The Interferometric Measurement of Near Crack Tip Displacements in a Nickel Base Superalloy at Ambient and Elevated Temperatures.

Abstract

An optical interferometric technique is used to measure the transverse displacement field in the vicinity of the tip of a fatigue crack. The feasibility of using such a technique at temperatures as high as 732 C is demonstrated. Measurements at the crack tip indicated a region of lateral constraint which is controlled in extent by the residual deforation field surrounding the crack tip. Real-time displacement measurements provide a means of evaluating the crack closure concept and indicate that the measurement of crack opening load from surface-based 'compliance' determinations leads to ambiguous results. The cyclic plastic zone within the monotonic plastic zone surrounding the crack tip is experimentally determined and compared with theory. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1979
Accession Number
ADA069648

Entities

People

  • J. Wayne Jones

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Air Force
  • Air Force Facilities
  • Chemical Engineering
  • Crack Propagation
  • Crack Tips
  • Creep
  • Engineering
  • Fracture (Mechanics)
  • Geometry
  • Materials
  • Materials Laboratories
  • Materials Science
  • Measurement
  • Mechanical Properties
  • Mechanics
  • Strain Gages
  • Video Recording

Readers

  • Materials Science (Mechanical Engineering).