Anisotropic mechanical properties of Dodecanophene nanosheets with pre-existing cracks by molecular dynamics simulation: Uncovering orientation- and temperature-induced variations.

Abstract

This work presents a comprehensive molecular dynamics simulation study investigating the anisotropic mechanical response and fracture mechanisms of defective Dodecanophene nanosheets, a novel two-dimensional carbon allotrope. Using the AIREBO-M reactive force field validated against Density Functional Theory (DFT) calculations, we systematically evaluate the effects of crack orientation (0°-90°), temperature-dependent behavior (200-1000 K), and pre-existing crack size (30-60 Å) on elastic modulus, tensile strength, fracture toughness, and energy absorption. The nanosheets exhibit clear anisotropy: the y-direction shows higher stiffness (562.41 GPa) and strength (148.38 GPa), while the x-direction shows superior toughness (34.53 GPa). Crack orientation plays a critical role, with perpendicular cracks causing severe degradation (48.0-54.0%) compared to moderate losses (16-24%) for parallel cracks. Temperature-dependent behavior is pronounced, as toughness rises 160% at 200 K but declines 65.0% at 1000 K. Increasing pre-existing crack length drastically reduces strength (75.0-86.0%) and toughness (79.0-86.0%). Distinct failure modes emerge: x-loading promotes ductile behavior with crack deflection and gradual bond breaking, while y-loading induces brittle catastrophic fracture with rapid crack propagation. This represents the first systematic investigation of pre-existing crack effects on Dodecanophene's fracture mechanics across extreme thermal conditions (200-1000 K), providing critical insights for defect-tolerant design of 2D carbon materials.