Layered sacrificial claddings under blast loading Part I — analytical studies

In this paper, we present the behaviour of layered sacrificial claddings subjected to blast loading.The cladding layers are constructed out of thin mild steel sheets. The blast load was modelled as an equivalent triangular blast pulse. Both experimental and numerical analyses have been carried out. The analytical work is presented in this paper. Finite element analysis with step by step time marching under large deformation and large strain is carried out. Contact interface elements are used at the foldings of the sheet metal during the collapse of the layers. Isotropic strain hardening with dynamic yield properties according to Cowper–Symonds relation were employed for the material properties at the integration points at every time step. The layers undergo large plastic deformations and absorb energy before collapsing to a more stable configuration. The layers collapse successively, one after the other. The mode of collapse of the unit cell in any layer is always same. Substantial reduction in impulse transfer is observed at the base of the cladding structure as much of the energy is absorbed due to plastic deformations. A simple analytical model is also proposed for the sacrificial cladding structures.Under blast loading, layered sacrificial claddings are very effective in energy absorption and they have a predictable behaviour. Hence, they can be used in design of reliable blast resistant structures.