Detection of In-Plane Fiber Waviness in Composite Laminates Using Guided Lamb Modes

This paper presents the study of Lamb wave interaction with in-plane fiber waviness in thin composite laminates. Previous studies show that a reduction in stiffness of the laminate occurs due to in-plane waviness. Aspect ratio and shear angles were used to define severity of waviness. Air coupled ultrasonic transducers were used to generate the fundamental anti-symmetric mode (A(0)), which was used in this study. A reduction in velocity of the A(0) mode was observed when it interacts with in-plane waviness. To confirm the findings, dispersion curves were plotted for straight fiber zone and waviness zone. Experimental B-Scans of wavy laminate were used to evaluate the velocity change. Conclusions were made based on the correlation between experimentally and analytically observed velocities.