CRACK PROPAGATION IN LOW-CYCLE FATIGUE OF MILD STEEL

The investigation reported is concerned with crack propagation in low-cycle fatigue of mild-steel plate specimens and has indicated that during crack propagation the type of loading cycle will affect markedly the fatigue behavior. Several types of reversed loading cycles have been included in the investigation, namely constant load, reduced loads and constant stress. In the constant-load tests the stress increases throughout the test as the crack propagates, and the rate of crack propagation continuously increases. If the load range is reduced throughout a test (reduced-load test) so as to produce constant net-section stresses, the rate of crack growth will decrease throughout the test. In the constant-stress tests the stress range was maintained constant during the test. In this latter use, the rate of fatigue crack propagation remained constant after a short initial period. Constant-stress tests were conducted at stress levels ranging from plus or minus 27 ksi to plus or minus 36 ksi, on 3/4-in. thick specimens with widths of 5 in. and 7 in., at test temperatures of 78 F and -40 F and for both unaged and aged specimens. It was found that the fatigue crack propagation behavior during a constant-stress test may be divided into an initial, linear, and final stage. A hypothesis relating the rate of crack growth and the stress has been developed to describe the behavior during the various stages of propagation.

  • Corporate Authors:

    University of Illinois, Urbana-Champaign

    Urbana, IL  USA  61801

    Ship Structure Committee

    National Academy of Science, 2101 Constitution Avenue, NW
    Washington, DC  USA  20418
  • Authors:
    • Rolfe, S T
    • Munse, W H
  • Publication Date: 1963-5-1

Media Info

  • Features: References;
  • Pagination: 50 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00331926
  • Record Type: Publication
  • Source Agency: Ship Structure Committee
  • Report/Paper Numbers: SSC-143 Prog Rpt.
  • Contract Numbers: NObs-77008, NObs-84321
  • Files: TRIS
  • Created Date: May 21 1981 12:00AM