Setting the process parameters for fabrication of thick composites having complex geometries is a challenging endeavor, with the best result being a high-quality part and less desirable results being parts that contain voids or fiber marcelling. An equal challenge is the nondestructive testing of these parts. Consider a U-shaped portion of a more complex part. The straight segments of the U-shape are approximately 10-mm thick, but a series of ply-drops reduce the thickness by one half at the center portion. Ultrasonic guided waves that have the potential to nondestructively test this part can be actuated by coupling transducers to the straight segments if and only if wave modes that are sensitive to the defects of interest can propagate through the ply drops, the curve, and the attenuation due to internal damping. A frequency domain finite element approach proposed in recent years for guided wave analysis is applied to this inhomogeneous waveguide problem in order to select modes and frequencies that are sensitive to marcelling.