Micro damage mechanics-based exponential power law acceleration of microscale damage and time-dependent crack propagation

Abstract

The critical acceleration of materials is a well-predicted precursor to catastrophic failure, the predictive power of which has been confirmed through analyses of volcanoes, landslides and rock failure experiments. Understanding the development, acceleration and physical controls of structural damages remains a core issue in engineering. Using a microscale damage mechanics model and a new geometric model for crack propagation, we derived the macroscopic strain function of the geometric parameters of damages under specified loads. The factors influencing the acceleration of crack development were revealed, along with the basis of the relationship between the evolution of damage and fracture parameters and external loads over different scales. We experimentally validated these results using intact samples and samples with pre-formed cracks. Although the mechanisms of crack propagation differed among samples, the observed behaviours were generally consistent with our theoretical results. Different samples exhibited different damage expansion characteristics and warnings before destabilisation; however, common features were observed at critical locations. These findings can provide foundations for predicting larger fractures in engineering settings under different conditions and thus, for improving the safety and stability of engineering projects.