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Deformation mechanisms in micro- and nanoporous foams monitored by acoustic emissionThursday (08.10.2020) 14:40 - 15:10 Part of:
Recently, open-cell metal foams with micron and nanometer pore size are extensively investigated due to their potential applications as battery electrodes, filters, heat exchangers. Even in functional applications, foams have to sustain a certain amount of deformation. Therefore, it is crucial to characterise the mechanical performance of these foams.
Acoustic emission (AE) is a non-destructive method, which gives information on sudden localised structural changes. Thus, AE yields information on the dynamic processes occurring during deformation, such as crack initiation and propagation or the formation of deformation bands . The most improtant advantage of this technique besides its cheapness is that it gives information on the entire volume of the sample with a very good time-resolution (µs-scale).
Our research aims to map the deformation mechanisms in foams with different pore sizes (from nano- to micrometre scale) with respect to the manufacturing process. Copper-based foams with varying pore sizes were investigated, for a prospective application as a Li-ion battery anode or a catalyst. The nano- and microporous foams were obtained by dealloying and freeze casting methods, respectively. Since during the deformation of foams concurrently, many AE sources are active, AE signals overlap. Therefore, the commonly used hit-based AE evaluation is not effective . To determine the most active deformation mechanism and to monitor the changes in deformation mechanisms during deformation, the AE data were analysed by using the adaptive sequential k-means algorithm. The effect of the changes in the scale is also investigated.