Thawed matrix method for computing local mechanical properties of amorphous solids

Area of Science:

• Computational materials science
• Solid mechanics
• Nonlinear dynamics

Background:

• Amorphous solids exhibit complex plastic behavior.
• Previous methods like the "frozen matrix" approach have limitations in accurately capturing local mechanical properties.
• Understanding localized plastic deformation is crucial for predicting material failure.

Purpose of the Study:

• To develop a novel method for computing locally varying nonlinear mechanical properties in particle simulations.
• To enable precise localization of plastic deformation in amorphous solids.
• To improve the prediction of plastic rearrangements from structural information.

Main Methods:

• Introduction of an external field to penalize nonaffine displacements, thereby suppressing plastic rearrangements outside a probed region.
• Localization of plastic deformation by increasing the strength of the external field.
• Characterization of local plastic yield stress distribution and spatial mapping of plastic activity.

Main Results:

• Demonstrated ability to localize plastic deformation by controlling the external field strength.
• Characterized the distribution of local plastic yield stresses.
• Assessed the correlation between spatial maps of yield stress and plastic activity in a 2D amorphous solid model.
• Reduced artifacts associated with the "frozen matrix" approach.

Conclusions:

• The presented method allows for the computation of locally varying nonlinear mechanical properties in amorphous solids.
• The approach enhances the prediction of plastic rearrangements by improving the accuracy of local stress and activity mapping.
• This technique offers a more refined understanding of plastic deformation in disordered materials.