Experimental and numerical studies on the dynamic response of steel plates subjected to confined blast loading

This paper presents the results of experimental and numerical investigations into the response of unstiffened and stiffened steel plates under confined blast loading. Experimental tests were carried out on square mild steel plates with different stiffener configurations under the loading produced by cylindrical TNT charge explored in a specially designed blast chamber. The permanent deformation profiles of specimens were recorded. In general, the plates show large inelastic global deformations with the maximum deflection occurring at the center of the plate. Through the comparison to the impulse in a free air blast with the same charge, the equivalent impulse applied to the plate could increase by up to 4.03-5.63 times in the confined blast cases due to the confinement effect of blast chamber. Besides, numerical simulations are conducted to gain further insight into the deformation modes of plates using ANSYS/AUTODYN. Very good correlation is obtained with regards to midpoint deflections and deformation profiles. The validated numerical models were further used to investigate the influence of the stiffener and vents on deformation modes of stiffened and unstiffened plates under confined blast loading. The results from numerical simulations demonstrate that the maximum plastic deformation decreases greatly with increasing the mass ratio of the stiffener to the steel plate. It was found that the stiffener location (on the side or opposite side of loading) has an insignificant influence on the deformation modes of the stiffened plates under confined blast loading. The numerical results also clearly show that the vents can reduce the degree of confinement of the blast chamber as well as the impulse applied to the plates in the confined blast cases, which results in the decrease of structural deformation.