Rotating bending fatigue tests for aluminum alloy 6061-T6, close to elastic limit and with artificial pitting holes

This work deals with rotating bending fatigue tests on aluminum alloy 6061-T6, under loading condition close to elastic limit of material. Results have been obtained for three types of specimens: without artificial pitting, specimens with one artificial pitting hole and specimens with two close artificial pitting holes. Results show that fatigue endurance is reduced in the case of one pitting hole and considerably for two close pitting holes. In order to explain this behavior, numerical analysis by FE were carried out to determine the stress concentrations for the three types of specimens. It is found that the stress concentration for two close pitting holes is an exponential function of the separation between the two holes, under uniaxial loading. The probability to find two or more close pitting holes in real industrial materials, such as cast iron, corroded or pitting metallic alloys is high; then, the stress concentration for two or more close pitting holes should be considered for the fatigue prediction life under fatigue loading and corrosion attack applications.