CONSTITUTIVE MODELING OF REINFORCED CONCRETE M55 PENETRATION OF PROJECTILES

Abstract

Concrete is commonly used most famous material for the construction of the protective structure. The behaviour of concrete under different loading conditions like ballistic loading, explosive loading etc., plays a significant role in designing and constructing protective structures. The current knowledge of the behaviour of concrete is minimal. Most of the research papers published on the ballistic impact of reinforced concrete are limited to the thickness of concrete 500-800mm. As the thickness of concrete increases, different mode of failure appears and material properties change with depth of penetration. It is a very challenging job to incorporate different failure modes at various stages of the simulation. Concrete is the material that offers resistance even after the complete failure of the material called Residual strength. In the Finite Element analysis after the failure failed elements are deactivated from the analysis thus, they can not offer residual stregth. Using the same modelling strategies and analysis settings for thin concrete targets doesn’t yield accurate results. This is because the material properties like residual strength, analysis settings like failure criteria, contact properties need to be updated according to the thickness of the concrete. The velocity of the projectile also plays an important role in deciding the failure modes. At low velocities, cracks appear on distal and proximal faces without penetration of the projectile. At medium velocities, spalling occurs where some material fails at the proximal face without penetration. At high velocities, scabbing happens where some material from both faces fails, and the projectile penetrates slightly into the material. For very high velocity ballistic impact, cone cracking appears in which the crater's diameter at the distal face is larger than the proximal face making a cone shaped hole in the material.