Penetration of shaped charge into layered and spaced concrete targets

This paper presents the results of a study about the influence of cone angles and liner materials on shaped charge penetrating layered and spaced concrete targets. The experiments are performed using shaped charges with a fixed aspect ratio (length : diameter = 1:1) detonated at a stand-off distance of 120.0 mm (equivalent to twice the diameter of the shaped charge). The penetrating performance of three different liner materials (steel, copper and aluminium) formed with varying cone angles is evaluated in terms of diameters of entry and exit craters and depth of penetration. The results indicate that shaped charge with the aluminium liner forms the largest crater in the concrete targets. The shaped charge with the copper liner causes the deepest penetration. The results also indicate that, when the cone angle is less than 120°, the spaced target can provide better protection than the layered target in resisting the impact damage by the shaped charge with steel and copper liner. Compared with the layered target, the spaced one does not improve the level of protection against the jet formed by the aluminium cone liner. The experiments are also simulated with the commercially available software Autodyn using material parameters from four different sources. The results from the simulations are compared and evaluated in terms of depth of penetration of the target. An analytical method proposed to predict the depth of penetration of the concrete target using rod length erosion shows good correlation with the experiments.