Boron carbide is an attractive candidate for use as armour material because of its lower density ... more Boron carbide is an attractive candidate for use as armour material because of its lower density combined with high hardness. The ballistic performance of boron carbide tiles were evaluated using standard Depth of Penetration (DOP) test method against hard steel 7.62 mm armour piercing (AP) projectiles. The effect of variation in thickness of tile and the projectile velocity on the ballistic efficiency of the material was studied. It has been found that the differential efficiency factor (DEF) increases with increase in projectile velocity from 600 to 820 m/s. And an insignificant or marginal increase in efficiency was observed for increase in tile thickness from 5.2 mm up to 7.3 mm. The effect of the type of radial confinement on the residual DOP was also studied. It was found that the steel radial confinement produces lower residual DOP values compared to aluminium alloy and with no radial confinement. Results along with photographs have been presented.
An experimental study has been carried out on the ballistic performance of 95% and 99.5% alumina ... more An experimental study has been carried out on the ballistic performance of 95% and 99.5% alumina ceramic tiles backed by metal plates, when subjected to normal impact of hard steel 12.7 mm armour piercing (AP) projectiles at velocities ranging from 500 to 830 ms−1. Typical damaged targets and broken projectiles are presented. The depth of penetration is measured in all the experiments, and the ballistic efficiency factor of the ceramic plates are determined.Results show that the efficiency factor increases with increase in projectile velocity. With the increase in thickness of the ceramic tile, the ballistic efficiency factor for a given velocity is observed to decrease in the case of 99.5% grade and increase in the case of 95% grade ceramic. The higher purity alumina (99.5%) shows higher ballistic performance when compared with the 95% alumina. The 99.5% alumina exhibited a predominantly transcrystalline fracture while the 95% alumina showed a less defined fracture surface.Experiments on 7.62 mm AP shots were also done keeping the (d/td/t) ratio same as in 12.7 mm AP experiments and results are presented.
A series of experiments was carried out wherein spinning armour piercing projectiles of core diam... more A series of experiments was carried out wherein spinning armour piercing projectiles of core diameter 6.2 mm were fired on mild steel plates of thicknesses varying from 10 to 25 mm. The projectile velocity in all the tests was about 820 ms−1 in both normal and oblique impacts. In successive tests on plates of each thickness, the angle of obliquity was increased from 0° (normal impact) until richochet occurred. The impact velocities in all tests and the residual velocities in tests wherein the plates were perforated, were measured. Velocity drop versus angle of obliquity curves are presented for plates of different thicknesses. The target damage is examined and the conditions at ballistic limit and ricochet are discussed.
An experimental study of the normal and oblique impact of armour-piercing projectiles on single a... more An experimental study of the normal and oblique impact of armour-piercing projectiles on single and layered plates of mild steel, RHA steel and aluminium is presented. The projectiles were fired at an impact velocity of ∼800–880 m s−1. The plate thickness varied in the range 4.7–40 mm and the ratio of the plate thickness to the diameter of the projectile varied in the range 0.75 – 6.5 for single plates and up to 13 for layered plates. Observations on target damage and measurements of incident and residual velocities and the angles in normal and oblique impact are presented. Determination of plate thickness t∗, for which the incident velocity is the ballistic limit, is considered and influences of various parameters, like plate material and its thickness, on t∗ and the residual velocity are discussed. Relations are developed to determine the residual velocity for a plate of thickness less than t∗, and to relate t∗ with the hardness of the material. Results for the residual velocity obtained from these relations are compared with those from the experiments.
Boron carbide is an attractive candidate for use as armour material because of its lower density ... more Boron carbide is an attractive candidate for use as armour material because of its lower density combined with high hardness. The ballistic performance of boron carbide tiles were evaluated using standard Depth of Penetration (DOP) test method against hard steel 7.62 mm armour piercing (AP) projectiles. The effect of variation in thickness of tile and the projectile velocity on the ballistic efficiency of the material was studied. It has been found that the differential efficiency factor (DEF) increases with increase in projectile velocity from 600 to 820 m/s. And an insignificant or marginal increase in efficiency was observed for increase in tile thickness from 5.2 mm up to 7.3 mm. The effect of the type of radial confinement on the residual DOP was also studied. It was found that the steel radial confinement produces lower residual DOP values compared to aluminium alloy and with no radial confinement. Results along with photographs have been presented.
An experimental study has been carried out on the ballistic performance of 95% and 99.5% alumina ... more An experimental study has been carried out on the ballistic performance of 95% and 99.5% alumina ceramic tiles backed by metal plates, when subjected to normal impact of hard steel 12.7 mm armour piercing (AP) projectiles at velocities ranging from 500 to 830 ms−1. Typical damaged targets and broken projectiles are presented. The depth of penetration is measured in all the experiments, and the ballistic efficiency factor of the ceramic plates are determined.Results show that the efficiency factor increases with increase in projectile velocity. With the increase in thickness of the ceramic tile, the ballistic efficiency factor for a given velocity is observed to decrease in the case of 99.5% grade and increase in the case of 95% grade ceramic. The higher purity alumina (99.5%) shows higher ballistic performance when compared with the 95% alumina. The 99.5% alumina exhibited a predominantly transcrystalline fracture while the 95% alumina showed a less defined fracture surface.Experiments on 7.62 mm AP shots were also done keeping the (d/td/t) ratio same as in 12.7 mm AP experiments and results are presented.
A series of experiments was carried out wherein spinning armour piercing projectiles of core diam... more A series of experiments was carried out wherein spinning armour piercing projectiles of core diameter 6.2 mm were fired on mild steel plates of thicknesses varying from 10 to 25 mm. The projectile velocity in all the tests was about 820 ms−1 in both normal and oblique impacts. In successive tests on plates of each thickness, the angle of obliquity was increased from 0° (normal impact) until richochet occurred. The impact velocities in all tests and the residual velocities in tests wherein the plates were perforated, were measured. Velocity drop versus angle of obliquity curves are presented for plates of different thicknesses. The target damage is examined and the conditions at ballistic limit and ricochet are discussed.
An experimental study of the normal and oblique impact of armour-piercing projectiles on single a... more An experimental study of the normal and oblique impact of armour-piercing projectiles on single and layered plates of mild steel, RHA steel and aluminium is presented. The projectiles were fired at an impact velocity of ∼800–880 m s−1. The plate thickness varied in the range 4.7–40 mm and the ratio of the plate thickness to the diameter of the projectile varied in the range 0.75 – 6.5 for single plates and up to 13 for layered plates. Observations on target damage and measurements of incident and residual velocities and the angles in normal and oblique impact are presented. Determination of plate thickness t∗, for which the incident velocity is the ballistic limit, is considered and influences of various parameters, like plate material and its thickness, on t∗ and the residual velocity are discussed. Relations are developed to determine the residual velocity for a plate of thickness less than t∗, and to relate t∗ with the hardness of the material. Results for the residual velocity obtained from these relations are compared with those from the experiments.
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Papers by Madhu Vemuri