Papers by Keyword: Cold Expanded Hole

Abstract: The residual stresses around clearance-fit mechanical fasteners have been found to be similar to those around cold expanded holes where compressive hoop stresses close to the fastener hole are balanced by far-field tensile stresses. This compressive zone has been shown to prolong fatigue lifetimes around fastener holes. Constant amplitude fatigue loading was applied to single plate rivet specimens for varying numbers of cycles to investigate the redistribution of these stresses after fatiguing. Synchrotron diffraction was used to map the evolution of the residual stresses around the rivets. Little change in the hoop stress local to the rivets occurred until visible fatigue cracks were observed suggesting that relaxation of these stresses is due to the cracks rather than their cause.

Abstract: Exact closed-form stress intensity factor (SIF) solutions have been developed for a mode- I through-thickness cracks in an infinite plate. Centre-crack problems have been analysed comprehensively in the literature, but the focus has been on the effect of simple loading about the crack centre. In the current work, the formula of Sih-Paris-Erdogan has been extended to consider the SIF difference on the left and right crack tips, under the local influence of general asymmetric and symmetric stress field. Exact SIF magnification factors convenient for computations have been derived that simultaneously circumvent the problem of crack-tip stress singularity. The solutions so obtained are applied to generate the residual SIFs that would act on a crack growing under the influence of the residual stress fields associated with welded plates and cold-worked holes using the measured residual stress profiles.