Early prediction of macroscale plastic strain localization in titanium from observation of mesoscale surface roughening. (October 2019)

• Record Type: Journal Article
• Authors: Romanova, V.; Balokhonov, R.; Emelianova, E.; Sinyakova, E.; Kazachenok, M.
• Is Part Of: International journal of mechanical sciences. Volume 161/162(2019)
• Publication Date: 2019-10
• Subjects: Plastic deformation -- Deformation-induced surface roughness -- Strain localization -- Nondestructive evaluation -- Micromechanical modelling; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2019.105047
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: Mesoscale roughening provides a link between micro- and macroscale patterns. A dimensionless parameter Rd is introduced to quantify deformation-induced roughness. The mesoscale Rd value exponentially grows in a neck region well before its macroscale evidence. Larger scale roughening intensifies when smaller scale deformation mechanisms are exhausted. Abstract: The numerical and experimental investigations have been performed to establish a correlation between local strains and mesoscale deformation-induced surface roughening in commercial purity titanium specimens. The evolution of surface profiles in selected regions of the specimens is examined in the course of uniaxial tension. Complementing the experimental studies, crystal plasticity finite-element simulations of deformation-induced surface roughening are performed for a model polycrystal. It has been shown that a series of out-of-plane surface displacements characterized by different amplitudes and frequencies are formed in the experimental and computational specimens under tension. Roughening intensifies on a larger scale when smaller length scale deformation mechanisms are exhausted. In order to quantify the multiscale surface patterns a dimensionless roughness parameter has been proposed. Unlike the traditional methods of roughness assessment, unfiltered profiles are analyzed to take into account the deformation mechanisms that are at work at different length scales. The dimensionless roughness parameter is shown to be sensitive to and well correlated with the local plastic strains. In the region of macroscopic necking, the mesoscale roughness begins to increase nonlinearly well ahead of the visible evidence of the macroscale strain localization, while in the other regions it ceases to increase at all. The results support the assumption that the plastic strain localization and fracture can be predicted early from estimations of mesoscale surface roughness.