Acoustic emission monitoring for necking in sheet metal forming

Madhav Baral, Ali Al-Jewad, Alexander Breunig, Peter Groche, Jinjin Ha, Yannis P. Korkolis, Brad L. Kinsey

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

There is extensive evidence in the literature that plastic deformation of metals is associated with an increase in Acoustic Emission (AE) activity. Thus, AE measurement techniques have the potential to monitor a forming process in real time and provide a signal for feedback control, to exploit optimum formability. In this work, custom-made AE sensors employing piezoelectric crystals are implemented to measure the emitted acoustic signal during uniaxial tension and cup drawing tests of an AA6013-T4 aluminum sheet (1.5 mm thick). The uniaxial tension tests are conducted with two AE sensors clamped to each end of the specimen gage section, along with full-field surface strain measurement using Digital Image Correlation (DIC) techniques. The AE signals along with the interrogation of the DIC images reveal that the maximum AE amplitude corresponds to the onset of diffuse necking, i.e., when the strain field starts to become spatially inhomogeneous. Interestingly, this onset occurs before the maximum force is attained. Comparing these observations to a model of dislocation activity supports the notion that dislocation is the main driver of AE activity. With these findings, AE measurements are performed in a cup drawing process where a custom-made Marciniak-type punch incorporates three AE sensors. These sensors are used to triangulate and determine the location of necking and eminent fracture based on the time difference of arriving signals to each sensor. The results from the cup drawing tests show that AE signals can identify the onset of necking and accurately predict the location of necking and fracture.

Original languageEnglish
Article number117758
JournalJournal of Materials Processing Technology
Volume310
DOIs
StatePublished - Dec 2022

Bibliographical note

Funding Information:
This research was supported by NSF award CMMI-1727490 and DFG award 386415239 . This support is acknowledged with thanks.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Acoustic emission
  • Cup drawing
  • Localization
  • Necking
  • Source triangulation
  • Uniaxial tension

ASJC Scopus subject areas

  • Ceramics and Composites
  • Computer Science Applications
  • Metals and Alloys
  • Industrial and Manufacturing Engineering

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