CONICET | Buscador de Institutos y Recursos Humanos

The interference and physical contact between mating fracture surfaces can lead, even under the action of traction loads, to the closure of a crack. Since a crack can not propagate while it remains closed, crack closure determines to a large extent the effects of load ratio, yield strength and load amplitude on fatigue crack growth. One of the main factors leading to crack closure is the residual compressive stresses like those resulting from welding, shot-peenning and cold expansion processes. Standard stress-intensity-factor solutions for partially closed cracks are not available in the literature, and so, relatively high-cost computer models based on finite or boundary element methods are usually used for their analysis. A low-cost numerical tool for the assessment of three-dimensional partially closed cracks is presented in this paper. The devised tool allows computing the geometry of the open part of the crack and the stress intensity factor along the complete crack front. The tool is based on the weight-function methodology known as the O-integral, which was originally proposed for the computation of stress intensity factors for embedded cracks and has been recently extended to deal with surface and irregular cracks. The accuracy and versatility of the proposed procedure is assessed by solving a number of examples and comparing the obtained results with those available in the literature.