Accession Number : ADP000010

Title :   A Nonlinear Fracture Mechanics Predictive Procedure for the Short Crack Effect in Fatigue,


Personal Author(s) : Ahmad,J. ; Hopper,A. T. ; Kanninen,M. F. ; Leis,B. N. ; Papaspyropoulos,V.

Report Date : SEP 1982

Pagination or Media Count : 26

Abstract : When the predictive techniques of linear elastic fracture mechanics (LEFM) are applied to physically short fatigue cracks, it is often found that the actual crack growth rate is considerably underestimated. This means that damage tolerance and other fracture control methods that rely on accurate crack growth predictions could be quite nonconservative. Consequently, considerable attention has been devoted to identifying the causes of the accelerated growth rates and on ways of improving upon the currently available predictions. Virtually all of these have been based exclusively upon LEFM considerations. In contrast, this paper addresses the short crack problem from the point of view that an elastic-plastic fracture mechanics parameter may offer the basis for a resolution of the dilemma. The specific approach that is taken is one that focusses on the crack-tip crack-opening displacement (CTOD) as a characterizing parameter. The use of CTOD is at least as general as current LEFM procedures. Of equal importance, the CTOD may possibly be valid where LEFM is not. An illustrative example is used to show the non-linear character of this approach.

Descriptors :   *Finite element analysis, *Metals, *Cracks, *Crack propagation, *Fatigue(Mechanics), Mathematical prediction, Numerical methods and procedures, Elastic properties, Plastic properties, Yield strength, Modulus of elasticity, Strain hardening, Equations, J integrals, Nonlinear analysis, Displacement, Algorithms, Experimental data, Aluminum alloys, Steel

Subject Categories : Metallurgy and Metallography
      Theoretical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE