Prediction of fatigue life using modal analysis for grey and ductile cast iron

The aim of this work is to investigate the capability of experimental modal analysis, as a nondestructive tool, to characterize and quantify fatigue behavior of materials. This is achieved by studying the response of modal parameters (damping ratio, natural frequency, and FRF magnitude) to variations in material microstructure, as a main factor affecting fatigue life. This helps in correlating modal parameters to fatigue behavior. Cast iron family represented by grey cast iron, ductile cast iron and austempered ductile iron (ADI) is used in experiments as a case presenting considerable variations in microstructure. Modal testing was performed on specimens made of the selected materials in order to extract the corresponding modal parameters. Rotating bending fatigue test was performed on standard fatigue specimens to correlate the modal parameters to the fatigue behavior. This enables the evaluation of the ability of modal testing to predict the fatigue life of mechanical components.