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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load history (calculated with eq. 1) as a uniform pressure field acting on two different areas, arbitrarily defined, with the pressure field in simulation B being 77% more intense than the one in simulation C. Nevertheless, these three methods were able to correctly predict the experimental deformation field with the only exception of the apex point in simulation B, overestimated by 14%. This confirms that the proposed methods are able to predict the structural consequences of the impacts independently from the local pressure distribution. In terms of stress waves (Fig. 8, Fig. 9 and Fig. 10), as well as resultant force at the constraints (Fig. 11), the three simulations gave very similar results. The observed differences hardly have any engineering relevance within the aim of the study. Moreover, the calculation time needed by simulation A was more than 10 2 times higher than the ones needed by simulations B and C, demonstrating the great advantage of the proposed load history method as a parsimonious tool for structural assessment by means of finite element explicit simulations.

Fig. 5. Epicenter of the impact showing the non-penetration as well as the traces of the fragments being deflected by the impacted surface. Dimensional reference is in cm.

Fig. 6. FSI simulation results showing the evolution of the interaction between bullet (red) and target (grey) from t=0 to t=0.05ms at constant 0.01ms time step.

‐1 1 3 5 7 9 ‐55 ‐50 ‐45 ‐40 ‐35 ‐30 ‐25 ‐20 ‐15 ‐10 ‐5 0 5 10 15 20 25 30 35 40 45 50 55 Residual displacements [mm] Distance from apex [mm] Field of residual displacements [mm] EXP. MIN EXP. MAX Sim. Load History R5.65 mm Sim. Load History R7.54 mm Sim. FSI

Fig. 7. Comparison between the range of experimental results (black dotted lines) and numerically predicted fields of residual displacements: simulation A (red) based on FSI; simulations B (green) and C (blue) based on load history.