Role of Anisotropy on the Ductile Fracture: Void Growth, Nucleation, and Coalescence

Gopi Gulivindala, Madhu Kiran Karnam, and Viswanath Chinthapenta*

Micro-Mechanics Lab, Department of Mechanical and Aerospace Engineering

Indian Institute of Technology Hyderabad, Kandi, Sangareddy

*Email: viswanath@mae.iith.ac.in

The ductile failure process typically starts with the nucleation of voids. The nucleated voids then grow and coalesce to form micro-cracks, eventually failing the material. The ductile failure process depends primarily on the geometry of the void, material anisotropy, work hardening, and the stress state around it. This work presents void growth, nucleation, and coalescence under necking using 3D RVE with a spherical void embedded in an FCC single crystal. The crystal plasticity framework accounted for the anisotropy arising from the orientation and the slip in the crystals. It is observed that the peak stress was found to be dependent on void volume fraction and initial crystallographic orientation. An additional geometrical parameter, diagonal distortions (Ddi), was introduced to classify the non-spheroidal void shapes observed in deformed anisotropic crystals. The material anisotropy significantly affected the void morphology and critical strain at which failure occurs, not the void coalescence strains at high triaxial values.

References:

1. Karanam M K, Chinthapenta V R, “Void growth and morphology evolution during ductile failure in an FCC single crystal” Continuum Mechanics and Thermodynamics (2021): 33, 497–513.

2. Karanam, Madhu Kiran, Gopi Gulivindala, and Viswanath R Chinthapenta, "Effect of anisotropy on the ductile fracture in metal reinforcements of brittle matrix composites" Theoretical and Applied Fracture Mechanics 112 (2021): 102923.

3. Gulivindala, Gopi, Karanam, Madhu Kiran, Kwong M Tse and Viswanath R Chinthapenta, "Influence of material anisotropy on void coalescence by necking for face-centered cubic single crystals" Materials Today Communications (2023) 35: 106010.