Parametric study of single confined fragment launch explosive device

In this article, parametric study of single confined fragment launch device was carried out. The configuration proposed was further studied to derive the empirical relationship for effect of fragment size,charge size, confinement thickness on fragment velocity. The simulations were carried out using ANSYSAUTODYNE explicit solver. Fragment velocities were estimated as a function of different parametric combinations of explosive quantities, charge length to diameter ratio, fragment height to diameter ratio,confinement thickness, fragment material and fragment mass. The data was further converted to charge to metal ratio under fragment and confinement. It was observed that, increase in confinement thickness,charge quantity and decrease in fragment height increases the fragment velocity. It is also noted that,charge to metal mass ratio under fragment significantly affects the fragment velocity. At the end, an empirical relationship for fragment velocity interms of all these parameters was established. Using these relations, two velocities 1831.92 m/s and 2523.9 m/s required for NATO STANAG 4496 IM test were estimated. The design parameters for these velocities are presented. Also, the results estimated using the empirical relationship has been compared with published experimental data. Error in the predicted velocities is within the acceptable range. The empirical relationship proposed will be useful for finalization of design of the fragment launch device.

Measurement of bullet impact conditions using automated in-flight photography system

Knowledge of impact conditions is critical to evaluating the terminal impact performance of a projectile.For a small caliber bullet,in-flight velocity has been precisely measured for decades using detection screens,but accurately quantifying the orientation of the bullet on a target has been more challenging.This report introduces the Automated Small-Arms Photogrammetry(ASAP)analysis method used to measure,model,and predict the orientation of a small caliber bullet before reaching an impact surface.ASAP uses advanced hardware developed by Sydor Technologies to record a series of infrared digital photographs.Individual images(four orthogonal pairs)are processed using computer vision algorithms to quantify the orientation of the projectile and re-project its precise position and orientation into a three-dimensional muzzle-fixed coordinate system.An epicyclic motion model is fit to the measured data,and the epicyclic motion is extrapolated to the target location.Analysis results are fairly immediate and may be reviewed during testing.Prove-out demonstrations have shown that the impact-angle prediction capability is less than six hundredths of a degree for the 5.56 mm ball round tested.Keywords:Yaw,Terminal ballistics,Exterior ballistics,Test&evaluation,Computer vision,Image processing,Angle of

Fabrication of AA7005/TiB2-B4C surface composite by friction stir processing: Evaluation of ballistic behaviour

The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles were processed by friction stir processing. Micro-hardness and depth of penetration tests were carried out to evaluate the ballistic properties of the surface composites. The surface hardness of the composite was found to be nearly 70 HV higher than base alloy. The depth of penetration of the steel projectile was 20e26mm in the composites as compared to 37mm in the base alloy. Ballistic mass efficiency factor of the surface composite was found to be 1.6 times higher than base alloy. This is mainly attributed to the dispersion strengthening from the reinforcement particles.

Quantification of projection angle in fragment generator warhead

Tactical Ballistic Missile(TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead(FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement logic.For conventional axi-symmetric warhead,dispersion is assumed to be normal with a standard deviation of 3~O.However,such information is not available in case of FGW.Hence,a set of experiments are conducted to determine the dispersion of fragments.The experiments are conducted with a specific configuration of FGW in an identical arena to quantify the scatter and then verified its applicability to other configurations having a range of L/D and C/M ratios,and contoured fragmenting discs.From the experimental study,it is concluded that the scatter in projection angle follows normal distribution with a standard deviation of 0.75° at Chi-square significance level of 0.01(x_(0.99)~2).

Dispersion sensitivity analysis&consistency im provement of APFSDS

The purpose of this study is to investigate and quantify some possible sources of dispersion of 120 mm APFSDS tank ammunition both experimentally and numerically.This paper aims to point out the most influential source during In-Bore Balloting Motion phase as well as in External Ballistics phase of the ammunition and quantifies its effect on dispersion.Data obtained from flight trials is critically analysed and parameters affecting dispersion such as initial yaw/pitch rates,yaw/pitch dampening,plane start angle,launch spin,clearance,centre of gravity shift,dynamic imbalance angle,cross wind,etc.are observed and,later on,studied in detail by extensive External Ballistics Monte Carlo(EBMC)simulation and Six Degree of Freedom(6-DOF)trajectory analysis.In Bore Balloting Motion simulation shows that reduction in residual spin by about 5%results in drastic56%reduction in first maximum yaw.A correlation between first maximum yaw and residual spin is observed.Results of data analysis are used in design modification for existing ammunition.Number of designs are evaluated numerically before freezing five designs for further soundings.These designs are critically assessed in terms of their comparative performance during In-bore travel&external ballistics phase.Results are validated by free flight trials for the finalised design.

Mass asymmetry and tricyclic wobble motion assessment using automated launch video analysis

This paper describes an approach to identify epicyclic and tricyclic motion during projectile flight caused by mass asymmetries in spinstabilized projectiles. Flight video was captured following projectile launch of several M110A2E1 155 mm artillery projectiles. These videos were then analyzed using the automated flight video analysis method to attain their initial position and orientation histories.Examination of the pitch and yaw histories clearly indicates that in addition to epicyclic motion's nutation and precession oscillations, an even faster wobble amplitude is present during each spin revolution, even though some of the amplitudes of the oscillation are smaller than 0.02 degree.The results are compared to a sequence of shots where little appreciable mass asymmetries were present, and only nutation and precession frequencies are predominantly apparent in the motion history results. Magnitudes of the wobble motion are estimated and compared to product of inertia measurements of the asymmetric projectiles.

Effect of firing conditions ＆ release height on terminal performance of submunitions and conditions for optimum height of release

Submunitions should exhibit optimum terminal performance at target end when released from certain pre-determined height. Selection of an optimum height of release of the submunitions depends on the terminal parameters like forward throw, remaining velocity, impact angle and flight time. In this paper,the effects of initial firing conditions and height of release on terminal performance of submunitions discussed in detail. For different height of release, the relation between range and forward throw is also established & validated for a number of firing altitude and rocket configurations.

Idiosyncratic behaviour of(Na_(0.49)5K_(0.455)Li_(0.05))(Nb_(0.95)Ta_(0.05))O_3-La_2O_3 ceramics: Synergistically improved thermal stability, ageing, and fatigue properties

La_2 O_3 doped(Na0.495 K0.455 Li0.05)(Nb0.95 Ta0.05)O_3 ceramics are prepared using modified milling process, and the influences of La2 O3 on ferroelectric behaviour, ageing characteristics, thermal stability, electrical stability, crystal structure, microstructure, dielectric and piezoelectric properties were reported. La_2 O_3 addition improved the ferroelectric characteristic substantially, and obtained remnant polarization(Pr) and maximum strain(Smax) around 34.3 C/cm^2 and 0.13% respectively.La_2 O_3 doped ceramics improved the thermal stability and were stable up to 180 ℃ compared to undoped ceramics(120 ℃). The Rietveld refinement along with the high-temperature X-ray diffraction studies suggested the presence of monoclinic phase in La doped compositions, which is responsible for their idiosyncratic behaviour. The maximum values were obtained around 179 pC/N and 0.385 for piezoelectric constant(d33) and electromechanical coupling factor(kp) respectively in La_2 O_3 doped samples(0.02 wt%), which also exhibited the lowest ageing rate and stable electrical fatigue behaviour.