Micro-structure of damage in thermally activated fracture of Lennard-Jones systems

Abstract

We investigate the effect of thermal fluctuations on the critical stress and the micro-structure of damage preceding macroscopic fracture of Lennard-Jones solids under a constant external load. Based on molecular dynamics simulations of notched specimens at finite temperature, we show that the crystalline structure gets distorted ahead of the crack in the secondary creep regime. The damage profile characterizing the spatial distribution of lattice distortions is well described by an exponential form. The characteristic length of the exponential form provides the scale of damage which is found to be an increasing function of the temperature: At low temperature damage is strongly localized to the crack tip, while at high temperature damage extends to a broader range leading to more efficient relaxation of overloads. As a consequence, the stress intensity factor decreases with increasing temperature. The final macroscopic failure of the system occurs suddenly which is initiated by the creation of vacancies and voids. The creep strength exhibits the inverse square root scaling with the notch size corrected by the extension of the process zone.

arXiv comment6 pages, 8 figures

References in corpus (11)

• Statistical Models of Fracture
• Creep failures in heterogeneous materials
• The effect of disorder on the fracture nucleation process
• Subcritical statistics in rupture of fibrous materials: Experiments and model
• Fluctuations and scaling in creep deformation
• Role of disorder in the size-scaling of material strength
• Andrade, Omori and Time-to-failure Laws from Thermal Noise in Material Rupture
• Discrepancy between sub-critical and fast rupture roughness: a cumulant analysis
• The cooperative effect of load and disorder in thermally activated rupture of a two-dimensional random fuse network
• A dynamical law for slow crack growth in polycarbonate films
• Nucleation of cracks in a brittle sheet

Cited by in corpus (2)

• Size scaling of failure strength with fat-tailed disorder in a fiber bundle model
• Scaling laws of failure dynamics on complex networks