Zhiyong Zhao

Whether mechanical failure in oxide glasses across length scales and loading modes is controlled by a unified microscopic mechanism remains unresolved. A systematic multiscale molecular dynamics investigation is conducted using LAMMPS on aluminosilicate glasses of varying Al2O3/R2O (R = Li, Na) molar ratio. Mechanical responses are examined under nanoscale tensile deformation and submicron-scale crack propagation, one-dimensional normal impact, and two-dimensional oblique impact conditions, enabling direct comparison between quasi-static fracture and high-strain-rate failure. Under tensile deformation and crack propagation, ultimate tensile strength, bond-breaking evolution, crack propagation velocity, and crack path stability are systematically quantified as functions of composition. The results demonstrate that tuning Al2O3/R2O ratio systematically modifies the fraction of Si–O–Al bonds, thereby altering network connectivity and local structural rigidity. These structural changes directly govern tensile load-bearing capacity and crack propagation resistance at multiple scales. Notably, when n(Al2O3)/n(R2O) = 1, the fraction of Si–O–Al bonds is maximized, corresponding to the highest tensile strength and greatest resistance to crack propagation. Under high strain rate impact, cracks do not initiate during compressive stage. Instead, crack initiation and rapidly propagates during rebound unloading, driven by transient tensile stresses induced by reflected rarefaction waves. This observation indicates that impact failure is fundamentally governed by the material's dynamic tensile instability, the structural origin of which is intrinsically consistent with that governing quasi-static tensile behavior and crack propagation. These findings establish a comprehensive structure-property–failure relationship that directly links network topology to multiscale fracture behavior in aluminosilicate glasses, providing mechanistic guidance for compositional design of high-strength oxide glasses.