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Title: Length scale effects on the shear localization process in metallic glasses: A theoretical and computational study
Authors: Thamburaja, P. 
Keywords: Finite-element method
Metallic glass
Non-local constitutive theory
Strain localization
Issue Date: Aug-2011
Source: Thamburaja, P. (2011-08). Length scale effects on the shear localization process in metallic glasses: A theoretical and computational study. Journal of the Mechanics and Physics of Solids 59 (8) : 1552-1575. ScholarBank@NUS Repository.
Abstract: Some recent experiments on sub-micron and nano-sized metallic glass (amorphous alloy) specimens have shown that the shear localization process becomes more stable and less catastrophic when compared to the response exhibited by large sample sizes. This leads to the discovery that the shear localization process and fracture can be delayed by decreasing sample volume. In this work we develop a non-local and finite-deformation-based constitutive model using thermodynamic principles and the theory of micro-force balance to study the causes for the aforementioned observations. The constitutive model has also been implemented into a commercially available finite-element program by writing a user-material subroutine. With the aid of finite-element simulations, our constitutive model predicts that metallic glass samples have the intrinsic ability to exhibit: (a) the delaying of (catastrophic) shear localization with decreasing sample size, and (b) homogeneous deformation behavior for sample volumes smaller than the shear band nucleus. The cause for the observations listed above is the increasing influence of a non-local interaction stress with decreasing sample volume. This interaction stress has energetic origins and it affects plastic deformation due to the strong coupling between plastic shearing and free-volume generation. Akin to strain-gradient plasticity theory, the role of the interaction stress is to strengthen the material at locations where the defect density/free volume is higher compared to the rest of metallic glass sample. © 2011 Elsevier Ltd. All rights reserved.
Source Title: Journal of the Mechanics and Physics of Solids
ISSN: 00225096
DOI: 10.1016/j.jmps.2011.04.018
Appears in Collections:Staff Publications

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