Study On Penetration And Perforation Of Concrete Targets

Penetration and perforation of targets by projectiles are of great significance for weapon design and protection engineering. In particular, concrete penetration and perforation involve highly complex processes due to the complexity of its constitute relationship. A study is carried out in this thesis on the penetration and perforation of concrete targets combined empirical, analytical and numerical methods, which mainly consists of following parts:Wen’s semi-empirical equation is extended to the penetration and perforation of concrete targets by rigid projectiles with different nose shapes(conical-nosed, flat-nosed, ogival-nosed, hemispherical-nosed and truncated-nosed). Empirical equations for the shear strengths of concrete targets are obtained by means of analyzing available experimental data for concrete penetration and perforation. It is shown that the model predictions are in good agreement with experimental observations in terms of penetration depth, ballistic limit and residual velocity over a wide range of impact velocity and concrete strength.The effects of abrasion on the penetration of an ogival-nosed projectile into concrete targets are investigated. A numerical procedure is constructed based on an abrasion model which is proposed based upon the experimental observations and a forcing function. The forcing function is a polynomial of the normal velocity which approximates the response of target and can be determined either empirically or theoretically or numerically. The proposed numerical procedure is easy to implement and can be used to calculate the time-histories of projectile velocity, penetration depth, deceleration, mass loss and its nose shape. It is found that the model predictions are in good agreement with available test data in terms of mass loss, penetration depth and nose shape change of the projectile.Dynamic spherical and cylindrical cavity expansion models for concrete are proposed by using Hoek-Brown strength criterion, in which elastic-plastic response and elastic-cracked-plastic response are discussed. The forcing function obtained from the cavity expansion analysis is then employed to construct a penetration model for concrete targets struck by ogival-nosed projectiles. It is demonstrated that the present model predictions are in good agreement with experimental observations in terms of penetration depth. Numerical simulations with ABAQUS/VUMAT into which Hoek-Brown strength criterion is incorporated are performed to examine concrete penetration. The user subroutine code with Hoek-Brown strength criterion is first used to study the dynamic spherical and cylindrical cavity expansions and then is utilized to simulate the penetration struck normally by ogival-nosed projectiles of semi-infinite concrete targets. The penetration depths calculated from the simulation are in good agreement with the experimental data.