PSI - Issue 13

Israr ul Haq et al. / Procedia Structural Integrity 13 (2018) 1955–1960 Israr ul Haq / Structural Integrity Procedia 00 (2018) 000–000

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1. Introduction Penetration resistance of materials remained key area under discussion for application of protective structures and critical components of all the products prone to impact. Situations like ballistic impact on concrete bunker, armored vehicles or casing of an aero engine, in fact almost every similar scenario needs protection from the penetration. A material, such as, Nickel based super alloy Inconel-718 is generally used in manufacturing of aero engine turbine blades. In order to evaluate strength of the material upon impact, while considering dynamic properties of the materials, ballistic impact tests are usually conducted. Same concept for various hemispherical/conical nose shape projectiles are presented in (Iqbal, Diwakar, Rajput, & Gupta, 2012; Rodríguez-Martínez, Rusinek, Pesci, & Zaera, 2013; Rodríguez-Millán, Vaz-Romero, Rusinek, Rodríguez-Martínez, & Arias, 2014; Vijayan, Hegde, & Gupta, 2017). Conical projectiles with apex angle and hemispherical nose shape projectile penetration has been studied on AISI 304 targets in (Rodríguez-Martínez et al., 2013), according to which, the conical projectile has ballistic limit greater than the hemispherical nose shape, and also deformation pattern varies with the nose shape. Further, In (Vijayan et al., 2017), the behavior of change in the apex angle for defomable conical projectiles has been studied, through the research is mainly focused on deformation of projectiles only. However, in (Iqbal et al., 2012), numerical simulation of ballistic impact by rigid conical projectile for apex angles were presented, and the conclusion that ballistic impact resistance decreases with the increase in apex angle from to has been made. Thus, this study presented a decreasing trend of ballistic limit with the increase in apex angles. None the less, the impact of apex angle conical, hemispherical and blunt nose shaped projectiles on 5754-H111 and 6082-T6 targets has been discussed in (Rodríguez-Millán et al., 2014), that shows deformation behavior as well as the ballistic limit of target varies with projectile nose shape, impact velocity, impact angle and target material. Therefore, in this paper, numerical simulation using ABAQUS/Explicit for spherical projectile impact on Inconel-718 is compared with the experimental data at ballistic limit. Johnson-Cook model is selected to define plasticity and failure properties of Inconel-718 material and the deformation mode has been analyzed for both experimental and simulation results. Furthermore, various apex angles of conical projectiles impact on Inconel-718 are evaluated, along with the deformation of target for each case, that is presented and discussed in terms of number of petals and crack length due to the radial stress. Ballistic limit is analyzed for conical projectile simulation, which indicates an increasing trend of ballistic limit from apex angle and then the decreasing trend from Details of strategy used for achieving the earlier mentioned results have been discussed in the subsequent sections. 2. Simulation Approach Numerical simulation is performed on 3D finite element model in ABAQUS/Explicit. Johnson-Cook constitutive model (Johnson, 1983; Johnson & Cook, 1985) is selected to define plasticity and failure properties for Inconel-718 target. Rigid spherical projectile with diameter and mass of are modeled. Target is modeled as a square plate with an edge length of and thickness of .

Fig. 1 3D Finite Element Model for Spherical Projectile Impact