Crack Branching Characteristics at Different Propagation Speeds: From Quasi-Static to Supersonic Regime

Abstract

Classical dynamic fracture mechanics predicts that the crack branching occurs when crack propagation speed exceeds a sub sonic critical velocity. In this paper, we performed simulations on the dynamic fracture behaviors of idealized discrete mass-spring systems. It is interesting to note that a crack does not branch when traveling at supersonic speed, which is consistent with others' experimental observations. The mechanism for the charac teristics o f crack branching at different propagation speeds is studied by numerical and theoretical analysis. It is found that for all different speed regimes, the maximum circumferential stress near the crack tip determines the crack branching behaviors.

Critical Condition of the Branching Behaviour of Running Brittle Cracks in Steels

“…specimen #5 homogenous material and the data of crack propagation history, the meandering of the crack occurs when the crack speed gets around 800 m/s. According to the previous study on elastic dynamic fracture theory, crack branches at subsonic speed [5]. The crack propagation behaviours are quite similar to that observed in elastic material, i.e., PMMA [3], mirror, mist and hackle, However, it is curious that the critical condition for the change to start unevenness fracture surface and bifurcation event is much different.…”

“…In our all ESSO tests including both of homogeneous plate and soft welded joint conducted at low temperature, crack branching was observed. Regarding to crack branching behaviour in fast crack, there are several candidate mechanisms in brittle material [2][3][4][5]. However, it is not satisfactory for elastic-plastic materials.…”