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Influence of Confining Prestress on the Transition from Interface Defeat to Penetration in Ceramic Targets



A set of impact experiments has been performed in which the transition velocity for four different levels of prestress has been determined. The velocities are compared to an analytical model for the influence of prestress on the formation and extension of a cone crack close to the impact zone (the crack is assumed to control the transition). The main conclusions can be summarized as follows: (i) the model shows a strong influence of prestress on the transition velocity; the projectile pressure at transition increases linearly with the level of prestress. (ii) The impact experiments show that prestress has an even stronger influence than predicted; the maximum contact pressure at transition is more than doubled if prestress is increased from zero to around 100 MPa. (iii) Further increase of prestress did not show the same strong influence and a transition velocity of 1500 m/s was found unaffected in spite of increased prestress.

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