Accession Number:

AD0650417

Title:

FATIGUE CRACK PROPAGATION UNDER PROGRAMMED AND RANDOM LOADS

Descriptive Note:

Corporate Author:

BOEING SCIENTIFIC RESEARCH LABS SEATTLE WA SOLID STATE PHYSICS LAB

Personal Author(s):

Report Date:

1966-07-01

Pagination or Media Count:

86.0

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.

Subject Categories:

  • Aircraft
  • Metallurgy and Metallography
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE