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1983

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Articles 1 - 30 of 156

Full-Text Articles in Mechanical Engineering

Modeling Of Purge Valve Closure, William W. Durgin, Benito Zannini Dec 1983

Modeling Of Purge Valve Closure, William W. Durgin, Benito Zannini

Office of the Provost Scholarship

In some nuclear reactor containment isolation applications, butterfly valves with pneumatic actuators are used to close pipelines in the event of containment pressure transients resulting from postulated accidents. A model is developed which predicts the closure time history of such valve/actuator systems under prescribed transients. Examples are presented which show the importance of the valve and actuator characteristics. It was found that actuation delays of sufficient magnitude could allow the dynamic torque to exceed the available actuator torque, thus preventing valve closure.


Quantitative Ultrasonic Nondestructive Evaluation Methods, R. Bruce Thompson Dec 1983

Quantitative Ultrasonic Nondestructive Evaluation Methods, R. Bruce Thompson

Ames Laboratory Publications

Quantitative ultrasonic techniques for determining the serviceability of structural components are reviewed. Particular emphasis is placed on the use of forward and inverse elastic wave scattering theory as a fundamental foundation for predicting such engineering parameters as the probability of flaw detection and for developing improved techniques for flaw sizing. Ultrasonic measurement techniques for the determination of distributed failure-related properties such as residual stresses are discussed, and the status of the prediction of failure by the detection of acoustic emission precursors is reviewed.


Augmentation Of Free Surface Heat And Mass Transfer Due To Electrostatic Fields, Alan F. Smelewicz, Mark P. Majcher, James B. Nystrom, William W. Durgin Nov 1983

Augmentation Of Free Surface Heat And Mass Transfer Due To Electrostatic Fields, Alan F. Smelewicz, Mark P. Majcher, James B. Nystrom, William W. Durgin

Office of the Provost Scholarship

Experiments were conducted to measure heat transfer rates and mass transfer rates from a water surface in the presence of electrostatic fields of various strengths generated between the water surface and a wire grid above the surface.

Heat transfer rates were determined by the temperature decay after heating the test and control basins. Mass transfer rates were determined by measuring the water loss while holding the basins at fixed temperatures.

It was found that very little increase in transfer coefficients took place for voltages below an onset voltage which depended on atmospheric conditions and test geometry. The heat transfer coefficient ...


Light Actuated Remote Control Security System, Jack C. Klaus, Larry D. Schroeder, Vincent H. Casteel, Kenneth E. Schwartz Oct 1983

Light Actuated Remote Control Security System, Jack C. Klaus, Larry D. Schroeder, Vincent H. Casteel, Kenneth E. Schwartz

Iowa State University Patents

A remote control security apparatus includes a lock element movable between locked and unlocked positions by an electrically actuated power device. The operator is provided with a portable transmitter adapted to generate light which is interrupted at a predetermined frequency so as to produce an encoded light signal. This signal is detected by a light transceiver which generates an independent signal at the same predetermined frequency and which compares the frequencies of the detected signal and independent signal. If these frequencies are substantially the same, the transceiver actuates the power means to move the lock element to its unlocked position ...


Dimensions Fall 1983, Iowa State University Department Of Mechanical Engineering Oct 1983

Dimensions Fall 1983, Iowa State University Department Of Mechanical Engineering

Dimensions

No abstract provided.


Flow Past A Liquid Drop With A Large Non-Uniform Radial Velocity, Satwindar S. Sadhal, Portonovo S. Ayyaswamy Aug 1983

Flow Past A Liquid Drop With A Large Non-Uniform Radial Velocity, Satwindar S. Sadhal, Portonovo S. Ayyaswamy

Departmental Papers (MEAM)

In this analysis, the translation of a liquid drop experiencing a strong non-uniform radial velocity has been investigated. The situation arises when a moving liquid drop experiences condensation, evaporation or material decomposition at the surface. By simultaneously treating the flow fields inside and outside the drop, we have obtained physical results relevant to the problem. The magnitude of the radial velocity is allowed to be very large, but the drop motion is restricted to slow translation. The solution to the problem has been developed by considering a uniform radial flow with the translatory motion introduced as a perturbation. The role ...


Finite Element Analysis Of The Femoral Head, Ghandikota Ramamurthy May 1983

Finite Element Analysis Of The Femoral Head, Ghandikota Ramamurthy

Theses

Femoral component loosening and Prosthetic stem fractures have renewed interest in conservative alternatives to conventional total hip replacements. One such alternative is the concept of surface replacement. The objective in this study is a finite element analysis of a femoral surface replacement cup with Particular attention given to the interfacial stresses. An axisymmetric model with a grid of two-dimensional isoparametric elements is generated. This study utilizes an adaptive model so as to include the effect of bone remodeling in response to stress. The stiffness is considered to be linearly proportional to the stress in the femoral head and neck. Isotropic ...


Computer Simulation Of Cavity Filling During Injection Molding Process, Sumit Banerjee May 1983

Computer Simulation Of Cavity Filling During Injection Molding Process, Sumit Banerjee

Theses

A numerical technique is proposed for the simulation of cavity filling process during injection molding of glass-bead filled polypropylene. The mold cavity is of cylindrical shape. Marker And Cell (MAC) method is utilized for solving the transient flow phenomena, after a mathematical simulation of the flow model is carried out by using the relevant continuity and-momentum equations governing the system. The complexity of the equations involved, results in the simplifying assumption of incompressible and isothermal flow process. A computer program is written on the basis of finite-difference equations developed during the application of MAC method under the prevailing conditions. The ...


One-Dimensional Compressible Flow Analysis : Isentropic And Normal Shock, Su-Bo Wong May 1983

One-Dimensional Compressible Flow Analysis : Isentropic And Normal Shock, Su-Bo Wong

Theses

A computer program to compute and analyse one-dimensional isentropic compressible flow through variable cross-sectional area with or without a normal shock is developed. The program is written in the "FORTRAN LANGUAGE".

In this work, the area change is the predominant cause of change of flow condition. One of the advantage of this program is set on general uses for isentropic flow. In common practice, the values of the isentropic flow property ratios were tabulated or graphically presented as function of the Mach number with a specified specific heat ratio, K (normally K=1.40 was presented). With todays technology, the ...


A Heat Pump Assisted Shower, Jim Mcgovern May 1983

A Heat Pump Assisted Shower, Jim Mcgovern

Articles

An energy-efficient water-heating system for a shower is proposed consisting of a low-powered heat pump, a storage tank and an instantaneous heater which, it is felt, may yield a favourable overall cost, in addition to reducing the primary energy consumption. Some preliminary work has been carried out in exploring this concept. It was considered at the outset that an overall coefficient of performance (COP) of 2 should be readily achieved. Values close to this have been realised with the first experimental prototype.


On The Space Shuttle Wing Thermal-Structural Analysis, Kumar Krishna Tamma Apr 1983

On The Space Shuttle Wing Thermal-Structural Analysis, Kumar Krishna Tamma

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element approach for efficient thermal-structural analysis of structures with thermal protection systems (TPS) is described. The approach is applied to Space Shuttle wing structure configurations subjected to reentry heating. New two and three-dimensional finite elements are developed to model heat transfer in the TPS and supporting structure. A typical TPS/Structural element predicts transient nonlinear temperature variations through the TPS thickness and detailed structural temperatures at the TPS/Structure interface. The accuracy of the TPS/Structure approach in two and three-dimensions is evaluated by comparisons with the conventional approach for various configurations of the wing structure. The results ...


Bicycle Rack, Robert J. Hostert, Michael J. Mathiasmeier, Robert J. Gilbert Feb 1983

Bicycle Rack, Robert J. Hostert, Michael J. Mathiasmeier, Robert J. Gilbert

Iowa State University Patents

A bicycle rack designed to support and lock a bicycle by the bicycle's front center post. Support and lock brackets for individual bicycles are horizontally disposed fork arrangements formed by two joined U-shaped members. Oppositely extending locking brackets allow pairs of bicycles to be conveniently placed along a series of evenly spaced posts and cross-bars.


Bevolute Gear System, Willis M. Carter Jan 1983

Bevolute Gear System, Willis M. Carter

Mechanical Engineering Faculty Patents

The present invention relates to a bevolute gearing system which transmits torque between non-intersecting shafts at right angles to each other. The bevolute gear system includes a pinion gear which is flat and in one plane. The pinion gear is designed to include teeth which are shaped in the form of an involute spiral. The bevolute gear system includes a second gear which is also designed to include teeth which are shaped in the form of an involute spiral. The second gear is mounted on a non-intersecting axis at a right angle to the axis of the pinion gear. The ...


An Improved Rotary Singulator, Burford J. Furman, J. M. Henderson Jan 1983

An Improved Rotary Singulator, Burford J. Furman, J. M. Henderson

Faculty Publications, Mechanical Engineering

A new operating approach for a previously existing rotary singulator was developed which improves the versatility of the device. This was accomplished by the implementation of a modular mechanism that performed the basic functions of agitation, gating, pocket formation, and exit, all inherent in this type of singulation device.


An Improved Rotary Singulator, Burford J. Furman, J. M. Henderson Jan 1983

An Improved Rotary Singulator, Burford J. Furman, J. M. Henderson

Burford J. Furman

A new operating approach for a previously existing rotary singulator was developed which improves the versatility of the device. This was accomplished by the implementation of a modular mechanism that performed the basic functions of agitation, gating, pocket formation, and exit, all inherent in this type of singulation device.


Electrical Breakdown And Ignition Of An Electrostatic Particulate Suspension , Tae-U Yu Jan 1983

Electrical Breakdown And Ignition Of An Electrostatic Particulate Suspension , Tae-U Yu

Retrospective Theses and Dissertations

An electrostatic suspension concept was successfully utilized in generating a uniform particulate cloud between two parallel electrodes in air at atmospheric pressure in order to investigate the effect of this cloud on electrical breakdown, electrical discharge, and ignition of combustible gases. Electrical breakdown was initiated by a fast moving injected needle electrode which resulted in a minimal disturbance of the suspension;It was observed that when using a negative needle (electrode), neither the breakdown voltage nor the needle position at breakdown depended significantly on the needle velocity or the particle number density. Conversely, the positive needle (electrode) breakdown voltage and ...


Ultrasonic Transducer Standards, N. Jayasundere, Leonard J. Bond Jan 1983

Ultrasonic Transducer Standards, N. Jayasundere, Leonard J. Bond

Review of Progress in Quantitative Nondestructive Evaluation

The piezoelectric transducer is the electromechanical conversion element in NDE. Existing transducers of this type are found to impose limits on the improvement in system performance and, at present, there is a lack of standards as required for calibration procedures. Physical “standards” based on equivalent circuits have been produced which model individual transducers, single transducers in pulse-echo mode and two-transducer configurations. The performance of these “standards” is shown to be in good agreement with that given by real transducers, and subject to less variability.


Acoustoelasticity: Scanning With Shear Waves, N. Shaikh, C. Steele, G. S. Kino Jan 1983

Acoustoelasticity: Scanning With Shear Waves, N. Shaikh, C. Steele, G. S. Kino

Review of Progress in Quantitative Nondestructive Evaluation

Acoustoelasticity is a promising method for the in situ analysis of both applied and residual stresses. The object of this investigation is to establish a technique for scanned shear wave measurements so as to determine the individual components of an inhomogeneous stress state and their directions. A computer-controlled scanning system with a dry contact rubber backed transducer has been developed which provides complete automation of scanning and data reduction.

The theory of acoustoelasticity for anisotropic material has been developed using perturbation techniques. The experimental results on rolled aluminum plates confirm that, to a reasonable approximation, the effects of material anisotropy ...


Ultrasonic Steel Cleanliness System, James M. Smith Jan 1983

Ultrasonic Steel Cleanliness System, James M. Smith

Review of Progress in Quantitative Nondestructive Evaluation

It is well known that nonmetallic inclusions can adversely affect the metallurgical properties of engineering alloys. For critical components such as aircraft engine gears and bearings it is important then to quantitatively assess the severity of the inclusion content in the alloy material before performing costly manufacturing operations. This poster paper will describe the operation and the initial results of a computer controlled steel cleanliness inspection system.

The severity of the inclusion content is determined by this system through a statistical analysis of the internally reflected ultrasonic indications from the alloy material as a transducer is scanned in a raster ...


Imaging And Characterization Of Defects With Digital Signal Processing Of Ultrasonic Data, B. A. Barna, J. A. Johnson Jan 1983

Imaging And Characterization Of Defects With Digital Signal Processing Of Ultrasonic Data, B. A. Barna, J. A. Johnson

Review of Progress in Quantitative Nondestructive Evaluation

This paper describes the continuation of the work1,2 on synthetic aperture focusing techniques (SAFT) and ultrasonic imaging as well as new work on the measurement of the amplitude and phase as a function of frequency and aperture position.


Real Time Signal Processing In An Ultrasonic Imaging System, Michael J. Moore, Frank J. Dodd Jan 1983

Real Time Signal Processing In An Ultrasonic Imaging System, Michael J. Moore, Frank J. Dodd

Review of Progress in Quantitative Nondestructive Evaluation

Reliable and repeatable flaw detection and accurate flaw characterization are critical to reliable evaluation of component serviceability. Digital filtering and signal processing techniques can be used in real time to reliably and repeatedly detect flaws even at low signal-to-noise ratios. The same techniques provide near optimum flaw resolution and dimensional precision using standard unfocused transducers. This paper describes these techniques and demonstrates their effectiveness with sample data. The data was processed and collected by an ultra-high-speed general purpose programmable signal processor which is used to detect, locate, and generate images of the component with flaw locations.


Cure Monitoring Of Thermosetting Polymers By An Ultrasonic Technique, Donald L. Hunston Jan 1983

Cure Monitoring Of Thermosetting Polymers By An Ultrasonic Technique, Donald L. Hunston

Review of Progress in Quantitative Nondestructive Evaluation

In the fabrication of components with thermosetting polymers, an essential step is the proper optimization of the cure cycle. In the early phases of the cure the polymer must have the appropriate flow properties to assure the proper wetting, spreading, and forming. It must then harden without excessive build up of residual stresses and flaws or the loss of adhesion at any interfaces that are present. To complicate the situation further, many applications such as composites, adhesives, paints, and protective coatings involve thin films whose cure behavior is significantly different than that for bulk samples. To help address this problem ...


Theoretical And Experimental Developments In Ultrasonic Evaluation Of Periodic Surfaces, Alain Jungman, Laszlo Adler, R. Roberts, J. D. Achenbach Jan 1983

Theoretical And Experimental Developments In Ultrasonic Evaluation Of Periodic Surfaces, Alain Jungman, Laszlo Adler, R. Roberts, J. D. Achenbach

Review of Progress in Quantitative Nondestructive Evaluation

Most ultrasonic NDE experiments and their theoretical models deal with perfectly smooth interfaces, but true materials generally exhibit rough interfaces. As an approach to include the ultrasonic scattering which occurs on the different interfaces along the beam path, the reflection factors of acoustic waves diffracted by periodic surfaces is investigated theoretically and experimentally by looking at the frequency dependence of the reflected signal. Mode conversion bulk and surface waves are shown to be the result of strong coupling between the incident wave and the geometry of the grating. As a consequence, the geometrical parameters of the interface can be obtained ...


An Analysis Of Electromagnetic Acoustic Transducer Arrays For Nondestructive Evaluation Of Thick Metal Sections And Weldments, C. M. Fortunko, R. E. Schramm Jan 1983

An Analysis Of Electromagnetic Acoustic Transducer Arrays For Nondestructive Evaluation Of Thick Metal Sections And Weldments, C. M. Fortunko, R. E. Schramm

Review of Progress in Quantitative Nondestructive Evaluation

A new type of electromagnetic-acoustic transducer (EMAT) has been developed that may be particularly suitable for use as an element of ultrasonic arrays. The new transducer can generate and receive compact ultrasonic pulses that exhibit a component of polarization parallel to the free surface. In the plane of symmetry that is normal to the free surface and bisects the EMAT (the sagittal plane), the ultrasonic signals generated by the new transducer are SH waves. In addition, the new transducer can efficiently receive ultrasonic signals from a very wide range of direction in the sagittal plane. This property is required to ...


Pattern Recognition Analysis Of Acoustic Emission Data From 7075-T651 Aluminum Simulated Joint Specimens, R. B. Melton, P. G. Doctor, D. S. Daly Jan 1983

Pattern Recognition Analysis Of Acoustic Emission Data From 7075-T651 Aluminum Simulated Joint Specimens, R. B. Melton, P. G. Doctor, D. S. Daly

Review of Progress in Quantitative Nondestructive Evaluation

The objective of the work described in this paper is to develop signal analysis techniques that can automatically discriminate be-tween non-critical acoustic emission (AE) from crack growth and acoustic noise signals, such as fretting, of fasteners. The ultimate application of this work is for in-flight AE monitoring of critical aircraft structures.

Fatigue crack growth experiments were performed with center notched plate specimens and simulated joint specimens of 7075-T651 aluminum. The experimental conditions were controlled such that acoustic signals were obtained from crack growth, crack interface rubbing, and from fastener fretting.

This paper reports the results of pattern recognition analysis of ...


Acoustic Emission Linear Pulse Holography, H. D. Collins, L. J. Busse, D. K. Lemon Jan 1983

Acoustic Emission Linear Pulse Holography, H. D. Collins, L. J. Busse, D. K. Lemon

Review of Progress in Quantitative Nondestructive Evaluation

This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth.

Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of ...


An Artificial Intelligence Approach To Ultrasonic Weld Evaluation, G. P. Singh, R. C. Manning Jan 1983

An Artificial Intelligence Approach To Ultrasonic Weld Evaluation, G. P. Singh, R. C. Manning

Review of Progress in Quantitative Nondestructive Evaluation

The inspection of butt-welded stainless-steel pipe joints in nuclear power plants is routinely performed using ultrasonic non-destructive evaluation methods. Field experience, based on conventional ultrasonic signal amplitude criteria, indicates that a large number of indications are recorded. Most of these are not due to cracks, but are inherent in the geometry of the specimen. Discrimination between crack and geometrical/weld (malignant vs. benign) indications is principally based on operator experience, variations in signal amplitude, and the location of the reflector. Field experience and round-robin tests show that indication discrimination is a very time-consuming process. Besides, significant variations in performance exist ...


Identification Of Acoustic Emission Sources By Pattern Recognition Techniques, R. K. Elsley, L. J. Graham Jan 1983

Identification Of Acoustic Emission Sources By Pattern Recognition Techniques, R. K. Elsley, L. J. Graham

Review of Progress in Quantitative Nondestructive Evaluation

Computer pattern recognition has been used to identify and separate acoustic emission (AE) signals that are similar in appearance but are due to different sources. Simulated joint specimens were tested in the laboratory in which a fatigue crack was grown from the edge of a central loading pin hole. The hardened steel loading pin produced fretting AE by its contact with the 7075 T651 aluminum plate specimens during cyclic loading. The fatigue crack produced AE due to crack growth and to crack face rubbing during load cycling. The AE signals detected at two transducers mounted on opposite sides of the ...


Wavefront Fields In The Scattering Of Elastic Waves By Surface-Breaking And Sub-Surface Cracks, Julius Miklowitz Jan 1983

Wavefront Fields In The Scattering Of Elastic Waves By Surface-Breaking And Sub-Surface Cracks, Julius Miklowitz

Review of Progress in Quantitative Nondestructive Evaluation

Of strong practical interest in the subject of fracture mechanics and related structural design and damage are the surface-breaking and sub-surface cracks. Indeed the scattered-wave fields generated by the interaction of incident surface or body waves with these cracks would be expected to yield most of the important in-formation about the geometries of the cracks. It follows, in the subject of quantitative non-destructive evaluation (QNDE) there is considerable interest in scattering by surface-breaking and sub-surface cracks, as important steps in solving the inverse problems of obtaining the crack geometries from the scattered wave fields. However, having the solutions to the ...


Equation Of State Of Fluid Nh3 From P-V-T And Ultrasound Measurements To 12 Kbar, R. L. Mills, D. H. Lienbenberg, Richard Alan Lesar, Ph. Pruzan Jan 1983

Equation Of State Of Fluid Nh3 From P-V-T And Ultrasound Measurements To 12 Kbar, R. L. Mills, D. H. Lienbenberg, Richard Alan Lesar, Ph. Pruzan

Richard Alan Lesar

A piston-cylinder apparatus was used to measure the pressure, volume, temperature, and ultrasonic velocity (P,V,T,u) of fluid NH3 from 195 to 320 K at pressures up to 12 kbar. Over 1200 sets of P-V-T-u and P-V-T data were fitted to a Tait-type equation of state (EOS) by non-linear least-squares minimization. With quadratic terms in T for the two fitted parameters, the rms deviation is ± 0.2% in V and ± 0.9% in u, which is comparable to the experimental error. The simple Tait EOS is useful over the entire fluid range between the vaporization and melting curves ...