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Kaur J.,Terminal Ballistics Research Laboratory | Arya V.P.,Terminal Ballistics Research Laboratory | Kaur G.,Terminal Ballistics Research Laboratory | Lata P.,PEC University of Technology
Central European Journal of Energetic Materials | Year: 2013

In the present paper, a series of bimodal PBX compositions containing coarse (90 μm) and fine (<1 μm) HNS (2,2'4,4'6,6'-hexanitrostilbene) and hybrid PBX compositions based on HNS and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) in varying mass ratios, along with the fluoropolymer Viton-A, a vinylidene fluoride and hexafluoropropylene copolymer, as abinder (5%), have been prepared on the lab scale. In order to observe any effectofincorporating fine HNS particles with coarse ones and the effect of replacing HNS with HMX in all types of bimodal and hybrid PBX compositions, the samples were characterized for composition analysis, thermal behavior and morphological analysis as well as evaluated for their mechanical and explosiveproperties including sensitiveness tests and detonic properties. The datashowed that incorporation of fine HNS into coarse particles of HNS in the bimodal PBX resulted in an increase in mechanical strength and a decrease infriction and impact sensitivity, as well as an enhanced performance compared to PBXs based on coarse HNS alone. Viton-A based hybrid PBX compositions provided better mechanical and sensitivity properties as compared to conventional explosive compositions based exclusively on HMX or HNS and the performance of the PBX compositions increased with increasing HMX content.

Khosla P.K.,Terminal Ballistics Research Laboratory | Khanna R.,Thapar University | Sood S.P.,Center for Development of Advanced Computing of India
Defence Science Journal | Year: 2014

The rail track rocket sled (RTRS) national test facility at Terminal Ballistics Research Laboratory (TBRL) has been established to provide simulated flight environment for carrying out aero dynamic studies, terminal studies and kinematic studies of variety of test articles. The sled velocity is a critical parameter in evaluation trials. This velocity is also used to ensure that the maximum speed and allowable g loading does not exceed the value which the test article will experience under free flight in air1. Overseas, the facilities have been set up to attain velocities ranging from sub-sonic to hypersonic2. The rocket sled at TBRL can be presently accelerated to travel along the rail track at velocities up to 500 m/s and capability is being built to increase velocity beyond 500 m/s. Signals acquired from existing magneto-inductive arrangement have been analysed in the present work. The experiments indicate that with increase in velocity the rate of change of flux increases, the amplitude of induced emf also increases but terminal voltage decreases and shape of the acquired pulse gets distorted. The parameters of magneto-inductive pick up have been modified in such a way that there is improvement in amplitude and shape of the received pulse with increase in velocity. The improved signals have been analysed and simulation results validated with feasible experiments. This paper also discusses issues, challenges and proposes recommendations in improving the sensor for measurement of velocity beyond Mach 1.5. It has been found that it is prudent to reduce the inductance by reducing the number of turns and changing the core from soft iron core to air core which will improve the response of inductive pick up coil at high velocity. © 2014, DESIDOC.

Sharma A.K.,Terminal Ballistics Research Laboratory
Proceedings - 27th International Symposium on Ballistics, BALLISTICS 2013 | Year: 2013

A well defined experimental programme coupled with computer simulation studies has been planned to design hemi spherical charge for defeat of hardened earth. The work reported in this paper is confined to theoretical and experimental aspects peripheral to the elements of hollow charge penetration in to earth. Before actual experimentation, hollow charge penetration analysis has been carried out by using a computer code. The emphasis on technology development and adaptation is towards hemi spherical charge penetration in to the earth and subsequent cratering to heave the shattered earth in to air for minimum ejecta fall back in to crater.

Sharma A.D.,Himachal Pradesh University | Sharma A.K.,Terminal Ballistics Research Laboratory | Thakur N.,Himachal Pradesh University
Philosophical Magazine | Year: 2012

Micro-sized copper powder has been compacted using explosives of various detonation velocities. Corresponding crystallographic and morphological characteristics along with particle size variation have also been compared. Cylindrical configuration has been used for the shock consolidation of metal powder. It has been observed that using an explosive mixture of detonation velocity 4.2km/s, the crystallite and micro-structure of the compacts remains the same with intact dendritic structure accompanied by a small variation in particle sizes. A good order of micro-hardness (88±4) H v and density of ∼94% of the theoretical value has been observed with lesser melting compared to the compacts obtained using explosive mixture with a high detonation velocity. © 2012 Copyright Taylor and Francis Group, LLC.

Kumar P.D.,Terminal Ballistics Research Laboratory
Proceedings - 29th International Symposium on Ballistics, BALLISTICS 2016 | Year: 2016

In explosive hardening and welding processes, one of the essential requirements is the preservation of the surface integrity of participant materials, for this the velocity of detonation (VoD) is kept low. For explosive hardening process, standard sheet explosives are used and for explosive welding process various types of powder explosives are widely used. Nevertheless, these types of powder explosives have limitations viz., difficulties in mixing and handling; cannot maintain uniform thickness along the large surface, large critical thickness, variation in VoD with thickness of explosives. To overcome the problems of conventional sheet explosive and powder explosives, a novel PETN based slurry casted explosives is developed which consists of PETN explosive mixed with inert additives, plastic binder and plasticizer. This slurry casted explosive has uniform density and thickness and easy to prepare and handle. The VoD can be maintained as desired in the range of 2000 m/s to 6000 m/s by varying the ratio. This chemical mixture was used for surface hardening of mild steel, and high manganese steel plates. Post hardening, it is observed that the plates were not damaged and their dimensional and material integrity remained unchanged. In explosive welding process slurry casted PETN based sheet explosive with low VoD was developed by mixing it with inert additives and used for explosive bonding of Aluminum to Stainless Steel, Copper to Stainless Steel. The VoD of the explosive was measured, and it detonated successfully during the trials. Since PETN has very small critical diameter, sheets can be made as small as 2 mm thickness with reliable and stable detonation. It is concluded that most of the problems of powder explosives can be surmounted by using high explosive based slurry casted sheet explosive. With these preliminary investigations, future work will be carried out to fully optimize and establish this new process for explosive hardening and welding.

Sharma A.K.,Terminal Ballistics Research Laboratory
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

Shock waves when propagate through materials produce sudden changes of pressure and temperature which result in the production of new phases/transformations. This paper describes the experimental work for the shock synthesis of IN 718 with unique properties and characterization of its pre and post shock compacts by spectroscopic methods. Super alloy powders of IN 718 of various chemical compositions and unique physical properties have been shock compressed to develop a new technology. From the spectroscopic records, intensity of reflected beam at a particular angle, the spacing between parallel planes, the lattice constant, the radius of an atom, FWHM value for each peak, etc. have been analyzed to investigate the unique properties of shock compacts. No porosity has been observed in the shock compacted specimens. On retrieval of samples from the compaction systems, the specimens are subjected to chemical composition, stress analysis and various other spectroscopic studies. The dendritic structure has been clearly observed in the centre with dendrites oriented in the radial direction which also happens to be the direction of heat flow. SEM analysis has indicated that the crystalline structure is intact in the shock compressed specimens. Copyright © 2009 by ASME.

Kumar R.,Indian Institute of Technology Mandi | Siril P.F.,Indian Institute of Technology Mandi | Soni P.,Terminal Ballistics Research Laboratory
Propellants, Explosives, Pyrotechnics | Year: 2014

Nanoparticles of cyclotrimethylenetrinitramine (RDX) were prepared by a simple re-precipitation method using acetone as solvent and water as the antisolvent. The effect of changing experimental parameters such as ratio of solvent to antisolvent, temperature of antisolvent during injection and concentration of solution on particle size and morphology of RDX was systematically studied. The size of the particles was characterized using dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM). The mean particle size of the RDX nanoparticles according to FESEM analysis ranged from 40 nm to 230 nm under different conditions of preparation. The UV/Vis absorption maximum of nano-RDX was found to be blue shifted when compared to the absorption maximum for bulk-RDX. Powder X-ray diffraction (XRD) results showed that RDX nanoparticles precipitated in stable α-crystalline form. Fourier transform infrared (FTIR) spectroscopy was used to characterize the chemical nature of the nano-RDX. Thermal characterization of the RDX-nanoparticles was done using simultaneous thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Singh M.,Terminal Ballistics Research Laboratory
Journal of Physics: Conference Series | Year: 2012

Dynamic methods utilizing strong shock waves are used for investigating the properties of condensed matter at very high pressures and temperatures. Explosive driven plate impact tests have been conducted to find out the shock Hugoniot of materials up to pressure of 2 Mbar. Explosive cascading utilizing overdriven detonation waves in high explosives produced by flyer impact from the first stage to accelerate comparatively thin flyer plates to very high velocities have been demonstrated. Numerical simulations using Autodyn 2D/3D have been performed to optimize the various parameters in two stage explosive assemblies to accelerate flyer to velocities exceeding 10 km/s. Shock pressure up to 20 Mbar has been successfully measured using explosive assemblies in a convergent flow. Expertise and infrastructure available in TBRL for launching metal flyers to high velocity and monitoring its in-flight velocity and profile have been discussed in this paper.

Martis R.R.,Indian Defence Institute of Advanced Technology | Misra A.,Indian Defence Institute of Advanced Technology | Singh A.,Terminal Ballistics Research Laboratory
AIAA Journal | Year: 2014

A numerical study of two microramp geometries has been conducted to study their effectiveness in controlling swept shock wave-boundary-layer interactions. The planar shock wave is generated by placing a 20 deg sharp fin in a supersonic flow atMach4. The heights of microramps were varied as 30, 40, 50, 60, 70, and90%of the boundary-layer thickness. The effect of microramp width and spacing is also studied. It is observed that boundary-layer separation is delayed significantly, downstream of the devices. Further, larger ramp heights were found to be more beneficial in delaying the separation. © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

Iqbal M.A.,Indian Institute of Technology Roorkee | Senthil K.,Indian Institute of Technology Roorkee | Sharma P.,Terminal Ballistics Research Laboratory | Gupta N.K.,Indian Institute of Technology Delhi
International Journal of Impact Engineering | Year: 2016

A detailed investigation has been carried out for studying the constitutive behavior of Armox 500T steel and armor piercing incendiary projectile (API) material under varying stress state, strain rate and temperature. The characterization of Armox 500T steel showed increase in its strength with increase in stress triaxiality as well as strain rate. Increment in temperature, on the other hand, induced significant increase in the material ductility while reducing its strength. The API projectile material remained insensitive to stress-triaxiality and strain rate; however, it was highly sensitive to thermal effects. Results thus obtained from experiments on the specimens of both the materials were subsequently employed for calibrating the material parameters of Johnson-Cook (JC) flow and fracture model. The calibrated JC model for Armox 500T steel has been validated by numerically simulating the high strain rate tension tests performed on split Hopkinson pressure bar apparatus. The ballistic experiments were carried out wherein 8 and 10 mm thick Armox 500T steel target plates were impacted by 7.62 and 12.7 API projectiles respectively at a normal incidence with a velocity of nearly 830 m/s. The results of the ballistic tests were reproduced through finite element simulations performed on ABAQUS/Explicit finite element code employing calibrated JC model for the target as well as the projectile material. Experimental and numerical findings with respect to failure mechanism and ballistic resistance of the target are presented and discussed. It is seen that the computed failure modes and residual velocities accurately matched the experiments. Further, the ballistic limit of the target material was obtained numerically and the values obtained were validated through the Recht-Ipson empirical model. © 2016 Elsevier Ltd. All rights reserved.

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