Terminal Ballistics Research Laboratory
Terminal Ballistics Research Laboratory
Senthil K.,Indian Institute of Technology Roorkee |
Iqbal M.A.,Indian Institute of Technology Roorkee |
Chandel P.S.,Terminal Ballistics Research Laboratory |
Gupta N.K.,Indian Institute of Technology Delhi
International Journal of Impact Engineering | Year: 2016
The flow and fracture behavior of 7075-T651 aluminum alloy has been studied under different stress-states, strain rate and temperature in order to explore the characteristics of the material under extreme situations developed in aerospace and armor structures. Influence of stress state was studied by performing quasi-static tension tests on notched specimens of different initial notch radii, 0.44 - 6mm. Strain rate sensitivity was studied by carrying out tension test in the range 5 × 10- 4 s-1 - 800s-1. Thermal sensitivity of the material was studied by performing quasi static tension tests in the range 25 - 600°C. The increase in stress triaxility described increase in strength while reducing ductility. Increase in temperature on the other hand, stimulated opposite characteristics in the material. The variation in strain rate could not influence the flow and fracture behavior of material. Anisotropy observed in the material has been carefully investigated by carrying out tests in different in-plane and out of plane orientations. The stress-strain relations obtained through these tests were employed for calibrating Johnson-Cook (JC) flow and fracture model in different orientations. The Hill's stress potentials were also obtained to incorporate the anisotropy in the material flow. Four different sets of parameters were calibrated and employed for numerically simulating the ballistic performance of 20mm thick 7075-T651 aluminum targets against 12.7 and 7.62 API projectiles. The results thus reproduced through each set of parameters were compared with the experimental findings and the limitation and accuracy of each calibrated model have been discussed. © 2017.
Majumdar A.,IITDelhi |
Laha A.,IITDelhi |
Bhattacharjee D.,Terminal Ballistics Research Laboratory |
Biswas I.,Terminal Ballistics Research Laboratory
Composite Structures | Year: 2017
Soft body armour panels have been developed by tuning the structure of 3D woven orthogonal aramid fabrics and reinforcing them with shear thickening fluid (STF). Five 3D woven orthogonal aramid fabric structures were prepared by changing the ratio of stuffer (X direction) to binder (Z direction) yarns and also by changing the relative position of the latter. Two types of ballistic evaluations, namely energy absorption against low velocity (165 ± 10 m s−1) bullets and back face signature (BFS) against high velocity (430 ± 10 m s−1) bullets were carried out for neat and STF impregnated 3D fabrics and their panels. STF impregnation improved impact energy absorption by 3D woven aramid fabrics. Increasing the ratio of stuffer to binder yarns was found to be beneficial in terms of impact energy absorption and resistance against bullet penetration. STF impregnated 3D fabrics having 4:1 stuffer to binder ratio performed the best in ballistic evaluations. Synergistic effect of 3D woven fabric structure and reinforcement of STF was found to be the key for successful design of soft body armour. © 2017 Elsevier Ltd
Sherpa B.B.,Terminal Ballistics Research Laboratory |
Upadhyay A.,Terminal Ballistics Research Laboratory |
Kumar S.,Terminal Ballistics Research Laboratory |
Mangla V.,Terminal Ballistics Research Laboratory |
And 2 more authors.
Materials Today: Proceedings | Year: 2017
Explosive welding is one of the high energy rate joining processes of similar and dissimilar metals. In this process, the force of controlled detonation is used to accelerate one metal plate into another creating an atomic bond. This process is capable of joining the large surface area as due to the distributing ability of high energy density available in the explosive over the welding area.This paper comprises of evaluation of joint obtained by joining of Aluminium and Stainless Steel using explosive welding process through ram tensile testing method and soundness of joints analysed using Ultrasonic Flaw Detector. Micro-structural analysis of joint interface was done using optical microscopy and scanning electron microscopy. The Ram tensile test results clearly showed that the explosive welded joint strength is higher than that of the weaker parent metal's tensile strength. © 2017 Elsevier Ltd.
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.