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Growth and closure of voids in metals at negative stress triaxialities

: Zapara, M.; Tutyshkin, N.; Müller, W.H.

Preprint urn:nbn:de:0011-n-2645755 (1.0 MByte PDF)
MD5 Fingerprint: f04227ca006332e58ef8e56a07f74ba3
Erstellt am: 22.11.2013

Alves de Sousa, Ricardo ; European Scientific Association for Material Forming:
The Current State-of-the-Art on Material Forming : Selected, peer reviewed papers from the 16th ESAFORM Conference on Material Forming, April 22-24, 2013, Aveiro, Portugal
Dürnten: Trans Tech Publications, 2013 (Key engineering materials 554-557)
ISBN: 978-3-03785-719-9 (Print)
ISBN: 978-3-03795-469-0 (CD-ROM)
ISBN: 978-3-03826-100-1 (eBook)
International Conference on Material Forming (ESAFORM) <16, 2013, Aveiro>
Deutsche Forschungsgemeinschaft DFG
MU 1752/25-2
Konferenzbeitrag, Elektronische Publikation
Fraunhofer IWM ()

Damage of metals subjected to large plastic deformations typical for forming processes is mainly governed by void nucleation, growth and coalescence. An opposite process may occur in deformation processes with negative stress triaxialities: The closure of strain-induced defects under large hydrostatic pressure. Understanding the mechanisms of damage growth and healing under plastic deformation of metals is still an urgent problem. In order to solve it a theoretical framework for anisotropic ductile damage based on a physically motivated concept for changes in the void volume and shape was recently developed [6]. Strain-induced damage was experimentally determined during uniaxial compression of cylindrical metallic specimens with artificial voids represented by fully-trough drilled holes. It was revealed that the governing physical mechanism of failure is a change in void shapes due to compressive stresses at low negative stress triaxialities in contrast to the growth of voids volume due to high positive stress triaxialities in the processes with dominating tensile stresses. The tensorial model presented in [6] proved to be able to describe kinetics of ductile damage, failure as the ultimate damage, and the closure of voids at negative stress triaxialities.