Beta Factors for Collinear Asymmetrical Cracks Emanating from an Offset Circular Hole in a Rectangular Plate
Defence Science and Technology Group Fishermans Bend Victoria Australia
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Beta factors, a nondimensional form of stress intensity factor, are a key input used in generating crack-growth curves as part of Damage Tolerance Analysis work. One specific damage scenario that is of interest is the case of collinear asymmetrical cracks emanating from an offset circular hole in a finite-width rectangular plate, which is representative of circumstances that can occur in aircraft fleets. Unfortunately, no handbook results are available for this geometry. Using a custom-written FORTRAN computer program, interfaced with an existing two-dimensional boundary element fracture analysis code, the present report provides an extensive set of Beta factor solutions covering a wide range of hole offsets and crack lengths. This work has also led to the derivation of an improved closed-form analytical two-dimensional Beta factor solution for the related case of symmetrical cracks emanating from a central hole in a finite-width strip. The availability of accurate Beta factors is an important element in the structural integrity management of aircraft in service with the Royal Australian Air Force. The database of results presented here supports research into probabilistic analysis of multi-site fatigue damage scenarios, as well as assisting the long-term ongoing structural integrity management of aircraft in service with the Royal Australian Air Force.
- Operations Research