Fatigue-Microcrack Behavior under the Influence of Surface Residual Stresses.

Abstract

Direct observations of the surface crack opening displacement (SCOD) of surface microcracks have been performed on samples of Ti-6Al-4V under both cyclic and static loading conditions. The observations were conducted in a specially-designed loading stage in-situ in a scanning electron microscope. SCOD's of cracks as small as 7 microns in surface length have been studied with this technique. Preliminary results have indicated that crack opening is purely elastic for the strain range studied although a significant residual opening is apparent when no load is applied. Concurrent with the experimental efforts, an analytical approach has been developed to predict SCOD for both elastic and plastic loading conditions based on crack geometry. The correlation between predicted SCOD values and independent data for microcracks is excellent. The approach will be modified to account for the influence of an imposed residual stress field and compared to experimental results on microcrack behavior. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 1979
Accession Number
ADA075285

Entities

People

  • G. R. Leverant
  • J. E. Hack

Organizations

  • Southwest Research Institute

Tags

Communities of Interest

  • Cyber

DTIC Thesaurus Topics

  • Aspect Ratio
  • Cantilever Beams
  • Computer Programs
  • Coordinate Systems
  • Crack Tips
  • Creep
  • Electron Microscopes
  • Engineering
  • Geometry
  • Materials
  • Measurement
  • Mechanics
  • Residual Stress
  • Scanning Electron Microscopes
  • Stresses
  • Surface Properties
  • United States

Readers

  • Materials Science (Mechanical Engineering).

Technology Areas

  • Microelectronics