Investigation of surface damages during sheet metal forming using acoustic emission

Abstract

In this article, the acoustic emission technique has been used to study a well-known surface damage mechanism, known as galling, during experimental simulation of sheet metal forming process. Results illustrated that the galling starts with relatively low-amplitude acoustic emission waves, corresponding to the elastic–plastic deformation of surface asperities (stage I), followed by a continually graduate rise in the acoustic emission activities related to the sheet material transfer to the slider tool along with lump growth (stage II), and ended to some waves with the highest amplitude and energy corresponding to the severe plowing and rupture of the friction junctions (stage III).

Wavelet-based acoustic emission characterization of surface damages during experimental simulation of sheet metal forming process

“…Moreover, as mentioned in Ref. [13], fractography studies of ruptured friction junctions demonstrated that for all junctions, ruptured area contained a combination of ductile fibrous rupture on marginal regions and brittle fracture (cracking) on centric regions of the area. This demonstration is important from the view that experimental results reported by Ki-Woo et al 26 indicate that the main frequency obtained by the time-frequency analysis of AE signals from crack propagation in super duplex stainless steel varies between 200 and 300 kHz regardless of the microstructure (austenitic or ferritic), rate of crack growth, and the crack length.…”

“…In order to clarify the relation between AE wave's characteristics and wear mechanism, firstly, AE waveforms should be studied in time domain. As been discussed in author's previous paper, 13 the study of the recorded waveforms during different stages of adhesive wear can be concluded as follows: 13 Stage I: AE waves detected during stage I, being relatively low-amplitude ones, are mostly related to the For comparison, three sample waveforms for the mentioned three stages are shown in Figure 5.…”

“…The experimental setup, same as the setup used in authors previous work, 13 is shown in Figure 2. As can be seen, a pneumatic jack forces slider over the sheet metal clamped on a moving horizontal bed.…”

“…It is needed to be mentioned that although AE signals have been studied in time domain by current authors in Ref. [13], this investigation attempts to present a detailed analysis of correlation between the AE activities and wear mechanisms using a new WPT signal processing technique based on signal's energy distribution in frequency domain of generated AEs.…”

A new method to estimate location and slip of simulated rock failure events

“…Acoustic emission analysis is performed on a wide range of materials, including metals (e.g. Aggelis et al, 2011;Farrelly et al, 2004;Huang et al, 1998;Marfo et al, 2013;Oh and Han, 2012;Sind et al, 2012), ceramics (e.g. Aggelis et al, 2013;Drozdov, 2013Drozdov, , 2014Maillet et al, 2014;Mei et al, 2013;Yonezu and Chen, 2014), polymers (e.g.…”