Étude analytique et numérique du développement de la striction multiple pour des cylindres métalliques en expansion dynamique

Abstract : This work deals with the fragmentation of dynamically expanding metal shells and covers a problem of interest for both civil and military industries. For both fields of application, it is crucial to predict the size and the speed of fragments, resulting from the destruction of shells in order to measure the consequences that it could have on structures. Current models study the growth of a defect within the material and are able to determine a characteristic size of fragments. Nevertheless, these models require a hypothesis whose validity is questionable when the rate of deformation is important. In this work, we propose a new analytical model for cylinders (equivalent to the dynamic extension of a plate) to overcome this hypothesis and study the influence of the initial defect by following its time evolution. The model is compared successfully with results performed with a finite element method. Our work notably expands the framework of classical linear stability analyses. As a major outcome, the proposed approach is able to track the evolution of a perturbation even for small plastic strain, when the flow may be stable. In addition it is shown that the present approach can predict accurately the time where the elastic unloading is observed in finite element simulations.
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Mathieu Xavier. Étude analytique et numérique du développement de la striction multiple pour des cylindres métalliques en expansion dynamique. Mécanique des matériaux [physics.class-ph]. Université de Lorraine, 2019. Français. ⟨NNT : 2019LORR0064⟩. ⟨tel-02329302⟩

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