Instabilities in Material Behaviors

The linked two of my studies can be used as references for Zhigang’s lecture on Instabilities.

(1) Catastrophic fracture

Fracto-emissions accompanying crack propagation were observed in recent experiments. The energy impulses during and after each atomistic fracture increment stimulate the fracto-emission.A model of the atomic scale cleavage processes is proposed to formulate a catastrophic fracture theory relevant to these phenomena.

A criterion for catastrophic jump of the cleavage potential is applied to representative crystals.We simulate the propagation of the emitted particles along a crack bounded by zigzag surfaces and quantify the long-time delay law of fracto-emissions after fracture.

(2) Catastrophic interface debonding

Energetic materials, such as solid propellants and plastic bonded explosives, can be considered as composite materials with energetic particles embedded in polymeric binder matrix. Dewetting of energetic crystals from the polymeric binder can significantly affect the macroscopic behavior of solid propellants and high explosives.

Large particles in high explosive PBX 9501 may lead to catastrophic debonding (i.e., sudden debonding even under static load) that may trigger the reaction or detonation of high explosives.Hotspot may form from the localized sudden interface debonding, thus trigger detonation of high explosives under low-level loading.