Fracture behavior and mechanical degradation of cracked tolanene nanosheets: A molecular dynamics study

• Crack length and angle significantly impacted fracture, with Y-direction more sensitive to orientation changes. • Crack angle increase (0°→90°) reduces modulus by 6.85% (X) and 8.91% (Y) due to stress concentration. • Cracked nanosheets exhibited Mode I fracture • SIF anisotropy linked to crystallographic orientation, with Y-direction’s weaker bonds accelerating crack growth. • Temperature rise (1000 K) lowered SIFs by >50%, promoting ductile failure over brittle fracture. The fracture behavior of tolanene nanosheets containing pre-existing line cracks is systematically investigated using non-equilibrium molecular dynamics (NEMD) simulations based on the AIREBO-M potential under uniaxial tensile loading. The influence of crack length (30–60 Å), crack orientation angle (0°–90° relative to the loading axis), and temperature (200–1000 K) on the mechanical response is thoroughly examined. Variation in crack orientation reveals a transition from mixed-mode to pure Mode I fracture as the angle increases. The pristine nanosheets exhibit high in-plane stiffness, with elastic moduli of 489 GPa and 542 GPa along the X- and Y-directions, respectively. The presence of cracks significantly reduces mechanical performance: increasing the crack angle results in elastic modulus reductions of up to 6.85% (X-direction) and 8.91% (Y-direction). Similarly, increasing crack length from 30 Å to 60 Å leads to modulus reductions of 29.0% and 31.1% and fracture toughness decreases of approximately 57% and 55% in the X- and Y-directions, respectively. Thermal softening becomes pronounced at elevated temperatures, with the elastic modulus decreasing by over 40% at 1000 K. The variation of elastic properties with crack orientation and length is accurately described using trigonometric and power-law expressions, while the Wachtman equation effectively models the nonlinear temperature dependence of stiffness.