Dynamic fracture

In the present section, attention will focus on the size of fragments created in a violent fragmentation event. The objective will be to explore some theoretical ideas which appear important to the dynamic fragmentation process. The two underlying phenomena that have dominated theoretical efforts in this area of dynamic fracture mechanics are the presence of an inherent flaw structure, and energy balance in the fracture process. 

In many applications and experimental configurations leading to dynamic fracture and fragmentation of a body, it is convenient to characterize the motion of the event through a single strain-rate parameter L When the re-... 

Dynamic Fracture and Fragmentation 289 an expression for the transition strain rate is obtained... 

Lastly, assuming that the rod fragments into pieces of nominal length given by (8.48), a dynamic fracture strain criterion, Sf = e , depending on the prob-... 

The present discussion of continuum modeling of dynamic fracture is not an exhaustive review. Rather, it points out the variety of approaches which have been, and are still being, pursued to provide methods for calculating dynamic fracture phenomena. Such work is still quite active and considerable effort... 

A void nucleation and growth fracture model embedded in a general viscoelastic-plastic material model is representative of approaches to ductile dynamic fracture (Davison et al., 1977 Kipp and Stevens, 1976). Other approaches include employing the plastic strain as a damage variable (Johnson and Cook, 1985) so that both spall and large strain-to-failure can be treated. 

Numerical simulation of a complex dynamic fracture application can be illustrated by calculations of impact induced damage in a ceramic cylinder. The computer model used was originally developed for oil shale explosive fragmentation (Grady and Kipp, 1980), with various extended applications considered by Boade et al. (1981) and Chen et al. (1983). In this model, stress and strain are related through... 

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