FATIGUE LIFE ESTIMATION USING SIMPLE FRACTURE MECHANICS

A reliable crack growth rule is required to assess the importance of cracks in loaded components. The law used is based on linear elastic fracture mechanics (LEFM), an approach originally developed to explain brittle fracture under static loads. The author shows how the LEFM can be adapted to the study of fatigue. Because some structural integrity programs depend upon fracture mechanics methods, an attempt is made to explain the principles so that engineers, who may not need to perform the calculations, can understand the specifications they are trying to meet. Three modes of crack extension are examined and the general form of stress-intensity factors are discussed. The significance of the Paris-Erdogan expression, the most used expression for crack propagation, is explained. Limitations of the equation are revealed and one, the difficulty in integrating the crack growth in terms of length, is examined in detail to suggest improvements to the Paris-Erdogan expression. The significance of fracture mechanics in cumulative damage is discussed also dealing with random loading. This article is the second of four articles on fatigue. (TRRL)

  • Supplemental Notes:
    • For abstracts of the other papers, published in the December 1982 and September and December 1983 issues of this journal, see TRIS nos. 373337, 388871 and 388872.
  • Corporate Authors:

    Modino Press Limited

    Keswick House, 3 Greenway
    London N20 8EE,   England 
  • Authors:
    • Sherratt, F
  • Publication Date: 1983-3

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Filing Info

  • Accession Number: 00388870
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD, TRIS
  • Created Date: Oct 30 1984 12:00AM