Behavior of structures subjected to projectiles

Some safety-critical industrial facilities require a review of the "projection" risk when it is deemed unacceptable, or when the projectiles generated can cause serious failures in potential targets, despite the risk reduction measures already in place at source. It is then necessary to explicitly study the behavior of the structures concerned.

Standard calculation methods and tools are unable to take this very specific accidental load case directly into account for design purposes. The violence of an impact calls for analysis techniques adapted to the fact that it is a violent phenomenon in terms of intensity, but of very short duration. It is therefore necessary to exploit the strength of materials beyond their elastic limit, sometimes to the point of failure, and to take into account their dynamic characteristics.

Various analysis methods have been developed, depending on whether the impact between two solids is to be studied globally, or whether local effects are also to be modeled, particularly in the case of penetration or even perforation. A wide range of methods is available, from empirical models to complex numerical models. In a given situation, the choice of approach depends on the nature of the projectiles under consideration, the level of detail required and, above all, the objectives of the study. A distinction is made between rigid, semi-rigid and soft shocks. For each of these, calculation techniques are presented, trying as far as possible to define the field of application, so that the engineer who has to dimension or reinforce such structures can find a suitable approach.

The concepts introduced will familiarize the reader with the problem of projectile impacts, whether accidental or intentional, both in terms of their modeling based on physical phenomena and the characterization of their effects on structures.