Statistics of dynamic fragmentation for a necking instability
CEA, DAM, DIF, 91297 Arpajon, France
Published online: 7 September 2015
In the aim of predicting the fragmentation of expanding structures, a Mott type approach is applied to the potential failure points driven from an instability analysis. Substantially, fragmentation is preceded by the localization of plastic deformation in multiple necks forming potential sites for failure. This pattern is predicted by a combination of periodic instable eigenmodes of the structure, the necks being the maxima with varying spacing and amplitudes of the instable perurbation. Obscuration conditions, linked to the propagation of unloading waves, are next written for this set of potential failure points and yield a distribution of fragments. The approach is developed for an expanding ring experiment justifying the scatter in fragment sizes. It shows incidentally that the unloading waves must propagate at a celerity much lower than the elastic wave speed.
© Owned by the authors, published by EDP Sciences, 2015
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