شبیه سازی عددی و تحلیلی پرتابه های فرسایشی سرعت بالا در اهداف بتنی مسلح به الیاف فولادی

In this paper, modeling of high speed projectiles with different nose shapes, penetrating into steel fiber reinforced concrete is investigated. This is a novel study because it considers the length to diameter ratio of steel fiber as well as projectile length to diameter ratio and volume fraction of fiber used in concrete matrix on the impact resistance of steel fiber reinforced concrete fibers at high speeds. Numerical simulation is used using LS-DYNA explicite code with Lagrangian method and axial symmetry form. The projectiles have an approximate mass of 45 (gr) and their velocities are about 2500 (m/s) penetrating into steel fiber reinforced concrete panel with volume fraction of 1.0%, 1.5% and 2.0%. In this article the exact behavior of steel fiber reinforced concrete confronting metallic projectiles at high speed is predicted. Here, Elastic-Plastic Hydrodynamic material model is used for prediction of projectile behavior. The results of the simulations are compared with experimental work of other investigators and, the results show that ogive nose projectiles are more efficient than other projectiles. In other words, by increasing the projectile length to diameter ratio from 0.5 to 0.9, for flat, hemispherical and ogive projectiles their residual velocities are increased. Also, it is shown that by increasing the volume fraction of steel fibers in concrete matrix, damage of top surface damage is reduced dramatically. The analytical model presented in this paper considers the speed variations of the projectile during the penetration process into steel fiber reinforced concrete is an important achievements this respect.