A numerical study on the influence of free water content on the ballistic performances of plain concrete targets

• Projectile deceleration driven by concrete confined strength in nose penetration phase.
• Tensile strength and softening of concrete influence the projectile penetration.
• A coupled plasticity–damage model allows simulating the penetration process.
• Concrete saturation ratio influences damage and ballistic behavior of the target.
• Effect of friction at projectile/target interface on the penetration resistance.

During the impact of a kinetic penetrator against a plain–concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in the case of perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile that involve mechanisms such as micro-cracking and collapse due to porosity. Both confined compressive and tensile behaviors are influenced by the concrete’s moisture content. Therefore, the constitutive model used for numerical calculation for describing the confined behavior and tensile resistance of the concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests have been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of the concrete material is modeled using the KST (Krieg–Swenson–Taylor) plasticity model and the so-called DFH (Denoual–Forquin–Hild) anisotropic damage model which allows the description of the tensile strength and softening behavior of concrete in tension. These calculations are used to investigate the influence of the concrete’s free water content through its confined behavior and tensile strength and the influence of friction at the projectile–target interface on the ballistic performance of concrete slabs.

Topographic analysis and numerical simulation of damage in the concrete slabs. Target with a thickness of 300 mm and impact velocity of 333 m/s.Figure optionsDownload as PowerPoint slide