Cold expansion method retards the crack initiation due to the compressive residual stress
developed on a hole surface. Most previous researches have shown only the beneficial distribution
of residual stresses in the retardation of the crack initiation at the stress concentration area. Also,
there have been only few studies on the relation between crack growth and residual stress around
other adjacent holes. A few fastener holes of aircraft structures is a shot distance which is less than
20mm between holes. The purpose of this study is to provide better understanding of the residual
stress effect around a hole in a structure as crack growth starts from another hole. By finite element
method, this study showed that residual stress in a CT specimen is redistributed by cold expansion
process and that tensile stress increases in proportion to the cold expansion ratio in the vicinity of
the crack. Stress intensity factor increases as the cold expansion ratio increases.