Repeated uniform blast loading on welded mild steel rectangular plates

The present research paper deals with a combined experimental and numerical assessment of the deformation mode and failure mechanism of welded rectangular plates exposed to three successive uniform blast loading. To perform the experimental study, three different categories of 0 W (a plate without any weld seam), 1 W (a plate with a single weld seam), and 2 W (a plate with double weld seams) were conducted and mounted onto the ballistic pendulum apparatus. The effect of the number of blasts, the number of weld seams, and the explosive charge mass was investigated on the structural dynamic response. Unlike 0 W plates, plates with double weld seams experienced large plastic deformation along with small thinning happening at the long side clamped boundary. Therefore, despite increasing the deformation resistance, the welding lines tended to mitigate the damage tolerance of the tested mild steel plates. To gain more insight into the influence of two other key parameters like the position of the weld seam and its orientation on the dynamic response and energy absorption capacity, numerical simulations were also performed using the ABAQUS/Explicit finite element solver in conjunction with the inbuilt ConWep blast function code. For modeling the amplified blast wave produced by the detonation of the explosive charge, the scaling factor of 4.1 was adopted. Due to the welding process on the tested plates, the material degradation at the Heat-Affected Zone (HAZ) was also incorporated into the simulation by obtaining the knockdown factor from quasi-static tensile tests on unwelded and welded specimens. An excellent agreement between experiments and simulation results was achieved in terms of the impulse of the applied load and central permanent deflection. Furthermore, the present paper provides the primary experimental data and numerical simulation support for the blast resistance design of metallic structures using welded specimens.