Dynamic Strength of Concrete Targets at Impact Interaction with a Spherical Projectile

The dynamic loading of concrete barriers is accompanied by a rapid development of strain and fracture. Consequently, the concrete behavior under the impact differs significantly from its behavior under quasi-static loading. The estimation of the dynamic strength and the development of computational models require reproducible experimental data that provide a correlation between the impact parameters and the nature and depth of damage to the concrete barrier. However, existing empirical and semi-empirical dependences obtained for the penetration depth limit the reliability due to different testing methodologies, material properties, projectile geometry, and evaluation criteria of damages. Purpose: The objective is to obtain the experimental data on the interaction between concrete barriers and spherical projectiles made of materials with the different elastic modulus and to determine the relationship between the penetration depth, impact velocity, and projectile parameters. Methodology/approach : Fine-grained concrete specimens (class B50) 300×300×150 mm in size are used in experiments. Spherical projectiles are made of steel and lead, with a diameter 17 mm and 20 and 26.7 g, respectively. Initial projectile velocities range from 259 to 556 m/s and are measured using two chronographs with a 0.1 m/s accuracy. The impact, penetration depth and crater dimensions are determined after the interaction. Geometrical fracture parameters are measured with 3D scanning of the front surface. Research findings : The penetration depth of the steel projectile increases from 9.34 to 22.62 mm with the velocity increasing from 259.4 to 556.1 m/s. The penetration depth of the lead projectile ranges from 12.1 to 14.8 mm at the impact velocity of 440.3 to 522.2 m/s. At the similar impact velocities, the penetration depth of the steel projectile exceeds that of the lead projectile. The dependence between the penetration depth and the impact velocity is well-defined. For the steel projectile, this dependence is characterized by more rapid growth. At comparable velocities, projectiles with a higher elastic modulus achieve a greater penetration depth, despite the lower weight of the steel projectile. Practical implications : The resulting experimental data can be used to describe empirical relationships governing high-speed impact interactions and to subsequently verify computational models of the dynamic strength and fracture of concrete.