Craze nucleation theory

Craze Nucleation Theory. In various ways it has been suggested that the role of the rubber particles is that of stress concentrators. Thus, Schmitt and Keskkula (33) believe that the multiplicity of stress concentrators (i.e., a multitude of weak points) produce a large number of small cracks rather than a few large ones more energy is needed to propagate a large number of small cracks, and stress fields of the various... 

Further, the Goodier equations predict that hard particles and voids produce higher stress concentrations (i.e., stronger craze nucleation) than rubbers, and thus hard particles and voids should toughen even better than rubbers if nucleation were the operative mechanism. This is not observed experimentally. The nucleation theory is thus seen to have substantial drawbacks. 

Craze nucleation appears controlled by the nucleation of voids in localized regions undergoing large unstable plastic deformation. The sensitivity of this process to the nature of the flaw structure of the surface makes a detailed comparison of data between different experimental groups or between experiment and theory very difficult. 

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