Influence of standoff distance on the deformation of square steel plates subjected to internal blast loadings

This study presents a combining experimental and numerical efforts on elucidating the influence of the standoff distance on large inelastic deformation of square steel plates subjected to the fully-confined internal blast loading from TNT detonation. Experimental results reveal that increasing standoff distance could lead to a monotonic increase of permanent central displacement of the target plate, which contradicts the well-known free-air blast scenarios. Detailed three-dimensional finite element simulations using LS-Dyna are carried out to provide additional insights into the pressure evolution and transient response of the ductile plates. The numerical results are validated against experimental data where they were found to be in reasonable agreements. Numerical predictions reveal that complex pressure wave interactions within the blast chamber, and the saturated impulse effect attribute, in part, or combination, to the aforesaid phenomenon. The discussions on the limitation of the current findings are also provided, highlighting its dependency on the confinement's geometry.