An Experimental Investigation of Fatigue Damage Growth in Composites Materials Using the Vibration Response Phase Decay

Abstract

The increasing use of polymer composites in the aerospace and wind turbine sectors demands faster and more cost-effective methods and standards for detecting material damage. This investigation introduces a novel characteristic parameter for fatigue damage, aiming to significantly reduce the experimental duration of fatigue testing. The phase decay, \(\Delta \Phi \), is employed as a proxy for crack growth in composite coupons. A new High Frequency Fatigue Testing (HFFT) experimental framework has been designed and deployed to shorten testing times. This framework operates with an initial excitation frequency set at the first bending mode resonance. The proposed methodology empirically correlates crack growth measurements from interrupted tests — sequentially halted after a specific number of cycles — with the structural phase decay response, serving as a distinctive indicator of material strength degradation.