Accession Number : AD0650417

Title :   FATIGUE CRACK PROPAGATION UNDER PROGRAMMED AND RANDOM LOADS

Corporate Author : BOEING SCIENTIFIC RESEARCH LABS SEATTLE WA SOLID STATE PHYSICS LAB

Personal Author(s) : McMillan, J C ; Pelloux, Regis N

PDF Url : AD0650417

Report Date : Jul 1966

Pagination or Media Count : 86

Abstract : The influence of maximum stress, stress range, and sequence of load application on the rate and mechanism of fatigue crack propagation in 2024-T3 aluminum alloy was studied by means of electron fractography. The macroscopic growth rates were determined on center-notched crack growth panels and the fracture surfaces were examined by electron fractography. An empirical equation relating relative microscopic growth rates at a given crack length to maximum loads and load amplitudes was obtained. It was also found that the advance of a fatigue crack front takes place only during the loading part of a cycle and that in the pseudorandom load case the sequence of load application can markedly influence crack growth rate on any one cycle.

Descriptors :   *AIRFRAMES, *ALUMINUM ALLOYS, *CRACK PROPAGATION, *FATIGUE(MECHANICS), FRACTOGRAPHY, LOAD DISTRIBUTION, LOADS(FORCES), STRESSES

Subject Categories : Aircraft
      Metallurgy and Metallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE