On the far-field structure of waves generated by a pencil lead break on a thin plate

Abstract

The overall objective of this work is the study of the structure of Lamb waves produced in thin plates and the techniques used to measure such waves. Laboratory experiments were conducted using a lead break source on an aluminum plate. Tgese experiments were used to vslidate a computer model for elastic waves in cylindrical symmetry. The computer model was used to study the influence of the characteristics of the source stress on the resulting waves. The rise time, source width, and the distribution of the stress over the some were all considered. The dependence of the results on the cell size used in the computer model was studied, and the computer requirements for an exten-sion of this work to three dimensions were considered. The effect of aperture size on the signal fidelity from potential scoustic sensors was examined. Validation of the computer model allows the model to be used for the study of certain acoustic emission phenomena which are difficult or impossible to measure in the laboratory