Crack-growth arrest by redirecting crack growth by drilling stop holes and inserting pins into them

A technical method for arresting further crack growth from cracks by drilling holes in the vicinity of the crack tips was investigated. A series of fatigue-crack-growth tests was performed using double-edge-pre-cracked specimens. In some specimens, holes were drilled in the vicinity of the crack tips. Also, pins were inserted into the holes in some cases. The crack growth lives of some specimens were longer than those of specimens without holes. The longest fatigue life was observed in the case of a specimen with the pins. Drilling holes and inserting pins could change the growth direction of the cracks, and then the coalescence of cracks, which grow from both edges of a specimen, could be prevented. Also, it was found that compressive residual stress, which occurred by inserting pins, was more effective to retard the crack growth than reducing the stress concentration around initial crack tips, which occurred by drilling holes. Therefore, it is concluded that inserting pins into holes drilled in the vicinity of the crack tips is the most effective method for retarding crack growth and for preventing cracks from coalescing.