The analysis of the sound generated by impacted ceramic utensils is perhaps one of the earliest methods for testing ceramics and the also the first application of sound analysis. The human ear appears to be an appropriate ‘tool’ for the qualitative defect identification in the audible range and the signal processing in the human brain is apparently very good at extracting those features in the audio signal that indicate the presence of a defect. This might suggest that it should be easy to identify all relevant defects in any technically used ceramic component using modern signal processing methods. Unfortunately, this is not the case in general. Rather, the applicability of sound analysis as an NDE tool must be verified for each application. However, some general rules are helpful in this process.In this contribution we consider two ceramic parts with very different technical utilizations: a small part for a medical application and a ceramic electrolyte cup, used in a prospective power cells design. For each sample type an adapted experimental arrangement for the sound excitation and the acoustic measurements was built and tested. In parallel, extensive numerical modal analysis simulations were performed using ANSYS. Insights in the resonance behavior could be gained by parametrical study of the modelled components, as there are the geometric dimensions, density and elasticity parameters and the size and position of defects, especially cracks. While the former parameter changes can be tolerated to some degree, parts with cracks must be sorted out in the manufacturing process and thus identified by the sound analysis.For both ceramic parts, the resonance spectra obtained by modelling agree with the experimentally determined spectra in such a way that the experimentally determined modes can be clearly identified. The experimental arrangement for the cups includes a microphone array. This allows us to identify the mode shapes in addition to the natural frequencies in some cases. As a means of validation, scanning laser vibrometer measurements have been carried out, confirming the mode shapes obtained during the simulation and acoustic field measurements.Finally, a concept for in-line vibration analysis of ceramic electrolyte cups is proposed and the following steps towards industrial application are summarized.

Vibration Analysis for Nde of Ceramic Components

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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