Nature of AE continuous wave produced by a 0.8 mm aperture air nozzle as a leak source in a steel plate was investigated. Analysis of the waveforms showed them to consist of multiple functions which cannot be expressed as a simple function. The separation of involved parameters was carried out by considering the effect of three basic phenomena in producing Rayleigh waves and subsequent out-of-plane displacements. These include the pressure drop wave, fluid jet wave and transmission through the nozzle walls. To achieve this, a series of experiments were conducted to set up different conditions of air nozzle relative to the plate. The sample was 10 mm thick. The lateral dimensions were 90 cm by 80 cm, which represented a large field-size sample. The out-of-plane displacement components of the resulting signals were detected by broad band transducers and digitized. For each case considered, the relative energy was recorded. The comparison of finite element model and experimental results is also presented and discussed. For all cases considered, the experimental measurements were in good agreement with the predictions of the finite element model.
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