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Full-Text Articles in Mechanical Engineering

Thermal Dynamic Problems Of Reinforced Composite Cylinders, Victor Birman Jan 1990

Thermal Dynamic Problems Of Reinforced Composite Cylinders, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Thermal dynamic problems of circular cylindrical composite shells reinforced in the axial and circumferential directions and subject to variations of temperature are considered. Nonlinear governing equations are formulated based on the extension of Donnell shell theory. These equations are used to determine the response of geometrically nonlinear and linear shells to a thermal loading represented by the Heaviside step function (thermal shock). The solution of the nonlinear problem obtained by the assumption that displacements are single-term functions of coordinates is discussed. The analysis of the linear problem illustrates different types of response to thermal shock. The condition of thermally induced …

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Thermoelastic Problem Of A Thick Orthotopic Beam On Twodirectiooal Elastic Foundation, Victor Birman Jan 1990

Thermoelastic Problem Of A Thick Orthotopic Beam On Twodirectiooal Elastic Foundation, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The thermoelastic problem of an orthotropic beam supported by an elastic foundation which resists lateral deformations as well as displacements parallel to the beam axis is considered. The solution for a relatively thick beam is obtained based on the first-order shear deformation theory. The problem is reduced to- the solution of an ordinary seventh-order differential equation which can be obtained in the closed form. The case of a slender beam is treated as a particular case of a more general solution for a shear deformable beam. © 1990 ASME.

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Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood Jan 1989

Measured Spectra Of The Hygroscopic Fraction Of Atmospheric Aerosol Particles, Darryl J. Alofs, Donald E. Hagen, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Relation between Dry Diameter (Xo) and Critical Supersaturation (Sc) for Atmospheric Submicron Aerosol Particles is Investigated. the Particles Are Passed through an Electrostatic Aerosol Size Classifier, and Then through an Isothermal Haze Chamber. Results Are Reported in Terms of an Apparent Volume Fraction of Soluble Material, Εv, Defined Such that for Particles Composed Only of Ammonium Sulfate and Water Insoluble Compounds, Εv is the Actual Volume Fraction of Soluble Material. the Probability Distribution of Εv is Found to Be Approximately Gaussian in the Εv Range 0.2 to 1.3. the Mean Εv is 0.5, for Electrostatic Aerosol Classifier Settings of …

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Adiabatic Shear Banding In Plane Strain Problems, R. C. Batra, De Shin Liu Jan 1989

Adiabatic Shear Banding In Plane Strain Problems, R. C. Batra, De Shin Liu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Plane strain thermomechanical deformations of a viscoplastic body are studied with the objective of analyzing the localization of deformation into narrow bands of intense straining. Two different loadings, namely, the top and bottom surfaces subjected to a prescribed tangential velocity, and these two surfaces subjected to a preassigned normal velocity, are considered. In each case a material defect, flaw, or inhomogeneity is modeled by introducing a temperature bump at the center of the specimen. The solution of the initial boundary value problem by the Galerkin-Adams method reveals that the deformation eventually localizes into a narrow band aligned along the direction …

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Nonlinear Tracking Control Of Brushless Dc Motors For High-Performance Applications, N. Hemati, Ming-Chuan Leu Jan 1989

Nonlinear Tracking Control Of Brushless Dc Motors For High-Performance Applications, N. Hemati, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The tracking control problem associated with brushless DC motors (BLDCMs) for high-performance applications is considered. To guarantee their high-dynamic-performance operation in motion control systems, the magnetic saturation and reluctance variation effects are accounted for in the BLDCM mathematical model. The trajectory tracking control problem is addressed in the context of the transformation theory of nonlinear systems. A nonlinear control law is implemented and shown to compensate for the nonlinearities of a BLDCM. A case study is presented in which a direct-drive inverted pendulum actuated by a BLDCM is used to investigate the effectiveness of the control law. The effectiveness of …

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Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai Jan 1989

Generic Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The singularities of the differential kinematic map, i.e. of the manipulator Jacobian, are considered. The authors first examine the notion of a generic kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator. For three-joint robots, an equivalent condition for genericity using determinants is derived. The condition lends itself to symbolic computation and is sufficient for the study of decoupled manipulators, i.e. manipulators that an be separated into a three-joint translating part and a three-joint orienting part. The results are illustrated by analyzing the singularities of two classes of three-joint positioning robots.

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Axisymmetric Vibrations Of Reinforced Orthotropic Shallow Spherical Caps, Victor Birman, George J. Simitses Jan 1989

Axisymmetric Vibrations Of Reinforced Orthotropic Shallow Spherical Caps, Victor Birman, George J. Simitses

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Axisymmetric vibrations of reinforced shallow, spherical caps manufactured from orthotropic materials are considered. The closed form solution is obtained for the natural frequency of the cap with a clamped and immovable circular edge by assuming that the motion component parallel to the cap boundary plane (in plane) is negligible. Parametric studies are performed to assess the effect of various geometric and structural parameters on the natural frequency of the cap and, most importantly, to identify the most influencing parameters of the problem. From the generated data, it is concluded that the national frequency increases with increasing extensional stiffness and eccentricity …

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Optimal Design Rules Applied To The Design Of High-Speed Mechanisms Under Deflection And Stress Constraints, Frank W. Liou, Jenny Liu Jan 1989

Optimal Design Rules Applied To The Design Of High-Speed Mechanisms Under Deflection And Stress Constraints, Frank W. Liou, Jenny Liu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Presented in this paper are two approaches for the design of flexible mechanisms under stress and deflection constraints. Based on the optimality conditions derived in this paper, two procedures are developed to design the minimum weight of mechanisms subject to stress and deflection limitations. The first procedure is the improvement of Thornton's design process r 17), and the second procedure is based on the interpolation technique. Several design examples are also presented to demonstrate these methods.

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A Comment On ‘Failure Modes Of Hybrid Composites …’, Serge Abrate Mar 1988

A Comment On ‘Failure Modes Of Hybrid Composites …’, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper comments on an earlier paper on the failure modes of hybrid composites by Pitkethly and Bader, which appeared in the Carbon Fiber Conference issue. © 1988 IOP Publishing Ltd.

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Characteristics And Optimal Design Of Variable Airgap Linear Force Motors, Ming-Chuan Leu, E. V. Scorza, D. L. Bartel Jan 1988

Characteristics And Optimal Design Of Variable Airgap Linear Force Motors, Ming-Chuan Leu, E. V. Scorza, D. L. Bartel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An analytical model for predicting the characteristics of variable airgap linear force motors is developed. the model takes into account magnetic losses including the leakage and fringing effects and the reluctance existing at the contacts between permanent magnets and pole pieces. the model is validated by comparing its predicted characteristics with the results obtained from experiments and a finite element program. with the use of the modelled characteristics, computer programs based on the method of constrained steepest descent with state equations are developed for automating and optimising the design of linear force motors. Numerical studies are made for both minimisation …

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Effect Of Nominal Strain-Rates On The Initiation And Growth Of Adiabatic Shear Bands In Steels, R. C. Batra Jan 1988

Effect Of Nominal Strain-Rates On The Initiation And Growth Of Adiabatic Shear Bands In Steels, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs Jan 1988

Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Cloud Simulation Facility Has Been Developed for the Study of Various Atmospheric Cloud Processes. the Initial Relative Humidity of the Air Sample Put into the Cloud Chamber is a Key Parameter in Virtually Any Experiment and Needs to Be Known Accurately. This Report Describes How the Cloud Simulation Chamber itself Has Been Used as a Condensation Type Hygrometer to Calibrate the System's Humidifier. Two Distinct and Physically Different Methods for Inferring Mixing Ratio Are Used, One Exploiting the Sensitivity of Aerosol Activation to Humidity, and the Other Exploiting the Sensitivity of the Rate of Growth of Cloud Droplets to …

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University Of Missouri-Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred R. Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker Dec 1987

University Of Missouri-Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred R. Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Graduate Center for Cloud Physics Research at UMR Has Developed a Cloud Simulation Facility to Study Phenomena Occurring in Terrestrial Clouds and Fogs. the Facility Consists of a Pair of Precision Cooled-Wall Expansion Chambers Along with Extensive Supporting Equipment. the Smaller of These Chambers, Described in This Article, is Fully Operational, and is Capable of Simulating a Broad Range of In-Cloud Thermodynamic Conditions. It is Currently Being Used to Study Water Drop Growth and Evaporation for Drops Nucleated (Activated) on Well-Characterized Aerosol Particles. Measurements Have Been Made Not Only for Continuous Expansions (Simulated Updraft) But Also for Cyclic Conditions, …

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The Force On A Lattice Defect In An Elastic Body, R. C. Batra Jan 1987

The Force On A Lattice Defect In An Elastic Body, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It is shown that the force on a lattice defect in an elastic body is, like the force on a disclination in a nematic liquid crystal, a real force which, for equilibrium, must be balanced by an external force applied to the closed surface enclosing the defect. © 1987 Martinus Nijhoff Publishers.

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Effect Of Material Parameters On The Initiation And Growth Of Adiabatic Shear Bands, R. C. Batra Jan 1987

Effect Of Material Parameters On The Initiation And Growth Of Adiabatic Shear Bands, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The thermomechanical problem involving simple shearing of a finite slab made of an isotropic and viscoplastic material is studied with the objective of finding the effect of the strain hardening parameter, strain-rate hardening parameters, thermal softening coefficient and thermal conductivity on the initiation and growth of adiabatic shear bands. The body is placed in a hard loading device, i.e., the velocity is prescribed at its top and bottom surfaces. A shear band is presumed to have formed if the addition of a perturbation in the temperature at the onset of plastic flow results in a localization of the shear strain. …

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Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig Jan 1986

Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne Jan 1986

Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Generalized root-loci techniques, for squirrel-cage motors have been extended to wound-rotor, slip-energy-recovery systems (static Scherbius drive). The influence of a feedback control loop on these root loci is considered. General conclusions on Scherbius drive dynamics, as well as supporting experimental results, are presented.

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Plasma Polymerization Investigated By The Substrate Temperature Dependence., H. Yasuda, Cheng Wang Jan 1985

Plasma Polymerization Investigated By The Substrate Temperature Dependence., H. Yasuda, Cheng Wang

Chemistry Faculty Research & Creative Works

In the reported experiments, plasma polymerization of tetrafluoroethylene (TFE), perfluoro-2-butyl-tetrahydrofuran (PFBTHF), ethylene, and styrene were investigated in various combinations of monomer flow rates and discharge wattages for the substrate temperature range of minus 50 to 80 degree C. The polymer deposition rates can be generally expressed by k//o equals Ae** minus **b**t, where k//o is the specific deposition rate given by k//o equals (deposition rate)/(mass flow rate of monomer), A is the preexponential factor representing the extrapolated value of k//o at zero absolute temperature, and b is the temperature-dependence coefficient. It was found that the value of b is not …

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Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles Jan 1984

Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles Jan 1984

Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Generalized root-loci techniques, developed in the mid 70's for squirrel cage motors, have been extended in the static Scherbius configuration to wound rotor, slip energy, recovery systems. This arrangement is now applied to large power drives in the 0.5 to 50 MW range. In this paper, general results applicable to all machines are presented for the open-loop control scheme, but only the sub synchronous mode of operation in which a voltage source type inverter is used is addressed. Copyright © 1984 by The Institute of Electrical and Electronics Engineers, Inc.

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Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra Jul 1983

Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Toupin's version of the Saint-Venant principle in linear elasticity is generalized to the case of linear elasticity with microstructure. That is, it is shown that, for a straight prismatic bar made of an isotropic linear elastic material with microstructure and loaded by a self-equilibrated force system at one end only, the strain energy stored in the portion of the bar which is beyond a distance s from the loaded end decreases exponentially with the distance s. © 1983 Martinus Nijhoff Publishers.

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Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs Jan 1983

Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Use of a Differential Mobility Analyzer to Perform Aerosol Size Spectrum Measurements Requires an Inversion Method to Go from the Measured Sensor Responses to the Desired Size Spectrum Information. Here We Present a Linear Inversion Method that Can Be Run on a Microcomputer or a Small Minicomputer. It Does Not Use Some of the Approximations Made in the Techniques Currently Available and Hence Gives Better Inversion Accuracy. the Method Shows Good Immunity to Both Random and Systematic Experimental Error. It is Applied to Numerous Test Case Aerosols. © 1983 Elsevier Science Publishing Co., Inc.

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A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood Jan 1982

A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar Jan 1982

Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

To Measure Size Distributions of Sub micrometer Aerosols with an Electrical Differential Mobility Analyzer (DMA) Requires an Inversion Procedure. the Knutson (1976) and the Hoppel (1978) Inversion Procedures Were Numerically Investigated for the Case of Log-Normal Aerosol Size Distributions. It Was Found that the Hoppel Procedure Converges to the Same Result as that Given by the Knutson Procedure. the Computational Range for Geometric Mean Diameter (Χg) Was 0.025-0.25 Μm, and for Geometric Standard Deviation (Σg) Was 1.1-2.4. the Inversion Error Was Found to Be Greater Than 10% in Certain "Forbidden Zones" of Χg and Σ …

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Feasibility Study For A Municipal Refuse To Energy Plant, Archie W. Culp Jr. Nov 1981

Feasibility Study For A Municipal Refuse To Energy Plant, Archie W. Culp Jr.

UMR-DNR Conference on Energy

No abstract provided.

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Estimation Of Water And Energy Requirements For Ground Water Heat Pumps In The United States, Ronald H. Howell, Harry J. Sauer Jr. Nov 1981

Estimation Of Water And Energy Requirements For Ground Water Heat Pumps In The United States, Ronald H. Howell, Harry J. Sauer Jr.

UMR-DNR Conference on Energy

No abstract provided.

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Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu Jan 1981

Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Concentrations of Cloud Condensation Nuclei in the Atmosphere Were Measured at Rolla, Missouri, Near Ground Level. a Total of 432 Spectra Were Measured over a 10-Month Period. No Consistent Seasonal or Diurnal Pattern Was Observed. Possible Implications for Fogs and Stratus Clouds and for Nuclei Chemical Composition Are Discussed.-From Authorscloud Condensation Nuclei Rolla Missouri Fogs

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Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel Jan 1980

Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The combined effects of buoyancy forces from thermal and species diffusion on the heat and mass transfer characteristics are analyzed for laminar boundary layer flow over a horizontal flat plate. The analysis is restricted to processes with low concentration levels such that the interfacial velocities due to mass diffusion and the diffusion-thermo/thermo-diffusion effects can be neglected. Numerical results for friction factor, Nusselt number, and Sherwood number are presented for gases having a Prandtl number of 0.7, with Schmidt numbers ranging from 0.6 to 2.0. In general, it is found that, for the thermally assisting flow, the surface heat and mass …

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Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra Jan 1980

Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of the indentation of a rubberlike layer bonded to a rigid cylinder and indented by another rigid cylinder is analyzed. The rubberlike layer is assumed to be made of a homogeneous Mooncy-Rivlin material. The materially and geometrically nonlinear problem is solved by using the finite-element code developed by the author. Results computed and presented graphically include the pressure profile at the contact surface, stress distribution at the bond surface and the deformed shape of the indented surface. © 1980 by ASME.

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Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr Jan 1979

Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nucleation Experiments with Monodisperse NaCl Aerosols Showed Good Agreement with the Kohler Theory Relating the Critical Super-Saturation S//c to the Dry Size. Aerosols Produced by Condensing NaCl Showed the Same S//c as Those Produced by Evaporating Aqueous NaCl Solution Droplets. This Indicates that If There is an Energy Barrier in Going from a Dry NaCl Particle to a Solution Droplet, This Energy Barrier is Small. the Fact that the Evaporation Aerosol Particles Are Cubical Crystals and the Condensation Aerosols Are Amorphous Spheres is Shown to Make No Difference in the Nucleation Threshold. the Investigation Also Gives Insights into the Performance …

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