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The dispersion distribution characteristics of prefabricated fragments from an improvised explosive device (IED) are essential in defense technology development. To improve warhead design, it is essential to predict a fragment’s velocity and dispersion distribution accurately. This paper investigates a fragment’s flying angle from a detonated warhead with a cylindrical charge under a one-end central detonation. A modified formula for calculating the fragment dispersion distribution at each axial position of the warhead was obtained based on experimental data and model analysis. The impacts of the following parameters on the flying angle were considered in the formula: ratio of charge mass to shell mass, charge diameter, axial sparse effect, and relative axial shell position. The formula was verified by experimentation to be suitable for wide applications using different validation samples. Theoretical calculations with the formula show good accuracy in predicting the flying angle of cylindrical-shell fragments, agreeing with experimental data. The proposed model meets the error requirements of engineering applications. This work provides a theoretical foundation for subsequent research on damage effectiveness and IED damage assessment.

Purpose The purpose of this paper is to study the operation performance of the high-speed ramjet kinetic energy projectile using solid fuel ramjet as power plant that is a new short-range and small caliber projectile. Design/methodology/approach The numerical investigation on combustion characteristic of polyethylene in high-speed ramjet kinetic energy projectile is carried out in this paper. The flow characteristics’ differences are analyzed when ramjet works or do not work, and both the combustion characteristics and propulsive performance are analyzed when ramjet works. Findings The results show that with the increase of the abscissa x, the flame front is close to solid fuel surface at first and then keeps away from solid fuel surface. With the increase of the abscissa x, the temperature of solid fuel surface and regression rate of solid fuel continues to increase before re-attachment point and then decreases, which a maximum locate at the re-attachment point. Both the average temperature and the regression rate on the surface of the solid fuel tend to rise as the increase of inflow Mach number. As the inflow of Mach number increases, the mass flow rate of gaseous fuel increases. Practical implications The research results can provide useful database for the subsequent research on high-speed ramjet kinetic energy projectile. Originality/value This paper studies the operation characteristics of the ramjet projectile, especially the effect of the change of the flight velocity on the performance of high-speed ramjet projectile.

This work compares the pure copper (T2 copper)’s stress-strain relationship at different strain rates in the uni-axial tension test and Split Hopkinson Pressure Bar (SHPB) test. Small samples were utilized in the high strain rate SHPB test in which the accuracy was modified by numerical simulation. The experimental results showed that the T2 copper’s yield strength at high strain rates largely outweighed the quasi static yield strength. The flow stress in the stress-strain curves at different strain rates appeared to be divergent and increased with the increase in strain rates, showing great strain strengthening and strain rate hardening effects. Metallographic observation showed that the microstructure of T2 copper changed from equiaxed grains to twins and the interaction between the dislocation slip zone grain boundary and twins promoted the super plasticity distortion in T2 copper.

To study the dynamic plastic properties of high-purity molybdenum materials at high temperature and high strain rate, we designed tests to compare the mechanical behaviour of two high-purity molybdenum materials with different purities and two with different processing deformation conditions under dynamic impact compression in the temperature range of 297–1273 K. We analysed the molybdenum materials’ sensitivities to the strain-hardening effect, strain rate-strengthening effect, and temperature-softening effect as well as the comprehensive response to the combined effect of the strain rate and temperature, the adiabatic impact process, and the microstructure at high temperature and high strain rate. Furthermore, based on a modified Johnson–Cook constitutive model, we quantitatively analysed the flow stresses in these materials. The calculation results strongly agree with the test results. Our findings indicate that the high-purity molybdenum materials show consistent sensitivity to the combined effect of strain rate and temperature regarding the dynamic plastic properties. The materials with higher purity are less sensitive to the combined effect of the strain rate and temperature, and those with less processing deformation experience more pronounced strain-hardening effects. Under high strain rate at room temperature, these materials are highly susceptible to impact embrittlement and decreases in dynamic plastic properties due to intergranular fracture in the internal microstructure. However, increasing the impact environment temperature can significantly improve their plastic properties. The higher the temperature, the better the plastic properties and the higher the impact toughness.

A target localization algorithm, which uses the measurement information from onboard GPS and onboard laser detector to acquire the target position, is proposed to obtain the accurate position of ground target in real time in the trajectory correction process of semi-active laser terminal correction projectile. A target localization model is established according to projectile position, attitude and line-of-sight angle. The effects of measurement errors of projectile position, attitude and line-of-sight angle on localization accuracy at different quadrant elevation angles are analyzed through Monte-Carlo simulation. The simulation results show that the measurement error of line-of-sight angle has the largest influence on the localization accuracy. The localization accuracy decreases with the increase in quadrant elevation angle. However, the maximum localization accuracy is less than 7 m. The proposed algorithm meets the accuracy and real-time requirements of target localization.

A shaped charge was produced with liner vertex initiation that could form explosively formed projectile (EFP), the mechanism of EFP formation was analyzed, based on the energy conservation law and data from LS-DYNA numerical simulation, analytical models of EFP velocities and penetration depth of finite thickness armor target were obtained, finished the experimental verification with flash X-ray and long distance penetration of EFP, comparing theoretical calculation results with experimental ones, the errors of EFP velocities, length and penetration depth are only 3.6%, 4.1% and 5.3% respectively, the theoretical results are consistent with the simulative and experimental ones.

In order to improve the acquisition probability for laser semi-active terminal correction projectile, the scheme of optimizing launch angle is proposed, the mathematical model of the strapdown seeker laser detector and the capture field model of target is established, and the scheme is verified by Monte Carlo ballistic simulation method. The results show that the scheme of optimizing launch angle improves the target acquisition probability, and will be of important significance to firing table modifying of laser semi-active terminal correction projectile.

The brushless DC motor applied on the electric steering gear of trajectory correction projectiles often requires getting real-time rotational speed value. The hall sensors output the hall signals for measurement, after the integration by the D-type flip-flop, an ideal pulse can be produced. Afterwards STM32F103ZE microcontroller is used to calculate the rotational speed value of the motor by the Improved M/T method. The resolution and precision can be analyzed after getting the result. This rotational speed measurement system has high precision and good real-time characteristics. It is significant for the meaning of the correction of the steering gear.

Traditional blast ammunition has a steel casing which turns into dangerous fragments after detonation. These steel fragments may kill civilians outside of the target. In order to adapt the need of fighting in an urban environment without hurting innocent bystanders in the process, one new kind of low collateral damage ammunition is put forward. The configuration and operational principle of this ammunition are introduced. From theoretical analysis it can be found the blast power is mainly determined by the metal powder. The effect of the metal powder’s type and magnitude on blast power is studied from static explosion test. In the test the overpressure curve is measured by the pressure sensor. The killing radius is computed from the sector target using the 25mm deal board. The initial casting velocity of the metal powder is obtained from the high speed photography. The results show tungsten powder is suitable for the low collateral damage ammunition, its diameter is about 50um. In this circumstance this ammunition can reduce collateral damage, however the damage effect is higher in the smaller area.

In order to study the effects of liner materials on the formation of Shaped Charges with Double Layer Liners (SCDLL) into tandem Explosively Formed Projectile (EFP), the formation mechanism of DLSCL was studied. Utilizing two-dimensional finite element dynamic code AUTODYN, the numerical simulations on the mechanical phenomenon of SCDLL forming into tandem EFP were carried out. X-ray pictures were obtained after Experiments on SCDLL. Comparisons between experimental results and numerical simulation results have good agreement. It can be concluded from the results that the materials properties and configurations of both liners are crucial to the formation of tandem EFP.

A new kind of low collateral damage ammunition with Carbon fiber composite material casing is put forward. The operational principle of this ammunition and its configuration are introduced. Then the casting velocity of lethal unit and air shock wave pressure is analyzed theoretically and simulated. In order to study the effect of casing material on blast power, two different kinds of explosive charges are detonated. Overpressure curve of these two charges is measured using the pressure sensors. From the measured overpressure curve and theoretical simulation results, the duration of the positive pressure of the air blast pressure wave caused by the prototype model of the low collateral damage ammunition is bigger than the explosive charge with Carbon fiber composite material casing and naked explosive charge. From the high speed photography, the lethal units flight to a halt at a small distance. These results show the explosive charge with Carbon fiber composite material casing and metal powder can reduce destruction outside the radius of an intended target while enhancing its destructive force on the target.