IWPDF2023

Strain Gradient Plasticity Analysis of Amorphous Plasticity

I. E. Unsal ∗ , T. Yalçinkaya

Department of Aerospace Engineering, Middle East Technical University, Ankara 06800, Türkiye

∗ erkin.unsal@metu.edu.tr

Keywords: strain gradient plasticity, amorphous plasticity, strain localization, size effect

Amorphous materials, such as metallic glasses, are produced by rapid cooling of liquid materials to prevent crystallization, garnering significant interest for their outstanding mechanical proper ties and wide-ranging applications in aerospace, micro-electro-mechanical systems (MEMS), and biomedical equipment [1]. Amorphous materials exhibit prominent shear bands, stemming from their heterogeneous, disordered nature. These shear bands represent narrow zones where com plex deformation patterns emerge due to intense shear stress. Understanding the deformation characteristics of amorphous materials remains an ongoing goal that has not yet been fully accom plished. In this regard, this study focuses on the numerical modeling of disorder within amorphous materials which uses fluctuating distribution of material parameters [2]. Recent experimental ob servations indicate that the shear band localization is delayed or even suppressed by reducing the sample size [3]. Therefore, a size dependent model is required to fully uncover the underlying micromechanical phenomenon. In the current work, a lower-order strain gradient plasticity (SGP) framework is employed to numerically analyze and discuss the size effect on microstructure evo lution in metallic glasses. Shear band formations under different sized specimens are studied and compared with the classical local plasticity approaches. References [1] Kumar, G., Desai, A., and Schroers, J. (2011). Bulk Metallic Glass: The Smaller the Better. Adv. Mater., 23(4), 461–476. [2] Sandfeld, S., and Zaiser, M. (2014). Deformation patterns and surface morphology in a minimal model of amorphous plasticity. J. Stat. Mech. Theory Exp., 2014(3), P03014. [3] Chen, D. Z., Jang, D., Guan, K. M., An, O., Goddard, and Greer, J. R. (2013). Nanometallic Glasses: Size Reduction Brings Ductility, Surface State Drives Its Extent. Nano Lett., 13(9), 4462–4468.

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