Modelling Ballistic Impact of Firearm Projectiles on Compressed Earth Bricks

Chung Han Lim.

Transactions on Science and Technology, 8(3-3), 476 - 484.

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In this study, the terminal ballistic behavior of firearm projectiles on compressed earth bricks (CEB) was simulated using finite element modelling. Bricks are very commonly used as cladding in buildings and compressed earth bricks have recently made a comeback as an environmentally friendly alternative to typical fired clay bricks. CEBs have proven to possess stronger strength, whilst requiring less energy to produce and emitting less CO2 in the process. Whilst its mechanical properties are now well understood, there are very few studies that looked into the terminal effects of projectile impact onto brick faces and none at all on the ballistic impact on CEBs. Quite often, for buildings situated in conflict areas or war zones, brick clad walls are expected to provide resistance against ballistic impact of small arms fire. Ballistic testing of bricks can be difficult to carry out as it requires access to ammunition and gunnery range. In this study, CEB bricks are modelled in a finite element software ANSYS to simulate the terminal impact behavior of 9 mm caliber projectile. The results of this modelling were validated using another model where the CEB was replaced with a piece of European oak based on actual ballistic test results from a past journal paper that used the same material. By comparing the results of both ballistic simulation and actual ballistic experiment, the deviation between two results can be determined. The reference journal paper presents two numerical ballistic simulation on the penetration depth of European Oak and compressed earth brick subjected to impact by 9 mm bullets. The modelled penetration depth of European Oak subjected to impact by a 9 mm projectile at velocity of 412.7 m/s was 35 mm. Comparatively, the actual penetration depth of European Oak subjected to impact by the same projectile at the same travel speed was 46.5 mm. The deviation between simulated and actual penetration depth of the 9 mm projectile in the European Oak was 24.73 %. The simulated penetration depth of compressed earth brick subjected to impact by a 9 mm projectile at velocity of 338.3 m/s was 17.34 mm. The deviation of 24.73 % is considered quite high by comparing to other researcher’s deviation therefore, more information such as exact dimension of the European Oak target and detailed material properties of European Oak and 9 mm bullet are needed to reduce the deviation gap.

KEYWORDS: Compressed earth bricks; ICEB; bricks; Terminal ballistics; Finite element modelling; Projectile impact.

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