Review of Progress in Quantitative Nondestructive Evaluation
This paper reports on the experimental examination of the transmission and reflection characteristics of arbitrarily shaped geometric obstructions in problems of plate wave propagation, such as joints, stiffeners, thickness transitions, and bends. The motivation for this work is noise source location in structures, the specific application being the location of air leaks in spacecraft skins, funded by NASA. In this work, it has been demonstrated that leaks can be located at a distance using array‐based sensors which determine direction of signal propagation at the sensor location. The limiting factor in practice is the influence of geometric obstructions between the leak and sensor. This work reports a quantitative examination of the transmission properties of various obstructions such as stiffening ribs. Surface motions arising from a distance source are recorded over a local array of spatial positions using a scanned laser vibrometer. Spatial Fourier analysis is then applied to determine the individual contributions of the constituent mode types to the measured signals. Transmission properties of intervening geometric obstructions are determined by comparison to unobstructed signals. Comparisons to theoretical predictions of transmission characteristics will be presented for selected cases.
American Institute of Physics
Reusser, Ricky S.; Chimenti, Dale E.; Holland, Stephen D.; and Roberts, Ronald A., "Plate wave transmission/reflection at geometric obstructions: Experiment" (2009). Center for Nondestructive Evaluation Conference Papers, Posters and Presentations. 68.