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Murali V.,University of Pune | Naik S.D.,Armament Research and Development Establishment
Journal of Defense Modeling and Simulation | Year: 2014

This paper reports important parameters that affect water ricochet studies for artillery projectiles. The factors affecting ricochet are critical angle and critical velocity of impact. This study has developed mathematical models for ricochet studies and derived expressions for critical angle and critical velocity. Simulations have been carried out for standard bullets, the data for which are available in open literature. The effects of mass, diameter, and length of the projectile on critical velocity and angle are studied through two non-dimensional parameters, µ and θ. The results suggest how ricochet conditions can be avoided by defining initial data at launch. © 2014 The Society for Modeling.

Dhote K.D.,Armament Research and Development Establishment | Murthy K.P.S.,Armament Research and Development Establishment | Rajan K.M.,Armament Research and Development Establishment | Sucheendran M.M.,Indian Defence Institute of Advanced Technology
International Journal of Impact Engineering | Year: 2015

Spatial dispersion of a Fragment Generator Warhead (FGW), in terms of projection angle and velocity, is essential to focus the maximum number of fragments on the target missile for effective neutralization. The authors carried out experiments to study the fragment dispersion in single, double and triple layered FGW configurations with tungsten alloy fragments. The projection angle and velocity are estimated by capturing the fragments in straw boards panel and correlating their position on the FGW. The paper presents the explanation of the phenomenon of fragment dispersion and deformation using one dimensional shock theory. © 2014 Elsevier Ltd. All rights reserved.

Arlulkar P.V.,Indian Defence Institute of Advanced Technology | Naik S.D.,Armament Research and Development Establishment | Naik S.D.,Applied Mathematics Group
Journal of Guidance, Control, and Dynamics | Year: 2014

An algorithm is developed to find the optimal two impulse solutions for a rendezvous problem between two noncoplanar elliptical orbits. The algorithm is based on the solution obtained using the dynamical approach for a MRLP (multiple-revolution Lambert problem). The algorithm requires a calculation of at most two solutions for any time of flight. The difference between velocity change for a stationary/fixed and a moving target is obtained. Sharp variation in velocity change is observed for the moving target. Coasting substantially reduces velocity change for rendezvous.

Sudarsan N.V.,Armament Research and Development Establishment | Das S.K.,Indian Defence Institute of Advanced Technology | Naik S.D.,Armament Research and Development Establishment
Propellants, Explosives, Pyrotechnics | Year: 2016

Determination of propellant formulation by ballistic requirement is an important area of research in recent times. In this study, a theoretical method for the design of gun propellant formulation using primary data of ingredients and necessary thermochemical properties of the resultant propellant was established. The employed method is based on a mathematical model of thermochemical properties of the propellant by optimizing the heat of explosion of the propellant using the fmincon tool in MATLAB. A graphical user interface (GUI) based code was generated and developed for the formulation design of solid gun propellants. The designed code was verified by available data in the literature. Such code will be useful to the researchers working in the area of high energy materials for the design of unknown propellant compositions. Further, it can be extended to redesign the existing propellant formulation in order to enhance the ballistic performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parkhi P.,Armament Research and Development Establishment | Bandyopadhyay B.,Indian Institute of Technology Bombay | Jha M.,Armament Research and Development Establishment
Proceedings of the 2010 11th International Workshop on Variable Structure Systems, VSS 2010 | Year: 2010

Sliding mode design based on Lyapunov matrices is proposed as roll autopilot for a tail controlled missile. The search of Lyapunov matrix for systems with unmatched uncertainties is formulated in terms of linear matrix inequality. The proposed scheme ensures robust roll position control even in the presence of large mismatched parametric uncertainties and external disturbances. The performance of roll autopilot design based on sliding mode technique is compared with the classical autopilot. The simulation results demonstrate that the sliding mode based roll autopilot maintains its performance over wide range of variation of parameters. © 2010 IEEE.

Vummadisetty P.N.,Symbiosis International University | Kumar R.,Armament Research and Development Establishment
Turkish Journal of Electrical Engineering and Computer Sciences | Year: 2016

Two CPW-fed compact printed slot antennas for UWB applications are proposed in this paper. In both antennas, the slot in the ground plane is of octagonal shape, while the patch is rectangular in one of the antennas and hexagonal in the other. Thin metallic stubs of different lengths are added to the ground plane and protrude into the slot. These stubs help to improve the impedance matching over a broader bandwidth. The antennas are very compact in size and designed on low-cost FR4 substrate. The measured impedance bandwidths (S11 < -10 dB) achieved by the rectangular and hexagonal patch antennas are from 3.1 GHz to 5.6 GHz and 3.14 GHz to 5.34 GHz, respectively. The slot antenna with hexagonal patch is further modified to have dual-band characteristics. An L-shaped stub is attached to the ground plane to achieve an additional band from 2.45 GHz to 2.52 GHz for WLAN applications. The radiation patterns of the antennas are dumb-bell shape in the E-plane and omnidirectional in the H-plane. Detailed parametric studies of the antennas have been carried out. The simulated results are found to be in good agreement with the measured results. © 2016 Tübitak.

Mukhedkar R.J.,Armament Research and Development Establishment | Naik S.D.,Armament Research and Development Establishment
Defence Science Journal | Year: 2013

Projectile path is dictated by estimated line of fire. Line of fire can be estimated by referring RT as well as trajectory model on computer. RT is prepared under ISA/ICAO meteorological standard conditions without wind effect. Meteorological conditions like density, humidity, pressure, wind, temperature affect the path of the trajectory. Meteorological data plays very important role in trajectory prediction. Trajectory is predicted using RT for a particular weapon where ICAO standard met data is used. Ind Std met data is different from ICAO data. Use of Ind Std data improves the accuracy of trajectory prediction for Indian field deployment. In this paper, comparative study of effect on projectile path under ICAO, Ind Std and actual Indian prevailing met have been carried out and analyzed. From this analysis, a new model has been established that if actual prevailing met is not available then trajectory prediction can be carried out using Ind Std met data with wind data as per date and time. It predicts trajectory very close to actual. Effect of wind has been studied and found that wind effect is very dominant on projectile path. Study of effect of density also has been carried out in this paper. It is observed that Ind Std density values are much close to actual as compared to ICAO. Therefore, if insufficient met is recorded then Ind std density can be used to fill density values for that region. © 2013, DESIDOC.

Rajan K.M.,Armament Research and Development Establishment
Proceedings of the 10th International Conference on Technology of Plasticity, ICTP 2011 | Year: 2011

Electro Slag Refined (ESR) AISI 4130 steel performs with fully tempered martensite microstructure having fine grain size of ASTM 7-8 have been used as the input material for a 3-pass reverse flow forming process for manufacturing high strength thin wall pressure vessel for a critical application. The forming machine parameters such as roller feed, spindle speed and roller stagger were experimentally fine tuned to achieve desired level of out of roundness and straightness of the finished flow formed tube for practical application. Heavily cold-formed thin wall tubes are likely to develop considerable residual stresses due to non-uniform deformation. Residual stresses can lead to failure of a component by buildup of stresses or by enhancing susceptibility to failure by mechanisms such as fatigue. Hence it is considered essential to measure the residual stress on the flow formed tube by x-ray diffraction technique. The measured residual stresses are quantified. A suitable sub-critical annealing process has been evolved and the flow formed tubes were subjected to the same. Residual stresses were measured again at the same locations and its magnitude was found to be negligible. The geometrical tolerances were found to be unaffected after the stress relief operation and hence a 3 pass forming followed by subcritical annealing has been followed for manufacture of large number of tubes. © 2011 IBF (RWTH Aachen) & IUL (TU Dortmund).

Nene M.J.,Defense Institute of Advanced Technology | Deodhar R.S.,Armament Research and Development Establishment | Patnaik L.M.,Indian Institute of Science
IEEE Sensors Journal | Year: 2015

In this paper, sensing coverage by wireless camera-embedded sensor networks (WCSNs), a class of directional sensors is studied. The proposed work facilitates the autonomous tuning of orientation parameters and displacement of camera-sensor nodes in the bounded field of interest (FoI), where the network coverage in terms of every point in the FoI is important. The proposed work is first of its kind to study the problem of maximizing coverage of randomly deployed mobile WCSNs which exploits their mobility. We propose an algorithm uncovered region exploration algorithm (UREA-CS) that can be executed in centralized and distributed modes. Further, the work is extended for two special scenarios: 1) to suit autonomous combing operations after initial random WCSN deployments and 2) to improve the network coverage with occlusions in the FoI. The extensive simulation results show that the performance of UREA-CS is consistent, robust, and versatile to achieve maximum coverage, both in centralized and distributed modes. The centralized and distributed modes are further analyzed with respect to the computational and communicational overheads. © 2001-2012 IEEE.

Harikrishnan S.,Armament Research and Development Establishment | Murthy K.P.S.,Armament Research and Development Establishment
Defence Science Journal | Year: 2010

Tandem shaped charge warhead is one of the efficient methods to defeat the explosive reactive armour (ERA) protected main battle tanks (MBT). In this concept, two shaped charges mounted in the same missile are initiated one after the other with certain time delay. First shaped charge jet would remove the ERA and the second jet would penetrate the bare armour. Both these explosive charges are mounted close to each other most of the time due to severe space constraints in the system. It is necessary to protect the second charge from the blast effects of first charge, during the time delay between the initiations of two charges. Blast effect of precursor charge on main charge is understood to have detrimental effects on the performance of warhead system.This paper presents a case study of an investigation into the inconsistent performance of a tandem warhead for a third generation antitank missile. The warhead generated a crooked jet resulting in inconsistent penetration performance. Typical crater profiles were observed when the penetration performance deteriorated. Systematic analysis was carried out and simulations were performed using Autodyn-3D to reproduce the phenomenon. Experiments were conducted using Flash X-ray which substantiated the assumptions made for simulation studies. © 2010, DESIDOC.

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