Guided plate wave scattering at vertical stiffeners and its effect on source location

• Published in: Ultrasonics 2012-08, Vol.52 (6), p.687-693
• Main Authors: Reusser, R.S., Chimenti, D.E., Roberts, R.A., Holland, S.D.
• Format: Article
• Language: English
• Subjects: Acoustic noise; Acoustics; Applied sciences; Arrays; Exact sciences and technology; Frequency ranges; Fundamental areas of phenomenology (including applications); Guided waves; Industrial metrology. Testing; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Leaks; Linear acoustics; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Noise; Non-destructive evaluation; Physics; Plate waves; Position (location); Stiffeners; Structural acoustics; Structural acoustics and vibration
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2011.10.012

► We investigate plate wave transmission and reflection past rectangular obstructions. ► We compare experiments to original boundary element method calculations. ► Theory matches experiment over a range of frequencies and two different geometries. ► Application of model to spacecraft leak location. This paper examines guided wave transmission characteristics of plate stiffeners and their influence on the performance of acoustic noise source location. The motivation for this work is the detection of air leaks in manned spacecraft. The leaking air is turbulent and generates noise that can be detected by a contact-coupled acoustic array to perform source location and find the air leak. Transmission characteristics of individual integral stiffeners are measured across a frequency range of 50–400kHz for both high and low aspect-ratio rectangular stiffeners, and comparisons are made to model predictions which display generally good agreement. It is demonstrated that operating in frequency ranges of high plate wave stiffener transmission significantly improves the reliability of noise source location in the plate. A protocol is presented to enable the selection of an optimal frequency range for leak location.