Tearing energy relationship

Figure 5.6 Tearing energy T vs knot diameter d showing the effect of tear rates on the size of knot diameter formed at 23 °C. The straight line shows the tearing energy-tip diameter relationship obtained from T ...

It should be noted that the tearing energy reduced rate relationship at the very low rate of 10 pm/s is obtained from constant load measurement. " This method of tear measurement is suitable only for non-strain-crystallizing rubbers that exhibit time-dependent tearing. Indeed, pre-stressed black-filled NR vulcanizate showed time-dependent tearing where the crack length increased with time when subject to constant load. This is more clear evidence indicating... 

Next, we consider the relationship between Go, the minimum mechanical energy required to disrupt an interface, and W, the equilibrium, thermodynamic work of adhesion. Firstly, however, we discuss the corresponding quantities for the cohesive fracture of a lightly cross-linked rubber. These are Goc, the threshold tearing energy (114), and ITc, the reversible fracture energy of the bonds... 

Tear Strength. A relation for the tearing stress of flexible foams that predicts linear increase in the tearing energy with density and increased tearing energy with cell size has been developed (180). Both relationships are verified to a limited extent by experimental data. 

The first quantitative studies of fatigue in polmers, which concentrated on rubbers [150-152], applied the tearing energy concept of fracture proposed by Rivlin and Thomas to fatigue crack propagation. Thomas [150] showed that the fatigue crack growth rate could be expressed in the form of an empirical relationship... 

The problem to be considered now is how to tear effectively a system of such units, units interconnected by material (and probably energy) flows. We assume that the input-output relationships are known for each unit, and that outputs must be calculated from the inputs. Each physical flow corresponds to several variables, and the criterion for tearing will be to minimize the number of variables that must be assumed to solve the torn system, i.e., to have the minimum number of variables associated with the total of the torn streams. 

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