An experimental investigation into deformation modes and failure mechanism of welded rectangular plates under repeated blast loading

In this paper, the dynamic response of steel plates under repeated blast loading using a ballistic pendulum system were investigated. In this regard, experiments were performed on three different configurations: unwelded, welded with single and double welding lines. To apply the dynamic load in a wide range, the plastic explosive charge (C4) in different masses of 25, 35, 45, and 50 g were used. Besides, to investigate the behavior of the structure under repeated loading, experiments were tested on up to 3 loads. Experimental observations demonstrate that with increasing charge mass, the large inelastic deformation with necking and tensile tearing around of the boundary were observed in higher charge masses and loading repetitions in higher numbers. For the unwelded plate, at the 3rd load with a charge mass of 25g, a change in the failure mode was observed (large inelastic deformation with necking around part of the boundary), however, for the welded plate with a single weld line, the same deformation mode occurred at the 3rd blast load by the charge mass of 35g. For the welded plate with two weld lines, the same failure mode was observed at the 3rd blast load by the charge mass of 45g. These observations indicate the effect of the weld line and its numbers on the variation of failure modes. The obtained result is one of the main objectives of the present study to show how using welding lines and their arrangements affect the deformation mode and the failure mechanism of steel plates.