PLATE WAVE ACOUSTIC-EMISSION

Plate theory is more easily applied to the analysis of composite laminates than exact three-dimensional elasticity theory. Under conditions such that plate theory is applicable, it is suggested that plate waves are useful for understanding acoustic emission (AE) phenomena. To test this idea, pencil leads were broken on aluminum plates and composite plates, and the resulting waves were detected with a broadband ultrasonic transducer. Both the fundamental extensional and flexural modes were observed. Their characteristics are described and the implications for AE source location are discussed as well. Several transducers, commonly used for acoustic emission measurements, are compared with regard to their ability to reproduce the characteristic shapes of plate waves. Their different responses show why similar test specimens and test conditions can yield disparate results.