Response of welded aluminium alloy plates for ballistic loads

Abstract

ABSTRACTLight-weight metals like aluminium are preferred to for building of high speed crafts, naval ships, superstructures of commercial ships and offshore platforms. In plate joining, the efficiency of joint is a measure of its impact resistance and structural-integrity. The plates welded together should function effectively against any external loads under emergencies. An ideal welded joint should possess superior weld strength with good impact resistance. Cold metal transfer (CMT) is a proven type of welding technique which is proposed for marine fabrications. Plates of aluminium alloys with grade AA5086-H111 and AA6061-T6 are welded together using a filler, AA4043. For the purpose of plate joining, parameters like current, voltage, arc length, shield gas pressure, etc. are varied to arrive at a continuous weld without any crack. In this study, welded thin plates are subjected to tensile test and thereafter impact loads are applied. The plates are subjected to impact loads in the range of sub-ordinance level velocities, feasibility of ordinance and ultra-ordinance can be scaled and compared. Thus, various ballistic loads are applied at the welded joints. Response and terminal ballistics limit are determined for thin plates of thickness 1.2 and 3 mm plates. This study consists of simulation in Abaqus software and experiments using a gun prepared in the laboratory. It was observed that, there was petaling in very thin plates and perforations by plugging for lower ballistic loads and thinner plates. The work gives new insights in the application of CMT in joining of plates of different metals with varied thickness values. The experimental results can be used as bench marks to compare results of simulations for thin plates. While experiments were done for thin plates, only computer simulation was done for thicker plate of 12 mm which is usually accepted for fabrication in industry.