Continued Observations on the Distribution of Stress in the Vicinity of a Crack in the Center of a Plate
Continued Observations on the Distribution of Stress in the Vicinity of a Crack in the Center of a Plate

Author: L. R. Jackson

Publisher:

Published: 1964

Total Pages: 50

ISBN-13:

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This memorandum supplements and augments information presented in DMIC Memorandum 178 (AD-422 463). In the present report, Neuber's stress equations are rewritten entirely in rectangular coordinates. In addition, numerical results have been extended to include the stress distribution around an indefinitely sharp crack. It is also shown that the stress function used in a British work for an indefinitely sharp crack yielded identical numerical results, even though the stress function was of a different type than that employed by Neuber. The Von Mises relation was chosen to delineate the area around a crack in which plastic flow is occurring. The numerical tables in this memorandum give values for the function of plane stress as well as one possible interpretation of plane strain. Values of the hydrostatic stress variant are also given for both plane stress and plane strain. (Author).

Some Observations of the Distribution of Stress in the Vicinity of a Crack in the Center of a Plate
Some Observations of the Distribution of Stress in the Vicinity of a Crack in the Center of a Plate

Author: L. R. Jackson

Publisher:

Published: 1963

Total Pages: 38

ISBN-13:

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The primary purpose of this memorandum was to make the results of Neuber's stress analysis more readily usable by those engaged in evaluating the crack sensitivity of materials. While the more intense effect of a crack dies out rapidly near the crack tip, a measurable effect does persist over a great enough area that strain gages could be used to determine the extent to which Neuber's analysis can be applied to granular materials like metals and alloys. The results indicate that, except in the immediate vicinity of the crack tip, the stress field is quite insensitive to crack geometry. (Author).

Observations on Delayed Cracking in Welded Structures of Unalloyed Titanium Sheet
Observations on Delayed Cracking in Welded Structures of Unalloyed Titanium Sheet

Author: R. H. Ernst

Publisher:

Published: 1964

Total Pages: 12

ISBN-13:

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A brief study of delayed fracture in a seam-welded titanium panel is summarized in this memorandum. Examination of the fracture surface with electron microscopy showed that the material cleaved, failing in a brittle manner. Although the nature of the embrittlement was not clearly defined, titanium hydride phase was suspected as a prime contributor to failure. Even though the hydrogen content of the titanium was only 65 ppm, hydride embrittlement was thought to have occurred from precipitation of hydride platelets on crystal planes oriented normal to welding stresses. Other work, briefly discussed in the memorandum, has confirmed that hydride platelets in titanium can be oriented by stress and that tensile ductility of Zircaloy (which behaves similarly with respect to hydrogen, to titanium) depends upon hydride orientation. Stress-relief annealing of welded titanium structures is recommended wherever possible to minimize embrittlement by stress-oriented hydrides. (Author).

Summary of the Eighth Meeting of the Refractory Composites Working Group
Summary of the Eighth Meeting of the Refractory Composites Working Group

Author: E. S. Bartlett

Publisher:

Published: 1964

Total Pages: 26

ISBN-13:

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This memorandum summarizes information on refractory materials and composites as presented at the Eighth Meeting of the Refractory Composites Working Group in Fort Worth, Texas, January 14-16, 1964. This memorandum is based on 45 papers covering a wide variety of subjects ranging from basic studies on oxidation mechanisms to the development of specific pieces of hardware. The papers are reviewed and discussed briefly within the framework of the following four broad areas: materials technology, process technology, specific hardware applications, and evaluation techniques. Included in the section on materials technology are discussions dealing with bulk refractory materials and coatedmetal systems. Hot spraying, chemical vapor deposition, powder processes, joining, and extrusion are discussed in the section on process technology. The specific hardware applications cover rocket-motor components, nose caps, leading edges, hot skins, and fasteners. (Author).