Coordinate transformation methodology for simulating quasistatic elastoplastic solids.

Area of Science:

• Computational Materials Science
• Solid Mechanics
• Amorphous Materials

Background:

• Molecular dynamics (MD) simulations often use periodic boundary conditions (PBCs) with moving images to apply deformation, like Lees-Edwards for simple shear.
• Precisely comparing MD simulations with continuum solid mechanics under deformation has been challenging.
• Understanding shear band formation in amorphous materials is crucial for predicting their mechanical behavior.

Purpose of the Study:

• To develop a simulation framework for accurately comparing MD simulations with continuum solid mechanics.
• To investigate the evolution of shear bands in bulk metallic glasses using a novel simulation approach.
• To analyze shear band growth under simple shear and pure shear conditions.

Main Methods:

• Employing a hypoelastoplastic mechanical model and a projection method to enforce quasistatic equilibrium.
• Introducing a simulation framework with a fixed Cartesian grid on a reference domain.
• Imposing deformation via a time-dependent coordinate transformation to the physical domain.
• Utilizing the shear transformation zone (STZ) theory of amorphous plasticity for bulk metallic glasses.

Main Results:

• Demonstrated a method for precise comparison between MD simulations and continuum solid mechanics.
• Successfully modeled the evolution of shear bands in bulk metallic glasses.
• Examined the influence of initial material preparation on shear band growth under simple and pure shear.

Conclusions:

• The developed simulation framework enables accurate comparison of deformation in MD simulations and continuum mechanics.
• The study provides insights into shear band dynamics in bulk metallic glasses, influenced by material preparation and deformation type.
• This work bridges the gap between atomistic simulations and macroscopic mechanical modeling of amorphous plasticity.