The Early Detection of Fatigue Damage
Final technical rept. 1 Jul 1968-30 Jun 1971
NORTH AMERICAN ROCKWELL CORP LOS ANGELES CA LOS ANGELES DIV
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The report is the final technical report for a program directed at the development of nondestructive test NDT methods for the detection of early fatigue and fracture damage in metals and alloys. The program is based on an interdisciplinary approach designed to interrelate the factors of early fatigue damage with measurable physical phenomena. The program initially concentrated on a comprehensive study of the existing knowledge of fatigue phenoma in metals, and the results of the study are described in terms of fatigue and fatigue- associated phenomena, metallurgical structure, effect of interrelating fatigue phenomena on physical properties, and the availability of appropriate measurement techniques and equipment. Next, the program developed a series of controlled fatigue experiments to quantitatively measure the fatigue effects in selected metal specimens. These tests also included a systematic metallographic evaluation to determine the actual depth and character of the surface layer affected by progressive fatigue, particularly in the early stages of fatigue. Finally, NDT methods were evaluated in terms of their potential detection and measurement capability of the observed fatigue-related effects and damage as determined by the study and fatigue evaluation tests.
- Test Facilities, Equipment and Methods