High-Velocity Impacts of Pyrophoric Alloy Fragments on Thin Armour Steel Plates.

Evaristo Santamaria Ferraro,Norbert Faderl,Marina Seidl,Tom De Vuyst

doi:10.3390/ma14164649

Evaristo Santamaria Ferraro, Norbert Faderl + Show 2 more

Open Access

https://doi.org/10.3390/ma14164649

Copy DOI

Abstract

The terminal ballistics effects of Intermetallic Reactive Materials (IRM) fragments have been the object of intense research in recent years. IRM fragments flying at velocities up to 2000 m/s represent a realistic threat in modern warfare scenarios as these materials are substituting conventional solutions in defense applications. The IRM add Impact Induced Energy Release (IIER) to the mechanical interaction with a target. Therefore, the necessity of investigations on IIER to quantify potential threats to existing protection systems. In this study, Mixed Rare Earths (MRE) fragments were used due to the mechanical and pyrophoric affinity with IRM, the commercial availability and cost-effectiveness. High-Velocity Impacts (HVI) of MRE were performed at velocities ranging from 800 to 1600 m/s and recorded using a high-speed camera. 70 MREs cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm. The influence of the impact pitch angle (α) on HVI outcomes was assessed, defining a threshold value at α of 20°. The influence of the failure modes of MRE and steel fragments on the critical impact velocities (CIV) and critical kinetic energy () was evaluated. An energy-based model was developed and fitted with sufficient accuracy the Normalised () determined from the experiments. IIER was observed in all the experiments involving MRE. From the analyses, it was observed that the IIER spreads behind the targets with velocities comparable to the residual velocities of plugs and shattered fragment.

Highlights

The interest of the defence industry towards Intermetallic Reactive Materials (IRM) is related to their structural properties, combined with the exothermal reaction triggered by a thermal or mechanical shock, as discussed by Aydelotte [1].IRM represent a valid substitute for inert casings of next-generation warheads, augmenting the post-detonation lethality abundantly
70 Mixed Rare Earths (MRE) cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm
Impact Induced Energy Release (IIER) was observed in all the experiments involving MRE

Summary

Introduction

The interest of the defence industry towards Intermetallic Reactive Materials (IRM) is related to their structural properties, combined with the exothermal reaction triggered by a thermal or mechanical shock, as discussed by Aydelotte [1]. The IRM fragments will eventually interact with a target, triggering the Impact Induced Energy Release (IIER) (d). In order to set up a coherent and reproducible methodology, High-Velocity Impacts (HVI) experiments were performed using a ballistic set-up, shooting commercial Mixed Rare Earths (MREs) cylindrical samples, with diameters of 3.5 mm and 5 mm and length L over diameter d ratios (L/d) of 1. The works from Waite et al [6] and Hillstrom [7] represent a valid reference in assessing the ballistic and pyrophoric investigation of MREs. The present work discusses the IIER of MREs using a state-of-the-art experimental set-up, described in detail in SecMaterials 2t0i2o1n, 142, 4.164.9Furthermore, the HVI of MREs described in this paper were performed using 3 of 22 armour steel plates with HB hardness significantly higher than targets used in previous studies, as they are representative of a realistic target in a modern warfare scenario. FiFvoersrheofetsrewnecere, Fpiegruforerm3esdhowwitsh3oufrtalmigehstifnrgomto tfhoecuhsigohnstpheeeIdIErRec. oTrhdiisngsest-oufpad5omesm noMt RalElofwraegvmaelunattiimngpathcetinagngale2omf mimpplaactteαatb8u8t9ismn/esc.eIstsiasryvitsoibfloectuhsaot nthreeapcltuiogn, tihneitfiarotinotnof and evolution

Materials

Analysis of Critical Impact Energy

Results

Plate Perforation