PLATE WAVE FLOW PATTERNS FOR PLY ORIENTATION IMAGING IN FIBER-REINFORCED COMPOSITES

Fiber orientations in graphite epoxy laminates of various configuratio ns are investigated by imaging flow patterns of leaky guided plate wav es. The plate wave flow pattern (PWFP) technique shows that the guided plate waves in laminated fiber reinforced composites tend to travel a long the preferred fiber directions, rather than in the direction of i mpingement, especially for inhomogeneous ply layups. This method utili zes two transducers, a transmitter and receiver in a pitch-catch mode, fixed at the same oblique angle. The flow patterns for multi-ply lami nates were mapped, and a global view of the ply directions was obtaine d. A frequency analysis of the ensuing signal showed that selective im aging of the fiber orientations in a multi-layered composite is feasib le.