Accession Number : AD0650417

Title :   FATIGUE CRACK PROPAGATION UNDER PROGRAMMED AND RANDOM LOADS,

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

Personal Author(s) : McMillan,J. Corey ; Pelloux,Regis M. N.

Report Date : JUL 1966

Pagination or Media Count : 85

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 grwoth 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. (Author)

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

Subject Categories : Aircraft
      Metallurgy and Metallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE