Fatigue Crack Propagation in a High-Strength Steel under Constant Cyclic Load with Variable Mean Loads

Abstract

Fatigue crack propagation studies were conducted on a 9Ni-4Co-0.25C high-strength steel using a constant cyclic load and variable mean loads. The load ratio, R, was varied from +0.5 to -1.0. Fatigue crack growth rates were analyzed using the crack tip stress-intensity factor, K. The results show that mean loads exert a strong secondary influence on fatigue crack propagation. Data were fitted to two crack propagation equations which seek to account for mean loads. Both equations significantly reduced, but did not eliminate, the "layered" scatter caused by mean loads.

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Document Details

Document Type
Technical Report
Publication Date
Nov 29, 1968
Accession Number
AD0681026

Entities

People

  • E. A. Lange
  • Thomas W. Crooker

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms
  • C4I
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Alloys
  • Aluminum
  • Aluminum Alloys
  • Crack Propagation
  • Crack Tips
  • Cracks
  • Cyclic Loads
  • Ferrium
  • Fracture (Mechanics)
  • Instability
  • Materials
  • Mechanical Properties
  • Mechanics
  • Military Research
  • Stress Intensity Factors
  • Stresses
  • Toughness

Readers

  • Materials Science (Mechanical Engineering).
  • Structural Health Monitoring of Composite Structures.