Vibration Response: A Non-Destructive Test for Fatigue Crack Damage in Filament-Reinforced Composites *

Abstract

Laminated, filament-reinforced epoxy beam specimens were fa tigued in vibratory flexure. The complex modulus of the specimens was measured periodically as fatigue crack damage accumulated. Changes in the real and imaginary parts of the modulus correlated with the amount of crack damage. The imaginary part of the modulus changed substantially. Measurement of these vibration response changes shows promise as a means to nondestructively test the structural integrity of filament-reinforced composite structural mem bers.