Notch Fatigue Behavior of Aluminum 2024-T6 in Four Point Bending Rotation

Abstract

In some engineering applications rotating machinery components experience bending stresses due to location supports or misalignments, which often leads to fatigue degradation of critical components. This effect is enhanced when there is a presence of notches or sharp bends. In this research, effect of notches on fatigue strength of an aluminum alloy is evaluated numerically and experimentally. The effect of notch root radius and depth of notch is investigated against fatigue failure. The fatigue behavior of un-notched and notched specimens was examined in ambient conditions under rotating four point bending fatigue loadings. Tests were performed using three types of notched specimens with three different stress concentration factors (Kt); 2.06, 2.46, and 3.64.The stress concentration increases with the increase of depth and decrease as root radius of specimen increases. It was clear from the experiments that all the notched specimens showed lower fatigue strength than un-notched and smooth specimens. Cracks initiated at the outer surface of notch root having very sharp notch having small root radius, and then propagated towards the neutral axis. It was also observed that such behavior depended strongly on loading levels and stress concentration factors. The specimens having small root radii showed lesser fatigue strength than those with larger radii.