Elasticity energy-driven

Unstable Brittle Fracture Driven by Elastic Energy. 13... 

An unstable crack is primarily driven by the elastic energy already stored in the specimen (and not so much by the energy introduced into the specimen by the continued deformation). A pertinent experiment was carried out by Stalder [30], who investigated the impact fracture of PMMA using an instrumented hammer nose and standard notched Charpy specimens with sprayed-on graphite strain gages. With this double-instrumentation technique... 

Fig. 1.10. Temporal evolution of a circular particle as a result of diffusive processes driven by the competing influences of interfacial and elastic energy. The parameter t is a dimensionless measure of the elapsed time (adapted from Voorhees et al. (1992)).

At the peak force (position A in Fig. 8.5a), there are two possibilities for the next strain state Elastic unloading along path AU, and further plastic straining along the path AN. A non-uniform strain state develops, as parts of the specimen elastically unload, and the plastic strain in one region increases to form a neck. The plastic deformation of the neck is partially driven by elastic energy release from the rest of the specimen. The condition that A is at the maximum in the force-extension or force-strain curve can be written... 

Clark, E.S. (1973) Mechanism of energy-driven elasticity on crystalline polymers, in Structure and Properties of Polymer Films, (eds R.W. Lenz and R.S. Stein), Plenum, New York, pp. 267-282. 

Figure 3.2 Energy-driven elasticity typical of crystalline solids.

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