Exploring effects of property variation on fragmentation of metal rings using a simple model

A simple finite element implementation of the Mott model for fragmentation of a thin walled ring has been implemented and used to explore the effect of local variations in fracture strain around the ring. The model has successfully reproduced the fragment size distributions previously reported, which follow a characteristic Mott distribution form, providing sufficient (1000) simulations are run. It has been shown that this form is retained even when there are large differences in the random distribution of fracture strains or a different choice of function used to describe the fracture strain scatter. In these cases, the strain rate has a much stronger effect than fracture strain distribution the on the average fragment size and fragment distribution. However, for cases where there are a small number of local defects that strongly reduce the fracture strain at certain locations around the ring, the predicted fragment size distribution develops a bimodal character. This is also the case for large but gradual variations in fracture strain with position around the ring. The results have implications for cases where a small number of large pre-existing defects exist, or processing has led to macrozones in the microstructure. The utility of a simple fast running model to study these cases is discussed.(c) 2022 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automated summary

This study implemented a simple finite element Mott model to investigate the fragmentation effect of a thin walled ring, and explored the influence of local variations in fracture strain around the ring. The results showed that the characteristic Mott distribution of fragment size can be reproduced successfully, regardless of the random distribution of fracture strains or the choice of function used to describe the fracture strain scatter, as long as a sufficient number of simulations are run.