After numerical simulation and result analysis, the conclusion is that a 30mm armor-piercing projectile at an impact speed of 750m/s achieves the full penetration effect on 30mm thick plates while in the case of a 40mm thickness, it jams into the plate.
For different purposes, it is of great importance to determine the limit (maximum) plate thickness for which the projectile with defined ballistic and material characteristics is able to achieve the full penetration effect.
For the additional simulation cases, the same input parameters are used for the projectile, and the only difference is the armor plate thickness.
Additional numerical simulations are carried out in accordance with the previously defined models using the same initial and boundary conditions. It is found that the full penetration effect is achieved on plates
with a thickness of up to 33mm, and after increasing the thickness to higher values, a limited penetration effect then occurs.
Case 3 – Plate thickness of 33mm
Figures 24-29 show the Von Misses equivalent stress and penetration effect for armor plate Weldox 460 with a thickness of 33mm.
As the results from Figures 24-29 show, the projectile has sufficient kinetic energy to achieve the full penetration effect in the plate of a thickness of 33mm. A large number of fragments are created behind the
armor plate as separated parts of both the projectile and the plate.
Figure 30 shows the projectile velocity from the moment when it starts penetration into the plate until the moment of passing through the plate.
The projectile velocity after penetration is 70m/s.
Figure 31 shows plate displacement as a function of time. It shows that the first movement of the plate occurs after 0.1ms. The maximum plate displacement is 1.2mm.
Case 4 – Plate thickness of 34mm
Figures 32-37 show the Von Misses equivalent stress and penetration effect for armor plate Weldox 460 with a thickness of 34mm.
As the results from Figures 32-37 show, the projectile does not have sufficient kinetic energy to achieve the penetration effect in the plate of a thickness of 34mm. After collision with the plate, the projectile jams into
the plate. But, differently from case 2 with the 40mm plate, in this case projectile’s semi penetration creates a number of fragments, which can also have a big impact on potential targets behind the plate. Figure 38
shows the projectile velocity from the moment when it starts penetration into the plate until the moment when it jams into the plate after 0.3ms.
Figure 39 shows plate displacement as a function of time. It shows that the first movement of the plate occurs after 0.1ms.
The maximum plate displacement is 1.4mm.
Conclusion
Armor-piercing projectiles are designed to penetrate either body armor or vehicle armor. Due to their high kinetic energy at the time of impact with an obstacle and their body’s exceptional endurance, they are
able to penetrate armor.
It is extremely difficult to represent the impact of an armor-piercing projectile, but the models created successfully describe the real issue of projectile penetration (or with a certain deviation). In recent times, analysis using the finite element method has proven to be one of effective approaches to solving such and similar problems.
In this paper, a numerical simulation of the penetration process of a 30mm anti-aircraft armor projectile into Weldox 460 alloy plates of different thicknesses was performed.
Spasić (2018) has also taken into account the analysis of Weldox 460 armor steel during numerical modeling of a projectile impact on metal structures and shown its behavior when it is in collision with projectiles of different shapes.
Based on a detailed review of the literature, it is found that deformation, strain rate, temperature, and pressure are the key factors that have the greatest influence on the penetration process.
In order to correctly describe these phenomena, it is necessary to define equations of state and models of material behavior. The Johnson–Cook material model and the Mie–Grüneisen equation of state were used
to define the models.
To determine the maximum penetrating ability of the projectile, four simulation cases with different plate thicknesses were performed.
In case 1, with a plate thickness of 30mm, and case 3, with a plate thickness of 33mm, the projectile had the full penetration effect into the defined plates, because the projectile’s impact velocity and kinetic energy
were higher than needed for the full penetration effect. The projectile velocity behind the plate in case 1 is 220m/s, and in case 3 the velocity is 70m/s.
In case 2, the projectile jammed into the plate with a thickness of 40mm, while in case 4, the projectile jammed into the plate with a thickness of 34mm, but its semi-penetration generated a larger number of fragments behind the plate. In all four cases, the first plate displacements occur after 0.1ms of the analysis.
The projectile with the defined ballistic material and characteristics has the ability to fully penetrate the Weldox 460 plate with a maximum thickness of 33mm.
The calculated ballistic armor steel plate thickness of 33mm is not produced as a standard monobloc plate, but in reality, this thickness can be achieved as a sandwich armor plate with one thicker (e.g., 30mm) and
one thinner plate (e.g., 3mm), or with one 30mm plate placed at some angle to the vertical axis.
When defining the ballistic protection of an armored vehicle against projectiles of defined characteristics, it is necessary to use armor steel with a thickness greater than the calculated one in order to neutralize a
potential effect of separate fragments from the other side of the plate.
Despite the fact that analytical and numerical methods of calculation can provide correct data about the character of certain phenomena, it is always desirable and necessary, first of all, to carry out experimental tests on the training ground and, after obtaining certain results, to make the necessary corrections and examine the given phenomenon with numerical methods in order to solve the problem more easily and economically.
