Velocity attenuation and force transfer by a single- and double-layer claddings made of foam materials

The mechanism of air blast attenuation in a single- and double-layer sacrificial claddings comprising a steel cover plate and a foam core is examined applying an analytical and numerical analysis. In contrast to the commonly used approach to idealise the foam material by the rigid-perfectly plastic locking model, the unique relationship between the strains and stresses in foam materials exhibiting strain hardening is used in the present analytical model. The present analytical approach allows for a further explication of the compaction mechanism of the foam layers in sacrificial claddings. It is established that the blast energy is absorbed by the cladding core due to multiple reflections of the compaction wave. The proposed model of foam compaction is used to obtain the strains and stresses at the stationary end of the cladding within the reflected compaction wave. It is confirmed that among the equal mass claddings, those with lower density core transfer lower stresses to the stationary end when subjected to identical load. The use of double-layer claddings comprising foam layers with different densities is discussed. It is demonstrated that a reduction of the total thickness of the cladding can be achieved by placing a higher density foam layer near to the loaded end while lower density foam layer is preferable near to the stationary end of the cladding. © Multi-Science Publishing.