Study on Fatigue Strength of Aluminum-Silicon Alloy and Spheroidal Graphite Cast Iron under Compressive Load

Abstract

Fatigue tests of aluminum-silicon alloy A4032FD and spheroidal graphite cast iron FCD600 were carried out under cyclic compressive loading using circumferential notched round bar specimens. Non-propagating cracks were observed at the notch bottom of the specimens after 1×10⁷ load cycles. It is considered that residual tensile stress caused by plastic deformation at the notch bottom is the driving force of crack propagation. Therefore we calculated the range of stress intensity factor ΔK of residual stress at the notch bottom. The ΔK was also compared with effective threshold stress intensity U·ΔK_thto predict the crack depth. It is considered that the crack propagation rate disappears when ΔK<U·ΔK_th. The predicted value of crack propagation depth was in line with the experimental value.