抄録
Surface fatigue crack is effectively retrofitted by closing the crack by creating plastic deformation, when the crack is rather small. When the crack remain closed due to appied stress range, the stress intensity factor ranges of the crack is reduced as if the surface crack is an internal crack. The technique is called ICR treatment, or Impact Crack Closure Retrofit treatment. Its effectiveness is proved by various fatigue tests. This paper deals with fracture mechanics analysis to estimate fatigue crack propagation behavior after the ICR treatment. The analyses are made on as-welded specimens for reference and fatigue cracked specimens with ICR treatment. Various assumptions are made to simplify the analytical procedure for engineering use.
