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Full-Text Articles in Engineering Science and Materials

Assessment Of Feasibility Of Proposed Bolted Connections For Tubular Structures, John Henry Tausch Nov 1977

Assessment Of Feasibility Of Proposed Bolted Connections For Tubular Structures, John Henry Tausch

Dissertations and Theses

The search for new and additional sources of energy -- from sun, wind, waves, and ocean currents -- is necessitating the development of structures in the open environment of the oceans as well as on land. The advantages of round or tubular members for use in such structures are shown; and to avoid the uncertainties of welded joints, two bolted connections are proposed and their feasibility explored.


Analysis Of Combustion Products Of Kynol And Nomex, Abdul Halim Hassan Housny May 1977

Analysis Of Combustion Products Of Kynol And Nomex, Abdul Halim Hassan Housny

Theses

The gaseous products generated by flaming combustion of Kynol and Nomex fibers under the same conditions (temperature 300-700°C, natural air) were quantitatively analyzed by infrared spectrophotometry, gas chromatography, mass spectrometry and a colorimetric tube method. The four techniques were chosen to examine the wide range of volatile and condensable products expected due to their different capabilities and sensitivities.

The main gases generated were carbon monoxide, carbon dioxide, methane and benzene.

The mass spectrometer was used to identify the condensed vapors. These were mainly phenol, methyl phenol and dimethyl phenol from the Kynol fiber and benzene, aniline, diaminobenzene, benzoic acid ...


Thermal Decomposition Products Of Kynol And Nomex With Reference To Structure And Toxicity, Shaker H. El-Sherbini May 1977

Thermal Decomposition Products Of Kynol And Nomex With Reference To Structure And Toxicity, Shaker H. El-Sherbini

Theses

The purpose of this investigation was to study the combustion products of KYNOL and NOMEX as a fire retardant fibers. From the quantitative analysis data of the combustion products, the polymer structure is discussed and the property of thermal stability is explained.

From the analysis of the combustion products, the toxicity indices for the two fibers are determined. It is found to be 0.1 for KYNOL and 0.71 for NOMEX. This can be interpreted to mean that, if one gram of MIDI, is decomposed and the combustion products were diffused in one cubic meter of air, the probability ...


An Experimental Investigation Of Unbraced Reinforced Concrete Frames, Nourollah Samiee Nejad May 1977

An Experimental Investigation Of Unbraced Reinforced Concrete Frames, Nourollah Samiee Nejad

Dissertations and Theses

The main objective of this investigation is to study experimentally the behavior of rectangular reinforced concrete frames subject to a combination of low column loads, beam loads, and lateral load. The analytical tool used in this investigation is a computer program which is a generalized computational method for non linear force deformation relationship and secondary forces due to displacement of the joints during loading.

In the experimental portion of this investigation, two rectangular frames, one design by the Ultimate Strength Design method and the other by a Limit Design method were prepared and tested to failure with short time loading ...


A Non-Phase Sensitive Transducer For Ultrasonics, J Heyman Jan 1977

A Non-Phase Sensitive Transducer For Ultrasonics, J Heyman

Review of Progress in Quantitative Nondestructive Evaluation

I would like to describe some of our programs at NASA, Langley Research Center, Hampton, VA, on the development and use of a new type of phase insensitive transducer we call an Acoustoelectric Converter, or an AEC. In the very short time I have here, I shall indicate why the AEC is significant and show some ultrasonic transmission results obtained from modified isometric attentuation scans of conventional NDE resolution test plates containing simple flaws.


Application Of Inelastic Electron Tunneling To The Study Of Adhesion, T Wolfram, H White Jan 1977

Application Of Inelastic Electron Tunneling To The Study Of Adhesion, T Wolfram, H White

Review of Progress in Quantitative Nondestructive Evaluation

The problem of devising meaningful and reliable methods for nondestructive evaluation of adhesively bonded joints has been the subject of considerable effort for many years. It remains an important and unsolved problem. The use of conventional NOT methods involving ultrasonics is not entirely satisfactory because the thickness of a bond line is small compared with typical acoustic wavelengths and, perhaps more importantly, because the strength and service life of an adhesive bond is dependent on its chemical as well as mechanical properties. That is, an adhesive bond that is mechanically perfect may fail because of chemical degradation initiated at the ...


Technology Transition-Opportunities And Progress, H M. Burte Jan 1977

Technology Transition-Opportunities And Progress, H M. Burte

Review of Progress in Quantitative Nondestructive Evaluation

Don Thompson in his introductory remarks, and many other speakers since then, have talked to the needs for NDE. These fall into three major categories: reliability of the complex constructs that seem increasingly to pervade our civilization; the role of NDE as an important factor in what I might call a rational approach to a "conservation ethic" or a "total life cycle cost" approach to systems;and the use of NDE as a tool for lower cost production. If we accept the validity of these and other needs let us consider the challenge posed by our keynote speaker.


Methods For Detecting Moisture Degradation In Graphite-Epoxy Composites, David H. Kaelble Jan 1977

Methods For Detecting Moisture Degradation In Graphite-Epoxy Composites, David H. Kaelble

Review of Progress in Quantitative Nondestructive Evaluation

This presentation reports on the second year of our participation in this NDE program. The purpose of this work is two-fold and this talk divides itself naturally into two segments which relctte to the following objer.tives:

  1. To determine the effects of moisture degradation on the mechanical properties of a graphite- epoxy composite under study for use on B-1.
  2. To apply promising techniques found in last year's program to detect moisture degradation nondestructively.


Optimization Of Electromagnetic Transducer Systems, R Bruce Thompson, C M. Fortunko Jan 1977

Optimization Of Electromagnetic Transducer Systems, R Bruce Thompson, C M. Fortunko

Review of Progress in Quantitative Nondestructive Evaluation

Electromagnetic transducers have a number of inherent advantages, some of which have been touched on by other speakers. Historically, their major disadvantage has been their high insertion loss. We have undertaken a project which has been designed to explore techniques for optimizing transducer efficiencies and increasing the dynamic response of ultrasonic systems which use electromagnetic transducers. Today, we would like to report the results of that project.


Characteristics And Applications Of Electromagnetic Surface Wave Transducers, T J. Moran Jan 1977

Characteristics And Applications Of Electromagnetic Surface Wave Transducers, T J. Moran

Review of Progress in Quantitative Nondestructive Evaluation

Tom Szabo mentioned during his presentation that there is a great deal of similiarity between the response of a meander line surface wave EMT and that of an interdigital transducer. We have been investigating their common properties to see if they can be exploited for NDE applications. The generation of bulk waves in delay lines is considered a problem for interdigital transducers,2 but for NDE it might provide a convenient means of generating bulk waves propagating at an angle to the surface.


The Use Of Continuous Wave Ultrasonic Spectroscopy For Adhesive-Bond Evaluation, Michael J. Buckley, J M. Raney Jan 1977

The Use Of Continuous Wave Ultrasonic Spectroscopy For Adhesive-Bond Evaluation, Michael J. Buckley, J M. Raney

Review of Progress in Quantitative Nondestructive Evaluation

The program to be described here was initiated during the past year at the Air Force Materials Laboratory. The problem of deterMining adhesive bond strength was undertaken with a rather bruteforce approach of simply collecting the best possible data, utilizing existing ultrasonic plane-wave theory for layed structures to calculate ultrasonic spectra, and then attempting the inversion of the d~ta to obtain the acoustic properties of the materlal or structure. An empirical correlation of these acoustic properties with the destructively measured bond strength is planned.


A Practical Approach To Fabricating Ideal Transducers, J J. Tiemann Jan 1977

A Practical Approach To Fabricating Ideal Transducers, J J. Tiemann

Review of Progress in Quantitative Nondestructive Evaluation

I was invited here to come to talk about transducers, and I'd like to tell you how that came about. It came about because the General Electric Jet Engine Dept. has been trying to perform water immersion ultrasonic inspection of engine forgings with commercially available inspection equipment and has found that this equipment is ill suited to the task. I would guess that most of these instruments were designed 5 or 10 years ago for applications in the steel industry. In any case, they do not have enough dynamic range to accommodate the large acoustic attenuation encountered in Jet ...


Durability Of Composites And Adhesive Bonds, Williard D. Bascom Jan 1977

Durability Of Composites And Adhesive Bonds, Williard D. Bascom

Review of Progress in Quantitative Nondestructive Evaluation

Any consideration of the durability of the high performance composite materials and structural adhesives used in aerospace construction must recognize that these are brittle materials and that their failure mode is characterized by flaw growth and propagation. One can easily anticipate a variety of flaws and defects; surface cuts, internal cracks due to stress relief and deliberate holes cut for fasteners. In this presentation we wish to discuss yet another type of flaw in fibrous composites and adhesive bonds that is inherently present because of the processing methods used to fabricate composites or bonded joints. These flaws are microvoids created ...


Concept And Mathematical Modeling Of Acoustic Emission Source, W J. Pardee Jan 1977

Concept And Mathematical Modeling Of Acoustic Emission Source, W J. Pardee

Review of Progress in Quantitative Nondestructive Evaluation

Presently, most acoustic emission applications in nondestructive testing involve placing transducers on a large structure, a bridge or hydrocarbon cracking pressure vessel, then loading the structure and listening for the burst-type acoustic emissions that ensue, and ,finally using triangulation to locate the flaws whence came those bursts. This technique is very effective at locating defects, and that means that the typical, most studied acoustic emission parameters are just the number of events, the event rate, and to a somewhat lesser extent, the maximum amplitude . It might be the root mean square. amplitude, or some other amplitude that characterizes the acoustic ...


Surface Acoustic Wave Electromagnetic Transducer Modeling And Design For Nde Applications, T L. Szabo Jan 1977

Surface Acoustic Wave Electromagnetic Transducer Modeling And Design For Nde Applications, T L. Szabo

Review of Progress in Quantitative Nondestructive Evaluation

I'll be talking mainly about surface acoustic wave electromagnetic transducers, EMT's. These are useful for examining near surface flaws, defects or stress gradients, and they are also very useful for examining rough or painted, or dirty, or hot, or curved surfaces, not necessarily in that order. Recently, this technology has developed to the point where it's possible to fabricate identical transducers. What I'd like to show this morning is that it's also very straightforward to design them. There is quite a large flexibility in the design of these transducers, and they give very clean, reproducible ...


Signal Processing With Surface Acoustic Wave Devices, R M. White Jan 1977

Signal Processing With Surface Acoustic Wave Devices, R M. White

Review of Progress in Quantitative Nondestructive Evaluation

Our interest is in analog signal processing as it might be applied to NDE, carrying out some sophisticated signal processing using an inexpensive, real-time analog system based on the surface acoustic- wave technology, or perhaps the CCD technology. To date we have considered an inverse filter for correcting for the frequency response of an NDT transducer: we have shown the feasibility of .making such a device and will show some experimental results here. We are making and testing some filters that have been designed to go with a commercial NDT transducer that we have purchased. We are also looking at ...


Wave Propagation And Acoustic Emission In Layered Composites, W R. Scott Jan 1977

Wave Propagation And Acoustic Emission In Layered Composites, W R. Scott

Review of Progress in Quantitative Nondestructive Evaluation

I will be presenting two different phases of our NDT composites program. The first of these, an in-house effort, is on the use of ultrasonic techniques, including spectrum analysis, for the nondestructive testing of composite materials. The second part of the presentation will be on characterization of acoustic emissions for boron/aluminum. This latter program is a joint effort between NADC and the University of Delaware. By way of background, Fig. 1 shows a diagram of an apparatus used for ultrasonic detection and mapping of flaws in composites. This is quite a conventional apparatus with the possible exception of the ...


Usaf Nde Program - Requirements For Technology Transition, D M. Forney Jr Jan 1977

Usaf Nde Program - Requirements For Technology Transition, D M. Forney Jr

Review of Progress in Quantitative Nondestructive Evaluation

The final session of our meeting is intended to be a change of pace with the express purpose of better focusing on the realistic aspects of the application of NDE in the field; practical problems and limitations, the requirements, potential and opportunities. Actually, Gerry Posakony did a good job of kicking off this end of the meeting subject last night with a discussion of his problem with the rather complex looking structures for which he has to develop operational inspection techniques.


Criteria For Nondestructive Testing R&D, C S. Smith Jan 1977

Criteria For Nondestructive Testing R&D, C S. Smith

Review of Progress in Quantitative Nondestructive Evaluation

Gentlemen, I'm probably more out of place than any of your other speakers. Some have noted that they're chemists; some have noted that they're metallurgists. I have no research results to report; I'm a bureaucrat, one of those hopefully nice, gray, faceless, beings from the Pentagon. I must ask your forebearance this morning if I seem.a bit obtuse; where I work a square corner has 108 degrees. Unfortunately, listening to your meeting I quickly concluded that my initial topic for this talk was unsuitable for this occasion. What follows is a different talk. My apologies ...


Nondestructive Evaluation Uncertainty And Inspection Optimization, Duane P. Johnson Jan 1977

Nondestructive Evaluation Uncertainty And Inspection Optimization, Duane P. Johnson

Review of Progress in Quantitative Nondestructive Evaluation

NDE decisions differ from most other engineering decisions in that the NDE response or responses used in making a decision with regard to the serviceability of a part are often only weakly correlated with the serviceability of the part. The impact of of this weak correlation or inspection uncertainty on inspection errors and the effectiveness of the inspection is discussed. A quantitative methodology for selecting the optimum NDI accept/reject decision thresholds in the face of the inspection uncertainty is outlined. Also discussed briefly is how inspection uncertainty analysis can be used to estimate the inspection reliability from field or ...


Optimization And Application Of Electrodynamic Acoustic Wave Transducers, B W. Maxfield Jan 1977

Optimization And Application Of Electrodynamic Acoustic Wave Transducers, B W. Maxfield

Review of Progress in Quantitative Nondestructive Evaluation

I'm going to talk about the use of electromagnetic acoustic wave transducers, or EMATS as I call them, as they are being used for bulk wave generation. They have been applied specifically to the problem of measuring the intensity distribution of acoustic waves that are scattered by defects of known geometries. Related studies have been done elsewhere for some time and have formed an integral part of this general program.


Trapped Acoustic Modes For Adhesive Strength Determination, George A. Alers Jan 1977

Trapped Acoustic Modes For Adhesive Strength Determination, George A. Alers

Review of Progress in Quantitative Nondestructive Evaluation

The most important aspect of measuring the strength of adhesion at an adhesive to metal interface is to understand the chemistry of the interface and to know what makes a good interface. The existence of a strong interface will make the joint less susceptible to fabrication defects that are going to be there no matter how carefully the joint is prepared.


Experiences Of Ndt Technology Transfer At Harwell, R S. Sharpe Jan 1977

Experiences Of Ndt Technology Transfer At Harwell, R S. Sharpe

Review of Progress in Quantitative Nondestructive Evaluation

I very much appreciate the opportunity of being able to come over to this meeting. I was a bit surprised when Don Thompson phoned me up and said, "Come and talk about technology transfer to a meeting on quantitative NDT," but having sat attentively during the past day and a half here, I think I can now appreciate the need for urgent discussion and debate on the subject. Now, when you are scheduled to speak on the last day like this, you usually find that you have got to completely rewrite your talk the evening before to fit in with ...


Adaptive Deconvolution To Improve Resolution, E S. Furgason, V L. Newhouse Jan 1977

Adaptive Deconvolution To Improve Resolution, E S. Furgason, V L. Newhouse

Review of Progress in Quantitative Nondestructive Evaluation

Deconvolution applied to ultrasonic flaw detection offers the possibility of greatly improved resolution through the elimination of the transducer response. Seydel has previously demonstrated that at least a modest increase in resolution is possible provided the signal-to-noise ratio of the signal being deconvolved is large enough. The random signal flaw detection system can be shown to be ideally suited to deconvolution since it provides enormous signal-to-noise ratio enhancement. Furthermore, the bandwidth compression inherent in this system allows A-D conversion of the output at a rate several orders of magnitude lower than the transmitted ultrasonic frequency. The computer program created to ...


Nuclear Resonance For The Nondestructive Evaluation Of Structural Materials, G A. Matzkanin Jan 1977

Nuclear Resonance For The Nondestructive Evaluation Of Structural Materials, G A. Matzkanin

Review of Progress in Quantitative Nondestructive Evaluation

It is appropriate that this presentation is in a session on new techniques because the program I will discuss this afternoon is sufficiently new that few concrete results are available to report. The program I will discuss was recently funded at Southwest Research Institute by AFOSR and involves examining the possibility of developing nuclear resonance techniques for the nondestructive evaluation of structural materials. What I hope to do this afternoon is to fill you in a bit with regard to the background involved in this program and bring you up to date regarding our research plans. I will discuss some ...


Theoretical Elements Of Acoustic Emission Spectra, J A. Simmons, R B. Clough Jan 1977

Theoretical Elements Of Acoustic Emission Spectra, J A. Simmons, R B. Clough

Review of Progress in Quantitative Nondestructive Evaluation

I will be describing an acoustic emission program at the National Bureau of Standards sponsored jointly by NBS and the Electric Power Research Institute. This is part of a larger comprehensive NDE program at NBS. The acoustic emission program uses the spectral analysis approach for the characterization of moving defects and, as I will point out, includes the development of an acoustic emission transducer calibration facility as well as the experimental study of crack motion in glass and pressure vessel steels. These require a quantitative theory which serves to guide the experimental design as well as to interpret the results.


Near Real Time Ultrasonic Pulse Echo Holographic Imaging System, G J. Posakony Jan 1977

Near Real Time Ultrasonic Pulse Echo Holographic Imaging System, G J. Posakony

Review of Progress in Quantitative Nondestructive Evaluation

Nondestructive flaw characterization has keen research interests throughout industry. The nuclear industry is no exception. Identifying the size, shape, orientation, type and position of material flaws in nuclear reactor pressure vessels has a top priority. Under a contract with the Electric Power Research Institute of Palo Alto, California, Battelle-Northwest is developing a demonstration model of a sequentially pulsed phased linear array system for ultrasonic inspection of reactor vessels. This program employs the linear array in both pulse echo and holographic modes and provides near real time images of the weld zone volume. The objectives of the program are to develop ...


Cohesive Strength Prediction Of Adhesive Joints, P L. Flynn Jan 1977

Cohesive Strength Prediction Of Adhesive Joints, P L. Flynn

Review of Progress in Quantitative Nondestructive Evaluation

My part of this program was to investigate a nondestructive method for measuring the cohesive strength properties of adhesively bonded joints.

I started this problem by viewing a reasonably fundamental study in modeling the adhesive as a layer between two infinite aluminum adherends. You can set up wave potentials in these different regions in terms of reflected and transmitted waves, as is seen in Fig. 1. If you set up your wave number in a very classical manner, where everything is elastic and there is no damping, you just get a regular Rayleigh-type solution. If you desire to include the ...


Report On The Symposium On Nondestructive Testing Standards, G Birnbaum Jan 1977

Report On The Symposium On Nondestructive Testing Standards, G Birnbaum

Review of Progress in Quantitative Nondestructive Evaluation

A symposium on nondestructive testing (NDT) standards reflecting widespread current concern with this area was held at the National Bureau of Standards (NBS) May 19-21, 1976. The symposium was cosponsored by the National Bureau of Standards (NBS), the American Society for Testing and Materials (ASTM), the American Society for Nondestructive Testing (ASNT), with the American National Standards Institute (ANSI) cooperating. The meeting provided the first general forum encompassing discussions on the processes by which NDT codes, standards, and specifications become accepted, and discussions on the status and needs that exist in all NDT methods. Major themes included standards documents, the ...


Sagamore, Nde Topics, George Mayer Jan 1977

Sagamore, Nde Topics, George Mayer

Review of Progress in Quantitative Nondestructive Evaluation

The 23rd Sagamore Army Materials Research Conference was held last week in upstate New York. The theme was Nondestructive Characterization of Materials, and the intent of this meeting was to approach the subject with a broad brush treatment, including historical aspects, the assessment of significant advances in each topic area, important new capabilities, and discussion of some exploratory techniques as contrasted with the generally more focused and in-depth studies that have been reported here at Asilomar.