynamic response on tangent track due to vertical and/or lateral track irregularities. The model represents the locomotive as a system of thirty-nine degrees of freedom. The nonlinearities considered in the model are primarily associated with stiffness and damping characteristics of the primary suspension system. The transient and steady-state responses of the locomotive are obtained for the linear and nonlinear primary suspension systems. The response time-histories of the locomotive obtained by integrating the generalized equations of motion are presented. The potential uses of the model are indicated for studying the influence of different design parameters and predicting subsequent dynamic response.
Design of Multivariable Controllers for an Advanced Turbofan Engine by Zakian’s Method of Inequalities
Authors: Taiwo O.
Published: November 2010

The Method of Inequalities is used to design controllers for the regulation of net thrust level, total airflow and inlet temperature of an F100 turbofan engine. Two models of the plant are considered, having orders 24 and 5, respectively, and simple controllers are designed for each model. As expected, the 24th order model is more difficult to control than the simplified 5th order model. In fact, it is found that the simplified model can give misleading results. Several useful features of the method of inequalities are illustrated by this appliction.
Vehicle-Follower Control for Dynamic Entrainment of Automated Guideway Transit Vehicles
Authors: Shladover S. E.
Published: November 2010

This paper describes a method of vehicle-follower longitudinal control which has been developed to enable automated guideway transit (AGT) vehicles to join (entrain) and leave (extrain) trains or close-formation platoons (at 30 cm spacings) while traveling at cruise speed. Because a linear controller cannot be designed to have the accuracy and response speed needed for operations at very close inter-vehicular spacings without producing excessive control action at large spacings, the suggested controller is a nonlinear vehicle follower in which the gains are continuous functions of the spacing between the vehicles. The nonlinear control law is defined and its simulated behavior in a typical dynamic entrainment is shown. Sample simulated responses of nine-vehicle platoons demonstrate the asymptotic stability which the control system must have to be applicable for long platoons. The use of a disturbance estimator to resist external force loadings and the implementation of the control system using sampled, smoothed data are explained and demonstrated via simulation.
State-Space Formulation for Bond Graph Models of Multiport Systems
Authors: Rosenberg R. C.
Published: November 2010

A novel procedure for systematically generating state-space equations for multiport systems is presented. The method is based upon a bond graph representation of the system and causal manipulation of the field equations. Principal advantages of the method are the ability to anticipate formulation properties before writing equations, the availability of a simple check for correctness of the initial system relations, and the specification of a systematic reduction procedure for obtaining state-space equations in terms of energy variables.
Multiparameter Identification in Linear Continuous Vibratory Systems
Authors: Dale O. Bruce , Cohen Raymond
Published: November 2010

A method is presented for identifying unknown parameters in linear continuous vibratory systems from frequency response data. The method is applicable to systems for which the steady-state equations of motion are reducible to a finite set of ordinary differential equations. After assuming a system model of partial differential equations and boundary conditions containing unknown parameters, initial value numerical integrations are performed to identify the unknown parameters. No analytic solution to the system model is required. For the identification of conservative or near conservative systems, only resonant frequency data are used and, for the identification of nonconservative systems, the data may consist of any state variable or combination of state variables at any arbitrary location within the system. The use of multiple response transducers is not required.
The Snow Ski as a Dynamic System
Authors: Piziali R. L. , Mote C. D.
Published: November 2010

Paper reports research on dynamic system characteristics of snow skis. Laboratory and field measurements of frequency response, running surface pressure excitation, and static system characteristics are intended to provide a data base of physical information to guide future design and research. Laboratory testing procedures used give meaningful information for “straight running” but not for “turning.” In general, the turning and straight running maneuvers must be examined independently. This paper summarizes the general research observations with a minimum of detail included.
A Finite State Approach to Vehicle Merging
Authors: Whitney D. E.
Published: November 2010

A state space approach is taken to vehicle merging on high speed highways. The vehicles are assumed to be traveling in equal sized “slots” which move at the group velocity. At points where two or more lanes merge, some vehicles must be moved forward or backward to other slots to accomplish the merge. The state of a group of vehicles to be merged is defined in terms of the slots occupied at any time. A finite set of admissible terminal states, representing possible merged configurations, is easily determined. The sequence of moves required to obtain a merge is found as a shortest path in the space of all states, running from the initial state to the terminal manifold. Various costs may be applied to moves in this space, such as time consumed, or number of vehicles being moved simultaneously. Costs may also be assigned to the terminal arrangements, reflecting, for example, the size of platoons in the resulting merge. Estimates are made of required computing load and the method is compared with other approaches.
Multiport Models in Mechanics
Authors: Rosenberg R. C.
Published: November 2010

Problems in mechanics involving rigid bodies in large-scale motion in force fields of both conservative and nonconservative types are approached from a multiport viewpoint. A procedure for constructing bond graph models based on key geometric variables and the velocity transformations relating them is described. Contributions of such models to improving the representation and communication of system structure, the formulation of governing state-space equations, and the direct digital simulation of complicated mechanics problems are suggested.
Simulated Flight Tests of a Digitally Autopiloted Stol-Craft on a Curved Approach With Scanning Microwave Guidance
Authors: Farrington F. D. , Goodson R. E.
Published: November 2010

A work is described which studied the capabilities of a STOL aircraft equipped with digital minicomputer serving as an autopilot making a curved approach to a runway along a path prescribed by the Air Traffic Control system using radio-navigation data supplied by the developing Scanning Fan Beam Microwave Landing Guidance System. The work involved the development of an ATC scheme for effectively generating a flyable curved approach path and specifying such a path to the aircraft being served. The paths produced are made up of alternating straight and circular segments along which the plane is to maintain prescribed constant airspeeds. The digital autopilot functions include Navigation, Control Trimming, Anticipatory calculations, Generation of Control Commands based on utilization of linear optimal state-feedback control theory, Filtering (including Kalman techniques) of state measurements, and Estimation of prevailing winds. A complete simulation of such a system aboard a McDonnell-Douglas 188/Breguet 941 STOL transport, with realistic winds, turbulence, and measurement noise, was created and exercised on the Purdue University CDC 6500 computer system, and showed the capability of excellent adhesion of the airplane to the commanded flight path.
Sinusoidal Excitation of a Free Turbulent Jet With Constant Amplitude Transverse Pressure Gradients Near the Nozzle Exit: Part II: An A-C Fluidic Model for the Jet Gain
Authors: Stiffler A. K. , Shearer J. L.
Published: November 2010

A free turbulent jet is perturbed transverse to the flow direction by a sinusoidal pressure gradient near the nozzle exit. An a-c model for the jet gain, based upon the control region dynamics and a uniform deflection of the jet downstream of this region, is generally verified in conjunction with attenuated mean shear velocities. A method is given to experimentally determine the effective amplitude of the input signal at the interface of the jet.
Optimization of Linear Vehicle Suspensions Subjected to Simultaneous Guideway and External Force Disturbances
Authors: Young J. W. , Wormley D. N.
Published: November 2010

The optimum linear suspension for a vehicle traveling over a guideway with random irregularities and subjected to random external force disturbances is derived. The optimization is based upon a performance index which weights mean square vehicle acceleration (a measure of passenger comfort) and mean square relative displacement between the vehicle and guideway (a measure of required suspension dynamic excursion). The form of the optimum suspension is not restricted to a specific mechanical, magnetic or fluid suspension configuration. Performance curves and numerical design examples are presented to illustrate the influence of both guideway and external force disturbances upon optimum suspension performance capability.
Dynamics of Exercise Hyperemia
Authors: Mohrman D. E. , Sparks H. V.
Published: November 2010

This paper describes a model of skeletal muscle metabolism and local control of vascular resistance. The model predicts changes in tissue PO2 and interstitial K+ concentration associated with muscle activity and the effects of these alterations on vascular resistance. We have attempted to use physiologically sound relationships, parameters and constant values throughout. Predictions based on the model match the experimentally determined responses of venous O2 saturation, venous K+ concentration, and vascular resistance to brief tetanus at both high and low constant flow. Model simulations of brief tetanus indicate that the resistance response at high flow is caused almost entirely by changes in interstitial K+, whereas the vascular response observed at low flow has a fast component due to K+ and a slow component caused by low tissue PO2. Our study supports the hypothesis that local vascular control involves more than one substance but that the relative importance of each influence on vascular resistance depends upon the experimental conditions.
On Growth, Form, and Function—A Fantasia on the Design of a Mammal
Authors: Iberall A. S.
Published: November 2010

The development of a system’s biology, as a common construct for both physiologist and engineer, requires both a theory of structures (form) and a theory of dynamics (function). A dynamic organizing principle—“homeokinesis”—for the living system was proposed earlier. Based on thermodynamic reasoning, homeokinesis attempts to capture the physical essence of homeostasis. Now, a primitive foundation is proposed from which a large family of design characteristics might emerge, by self-organization, in complex biological organisms. This foundation is directed at the emergence of major form parameters of the entire class of mammalia, from 3 gm adult shrews to 100,000 kg whales.
Dynamic Path Synthesis and Optimal Control
Authors: Starr P. J.
Published: November 2010

Dynamic Path Synthesis refers to a class of linkage synthesis problems in which constraint paths between specified positions are determined in such a way as to optimize some measure of the resulting dynamic behavior. These problems can be transformed into nonlinear optimal control problems which are generally non-autonomous. The physical nature of the system allows general comments to be made regarding uniqueness, controllability, and singular control. The ideas are developed in the context of a two-link device yielding a fourth order non-linear control problem, for which a numerical example is presented.
A Structured-Data, Interactive Dynamic System Simulation Language Suitable for Mini-Computer Implementation
Authors: Auslander D. M.
Published: November 2010

A data-structure oriented dynamic system simulation language which operates in a command mode is described. It is a highly modular, easily segmented language that lends itself to iteractive use. It is designed so that significant simulation problems can be solved on a mini-computer with as little as four thousands words of memory and nothing but a teletype for input and output. At current costs, interactive simulation of nonlinear systems, with graphical output, can be done using this language for as little as $2/hr, compared to $10 to $15/hr on a commercial time-shared computing system without graphics. The language has been implemented on a 8000-word PDP-7, using no peripherals other than a teletype and oscilliscope. Solutions of sample nonlinear problems are included.
A Design Procedure for Multivariable Control Systems
Authors: Anakwa W. N. , Pearson A. E.
Published: November 2010

A design procedure is presented which focuses upon a dynamic compensator of prespecified structural form. The order and feedback matrices of the compensator are first chosen to achieve stability through pole assignment via plant output feedback. The compensator feedforward matrices are then selected to satisfy various steady state and static or dynamic decoupling constraints. Results are summarized in application to a large scale power plant.
A Topological Procedure for Converting a Bond Graph to a Linear Graph
Authors: Ort J. R. , Martens H. R.
Published: November 2010

A procedure for converting causally assigned bond graphs into corresponding linear graphs is presented. Topological relations between bond graphs and linear graphs are stipulated. Correspondences between bonds of a bond graph and edges of a system graph, power flows on bonds and orientation of edges, and a causal assignment and the selection of a tree are discussed. Special consideration is given to the uniqueness of the results, odd loops, and causal loops.
The Development of Adaptive Systems in Germany and France
Authors: Landau I. D. , Unbehauen H.
Published: November 2010

The paper presented shows the development of adaptive control systems in Germany and France. After a review of the historical development, typical theoretical principles and some representative examples of adaptive control systems in several fields of application are discussed. The paper shows that important results were obtained both from theoretical and experimental point of view by investigators in both countries.
The Effect of Modeling Errors on Linear State Reconstructors and Regulators
Authors: Thau F. E. , Kestenbaum A.
Published: November 2010

The effect of imprecise knowledge of system parameters on the reconstruction error of linear observers and on the stability of a class of linear regulators is examined. An upper bound on the reconstruction error for linear unforced systems is obtained. It is shown that in the regulator problem consideration of parameter uncertainty leads to the inclusion of step disturbances. An upper bound on allowed parameter variations that guarantees stability of a class of closed-loop regulators is obtained. It is also shown that by properly choosing parameters of a low-order observer, the output of this low-order model can be made to follow closely the output of a higher-order dynamic systems. The effect of modeling errors on randomly perturbed systems is also examined.
Data Storage in the Cerebellar Model Articulation Controller (CMAC)
Authors: Albus J. S.
Published: November 2010

The storage of manipulator control functions in the CM AC memory is accomplished by an iterative process which, if the control function is sufficiently smooth, will converge. There are several different techniques for loading the CM AC memory depending on the amount of data which has already been stored and the degree of accuracy which is desired. The CM AC system lends itself to a “natural” partitioning of the control problem into manageable subproblems. At each level the CM AC controller translates commands from the next higher level into sequences of instructions to the next lower level. Data storage, or training, is accomplished first at the lowest level and must be completed, or nearly so, at each level before it can be initiated at the next higher level.
Application of Vortex Shedding and Fluidics to the Control of Volumetric Flow Rates
Authors: Frederick G. L. , Hedrick J. K. , Jankowski D. F.
Published: November 2010

The phenomenon of vortex shedding behind a bluff body in a fluid stream was investigated to determine its applicability to the measurement of the volumetric flow rate of air. Laboratory tests were performed to determine the best bluff body configuration for generating vortex-dependent pressure signals which could be sensed and processed by fluidic circuits. The feasibility of using fluidics to sense the vortex shedding frequency and to produce a usable output signal was demonstrated by tests performed on a volumetric flow controller consisting of a rectangular bluff body, fluidic circuitry, and a diaphragm-actuated butterfly valve.
Feedback Control of Two Beam, Two Joint Systems With Distributed Flexibility
Authors: Book W. J. , Maizza-Neto O. , Whitney D. E.
Published: November 2010

The control of the flexible motion in a plane of two pinned beams is addressed with application to remote manipulators. Three types of linear feedback control schemes are considered: joint angle and velocity feedback with (GRC) and without (IJC) cross joint feedback, and feedback of flexible state variables (FFC). Two models of the distributed flexibility are presented along with some results obtained from them. The relative merit of the three control schemes is discussed.
Some Bond Graph Identities Involving Junction Structures
Authors: Karnopp D.
Published: November 2010

When bond graphs are generated from reasonable physical systems according to standard rules, there are only rare cases in which power loops arise that yield singular algebraic relations among effort and flow variables. On the other hand, if one assembles bond graphs from subsystem models, paradoxical situations may arise in which sign conventions and causality interact strangely and in which physically impossible situations seemingly occur. Some useful bond graph identities are shown which often eliminate such paradoxes. The general conclusion is that a bond graph containing a junction structure power loop should be carefully examined with respect to sign convention and to see whether a simplifying identity can be used before causality is applied and equations are formulated.
Control of a Flexibly Mounted Stabilized Platform
Authors: Burrows C. R. , Adams T. P.
Published: November 2010

The governing equations for a flexibly mounted stabilized platform are derived and solved using digital simulation. Theoretical predictions for the static and dynamic performance are compared with experimental results. This leads to a study of the effects of modifying the control system to improve stability and steady-state positional accuracy.
Passive Suspension Design for a Magnetically Levitated Vehicle
Authors: Be´langer Pierre R. , Guillemette Raymond
Published: November 2010

This paper presents a passive suspension designed to stabilize a magnetically-levitated vehicle, using both vertical and lateral suspension elements. The two-mass system is broken up into six subsystems, one for each degree of freedom, assumed to be independent. The suspension design is seen to be an attempt to obtain satisfactory dynamics for several subsystems simultaneously. Steady-state constraints are shown to be in conflict with optimal dynamical behavior. Response to disturbances due to guideway roughness and wind are considered, and it is shown that the suspension can attain, although marginally, satisfactory performance.
Analysis of the Effect of Strain Hardening on Central Bursting Defects in Drawing and Extrusion
Authors: Zimerman Z. , Avitzur B.
Published: November 2010

Central bursting defects in a strain-hardening material are analyzed. A criterion has been derived for the conditions that promote these defects, as a function of the coefficient of strain hardening, the percent reduction, the die semicone angle, and the coefficient of friction. The criterion was experimentally verified for homogeneous materials.
Seam Puckering as a Mechanical Instability Phenomenon
Authors: Zorowski C. F. , Patel G. C.
Published: November 2010

Results are presented from a study directed toward establishing quantitative relationships among the important systems parameters involved in the puckering of fabric seams treating the phenomena as a problem in mechanical instability. Using idealized models to simulate the mechanical behavior of a simple seam, the elastic stability problem encountered is that of a compressed member supported on a nonlinear foundation which is discontinuous and depends on the final shape of buckling. An energy method is used to obtain approximate theoretical solutions for the buckling behavior of such a model for the case of a straight edge seam subjected to excessive sewing thread tension. These solutions both identify the important system variables and predict what combinations will produce puckering. An experimental study conducted on simulated seam models to verify the theory shows acceptable agreement with predicted results.
Optimum Design of Rotating Disks
Authors: Seireg Ali , Surana K. S.
Published: November 2010

This paper presents a procedure for rational design of high speed rotating disks. Optimum configurations are automatically calculated to satisfy the designer’s objective within given constraints. The study illustrates the applicability of programming techniques to the optimal selection of the dimensions for such disks. The influence of the design criterion on the disk profile is demonstrated.
The Frictional Properties of Polytetrafluoroethylene Coatings Rubbing a Polyether Polyurethane Material
Authors: March W. A. , Kolcun J. P. , Krzysik A. J.
Published: November 2010

The frictional properties of several polytetrafluoroethylene (PTFE) coatings versus a 70 Shore D polyether polyurethane valve seat material were evaluated in ambient air, dry mica, and water immersion conditions. Plots were made of coefficient of friction versus time. The frictional properties of one of the coatings was dependent on its thermal history during curing. Of particular interest was the maximum and reversal in coefficient of friction noted for some of the coatings. From the data obtained in the mica immersions an estimate of the comparative wear life of the coatings was made. The mechanism involved in visco-elastic friction is discussed.
Degrees of Freedom of Motion in Mechanisms
Authors: Bagci Cemil
Published: November 2010

The general form of the mobility equation is presented, which predicts the number of inputs required to drive a multiloop mechanism having redundant freedoms, passive freedoms, different general constraints in different loops, and groups of loops having over-closing constraints. Redundant freedoms, passive freedoms, general constraints, over-closing constraints are described, and the use of the mobility equation is illustrated through numerous examples. A method of identifying the class of a mechanism is also given.
Synthesis of a Geared N-Bar Linkage
Authors: Dimarogonas A. D. , Sandor G. N. , Erdman A. G.
Published: November 2010

For certain tasks, four-bar linkages may not provide needed accuracy and/or structural characteristics. To overcome this, one or more bars may be added to the coupler with geared pairs to maintain a “one-degree-of-freedom” system. Utilizing complex numbers and matrix methods, a general geared n-bar function generator is developed in this paper. The computer program devised synthesizes four-bar linkages to approximate the desired function and increases the number of links by one if specifications for accuracy and other requirements are not met. Synthesized linkages are analyzed and then optimized by way of minimizing a multidimensional objective function. As a practical illustration of the n-bar theory, geared five-bar, one-loop function generators are designed to simulate the dynamic response of a two-degree-of-freedom vibrating system.
Dynamic Analysis of Mechanisms Using Screw Coordinates
Authors: Woo L. S. , Freudenstein F.
Published: November 2010

A method is described using screw coordinates for the dynamical analysis of systems of pair-connected rigid bodies, such as plane and three-dimensional mechanisms, including gyroscopes. The use of screw coordinates leads to general, linear, and computationally efficient numerical procedures, which are illustrated by a dynamic analysis of a constrained spatial RSKR (or R4S) linkage.
Managerial Progress in the Sixties—Some Summary Reactions
Authors: Smiddy Harold F.
Published: November 2010

The Sixties saw notable progress. NASA’s decentralized approach landed man on the moon. Multinational firms spread widely from numerous nations. The United States economy functioned at substantially a trillion dollar annual level. Yet, regional, racial, and religious conflicts persisted, even to spreading violence currently on campus and streets. Political leadership was overtaxed; inflation varied only in degree in old and “new” countries. Noneconomic institutions—universities, unions, hospitals, even churches—grew to use large human and material resources, but too often with ineffective managerial guidance. Notable progress, or lag, is indicated in five fields: general gains, and drags, in the Sixties; managerial advances in business and government; manager education; information for managing; managerial concepts for the future. In conclusion, the lag of classic authority to produce needed new orders of organized teamwork becomes startingly visible—but does so just as the supply of trained brains, and the availability of needed new kinds of information, take on dimensions already competent to keep order ahead of chaos while still keeping man free.
Management Education—Industrial, 1960–1969
Authors: Rothe F. S. , Young J. F.
Published: November 2010

This paper stresses the continuing education of engineers in industry for the period 1960–1969. The forces conditioning engineering education are delineated with particular emphasis on the acceleration of technology and the shift in importance of diagnosis. Engineering education courses designed to meet the new demands are described. Discussed are the influences that will shape the next decade. They will be dominated by “new” concerns for human problems and the task of setting priorities.
Prediction of Loads and Stresses in Closed-Die Forging
Authors: Altan T. , Fiorentino R. J.
Published: November 2010

Various empirical formulas for predicting the maximum load in practical forgings are reviewed. Assuming a constant friction shear stress at the material-tool interface, the slab method of analysis is applied to the general upsetting operation under inclined surfaces. The stress and load equations are derived for plane strain and axisymmetric deformation. A method for determining flow models in practical forgings is presented. This method gives better approximations of forging loads than the fictitious disk model. The theory presented in this work is applied to a lead forging at room temperature and to a 1043 steel forging at 1180 C. The agreement with predictions and experimental results are within useful engineering accuracy.
A Continuing Study in the Determination of Temperatures in Metal Cutting Using Remote Thermocouples
Authors: Groover M. P. , Kane G. E.
Published: November 2010

The results of research are presented whose objective was to develop a remote thermocouple technique for measuring cutting temperatures in a turning operation. The measuring scheme relies on the signals from two standard thermocouples located beneath the cutting tool insert. These signals are fed into an analog computer which calculates on-line the temperature at the tool point. The on-line computation provides an estimate of the tool point temperature within about one second rather than requiring the tool thermal system to come to steady state before temperatures are estimated. The research included two development phases. The first involved the use of digital computer simulations of the heat transfer process in a generalized cutting tool. This led to the derivation of a simple equation to estimate the cutting temperature from measurements taken at two remote points. The second phase concerned experimental validation of the computer simulations under a variety of cutting conditions.
Sound and Vibration Transmission Through Panels and Tie Beams Using Statistical Energy Analysis
Authors: Crocker M. J. , Battacharya M. C. , Price A. J.
Published: November 2010

The transmission of sound and vibration through structures is of interest in many noise control problems, including architectural acoustics, sound transmission through aircraft, spacecraft and ships, and the transmission of noise through machinery and engine enclosures. Statistical energy analysis provides a simple and accurate method of approaching these problems. In this paper, theory is examined for the transmission of acoustic energy through single panels, independent double panels, and double panels connected with tie beams. In the single panel case, the theoretical model consists of three linearly coupled oscillators; room-panel-room. The independent double panel case consists of five oscillators; room-panel-cavity-panel-room. In the connected double panel case, the tie beams must be accounted for as the sixth oscillator. A coupling loss factor is determined for the ties by considering the transmission of longitudinal waves, bending waves, and lateral shear waves in the ties. Both resonant and nonresonant transmission are included in the theory. It is shown that for a single panel, the experimental sound transmission loss, panel radiation resistance, and vibration amplitude are all well predicted by the theory. The experimental sound transmission loss is also well predicted in the independent double panel and coupled double panel cases.
Vibration Response and Wave Propagation in Periodic Structures
Authors: Mead Denys J.
Published: November 2010

The vibration response of periodic, beam-like structures has conventionally been studied either by transfer matrix or normal mode methods. The latter method becomes unwieldy if the damping and modal density are high, whereas the former method does not lend itself readily to giving physical understanding. It is shown in this paper that a special class of flexural wave groups can exist in periodic structures; an understanding of them permits a ready formulation of the response-calculation problem. The formulation can be applied to both infinite and finite structures, and the amount of damping present may have any value. The method is specially well adapted to studying response due to convected pressure fields and loadings and gives great physical insight. Illustrations are given relating to beams resting at regular intervals on flexible supports and to aeronautical rib-skin structures. Some calculated values of vibration response are presented and discussed and optimum structural configurations are considered.
Stress Analysis of a Spherical Acrylic Pressure Hull
Authors: Snoey M. R. , Katona M. G.
Published: November 2010

This study was initiated to: (1) perform an analytical structural analysis on an acrylic pressure hull, (2) compare the analytical results with all available experimental results, and (3) present an operating-depth curve. The design analyzed was a pressure hull incorporating twelve spherical pentagons of acrylic plastic bonded together to form a sphere with an outside diameter of 66 in. and a wall thickness of 2.5 in. Conical steel penetrations were located at the two poles. The experimental results were obtained from strain-gage data from two independent pressure tests to 500 psi on two acrylic hulls of the same design. The analysis on the structure was performed with a finite-element computer code with particular emphasis on the acrylic-steel boundary. The boundary conditions at the acrylic-steel interface were two extreme cases: perfectly fixed and perfectly free. A time-dependent yield-failure criterion for acrylic plastic was combined with the structural analysis to provide an operating-depth curve as a function of both time and temperature. Comparison of analytical and experimental results indicated excellent agreement. At a temperature of 70 deg F and a maximum of 50 hr load duration, the acrylic hull can operate to 1000 ft with a safety factor of 1.5 based on yield and a safety factor of 2.6 based on collapse.
Drill Temperature Distributions by Numerical Solutions
Authors: Saxena U. K. , DeVries M. F. , Wu S. M.
Published: November 2010

The backward finite-difference method is used to determine three-dimensional drill temperature distributions. The geometry of the drill was described by (1) approximating the drill as a one-quarter cone and (2) sectioning a true drill point and measuring its profiles. The three-dimensional temperature distributions provided both drill cutting edge and drill flank temperature profiles which were close to prior experimental data and showed improvement over the previous analytical solutions.
Optimization of the Constrained Machining Economics Problem by Geometric Programming
Authors: Ermer D. S.
Published: November 2010

A more complete solution to the machining economics problem is one that takes into account several constraints of the actual machining operation. The object of the paper is to illustrate how a relatively new mathematical programming method called geometric programming can be used to determine the optimum machining conditions when the solution is restricted by one or more inequality constraints. This optimizing method is especially effective in machining economics problems, where the constraints may be nonlinear and the objective function of more than second degree. Furthermore, the geometric programming approach furnishes a unique insight into how the optimizing criterion is distributed among its components for a given set of input parameter values.
Refrigeration Requirements of the LN2 Cryo-Cable
Authors: Graneau P. , Parish H. C. , Smith J. L.
Published: November 2010

The paper considers the smallest size refrigeration plant likely to be required for liquid nitrogen cooled electric power transmission lines. Nitrogen, neon, hydrogen, and helium cycles are compared and it is shown that a neon cycle has considerable potential. An outline is given of a practical plant utilizing the nitrogen cycle and mainly rotating machinery, all based on present-day technology. The advantages which evaporative cooling confers on the operation of LN2 cryo-cables are explained.
Gas Piping Design for High Speed Reciprocating Compressor Units
Authors: Barta M. L. , Bass T. P.
Published: November 2010

This paper discusses the problems associated with gas piping designs incorporating acoustic low pass wave filters for high speed reciprocating compression equipment. It develops a procedure where effective acoustic filtering can be incorporated analytically in the time allowed by the industry. The basic equations for determining surge drum sizes, line sizes, and acoustic filter sizes are developed according to several basic guidelines, and are used in several example problems.
Fatigue-Crack Propagation in Steels of Various Yield Strengths
Authors: Barsom J. M.
Published: November 2010

The useful life of highly constrained welded structures subjected to cyclic loads often depends on the crack-propagation behavior of the material. Thus, to predict the service life of many structures and to establish safe inspection intervals, an understanding of the rate of fatigue-crack propagation in steel is required. Accordingly, an investigation was conducted to determine the fatigue-crack-growth rates in structural steels ranging in yield strength from 36 to 191 ksi; for this study, wedge-opening-loading (WOL) specimens were used. The tests were conducted at room temperature in an air environment, and the results were compared with published fatigue-crack-growth data for steels having similar yield strengths. The results showed that the primary factor affecting fatigue-crack-growth rates in structural steels is the applied stress-intensity-factor range, ΔKI, and that conservative estimates of fatigue-crack growth per cycle of loading, da/dN, for martensitic steels are obtained from the relationship dadN=0.66×10−8(ΔKI)2.25 where a is in inches and ΔKI is in ksi in. Similarly, the data showed that conservative estimates of da/dN for ferrite-pearlite steels are obtained from the relationship dadN=3.6×10−10(ΔKI)3 As indicated in these equations, the fatigue-crack-growth rates were higher for martensitic steels than for ferrite-pearlite steels. The data also showed that the fatigue-crack growth per cycle accelerated for all the steels, and that this transition from the above relationships to increased rates occurred when the crack-opening-displacement range, Δδ, which is a measure of the strain range at the crack tip, reaches a critical value. The fatigue-rate transition in martensitic steels occurred when Δδ was about 1.6 × 10−3 in. However, the fatigue-rate transition in ferrite-pearlite steels occurred at a Δδ value slightly higher than 1.6 × 10−3 in. A model based on micro structural considerations is presented, which accounts for these differences in the fatigue-crack-growth behavior between martensitic and ferrite-pearlite steels.
Creep/Fatigue Interaction Correlation for 304 Stainless Steel Subjected to Strain-Controlled Cycling With Hold Times at Peak Strain
Authors: Campbell R. D.
Published: November 2010

A numerical integration of creep relaxation curves from strain-controlled fatigue tests with hold times introduced at peak strain is performed to sum creep damage by the linear life fraction rule. Fatigue damage is summed and an interaction diagram for creep and fatigue damage is constructed. Data scatter about the interaction curve is compared to scatter for independent creep rupture and fatigue tests from the identical heat of material.
Analytical Investigations of Compact Reinforcement for Radial Nozzles in Spherical Shells
Authors: Gwaltney R. C. , Corum J. M.
Published: November 2010

Compact reinforcement for a series of models having single nozzles radially attached to spherical shells was examined by means of finite element analyses. Parameters studied were diameter-to-thickness ratios of the nozzles, diameter-to-thickness ratios of the spherical shells, percentage of reinforcement, outside reinforcement, inside reinforcement, and “balanced” reinforcement (reinforcement on both the inside and outside surfaces). The loading was internal pressure. Comparisons of theoretical predictions with experimental results are presented for one reinforced model. Twelve models were analyzed to examine the effect of compact reinforcement.
Experimental Stress Analysis of 24-In. Tees
Authors: Hayes J. K. , Roberts B.
Published: November 2010

This paper describes the experimental stress analysis and low cycle fatigue test of one 24-in. dia, schedule 40 carbon steel, ASA Standrd B16.9 tee performed by Combustion Engineering, Inc. This program is part of the Oak Ridge National Laboratory Piping Program for the development of design criteria for nuclear service piping components. The tee was instrumented with 230 rectangular strain gage rosettes. Elastic data was obtained for 12 loading conditions consisting of internal pressure and orthogonal pure moment and orthogonal direct forces applied individually to the free branch and run ends of the tee. One of the run ends of the tee was “built in” throughout the test. All loads were applied through pipe extensions welded to the tee. The tee was tested to failure in a low cycle fatigue test with an in-plane bending moment on the branch pipe. The tee was pressurized to the design pressure of 1025 psig during the fatigue test. A cyclic stress of approximately ±83,600 psi was imposed on the tee and a through-the-wall fatigue crack occurred at 18,532 cycles. Significant test results are summarized and compared with design values tabulated in the current issue of the Nuclear Power Piping Code, USAS B31.7-1969.
Effective Elastic Constants for Thick Perforated Plates With Square and Triangular Penetration Patterns
Authors: Slot T. , O’Donnell W. J.
Published: November 2010

An exact formulation is presented of the relationship between the effective elastic constants for thick perforated plates (generalized plane strain) and thin perforated plates (plane stress). Extensive numerical results covering a wide range of ligament efficiencies and Poisson’s ratios are given for plates with square and triangular penetration patterns.
The Effects of Shear Deformation and Rotary Inertia on the Lateral Frequencies of Cantilever Beams in Bending
Authors: Carnegie W. , Thomas J.
Published: November 2010

This paper deals with the effect of shear deformation and rotary inertia on the frequencies of flexural vibration of pre-twisted and non-pre-twisted uniform and tapered cantilever beams. The equations of motion are derived and transformed into a set of linear simultaneous algebraic equations by using finite-difference solutions for the derivatives. The resulting eigenvalue matrix equation is solved for the frequency parameters by a QR transformation. The effects of various tapers, depth-to-length ratios and pre-twist angles on the frequencies of vibration are investigated for the first five modes. Results obtained are compared with those presented by other investigators where available and show good agreement. The experimental results presented also show good agreement with the corresponding theoretical values.
Optimum Thermal Design of Radiative-Conductive Systems
Authors: Palmquist R. W. , Beckman W. A.
Published: November 2010

In applying nonlinear programming to optimization of temperatures in a system with radiation and conduction heat transfer, design requirements on the temperatures are translated into mathematical functions in which the design variables are the radiation surface properties, infrared emmittance and solar absorptance. Physical limitations in the surface properties and design objectives form the constraints of the nonlinear programming problem. A mathematical model of a radiative-conductive system employs a nodal analysis. Radiative heat transfer is treated under the semi-gray assumption and a total exchange factor allows surfaces to be specular-diffuse reflectors. Two types of design problems formulated consider (a) the case in which components of a system must operate within certain temperature limits and (b) a system in which uncertainty in the parameters produces uncertainty in the temperatures.
An Analytical Model Predicting Fixed Index Assembly Machine Performance
Authors: Heginbotham W. B. , Rippon G. E.
Published: November 2010

A simplified method of analyzing the performance of fixed index assembly machines using the matrix operator technique is described. This method can be used widely for exploring the effects of operating methods for assembly machines, and an example is quoted where each workhead has a different reliability. By using a digital computer, an exact mathematical model can be built which will enable studies to be made about machine performance when all the head parameters and method of operation are different for each individual head.
IMP (Integrated Mechanisms Program), A Computer-Aided Design Analysis System for Mechanisms and Linkage
Authors: Sheth P. N. , Uicker J. J.
Published: November 2010

An experimental software system for automating the kinematic, static, and dynamic analyses of arbitrary mechanisms is described. The development of a comprehensive analytical technique based on network theory and matrix methods is summarized. The concept of free generalized coordinates of a mechanism and the importance of automatic identification of these coordinates at each position of the mechanism are explained. The application of the ring data structure concepts of SKETCHPAD to mechanism problems is discussed. The interactive capability of this data structure is then combined with a problem oriented language to develop a general purpose design analysis system. The application of this system to mechanism problems is illustrated by examples of varying complexity.
Dynamic Analysis of Elastic Link Mechanisms by Reduction of Coordinates
Authors: Winfrey R. C.
Published: November 2010

Techniques for the solution of linear matrix differential equations have previously been applied to the dynamic analysis of a mechanism. However, because the mechanism changes geometry as it rotates, a large number of solutions are necessary to predict the mechanism’s elastic behavior for even a few revolutions. Also, a designer is frequently concerned with the elastic behavior of only one point on the mechanism and has no practical interest in a complete solution. For these reasons, a method is given here for reducing the total number of coordinates to one coordinate at the point of design interest. A considerable saving in computational time is obtained since the dynamic solution involves one degree of freedom instead of many. Further, since any solution will make use of some limiting assumptions, results here indicate that, for design purposes, reducing the coordinates does not significantly affect comparable accuracy.