RESIDUAL STRESS MEASUREMENT AND FATIGUE CRACK GROWTH PREDICTION AFTER COLD EXPANSION OF CRACKED FASTENER HOLES

The cold expansion method is often used to introduce beneficial compressive stress at fastener holes and can be used for remedial work where cracks already exist. This paper presents results showing the effect of preexisting cracks on the residual stress field produced by cold expanding a fastener hole, and on subsequent fatigue crack growth. The effect on residual stresses was experimentally evaluated in 2 ways: indirectly, in terms of retained expansion and directly, by measurement of the stresses using the X-ray and neutron diffraction techniques. The retained expansion ratio showed cold expansion is more sensitive to existence of precracks at lower levels of applied interference, and the inlet and outlet faces have different behavior. The stress measurements showed that preexisting cracks reduce the compressive residual stresses more on the mandrel inlet face than on the outlet face and in the middle of the specimen. The effect on fatigue crack growth rates was modeled using a linear-elastic fracture mechanics approach. It was found that cold expansion of a hole containing a preexisting crack longer than 1 mm introduces little benefit for subsequent fatigue crack growth behavior.

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• Corporate Authors:

  American Society of Civil Engineers

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• Authors:
  • Stefanescu, D
  • Santisteban, J R
  • Edwards, L
  • Fitzpatrick, M E
• Publication Date: 2004-7

Language

• English

Media Info

• Features: Figures; Photos; References;
• Pagination: p. 91-97
• Serial:
  • Journal of Aerospace Engineering
  • Volume: 17
  • Issue Number: 3
  • Publisher: American Society of Civil Engineers
  • ISSN: 0893-1321
  • EISSN: 1943-5525
  • Serial URL: http://ascelibrary.org/journal/jaeeez

Subject/Index Terms

• TRT Terms: Aerospace engineering; Aircraft; Cracking; Diffraction; Fasteners; Fatigue (Mechanics); Fatigue limit; Residual stress
• Subject Areas: Aviation; Vehicles and Equipment;

Filing Info

• Accession Number: 00976407
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 5 2004 12:00AM