A Study of Moving Distance of Ricocheted Debris for Various Debris Shape with Air Drag Coefficient

When a building is detonated, the debris generated collides with the ground with very high energy and bounces back. This phenomenon is called ricochet. Ricochet increases risk by increasing the moving distance of the debris. The ricochet of debris is affected by the shape of the debris. In this paper, the behavior and moving distance of debris along the shape of debris were studied. For various initial conditions, the ricochet of debris was studied through the FEM, and the results were fitted to a 3D curved surface to predict the speed and angle after the ricochet. The moving distance of the debris was calculated using the trajectory formula considering the drag coefficient using the MATLAB. The ricochet of debris is affected by the contact area with the medium. As the contact area increases, the reflection angle increases because of the increase of the repulsive force. As the size of the debris increases, the energy loss also increases because of the increasing of the contact area. Thus, the moving distance of the cylinder debris is shorter than that of the sphere debris.