Science of Armour Materials

This article discusses some basic principles that underlie design of effective armour materials against various modes of attack

Acoustic transducer apparatus with reduced thermal conduction

A horn is described for transmitting sound from a transducer to a heated chamber containing an object which is levitated by acoustic energy while it is heated to a molten state, which minimizes heat transfer to thereby minimize heating of the transducer, minimize temperature variation in the chamber, and minimize loss of heat from the chamber. The forward portion of the horn, which is the portion closest to the chamber, has holes that reduce its cross-sectional area to minimize the conduction of heat along the length of the horn, with the entire front portion of the horn being rigid and having an even front face to efficiently transfer high frequency acoustic energy to fluid in the chamber. In one arrangement, the horn has numerous rows of holes extending perpendicular to the length of horn, with alternate rows extending perpendicular to one another to form a sinuous path for the conduction of heat along the length of the horn

Armour Protection and Affordable Protection for Futuristic Combat Vehicles

Protection creates a shift in the internal paradigm of the soldier and leads to multiplied psychological stamina for moving fearlessly in the battlefield which generates a major force-multiplier effect. Hence, the mechanized forces are still likely to be one of the dominant forces on the futuristic battlefield and would be the primary target of enemy forces capable of engaging from tank guns up to 4-5 km in a direct fire mode and up to 8-10 km in an indirect fire modes. Increased protection is possible only using advanced armour technology. Throughout the history of warfare, materials technologies have had a significant impact on land-combat force capabilities. Armour materials have progressed through improvements in metallic systems and development of advanced, lightweight (low areal density) composite materials. The advancements in ceramic systems have further improved the performance. Similarly, the advances in development of explosive reactive armour has generated efficient armour system against all contemporary high explosive antitank (HEAT) ammunition and missile threats for armoured vehicles. Yet, to achieve armour performance exceeding that of the current light combat vehicles and main battle tanks for new vehicular systems, weighing significantly less than the present combat vehicles, advances in new armour materials, systems, and survivability technologies are required. This paper describes various approaches and advancements in the metallic, ceramic, and composite armour materials and new dynamic armour systems that are essential to improve the survivability of armoured vehicles in the futurisitic multi-spectral battlefied scenarios.Defence Science Journal, 2011, 61(4), pp.394-402, DOI:http://dx.doi.org/10.14429/dsj.61.36

Normal and Oblique Impacts of Hard Projectile on Single and Layered Plates-An Experimental Study

The phenomenon of ordnance velocity impact of projectile on single and layered plates is of interest for many applications. In this paper. an experimental study of normal and oblique impacts or an ogive shaped, hard steel projectile on single and layered plates of mild steel and aluminium is presented. The projectiles were fired at an impact velocity of about 820 ms-1. The plate thickness was varied in the range 10 mm to 40 mm and the ratio of plate thickness to the diameter of the projectile varied in the range 1.5 to 13.0. Observations on target damage and measurements of incident and residual velocities for different angles of impact are presented. Plate thickness t*, for which the incident velocity is the ballistic limit, is determined. Computer simulations were carried out using a hydrodynamic code to simulate the normal impact of a projectile and compared these with the experimental results. Experiments were performed to evaluate the response of these plates of intermediate thickness when layered. and the results were compared to the results of single plate of same total thickness

Differential Ballistic Response of Aramid-Glass Fibre Laminates to Soft and Hard Shots .

Ballistic perfonnance of all-glass, all-aramid and aramid-glass fibre-reinforced phenolic resincomposite laminates has been evaluated against 0.30 in. calibre soft ball and hard armour piercing (AP) bullets. It is observed that mass effective ness of glass fibre phenolic composites against impacts by APbullets can be improved by aramid fibre'reinforcement in the back of laminate. The perfonnance of a ramid phenolic composites against ball ammunition can be improved by hybridisation with glass fibre reinforcement at the front

Determination of Surface Area of Head for Biomedical and other Applications

A simple, rapid and reproducible method has been devised for measuring the surface area of the head relevant for armour design. In this method, the following stages are involved: (i) securing a kraft paper over the head with the help of elastic band, (ii) tightly folding the paper wherever necessary to make a snug contour-matched paper dome, (iii) marking the folded areas with lines, (iv) spreading the paper and cutting out areas within the folds and the area filling outside the marked periphery of interest, (v) weighing the cut-out pieces and few pieces of known area from the same sheet, and finally (vi) calculating the head-surface area. Preliminary data on 12 volunteers indicated that head-surface area has no significant correlation with their age, total body-surface area calculated from height and weight or with the circumference of their heads. A significant and positive correlation was found with cephalic length. The new method can find application in biomedical studies and head gear designs (e.g. helmets)

Computer Applications in Metallurgical Research

This paper outlines the current efforts in computer applications in metallurgical research at the Defence Metallurgical Research Laboratory, Hyderabad. Work being done on armour penetration studies, optimization of armour profiles for fighting vehicles, computer control of multifunction 2000 tonne forge press, drawing of processing mechanism maps, process modelling of titanium sponge production and methods of curve fitting to experimental data, is described and briefly discussed

Influence of Polymer Restraint on Ballistic Performanceof Alumina Ceramic Tiles

An experimental study has been carried out to evaluate the influence of confinement ofalumina ceramic tiles through polymer restraint, on its ballistic performance. Tiles of 99.5 per centpurity alumina were subjected to ballistic impact against 7.62 mm armour piercing projectiles atvelocities of about 820 m/s. The tiles of size 75 mm x 75 mm x 7 mm were confined on both facesby effectively bonding varying numbers of layers of polymer fabrics. These were then bondedto a 10 mm thick fibre glass laminate as a backing using epoxy resin. High performance polyethyleneand aramid polymer fabrics were used in the current set of experiments for restraining the tiles.Comparative effects of confinement on energy absorption of tiles with varied number of layersof fabrics were evaluated. It was observed that by providing effective confinement to the tile,energy absorption could be doubled with increase in areal density by about 13 per cent.Photographs of the damage and the effects of restraint on improvement in energy absorptionof ceramic tiles are presented and discussed

A Thermodynamic Analysis of Urbanization

This article deals with application of concepts in thermodynamics to the process of urbanization which is a global phenomenon. The disorder in urban environment due to high density of population is likened to the entropy concept of thermodynamics which is assumed to increase with population size. This introduces a check on urbanization and leads to a dynamic equilibrium between urban and rural population components. A discussion is provided on a few factors which may be monitored to control urbanization particularly in the less developed regions of the world