Generalized Mohr-Coulomb strain criterion for bulk metallic glasses under complex compressive loading.

Area of Science:

• Materials Science
• Solid Mechanics
• Mechanical Engineering

Background:

• The Mohr-Coulomb (M-C) stress criterion is commonly used for bulk metallic glasses (BMGs) but fails to predict fracture angle variations and plastic fracture under compression.
• Existing models struggle with the pressure sensitivity and post-yield behavior of BMGs.

Purpose of the Study:

• To develop and validate a generalized M-C strain criterion for BMGs.
• To accurately predict fracture behavior, including angles and yielding stress, under complex compressive loading.

Main Methods:

• A novel generalized M-C strain criterion was formulated.
• The criterion was applied to analyze fracture in Zr-based BMG round bar specimens under complex compression.
• Theoretical predictions were compared with experimental data.

Main Results:

• The proposed M-C strain criterion shows good agreement with experimental initial yielding stress.
• The criterion successfully predicts critical shear strain and fracture angles for BMGs.
• It accounts for deformation mode-dependent fracture characteristics.

Conclusions:

• The generalized M-C strain criterion offers a more accurate approach to modeling BMG fracture behavior than the traditional stress-based M-C criterion.
• This advancement is crucial for understanding and engineering BMGs under various loading conditions.