Simulation of shear plugging through thin plates using the GRIM Eulerian hydrocode
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I. INTRODUCTION
THE terminal effectiveness of kinetic energy penetrators, whether long rods or explosively formed projectiles (EFPs), is strongly dependent upon the material response of the target. At impacts below the limit velocity, single plates bulge around the impact region. As the impact velocity increases, an intact plug of plate material is ejected. With further increases in impact velocity, the plug fractures into a number of pieces as can the projectile. The accurate simulation of this complex deformation and fracture behavior requires advanced numerical techniques and material algorithms, particularly the fracture and strain localization processes. One of the major limitations of many impact and penetration modeling studies has been the inability to properly treat target and penetrator fracture. Without such a capability, hydrocode simulations tend to overestimate the loss of penetrator mass and velocity associated with the penetration process, especially for thicker target plates. While Lagrangian techniques have been successfully used[1] to simulate shear plugging, they rely upon element deletion or erosion, based upon various failure criteria. As a result, this criteria tends to be problem dependent and is therefore not predictive. Little work has been reported using Eulerian methods. Initial work centred on aluminum spheres against steel target plates.[2] The aim of this work was to obtain shear P. CHURCH, Technical Leader, Material Algorithms, R. CORNISH, Professional Scientist, and I. CULLIS, Technical Leader, Hydrocode Group, and N. LYNCH, Technical Leader, Kinetic Energy Projectiles, are with the Terminal Effects Division, Defence Evaluation & Research Agency, Fort Halstead, Sevenoaks, Kent, TN14 7BP, United Kingdom. This article is based on a presentation given in the symposium entitled “Dynamic Behavior of Materials—Part II,” held during the 1998 Fall TMS/ ASM Meeting and Materials Week, October 11–15, 1998, in Rosemont, Illinois, under the auspices of the TMS Mechanical Metallurgy and the ASM Flow and Fracture Committees. METALLURGICAL AND MATERIALS TRANSACTIONS A
plugging data for a variety of armour materials and to use these data to validate advanced constitutive models and numerical techniques being developed by DERA. The results also provide a benchmark for sensitivity studies of existing numerical methodologies, including adaptive meshing techniques. Some of these aspects are discussed in this article. II. EXPERIMENTS A. Projectile and Targets Aluminum alloy spheres, 25.4 mm in diameter, made from 2017-H13 material, were used as impactors. The typical projectile mass was 23. 9 g with the surface finish and geometric tolerances being very good, since these spheres are normally used for ball bearings. The spheres were launched from a 40-mm smooth bore gun using a two-petal nylon 66 sabot. The target plates were cut into 200-mmdiameter discs and were bolted onto a range stand having an inner supporting diameter of 160 mm. The target plate materials studied were United Kingdom rolled homog
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