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Mechanics of ballistic impact with non-axisymmetric projectiles on thin aluminium targets. Part II: Energy considerations

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posted on 2022-12-16, 13:54 authored by Theodosios Stergiou, Konstantinos BaxevanakisKonstantinos Baxevanakis, Anish RoyAnish Roy, Vadim SilberschmidtVadim Silberschmidt

In Part I of this study, the ballistic performance and failure mechanisms of a thin aluminium target impacted by plate-like, non-axisymmetric projectiles with three different geometries, were considered using the gas-gun experiments. Failure mechanisms of the target material were found to depend strongly on the projectile’s geometrical features. Also, the local target’s response was not a reliable predictor of the critical kinetic energy for perforation or penetration. In order to improve the prediction of ballistic performance of thin targets, a nonlocal target behaviour should also be accounted for. In this part of the study, the global target response is examined, and a heuristic approach is introduced for the energy balance. The approach involves a new factor that represents additional energy-dissipating mechanisms between the projectile’s critical energy and the local work in target defeat. The methodology is based on the identified strong correlation of the normalised impact-induced peak kinetic energy in the target, KETmax, and the normalised target impact-induced nonlocal internal energy, UT(PL+KE), associated with plastic deformation and increase in kinetic energy. A physically-based semi-analytical formulation for KETmax  is developed by decomposition of the contributions by the inclined and blunt projectile sections, succeeding statistical analysis of key projectile’s geometrical and impact parameters. The developed approach was assessed for 17 projectile geometries implementing a total of 119 finite-element simulations with experimentally validated numerical models at subcritical (50) and critical/supercritical (69) projectile velocities. The obtained predictions had an average absolute error of less than 6.5% for impact velocities at and above the ballistic limit, while at subcritical velocities a higher scatter was observed as a result of secondary interaction effects between the projectile and the target. Overall, the methodology yielded results for the ballistic limit with an error below 5%, improving the otherwise derived results nearly twofold. The method was proven to be a practical and accurate way to improve the projectile’s critical energy prediction for thin targets, and, even though developed for non-axisymmetric projectile cases, its framework is directly transferable to axisymmetric projectiles.

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Engineering Failure Analysis

Volume

143

Issue

Part B

Publisher

Elsevier

Version

  • VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (CC BY-NC-ND). Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

2022-09-09

Publication date

2022-10-02

Copyright date

2022

ISSN

1350-6307

eISSN

1873-1961

Language

  • en

Depositor

Dr Konstantinos Baxevanakis. Deposit date: 15 October 2022

Article number

106818

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