Deformation Localization in Constrained Layers of Metallic Glasses: A Parametric Modeling Analysis

Localized plastic deformation known as shear banding is a prominent feature in metallic glasses. In this study we perform parametric three-dimensional finite ele- ment analyses, using primarily a thin layer of metallic glass on top of a cylindrical base, to study how physical constraint can affect this localized form of deformation and the corresponding macroscopic stress-strain response. Random perturbation points are added to the metallic glass model to facilitate the formation of shear bands. The modeling result suggests that the mechanical behavior of metallic glasses can be significantly influenced by the geometrical confinement. Under nominally uniaxial compressive loading, a lower thickness-to-diameter ratio results in higher plastic flow stresses. Shear bands tend to concentrate in regions away from the interface with the base material. The findings provide a mechanistic rationale for experimental ob- servations based on the micropillar compression test. The deformation pattern in a multilayered metallic glass structure as well as the deformation pattern in a metallic glas beam subjected to four point bending are also examined

Deformation Localization in Constrained Layers of Metallic Glasses: A Parametric Modeling Analysis

Localized plastic deformation known as shear banding is a prominent feature in metallic glasses. In this study we perform parametric three-dimensional finite ele- ment analyses, using primarily a thin layer of metallic glass on top of a cylindrical base, to study how physical constraint can affect this localized form of deformation and the corresponding macroscopic stress-strain response. Random perturbation points are added to the metallic glass model to facilitate the formation of shear bands. The modeling result suggests that the mechanical behavior of metallic glasses can be significantly influenced by the geometrical confinement. Under nominally uniaxial compressive loading, a lower thickness-to-diameter ratio results in higher plastic flow stresses. Shear bands tend to concentrate in regions away from the interface with the base material. The findings provide a mechanistic rationale for experimental ob- servations based on the micropillar compression test. The deformation pattern in a multilayered metallic glass structure as well as the deformation pattern in a metallic glas beam subjected to four point bending are also examined.Mechanical EngineeringMastersUniversity of New Mexico. Dept. of Mechanical EngineeringShen, Yu-LinTarefder, RafiqulThomas, Jess