Propagation slips

Inner slip, between the solid wall and an adsorbed film, will also influence the surface-liquid boundary conditions and have important effects on stress propagation from the liquid to the solid substrate. Linked to this concept, especially on a biomolecular level, is the concept of stochastic coupling. At the molecular level, small fluctuations about the ensemble average could affect the interfacial dynamics and lead to large shifts in the detectable boundary condition. One of our main interests in this area is to study the relaxation time of interfacial bonds using slip models. Stochastic boundary conditions could also prove to be all but necessary in modeling the behavior and interactions of biomolecules at surfaces, especially with the proliferation of microfluidic chemical devices and the importance of studying small scales. 

In the study of the nucleation and propagation of dislocations (Figure 10.11) from scratches in a geometry designed to produce slip on non-basal planes, edge dislocations were found to glide on non-basal planes, but screw dislocations were completely immobile except in the basal plane. Detailed measurements of the dislocation velocities using stress pulse techniques showed that... 

Fig. 2 a and b. Schematic load versus displacement curves for crack propagation in epoxy polymers obtained using a double torsion specimen a Stable continuous propagation, b Unstable stick/slip propagation... 

LEFM, for fractures occurring in the elastic domain, leads us to characterize the materials using critical characteristics for crack initiation (or arrest in the case of stick-slip propagation). 

At a constant temperature, the increase of e involves an increase of crack propagation is generally of the stick-slip type (see Fig. 12.4), at low e, and becomes brittle-unstable when e increases (Galy et al., 1994). KIca (for arrest) remains at an almost constant value (Kinloch, 1985). 

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