A New Find in Experimental Research on Coalescence Between Two Holes in Aluminum Alloy Strip under Cyclic Tensile Loading

This note reports an interesting phenomenon found in authors' experimental investigation to the coalescence between two neighborly located holes in an aluminum alloy strip under cyclic tensile loadings.Unlike expected,the initial fatigue crack was found not to nucleate in the center region between the two holes,where the stress concentration is much higher than the other positions,rather,the initial crack always nucleated at the outside rim of holes far apart from the center region.The coalescence between the two holes always occurred far after the initial fatigue crack nucleation.This phenomenon cannot be explained by the classical theories.