Numerical Analysis of Concrete Fracture under Shock WaveLoading
П. А. Радченко, С. П. Батуев, А. В. Радченко
Abstract
Concrete is known for its low tensile strength. The difference between its compressive and tensile strengths can reach a factor of 15–20. Therefore, it is important to predict the behavior of concrete structures under various operating conditions and unexpected loads. This paper reports the numerical results on the fracture behavior of a high-strength concrete target struck by an ogival-nosed projectile. The problem of impact interaction is numerically solved by the finite element method in a three-dimensional formulation within a phenomenological framework of solid mechanics. Numerical modeling is carried out using an original EFES 2.0 software, which allows a straightforward parallelization of the numerical algorithm. Fracture of concrete is described by the Johnson–Holmquist model that includes the strain rate dependence of the compressive and tensile strengths of concrete. The computational algorithm takes into account the formation of discontinuities in the material and the fragmentation of bodies with the formation of new contact and free surfaces. The behavior of the projectile material is described by an elastoplastic medium. The limiting value of the plastic strain intensity is taken as a local fracture criterion for the projectile material. For the computational experiment, the target was divided into 19 × 106 finite elements (tetrahedrons). A detailed numerical analysis was performed to study the stress and strain dynamics of the concrete target and the effect of shock-wave processes on its fracture. It was found that the decisive role in the fracture of the target, with the considered kinematic and geometric interaction parameters, is played by wave processes. Target fracture occurs in unloading waves generated on its free surfaces. As a result, three fracture zones are formed in the target in front of the penetrating projectile. The first zone is formed near the front surface of the target. The second one is a spall fracture on the rear surface. The third fracture zone is formed in the central part of the target due to the interference of unloading waves propagating from its lateral surface. These fracture zones merge with time, and the target shows almost no resistance to the projectile penetration.