Abstract
The present work investigates the impact behaviour of Al 2024-T3 alloy using FEM analysis performed through LS DYNA software. Johnson–Cookvisco-plastic model is used to study the ballistic impact resistance of target Al alloy impacted by a rigid steel cylindrical projectile. The tensile properties of Al 2024-T3 alloy reported in the literature are used to estimate the J.C. model parameters. Impact velocities within a range of 50 m/s–900 m/s of the projectile were triggered onto Al alloy target thicknesses in the range of 3.18 mm–6.35 mm. To understand the accuracy of the FEM model, an analytical model proposed by Chen et al. for blunt-nosed projectiles on the ductile targets was used to compare with the obtained residual velocities from FEM simulations. It was observed that the ballistic limit velocities have led to the highest energy absorption behaviour of the Al 2024-T3 alloy for an impact velocity of 183 m/s and a 6.35 mm target thickness. The ballistic limit velocities have increased from 97 m/s to 183 m/s for the considered thickness range of 3.18 mm–6.35 mm. The impact failure was observed to have a petalling formation with two petals for thinner targets, while a full-fledged plugging with no petal formation for the 4.00 mm and 6.35 mm target thicknesses was observed.
Highlights
The present work investigates the impact behaviour of Al 2024-T3 alloy using FEM analysis performed through LS DYNA software
An analytical understanding of the realistic problems from the graphical output with the given input parameters is still a key focus area of research in impact engineering [32,33]. This could be aided by performing ballistic numerical simulations for probable combinations of inputs, such as material properties, boundary conditions, contact at the interface, element size and type used, etc., that would affect the key parameters such as instantaneous stress, residual velocity of projectile, energy absorption characteristics of the target, failure mechanisms involved by the target, etc., which result from ballistic impact simulations
Among the 276 material models available in LS DYNA, 60 models are related to various materials constitutive behaviour [36]
Summary
The Al 2024 alloy is widely used in aerospace structural applications due to its high specific strength, fracture toughness, fatigue resistance, and thermal shock resistance [1]. An analytical understanding of the realistic problems from the graphical output with the given input parameters is still a key focus area of research in impact engineering [32,33] This could be aided by performing ballistic numerical simulations for probable combinations of inputs, such as material properties, boundary conditions, contact at the interface, element size and type used, etc., that would affect the key parameters such as instantaneous stress, residual velocity of projectile, energy absorption characteristics of the target, failure mechanisms involved by the target, etc., which result from ballistic impact simulations. The present study is focused to understand influence of the strain, strain rate and the thermal softening effect, using Johnson–Cook plasticity model (J.C. model), on the various target material thicknesses when it is subjected to different impact velocities of projectile. It can be considered as a substitute for experimental studies, as the modelling studies can be implemented for any structure with different boundary conditions and for different velocities and loads without significant effort
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