A Study On The Penetration Of Concrete Targets By Ogival-nosed Projectiles At Different Velocities

Based on the relevant theory for the penetration of semi-infinite metal targets by long rod projectiles,together with the abrasion model developed in concrete penetration.a theoretical study is performed on the penetration of semi-infinite concrete targets by ogival-nosed long rod penetrators at different velocities in this dissertation,numerical simulations are conducted on the response and failure of concrete targets struck by long rod penetrators,employing the new dynamic constitutive model for concrete developed in our laboratory.The main research results are as follows:1.A theoretical model is proposed for the penetration of semi-infinite concrete targets by ogival-nosed long rod projectiles within a unified framework.On the basis of the theory for the penetration of long rods into semi-infinite metal targets and the experimental observations for concrete penetration,depending upon initial impact velocity,concrete penetration can be divided into three modes,namely,penetration by a rigid penetrator,penetration by a deformable penetrator and penetration by an erosive penetrator.The abrasion effect is considered when the projectile penetrating the concrete targets in a rigid mode as well as deformable mode,and the penetration by the tube formed out of ejected debris is also taken into consideration in the erosive penetration phase.The transition velocities between the different modes of penetration(i.e.the rigid body velocity VR and the hydrodynamic velocity VH)have been obtained theoretically,and the theoretical model is compared with available experimental data as reported in the literature.It is shown that the model predictions are in good agreement with experimental observations in terms of the DOP(depth of penetration),projectile nose shape,projectile residual length(residual mass)and load-time history.It is also shown that the load-time history predicted by the present model when abrasion effect is considered is better than by the rigid model with abrasion effect ignored as compared to the test data.2.Numerical simulations are conducted of the penetration of semi-infinite concrete targets by long rod projectiles at different velocities.The newly developed dynamic constitutive model for concrete are incorporated into AUTODYN-2D using material modeling user subroutines,and then used to simulate the concrete penetration.It is demonstrated that numerical predicted the depth of penetration and load-time histories(in quasi-rigid penetration)are in good agreement with available experimental data.It is also demonstrated that three penetration modes(i.e.penetration by a rigid projectile,penetration by a deforming projectile and penetration by an erosive penetrator)were reproduced in the numerical simulations,and that the transition velocities between the different modes of penetration(i.e.rigid body velocity VR and hydrodynamic velocity VH)determined numerically are in good agreement with those determined from the theoretical model.