STUDY OF CRACKS IN CONCRETE TARGET UNDER DEEP PENETRATION BY A PROJECTILE

Abstract

A LARGE NUMBER OF CRACKS OCCUR IN CONCRETE STRUCTURE AFTER PROJECTILE PENETRATION. IN THIS PAPER, WIRE SAW CUTTING, X-RAY COMPUTED TOMOGRAPHY (X-CT) AND MECHANICAL PROPERTY TESTING OF DAMAGED CONCRETE WERE CARRIED OUT ON DEEP PENETRATION TARGETS. ACCORDING TO X-CT IMAGES AND THE MECHANICAL PROPERTIES OF DAMAGED CONCRETE, THE CRACK DISTRIBUTION OF THE TARGET WAS DIVIDED INTO A PLASTIC DAMAGE ZONE AND A BRITTLE DAMAGE ZONE; THE MICROCRACKS IN THE PLASTIC DAMAGE ZONE WERE TRANSFORMED BY MACROCRACKS, AND THE MACROCRACKS IN THE BRITTLE DAMAGE ZONE PROPAGATED LOCALLY. THE INITIAL GROWTH PROCESS OF THE CRACKS WAS OBTAINED BY X-CT IMAGES; THE CRACKS IN THE PURE MORTAR TARGET BEGAN TO PROPAGATE IN THE RADIAL DIRECTION AND GRADUALLY TURNED TOWARD THE TANGENTIAL DIRECTION, WHILE THE TARGET CONTAINING COARSE AGGREGATE DIRECTLY FORMED TANGENTIAL CRACKS. THE PROPAGATION OF CRACKS WAS ANALYZED IN IMAGES OF TARGET SECTIONS; TANGENTIAL CRACKS PROPAGATED ASYMMETRICALLY, AND THE NUMBER OF RADIAL CRACKS GRADUALLY DECREASED DUE TO BEING BLOCKED BY TANGENTIAL CRACKS; THE TANGENTIAL CRACKS BENT IN THE PURE MORTAR TARGET AND WERE RELATIVELY STRAIGHT IN THE TARGET CONTAINING COARSE AGGREGATE. A CRACK PROPAGATION MODEL WAS ESTABLISHED, AND THE TANGENTIAL CRACK FORMULA AND THE CRACK PROPAGATION VELOCITY WERE OBTAINED.