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Influence of Groove Depth on the Breakup of a Controlled Fragmentation Shell



FOI is presently performing a basic study on a generic controlled fragmentation charge where the influence of groove depth on the casing breakup and acceleration of the fragments are studied by both experimental and numerical means. In this study we have used casings with internal grooves in a 60 degree diamond pattern. The groove depth was varied from 8 to 67 % of the case thickness. Charges were detonated in a sawdust pit, fragments were soft recovered and the fracture surfaces were analysed. In all cases the casings broke up in the desired shape, though the thickness of the fragments and the fracture surface showed considerable differences. Complementing experiments using flash X-ray flashes were conducted in order to determine the fragment velocity. Material test data for fracture strain as function of triaxiality and Lode parameter were used in numerical simulations using LSDYNA to analyse the breakup process. Good agreement between the numerical simulations and final shape of the fragments are obtained.

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