Mechanisms governing crack speed in peridynamic model.

• Uncovering the inherent limitations of peridynamic model in predicting dynamic crack velocity. • The influence mechanism of size and stiffness of the nonlocal region on crack velocity is elucidated. • Exposing wave speed degradation rules in peridynamic and formulating a prediction formula for limiting crack velocity. • The crack velocity is regulated by the local stiffness and point density. Peridynamic, an innovative solid mechanics method in continuum theory, offers unique advantages for discontinuity modeling such as fracture simulation. This study addressed a puzzling phenomenon observed in peridynamic dynamic fracture modeling, where the predicted normalized limiting crack velocity remained nearly constant across different material parameters input. Delving into the mechanism influencing predicted crack velocity in peridynamic model, we systematically explored the impacts of stiffness distribution of the nonlocal region around the crack tip, through numerical simulations and theoretical analyses. Additionally, the implicit wave velocity degradation in the damage zone of the peridynamic model was uncovered. A prediction formula for the limiting crack velocity was then derived based on these analyses. Furthermore, the wave velocity degradation scheme and the proposed prediction model were validated through numerical instances, involving convergence studies and material density degradation investigation. This work contributes to a further understanding of the peridynamic model and provides new insights for crack velocity prediction in dynamic fracture scenarios. [ABSTRACT FROM AUTHOR]