This study presents a comprehensive molecular dynamics investigation into the mechanical behavior of Y-Graphene nanosheets under uniaxial tensile loading, with particular emphasis on the effects of crack orientation, temperature, and defect size. The elastic modulus, ultimate tensile strength, fracture toughness (KIC), and energy absorption capacity (toughness) are systematically analyzed for various crack angles (0° to 90°), temperatures (200 K to 1000 K), and crack lengths (30 Å to 60 Å). Results indicate a strong dependence of mechanical properties on crack geometry, with significant degradation observed when cracks are oriented perpendicular to the loading direction. Elastic modulus and strength decrease progressively with increasing crack angle, while elevated temperatures further accelerate mechanical failure due to thermal softening and bond destabilization. Crack length analysis confirms that larger defects drastically reduce load-bearing capacity and fracture resistance, highlighting the brittle nature of Y-Graphene even under moderate structural imperfections. Fracture process visualization reveals rapid, cleavage-like crack propagation with minimal plasticity, consistent with classical linear elastic fracture mechanics. The material exhibits intrinsic anisotropy, with directional differences in stiffness and strength attributed to the unique bonding topology of Y-Graphene. Comparative analysis with pristine configurations shows that even small cracks can induce substantial performance loss, emphasizing the critical role of defect engineering in high-strength applications. Unlike graphene’s purely sp²-bonded hexagonal lattice or graphyne’s acetylenic linkages, Y-graphene features a distinctive sp/sp² hybrid structure with Y-shaped junction nodes. Molecular dynamics simulations reveal that Y-graphene exhibits approximately 60% of graphene’s elastic modulus and tensile strength, with fracture behavior dominated by preferential crack propagation through Y-junction sites. Results demonstrate stronger directional anisotropy in mechanical degradation compared to graphene, with elastic modulus decreasing from 600 GPa (0° crack) to 285 GPa (90° crack), representing 52.5% retention versus graphene’s 68.5% retention under identical conditions. Fracture toughness <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{K}_{IC}\)</EquationSource> </InlineEquation> ranges from 2.8 to 0.72 <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:\text{M}\text{P}\text{a}.\sqrt{\text{m}}\)</EquationSource> </InlineEquation> across crack orientations, approximately 70% of graphene’s corresponding values. These findings provide essential insights into the mechanical reliability of Y-Graphene-based nanostructures and underscore the necessity of integrating geometric and environmental factors in the design of advanced 2D materials for structural and electronic applications.

Anisotropic Mechanical Properties and Fracture Toughness of Y-Graphene: Role of Crack Geometry and Thermal Environment

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发表日期：

2026年3月30日

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Yanmin Li

摘要

This study presents a comprehensive molecular dynamics investigation into the mechanical behavior of Y-Graphene nanosheets under uniaxial tensile loading, with particular emphasis on the effects of crack orientation, temperature, and defect size. The elastic modulus, ultimate tensile strength, fracture toughness (K_IC), and energy absorption capacity (toughness) are systematically analyzed for various crack angles (0° to 90°), temperatures (200 K to 1000 K), and crack lengths (30 Å to 60 Å). Results indicate a strong dependence of mechanical properties on crack geometry, with significant degradation observed when cracks are oriented perpendicular to the loading direction. Elastic modulus and strength decrease progressively with increasing crack angle, while elevated temperatures further accelerate mechanical failure due to thermal softening and bond destabilization. Crack length analysis confirms that larger defects drastically reduce load-bearing capacity and fracture resistance, highlighting the brittle nature of Y-Graphene even under moderate structural imperfections. Fracture process visualization reveals rapid, cleavage-like crack propagation with minimal plasticity, consistent with classical linear elastic fracture mechanics. The material exhibits intrinsic anisotropy, with directional differences in stiffness and strength attributed to the unique bonding topology of Y-Graphene. Comparative analysis with pristine configurations shows that even small cracks can induce substantial performance loss, emphasizing the critical role of defect engineering in high-strength applications. Unlike graphene’s purely sp²-bonded hexagonal lattice or graphyne’s acetylenic linkages, Y-graphene features a distinctive sp/sp² hybrid structure with Y-shaped junction nodes. Molecular dynamics simulations reveal that Y-graphene exhibits approximately 60% of graphene’s elastic modulus and tensile strength, with fracture behavior dominated by preferential crack propagation through Y-junction sites. Results demonstrate stronger directional anisotropy in mechanical degradation compared to graphene, with elastic modulus decreasing from 600 GPa (0° crack) to 285 GPa (90° crack), representing 52.5% retention versus graphene’s 68.5% retention under identical conditions. Fracture toughness \(\:{K}_{IC}\) ranges from 2.8 to 0.72 \(\:\text{M}\text{P}\text{a}.\sqrt{\text{m}}\) across crack orientations, approximately 70% of graphene’s corresponding values. These findings provide essential insights into the mechanical reliability of Y-Graphene-based nanostructures and underscore the necessity of integrating geometric and environmental factors in the design of advanced 2D materials for structural and electronic applications.