Lip Height and its Significance in Ballistic Studies

The mechanism of lip formation in steel arrnour plates has been investigated. Low alloy steelarrnour plates of20, 40 and 80 mm thickness were impacted at zero incidence by steel projectiles of 6.l ,20 and 40 mm diameter, respectively at.different velocities. The lip height was observed to exhibitdefinite correlations with other ballistic parameters like depth of penetration, crater volume, plasticzone and kinetic energy of the projectile

Complexities of Add-on Armour and Remedial Measures

Armoured fighting vehicles are under constant threat against newly developed antitank ammunition having higher penetration capabilities. Enhancing protection levels of existing tanks is associated with increased weight and volume penalties, affecting tactical mobility of the tank. The complexities arising in designing add-on armour are described along with the remedial measures. It is observed that even optimum add-on design calls for minor compromise in the usage of a battle tank

Ballistic Behaviour of Thick Steel Armour Plate under Oblique Impact : Experimental Investigation II

The ballistic behaviour of thick steel armour plate at different obliquities has been investigated. Ballistic experiments were conducted in the velocity range 300-800 mls at 0°, 15°, 30° and 45° obliquity .A steel, conical projectile or 6.1 mm diameter was impacted on a 10 mm thick steel armour plate. At 30° and 45° obliquity, the plate offers protection up to a striking velocity of 800 mls. At zero obliquity, the plate provides protection below 6~ m/s. The depth of penetration decreases with increasing obliquity. The plate resistance does not decrease at higher obliquity observed in an earlier work

Influence of Hardness on Perforation Velocity in Steel Armour Plates

In an earlier investigation3, the influence ofh'ardness on tempered steel armour plates of 20 mm thickness, impacted by. 20 mm diameter steel ogive-shaped projectile at normal , was studied. Additional data is investigated with relation to the perforation velocity of the plates. It is observed that the plate perforation velocity and the plate plugging velocity decrease with increasing plate hardness

Oblique Impact Study in Thin Steel Armour Plate

Results of a study on the perfom1ance of 10 rnrn low alloy, rolled-homogeneous armour (RHA)plate when impacted by 20 mm diameter steel ogive-shaped projectile at 15,30 and 45° angles ofattack in the subordnance velocity regime are presented. Experimental results show that 10 rnrn steelplate provides full protection at 45° obliquity up to a striking velocity of 530 rn/s. At low velocity(V < 350 rn/s), the plate provides protection at 30° obliquity, but fails to provide protection at an angleof attack of 15 0, even at low velocity ( V = 300 rn/s ).It is also observed that nom1al component of the strikiug velocity of the projectile is the main cause of plate perforation

Ballistic Behaviour of Thick Steel Armour Plate under Oblique Impact: Experimental Investigation .

The ballistic behaviour of thick steel amlOW- plate has been investigated at different obliquity when impacted by an ogive-shaped steel projectile. The ballistic experiments have been conducted in the velocity range 300-800 m/s. Both the thickness of the target plate and the diameter of the projectile were 20 Inm. At 30 and 45. obliquity 20 mm plate provides full protection at 800 m/s, whereas at 0 and 15. obliquity, the plate provides protection up to 600 m/s. At 15 and 30° obliquity, the plate exhibits lesser energy absorption capacity due to higher crater volume

Ballistic Behaviour of Tempered Steel Armour Plates under Plane Strain Condition .

The present investigation deals with the ballistic behaviour of tempered steel armour plates under plane strain condition at normal angle of attack. A conical-shaped steel projectile of 6.1 mmdiameter was impacted on 20 mm thick steel annour plates of 350, 450 and 550 Hv hardness, in the velocity range 200 -700 m/s at zero obliquity. Ballistic performance measured in terms of the depthof penetration indicates that, under plane strain condition, behavio1Do" f 550 Hv steel plate is better than those of the other two plates. However, front spalling causes damageto the entry side of the high hardness plate, thus affecting its multihit capability in a limited manner

The dynamic indentation behavior of steel at large depths of penetration

The objective of the present study is to investigate the dynamic indentation behavior of steel plate material when impacted by ogive-shaped projectiles and in particular under indentation conditions involving large depths of penetration (i.e., depth of penetration greater than projectile radius). Toward the above purpose, dynamic indentation of steel plates of thickness 20, 40, and 80 mm have been carried out using projectiles of diameter 6.2 and 20 mm, and over a range of impact velocities so as to attain depths of penetration in the range 1.4 to 3.6 times the projectile radius. The results indicate that the dynamic hardness, the plastic zone size, specific energy consumed in plastic deformation within the plastic zone, and the average plastic strain within the plastic zone increases continuously with increasing values of depth of penetration normalized by projectile radius. Certain subtle differences regarding the nature of plastic deformation between indentation at large and shallow depths of penetration are presented. However, on a macroscopic scale, the indentation mechanisms and processes are broadly similar and show continuity in terms of behavior across the whole penetration depth range

Effect of Clamping Rigidity of the Armour on Ballistic Performance

Influence of the manner in which the armour plates are held during their ballistic testing on the armour performance, has been evaluated. One armour plate was clamped rigidly to the test stand while a second plate of identical composition, hardness, and dimensions was hung loosely from the target holder. Both these plates were impacted with the same type of projectiles and over the same impact velocity range. The nature of ballistic damage evaluated indicates that the manner in which the armour is held during ballistic testing has a negligible influence on its performance at least when the mass of the plate is substantially higher than that of the projectile

Determination of rainfall thresholds for landslide prediction using an algorithm-based approach: Case study in the Darjeeling Himalayas, India

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. Landslides are one of the most devastating and commonly recurring natural hazards in the Indian Himalayas. They contribute to infrastructure damage, land loss and human casualties. Most of the landslides are primarily rainfall-induced and the relationship has been well very well-established, having been commonly defined using empirical-based models which use statistical approaches to determine the parameters of a power-law equation. One of the main drawbacks using the traditional empirical methods is that it fails to reduce the uncertainties associated with threshold calculation. The present study overcomes these limitations by identifying the precipitation condition responsible for landslide occurrence using an algorithm-based model. The methodology involves the use of an automated tool which determines cumulated event rainfall–rainfall duration thresholds at various exceedance probabilities and the associated uncertainties. The analysis has been carried out for the Kalimpong Region of the Darjeeling Himalayas using rainfall and landslide data for the period 2010–2016. The results signify that a rainfall event of 48 h with a cumulated event rainfall of 36.7 mm can cause landslides in the study area. Such a study is the first to be conducted for the Indian Himalayas and can be considered as a first step in determining more reliable thresholds which can be used as part of an operational early-warning system