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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Fault determinations in electroexplosive devices by nondestructive techniques

Several nondestructive test techniques were developed for electroexplosive devices. The bridgewire responds, when pulsed with a safe level current, by generating a characteristic heating curve. The response is indicative of the electrothermal behavior of the bridgewire-explosive interface. Bridgewires which deviate from the characteristic heating curve were dissected and examined to determine the cause of the abnormality. Deliberate faults were fabricated into squibs. The relationship of the specific abnormality and the fault associated with it is demonstrated.

Menichelli, V. J.↗
NASA NTRS1971

Development of nondestructive testing techniques for plated-through holes in multilayer printed circuit boards

The development of a nondestructive test with the capability to interrogate plated-through holes as small as 0.51 millimeters inside diameter is discussed. The system can detect defects such as holes, voids, cracks, and thin spots that reduce the current carrying capability of plates-through interconnects by 20 percent or more. Efforts were directed toward the design and fabrication of magnetic circuitry mutual coupling probes and to evaluate the effectiveness of these devices for detecting in multilayer board plated-through holes.

Anthony, P. L.↗
NASA NTRS1972

Nondestructive testing of Scout rocket motors

The nondestructive tests applied to Scout rocket motors were reviewed and appraised. Analytical techniques were developed to evaluate the capabilities of the radiographic and ultrasonic procedures used. Major problem areas found were the inadequacy of high voltage radiography for detecting unbonds and propellant cracks having narrow widths, the inability to relate the ultrasonic signals received from flat-bottomed holes in standards to those received from real defects and in the general area of the specification of acceptance criteria and how these were to be met. To counter the deficiencies noted, analyses were conducted to the potential utility of radiometric, acoustic, holographic and thermographic techniques for motor and nozzle bond inspection, a new approach to qualifying magnetic particle inspection and the application of acoustic emission analysis to the evaluation of proof and leak test data.

Oaks, A. E.↗
NASA NTRS1972

Evaluation of electroexplosive devices by nondestructive test techniques and impulsive waveform firings

Special requirements of the space industry for more detailed knowledge of the quality and reliability of each electroexplosive device (EED) selected for use aboard a spacecraft are described. Statistical methods do not practically demonstrate the high reliability needed. To close this gap, nondestructive test techniques and instrumentation for 1-W/1-A no-fire devices have been developed. Several lots of squibs have been evaluated using these techniques and instrumentation. They yield data as to the quality and normal behavior of each electroexplosive device without firing or degrading the unit. Performance data were obtained by initiating the EED's with an impulsive waveform and sensing the initiation characteristics, sensitivity, and output.

Menichelli, V. J.↗
NASA NTRS1972

Nondestructive test of regenerative chambers

Flat panels simulating internally cooled regenerative thrust chamber walls were fabricated by electroforming, brazing and diffusion bonding to evaluate the feasibility of nondestructive evaluation techniques to detect bonds of various strength integrities. Ultrasonics, holography, and acoustic emission were investigated and found to yield useful and informative data regarding the presence of bond defects in these structures.

Malone, G. A.↗
NASA NTRS1971

A systems approach of the nondestructive evaluation techniques applied to Scout solid rocket motors.

Review and appraisal of the status of the nondestructive tests applied to Scout solid-propellant rocket motors, using analytical techniques to evaluate radiography for detecting internal discontinuities such as voids and unbonds. Information relating to selecting, performing, controlling, and evaluating the results of NDE tests was reduced to a common simplified format. With these data and the results of the analytical studies performed, it was possible to make the basic appraisals of the ability of a test to meet all pertinent acceptance criteria and, where necessary, provide suggestions to improve the situation.

Oaks, A. E.↗
NASA NTRS1971

Interrelationship of nondestructive testing to fault determination.

Several nondestructive test techniques have been developed for electroexplosive devices. The bridgewire will respond, when pulsed with a safe level current, by generating a characteristic heating curve. The response is indicative of the electrothermal behavior of the bridgewire-explosive interface. Bridgewires which deviate from the characteristic heating curve have been dissected and examined to determine the cause for the abnormality. Deliberate faults have been fabricated into squibs. The relationship of the specific abnormality and the fault associated with it is discussed.

Menichelli, V. J.↗
NASA NTRS1972

Nondestructive determination of fatigue crack damage in composites using vibration tests.

The vibration response of glass reinforced epoxy and polyester laminates was investigated. The complex modulus and the damping capacity were measured as fatigue crack damage accumulated. Changes in the Young's modulus as well as the damping capacity correlated with the amount of crack damage. The damping was especially sensitive to debonding of the reinforcement from the resin matrix. Measurement of these vibration response changes shows promise as a means to nondestructively test the structural integrity of filament-reinforced composite structural members.

Dibenedetto, A. T.↗
NASA NTRS1973

Microwave holography for nondestructive testing

Holographic methods permit use of very large effective apertures so that weak signals can be collected over wide area and integrated to form image. Technique, modification of side-looking radar principle, can be used at very short ranges needed for nondestructive inspection of test specimens.

Cribbs, R. W.↗
NASA NTRS1972

Evaluation of nondestructive testing techniques for the space shuttle nonmetallic thermal protection system

A program was conducted to evaluate nondestructive analysis techniques for the detection of defects in rigidized surface insulation (a candidate material for the Space Shuttle thermal protection system). Uncoated, coated, and coated and bonded samples with internal defects (voids, cracks, delaminations, density variations, and moisture content), coating defects (holes, cracks, thickness variations, and loss of adhesion), and bondline defects (voids and unbonds) were inspected by X-ray radiography, acoustic, microwave, high-frequency ultrasonic, beta backscatter, thermal, holographic, and visual techniques. The detectability of each type of defect was determined for each technique (when applicable). A possible relationship between microwave reflection measurements (or X-ray-radiography density measurements) and the tensile strength was established. A possible approach for in-process inspection using a combination of X-ray radiography, acoustic, microwave, and holographic techniques was recommended.

Tiede, D. A.↗
NASA NTRS1972

Nondestructive evaluation: A survey of NASA contributions, chapter 1, Chapter 11, cover page, acknowledgements, and contents

A survey of nondestructive evaluation (NDE) technology, which is discussed in terms of popular demands for a greater degree of quality, reliability, and safety in industrial products, is presented as an overview of the NDE field to serve the needs of middle management. Three NDE methods are presented: acoustic emission, the use of coherent (laser)light, and ultrasonic holography.

Source record↗
NASA NTRS1972

Assessment of and standardization for quantitative nondestructive test

Present capabilities and limitations of nondestructive testing (NDT) as applied to aerospace structures during design, development, production, and operational phases are assessed. It will help determine what useful structural quantitative and qualitative data may be provided from raw materials to vehicle refurbishment. This assessment considers metal alloys systems and bonded composites presently applied in active NASA programs or strong contenders for future use. Quantitative and qualitative data has been summarized from recent literature, and in-house information, and presented along with a description of those structures or standards where the information was obtained. Examples, in tabular form, of NDT technique capabilities and limitations have been provided. NDT techniques discussed and assessed were radiography, ultrasonics, penetrants, thermal, acoustic, and electromagnetic. Quantitative data is sparse; therefore, obtaining statistically reliable flaw detection data must be strongly emphasized. The new requirements for reusable space vehicles have resulted in highly efficient design concepts operating in severe environments. This increases the need for quantitative NDT evaluation of selected structural components, the end item structure, and during refurbishment operations.

Neuschaefer, R. W.↗