Spherical flaw growth

The thermodynamic conditions for spherical flaw growth were derived in Ref. 113 for a body with a sinusoidally displaced boundary. The final expression for the oscillatory displacement u = u0 sin mt is given as ... 

Figure 28. Spherical flaw growth caused by oscillatory displacement u = u sin wt for a polyurethane elastomer (5 c.p.s.). Curve generated by Equation 28...

An approach suggested by Williams et al. (117) uses an energy balance equation for initiation of flaw growth in a linearly viscoelastic material. A spherical flaw geometry was selected for simplicity since the expressions for the critical values of applied stress to cause fracture were similar for several flaw geometries. The critical conditions are based on a power (energy rate) balance... 

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