Study of moving distance of ricocheted debris for various medium with air drag force coefficient

When a building explodes, debris generated bounces after hitting the ground with high energy. It is called the ricochet phenomenon. Ricochet phenomena increase the risk of damage by increasing the moving distance of the debris. The ricochet of debris is impacted by the type of medium. In this paper, the behavior and travel distance of debris after ricocheting are studied according to the type of medium. For various initial conditions, the ricochet of the debris was studied through FEM, and the resulting values were fitted to the 3D curved surface, to predict the speed and angle after the ricochet. The trajectory of the sphere was calculated with the flight formula, considering drag force by using the MATLAB. The ricochet of debris is impacted by the contact area with the medium. As the contact area increases, the reflection angle increases due to the increase of the repulsive force. As the size of the debris increases, the contact area increases and the energy loss increases, but it moves further because of the increase of the weight and kinetic energy. The type of media around the building can be used as an appropriate means of controlling the travel distance of the debris.