Non destructive evaluation of composite materials using ultrasonic spectroscopy

The usefulness of longitudinal ultrasonic mode spectroscopy for the nondestructive study of composite materials is demonstrated. An absorption phenomenon for the reflected and transmitted energy is demonstrated for cross-ply fiber reinforced materials. This may be due to the reflection of waves at the ply interfaces. Results reported pertain to the transmission and reflection of longitudinal ultrasonic waves. The relation between the forbidden band gap center frequency and the periodicity in the orientation of piles is studied. Potential applications in the nondestructive evaluation area are discussed