Stress concentration at stop-drilled holes and additional holes

A stop-hole method for marine and offshore structures

“…As a relatively inexpensive and easy application, the stop-hole method (Song and Shieh 2004;Murdani et al 2008;Wu et al 2010) has been widely used in the marine and offshore engineering to extend the service life of cracked structural components that cannot be moved in the near term to a repair facility and replaced. As shown in Fig.1, the purpose of this method is to transform a crack into a notch by drilling a hole in the vicinity of, or centred at, the crack tip.…”

Effects of stop hole on crack turning, residual fatigue life and crack tip stress field

“…3) Calculate extension distance for each node along current crack front direction, this could be done according to Eq. (13). The whole process is shown in Fig.…”

“…where Δa i is the extension distance for node i; Δa m is the median extension distance specified manually, of which the recommended value is about 15% of the sample thickness [4]. Thus, 0.75 mm is the recommended value for Δa m ; m is the material parameter of Paris formula, and it is determined (13)…”

“…For example, Nateche [12] proposed a drilling repair index method to evaluate the efficiency of crack growth retardation. Murdani et al [13,14] also suggested that the effects of stop holes on crack tip stress field depended on the arrangement of stop holes and proposed a new technology to retard crack growth, in which two ancillary holes were drilled to reduce the stress concentration caused by a stop hole. Razavi et al [15] reported that the double stop hole method had a significant improvement in fatigue life by comparing with the traditional single stop hole method.…”

Elastoplastic analysis of cracked Aluminum plates with a hybrid repair technique using the bonded composite patch and drilling hole in opening mode I

“…iii) drilling a hole at the crack tip is one of the easiest and most accessible crack arresting procedures. Cracking resumes very shortly after drilling because of the high stress concentration associated with hole and this is why it remains temporary and relatively ineffective method [3,4]; iv) a much superior approach is to stop drilling and then expand the stop hole, usually with a special sleeve to develop favorable compressive stresses that reduce or prevent crack opening, while this approach is often highly effective in stopping crack growth [4][5][6]. [5] studied the influence between the holes of different diameters and also between the expanded holes and non-expanded holes on arresting the crack propagation, finding that the number of cycles to initiate a new crack is three times longer than non-expanded holes; v) repair of corrosion types such as pitting or exfoliation in aluminum alloy structures generally involves the removal of visible damage by grinding followed by an extra confidence cut to ensure that all the corrosion is removed.…”