Effect of ballistic impact on Ti6Al-4V titanium alloy and 1070 carbon steel bi-layer armour panel

Abstract

PurposeBallistic missile-resistant impact panels have seen fair advancement over the years, especially in military applications. However, high cost, as well as a changing materials landscape, has impressed the need for a deeper understanding of impact mechanism as well as of new permutations in design strategy development. Parameters such as projectile impact angle, panel impact location as well as application of multilayer sandwich panels are not fully explored and characterised. In this work, finite element method simulation methodology is used on a 25 mm by 25 mm plate of 3.5 mm thickness to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles of 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels. Subsequently, a bilayer panel comprising of titanium alloy at the impact layer with the same overall plate thickness is investigated for impact at five different impact speed (ranging from 100 ms-1 to 500 ms-1). The displacements and von Mises stresses are documented for all cases, and it is shown that angular impact angles bring about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also indicate that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved (up to twice the impact load), especially at higher impact velocities. The study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.Design/methodology/approachIn this work, finite element method simulation methodology is used to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels, and, subsequently, a bilayer panel comprising of titanium alloy for the outer layer is investigated for the combination of the same aforementioned materials. Five different impact speed effects are studied.FindingsThe effects and trends of displacements and stresses are documented for all cases and shown to indicate angular impact angles bringing about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also show that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved, especially at higher impact velocities.Originality/valueThe study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.