PSI - Issue 51

R. Andreotti et al. / Procedia Structural Integrity 51 (2023) 37–43 R. Andreotti et al. / Structural Integrity Procedia 00 (2023) 000–000

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2.1. Target’s material and mechanical characterization: Creusabro® high strength steel The target’s material was analyzed both chemically (the composition is summarized in Table 1) and mechanically (stress-strain curve in Fig. 2). The tensile tests in quasi-static regime assessed a Young’s modulus of 206000MPa, a yield stress of 1191MPa, an ultimate engineering stress of 1720MPa and an engineering failure elongation of 11%.

Fig. 1. Monolithic copper Hasler® .308 Win. Ariete 9.6g / 148gr.

Fig. 2. Engineering stress [MPa] vs strain [%] curve obtained from the tensile tests performed on Creusabro®.

Table 1. Chemical composition of Creusabro®.

C

Si

Mn

P

S

Cr

Ni

Mo

Cu

Fe

0,205

0,743

1,18

0,0093

0,0022

0,697

0,490

0,26

0,21

96,073

2.2. Numerical simulation methods and models Three simulations were conducted by means of the explicit solver LSDYNA according to the standard keyword manual by LSTC (2015). Simulation A was conducted in accordance with the simplified fluid structure interaction (FSI) method based on Arbitrary Lagrangian Eulerian formulation (ALE) fully described by Andreotti et al. (2021). Simulations B and C were instead conducted by applying the simplified load history formula (eq. 1) introduced by Andreotti et al. (2022), as a uniform pressure field acting on a circular area around the impact epicenter. In simulation B the radius of the loaded area is 1.5 times the bullet’s radius (1.5 x 3.77mm = 5.65mm). In simulation C the radius of the loaded area is 2.0 times the bullet’s radius (2.0 x 3.77mm = 7.54mm). Both B and C simulations use a full shell finite element model with element size 2.5mm as detailed by Andreotti et al. (2022). The constitutive model associated with the Creusabro® plates is a kinematic elastic-plastic model with failure. The post-yield hardening is regulated by a constant modulus of 11891.7 MPa; the initial necking strain is set to 0.05827. The rate effect was implemented