Fragmentation Warhead Research Articles

Numerical Simulations of 122 mm M-21OF Missile Fragments Propulsion

This paper presents numerical simulations of 122 mm M-21OF rocket fragments propulsion. A simplified geometry of the rocket was constructed and analysed with two main numerical FE approaches: a mesh-based lagrangian-eulerian FSI method and a coupled meshless SPH–lagrangian approach. The resulting fragment velocities were compared with those obtained from an analytical approach (Gurney formula). The shell fragmentation process was also successfully depicted. Both numerical approaches differed from the analytical velocity results to a comparable degree. Considering that the Gurney energy of a high-explosive is obtained from cylinder expansion tests, results obtained with the Gurney method can be treated as a reference point and validation method for natural fragmentation warhead models.

Fracture behavior and mechanism of highly fragmented steel cylindrical shell under explosive loading

An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments formed. This study investigated the fragmentation performance of a new high-carbon silicon-manganese (HCSiMn) steel cylindrical shell through fragment recovery experiments. Compared with the conventional 45Cr steel shell, the number of small mass fragments produced by the HCSiMn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution model. The fragmentation process of the HCSiMn shell exhibited more brittle tensile fracture characteristics, with the microcrack damage zone on the outer surface being the direct cause of its high fragmentation. On the one hand, the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite, so that microscopic intergranular fracture reduces the characteristic mass of the fragments; on the other hand, the distribution of alloy carbides can exert a "pinning" effect on the substrate grains, causing more initial cracks to form and propagate along the brittle carbides, further improving the shell fragmentation. Although the killing power radius for light armored vehicles was slightly reduced by about 6%, the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26% based on theoretical assessment. These results provided an experimental basis for high fragmentation warhead design, and to some extent, revealed the correlation mechanism between metallographic structure and shell fragmentation.

Efficiency Analysis of Fragmentation Warheads Through Advanced Modeling Techniques: Experimental and Numerical Study

This research investigates the efficiency of fragmentation warheads through a comprehensive comparison of numerical and analytical modeling techniques, supplemented by arena tests. Advanced numerical models developed within Ansys Autodyn, alongside the mean area of effectiveness software, demonstrate robust capabilities in predicting warhead‐soft target interactions. Our numerical model is supplemented with a complex analytical model, and the integration of these two approaches addresses a significant research gap by providing a thorough evaluation of warhead efficiency. This integrated model serves as a valuable tool for warhead design and optimization. Validated with experimental results, the simulation outcomes show excellent agreement with the arena test data, confirming the accuracy and reliability of the developed models. This study explicitly addresses key research gaps, including the integration between experimental and numerical analyses, the gap between explosive propulsion and the determination of efficiency, and the need for a comprehensive tool for warhead design and optimization. By exploring various warhead design configurations and initiation methods, the research offers critical insights for optimizing warhead performance. Notably, nonuniform barrel‐shaped warheads exhibit a wider fragment distribution, significantly improving weapon‐target interactions, particularly at lower impact angles. The study delves into the key parameters influencing warhead performance, providing detailed justifications for their selection and evaluating the sensitivities of these parameters on the results. This analysis underscores the importance of choosing appropriate parameters for accurate predictions and effective warhead design. In addition, the research highlights the original achievements in overcoming major difficulties and challenges in the field, such as integrating complex numerical and analytical models for comprehensive evaluation. The findings contribute to the advancement of fragmentation warhead design, offering designers reliable tools and guidelines to enhance lethality and efficiency in weapon‐target engagements. Future work aims to expand the software’s capabilities to include diverse targets, fragment types, and interaction geometries, further advancing the field of fragmentation warhead design. By addressing the gaps and challenges identified, this research paves the way for more effective and optimized warhead configurations, enhancing their overall performance and impact.

Double casing warhead with sandwiched charge: The axial distribution of fragments velocities

The double casing warhead with sandwiched charge is a novel fragmentation warhead that can produce two groups of fragments with different velocity, and the previous work has presented a calculation formula to determine the maximum fragment velocity. The current work builds on the published formula to further develop a formula for calculating the axial distribution characteristics of the fragment velocity. For this type of warhead, the simulation of the dispersion characteristics of the detonation products at different positions shows that the detonation products at the ends have a much larger axial velocity than those in the middle, and the detonation products have a greater axial dispersion velocity when they are closer to the central axis. The loading process and the fragment velocity vary with the axial position for both casing layers, and the total velocity of the fragments is the vector sum of the radial velocity and the axial velocity. At the same axial position, the acceleration time of the inner casing is greater than that of the outer casing. For the same casing, the fragments generated at the ends have a longer acceleration time than the fragments from the middle. The proposed formula is validated with the X-ray radiography results of the four warheads previously tested experimentally and the 3D smoothed-particle hydrodynamics numerical simulation results of several series of new warheads with different configurations. The formula can accurately and reliably calculate the fragment velocity when the length-to-diameter ratio of the charge is greater than 1.5 and the thickness of the casing is less than 20% its inner radius. This work thus provides a key reference for the theoretical analysis and the design of warheads with multiple casings.

Terminal attitude selection method of missile attack aircraft

The appropriate terminal attitude of missile is important to improve the damage effectiveness of fragmentation warhead against aircraft targets. In this paper, three missile terminal attitude selection methods are proposed to solve the problem of terminal attitude selection in different situations according to their respective evaluation indexes. The MVE-based method uses the damage probability of each detonation point around the aircraft at a given attitude of missile to calculate the Mean Volume of Effectiveness (MVE) at the corresponding attitude, and then uses the MVE for different attitudes to select the terminal strike attitude. The detonation position-based method addresses the case where the missile detonation position can be assessed in advance. Given the effects of missile guidance errors and fuze activation position errors, Monte Carlo simulations are used to calculate the damage probability of aircraft with different strike attitudes, from which the terminal strike attitude is selected. The BP-ANN model-based method uses the constructed Back Propagation Artificial Neural Network (BP-ANN) model instead of simulation to calculate the evaluation indexes in the corresponding cases of MVE-based method and Detonation position-based method, which can improve the efficiency of attitude selection. Simulations are conducted for different scenarios to verify the feasibility and effectiveness of the proposed method.

Research on the Effect of Inner Lining on Fragment Scattering Characteristics of Fragmentation Warhead

In order to improve the axial fragments killing power of fragmentation warhead, based on the Shapiro formula, a design method of the lining curve of the fragmentation warhead was proposed, and the fragmentation warhead was designed with a fragment scattering angle of 5° and 9° by using this method. Using LS-DYNA software and ALE algorithm, the numerical simulation calculation of fragment scattering process was carried out, and the static explosion test of the warhead prototype was carried out to verify the rationality of the lining curve design method. The influence of the shape and thickness of the inner lining curve on the scattering characteristics of the fragments is analyzed. The results show that the error value between the experimental value and the simulated value of the scattering angle and the theoretical design value is within 8%; the smaller the design value of the fragment scattering angle, the greater the curvature of the lining curve, and the smaller the initial scattering speed of the fragment; When the thickness of the inner lining is appropriately increased, the initial scattering speed of the fragments increases, and the scattering angle of the fragments decreases.

Study on Radial Distribution of Fragments Velocity of D-shaped Fragmentation Warhead

For the asymmetric D-shaped fragmentation warhead with high charging coefficient and space efficiency, we simulate the driving process of fragments under typical eccentric initiation by using the fluid-structure interaction algorithm, and obtained the change rule of the fragment velocity radial distribution with the central angel, the thickness and material of the upper end cap. The results of numerical simulation show that the fragment velocity of D-shaped warhead increases gradually from the reverse to the forward direction, the velocity of fragment in forward direction increases by about 10% under single-point eccentric initiation compared with the cylindrical casing under center initiation, and the fragment velocity under double-point eccentric initiations is higher than single-point eccentric initiation; The initial velocity of the fragment has a positive correlation with the thickness and density parameters of the upper end cap; the mass of the warhead and the total kinetic energy of the fragments in the forward area increase with the increase of the central angle, but their ratio increases first and then decreases with the increase of the central angle. The results can be applied to structural optimization design and power evaluation of the warhead.

Calculation and optimization of lethal power of controlled fragmentation warheads with diamond notch grid

The lethal power is the critical design index of the explosive warhead, mainly related to the number and mass of fragments formed by the warhead case. For the controlled fragmentation warhead case containing notches, the notch depth and spacing are the main factors affecting the fragment formation. This paper analyzes the influence of the notch number and depth on the network of fracture trajectories. It establishes a calculation model for the mass and number of fragments of warheads with various groove parameters. The lethal radius is obtained from the calculated fragment data and compared with the results of the experimental data and numerical simulation. The paper uses the genetic algorithm to obtain the optimal solution under various design variables, taking the groove depth and the number of circumferential grooves as the design variables and the lethal radius as the optimization objective. The optimized result is higher than without optimization.

Optimization method of ballistic blast fragmentation warhead striking aircraft in aircraft shelter

For evaluating the economy and feasibility about blast fragmentation warhead striking aircraft in aircraft shelter, taking a typical aircraft and single/double aircraft shelter as study objects, based on the thought of simple/quadratic surface fitting, the 3D surface models of aircraft and shelter are built. According to the velocity and position model of fragment, combined with the transformation relationship of coordinate system, the missile-target encounter algorithm is given. The ruin tree model of aircraft is constructed to calculate the ruin probability algorithm of aircraft. For reducing the computation of missile-target encounter, a mean ruin probability algorithm of aircraft based on integration method is proposed, which slices target area to grids and takes grids as alternative aim point. Taking maximum to entire ruin effect of all aircrafts as target, the optimizing algorithm to strike scheme about minimum missile consumption and find best aim point based on advanced PSO algorithm are proposed. The striking scheme optimizing about fragmentation warhead striking aircraft in single/double aircraft shelter is simulated. The result shows that, low blast height, small CEP, combination strike strategy with multiply aim points can reduce the minimum missile consumption effectively.

Design Methods for the Lethality of Fragmentation Warhead based on a Multi-Objective Optimization Algorithm

Abstract Fragmentation warhead is the main weapon used to damage personnel and light armored objectives, with the lethal parameters primarily consisting of the number and velocity of fragments. Increasing the lethality of fragmentation warhead is currently the most important development direction for fragmentation warhead. The formation process of natural fragment is complicated and there are several factors that affect the properties of fragment, so there are still many techniques of developing the lethality of fragmentation warhead. In this paper, our object is to focus on the optimization design for the lethality of fragmentation warhead, based on the optimal Latin hypercube test design method and the radial basis function neural network surrogate modelling, taking the number of effective fragments per unit mass and the average kinetic energy of the effective fragments as the optimization objectives, and the explosive charge, the fragment material, the overall structure and initiation method are considered, respectively. The Pareto optimal solution sets under different design variables are obtained, and the optimal matching of multiple design parameters is realized, establishing the integration design method for “explosive - material-structure” of the fragmentation warhead. The research results can provide technical support for the structural optimization design of the fragmentation warhead.

ОСОБЛИВОСТІ РОЗРАХУНКУ ОСНОВНИХ ПАРАМЕТРІВ ПРИВЕДЕНИХ ЗОН УРАЖЕННЯ ІЗ ЗАСТОСУВАННЯМ ІМІТАЦІЙНОГО МОДЕЛЮВАННЯ

During the scientific and technical support of work on the development of promising models of artillery and missile weapons, a large number of applied studies are carried out, including those related to the evaluation of the effectiveness of the defeat of promising models of weapons of typical purposes. Thus, even at the stage of designing promising models of weapons, it is possible to evaluate the technical solutions proposed by the Developer, which can be considered as a safeguard against design errors and unnecessary costs. Assessment of the impact of the impact of promising ammunition, including combat equipment of missiles and rockets is carried out, as a rule, by calculating the basic parameters of the above areas of destruction of typical targets. It is known that the given area of the target by a certain type of ammunition means a certain conditional area around the object within which the explosion of ammunition leads to a guaranteed damage to the object. When solving the problem of assessing the effectiveness of hitting targets with ammunition zone (remote) action instead of the actual shape (configuration) of the given zones of destruction of elementary targets use one of the simple geometric shapes – a rectangle or circle. These simplifications affect the accuracy and quality of calculations, especially in solving problems of quantitative and qualitative assessment of the power of promising ammunition zone (remote) action. The article highlights the features of the calculation of the main parameters of the given zones of destruction of elementary targets by ammunition of zone (remote) action with the use of simulation modeling, and also describes the main features of the developed simulation model. Keywords: target destruction efficiency, reduced impact zone, simulation, missile, rocket, high-explosive fragmentation munition, high-explosive fragmentation warhead.

Analiza efikasnosti bojnih glava parčadnog dejstva protiv "mekih" ciljeva

The efficiency of the weapon system has been usually studied by altering the guidance and control or aerodynamics of the missile. This research investigated methods of enhancing the efficiency of the weapon system against soft targets based on the fragmentation warhead design. Different warhead geometric configurations, initiation points, as well as premade fragment material and shapes have been studied to enhance overall weapon efficiency against soft target. The study considered the static fragment distribution and velocity as the base for the analysis. A new vulnerability code has been developed based on the mean area of effectiveness to prove the study using both simulations and field tests. There were significant improvements on the weapon efficiency by altering the warhead parameters. The simulated results showed good correspondence with the test results. The newly developed vulnerability code can be considered as an additional system engineering analysis tool for the calculations of weapon efficiency.

The Lethal Range Testing of Effective 80mm Air to Ground Warhead

The air force is the most important weapon during wars and battles. Through it, armies can control and isolate enemy territory, carry out their own operations and missions, allow for the increased bombing, tactical air support for ground forces, parachuting, airdrops, and the passage of cargo planes. Countries are working to enhance their air force by increasing the number of their aircraft and providing them with the latest modern technologies in monitoring targets, accurate and efficient missiles. This paper will present a completely new design of 80 mm controlled fragmentation warhead for air to surface missile has been designed and tested, the results of the experiment showed a good performance for tactical characteristics such as lethal range which is about 19 meters.

Double casing warhead with sandwiched charge to produce multiple fragment groups for sequential hits: Concept and analysis of fragment velocity

This work introduces a novel fragmentation warhead that can produce two groups of fragments with different velocity characteristics and strike the target sequentially. The two groups of fragments come from two separate casings in one warhead, and the different velocities of fragments from different groups are attained by having a charge compartment sandwiched between the two casings in the warhead. A theoretical analysis formula is established to predict the maximum velocity of fragment from each casing based on energy balance. The results of X-ray radiography experiment and 3D smooth-particle hydrodynamics numerical simulation indicate that the proposed formula is accurate and reliable in calculating the fragment velocity as long as the thickness of the inner casing is less than 30% the radius of the inner charge. The fragment velocities of warheads with different structure are further analyzed, and the results show that the fragments of the two casing exhibit greater disparity in their maximum velocity when more charge is packed in the sandwiched compartment instead of enclosed in the inner casing.

A Calculation Method of Fragment Initial Velocity of Blast-fragmentation Warhead Based on Neural Network

This paper analyzes the theoretical calculation method of the initial velocity of the static bursting disc and the factors affecting the initial velocity of the static bursting disc. On this basis, a calculation method and device of the initial velocity of the fragmentation warhead based on the neural network is proposed. The strong nonlinear mapping ability of the BP neural network and the associative memory ability of the external stimulation and input information are used to determine the initial velocity of the fragment of the kill warhead and improve the efficiency. The speed of calculation and the accuracy of the results are given.

파편형 탄두의 표적무력화거리 예측을 위한 확률식 기반 해석 방법과 시험기반 해석 방법

This paper addresses two methods to estimate the target incapacitation distance and probability of the arbitrary fragmentation warhead under the static detonation test condition. One is based on the probability equation suggested by Sperrazza and Kokinakis. The other is originated from the stationary detonation test concept to measure the performance of the fragmentation warhead. In the arbitrary fragmentation warhead, the target incapacitation probabilities obtained from the two methods were compared with each other. We found that the size of the fragment with cubic shape should be more than 3.5 mm to maximize the target incapacitation distance in the test method. And we also realized that the difference between the target incapacitation distance of the analysis method based on the test (AMBT) and that of the analysis method based on the probability equation (AMBPE) is decreased according to the increase of the fragment size. In conclusion, this paper can be useful for the estimation of the fragmentation warhead performance at the design stage.

Finite element-smoothed particle hydrodynamics adaptive method in simulating debris cloud

The meshless algorithms, especially the smoothed particle hydrodynamics (SPH), are attempted to solve the hypervelocity impact (HVI) problem. However, several limitations of SPH exist in the current studies, such as the tensile instability, the material boundary uncertainty, and the difficulty in defining boundaries. Furthermore, it cannot accurately provide the parameters of the generated fragments. In this paper, we formulate the finite element-smoothed particle hydrodynamics (FEM-SPH) adaptive method to solve the HVI problem by LS-DYNA. It combines the advantages of FEM and SPH by transforming the failed elements into the SPH particles during the simulation. The debris cloud shape is represented by the distribution of the particles in SPH and the exact fragment parameters in FEM, including geometry, temperature, energy, and distribution. By analyzing and optimizing the implementation method, the contact and coupling algorithm, and calculation parameters, we reproduce the experimental results by Piekutowski [39,40] in the numerical simulation. Based on the proposed three typical shapes of the fragments, a systematic statistical analysis is proposed to classify the fragments and analyze their parameters, including speed, momentum, and energy. Risky fragments, i.e., the fragments with large size and high speed, are selected from the overall fragments. We further study the distribution of risky fragments with the details of the evolution in the space and time, which paves the way for further systematic research on the subsequent impact of the debris cloud. Our work shows that the method has a significant and wide application to the debris cloud simulation. The current algorithm can be applied to simulate the Whipple shields with complex structures and advanced material, e.g., sandwich materials, composite materials, foam materials, and gradient materials, or analyze the implosion and fragmentation warhead.

Metallic reactive materials application in fragmentation warhead

The composition, structure, manufacturing process and properties of Metallic reactive materials are introduced. The typical ternary mixture of Ni-Al-W have high density of 7.37g/cm3 and static tensile strength of 228MPa, which make the reactive fragments gain high penetration capability to perforate the target&s skin and can survive under explosive. The Ni-Al-W fragments undergo intermetallic reaction and oxidation reaction upon impacting. The energy release characteristics of Ni-Al-W reactive material were analysed. The chemical energy and pressure generated by reaction of the reactive material have a linear relationship with the impact velocity. A warhead prototype of Ni-Al-W fragment warhead was designed and the warhead explosion testing was carried out. The results show that the Ni-Al-W fragments are capable of withstanding to explosive loading with acquiring initial velocity of 2256m/s. The Ni-Al-W fragments also have advantage of perforation in area against the bi-layered space plates. The metallic reactive fragment warhead can increase the lethality of fragmentation warheads against aircrafts and phased array antenna, which increasingly get mature and have a wide application prospect.

THE METHOD OF DETERMINING THE PUNCHING ACTION OF THE READY-MADE DAMAGE ELEMENT OF FRAGMENTATION OF HIGH-EXPLOSIVE WARHEAD

The subject of this article is the development of a method for determining the penetration capacity of ready-made elements of damage to a fragmentation and high-explosive warhead. The analysis of the existing methods of determining the penetration capacity of the damage elements indicates their inconsistency with the modern requirements for determining the power of means of destruction of combat parts of missiles, tactical and cruise missiles and aircraft bombs. Existing techniques that were proposed in the late 19th and early 20th centuries are based on the systematization of empirical research and are outdated and have a limited range of applications. Since they do not take into account the zone of contact interacting between the element of the impact and the obstacle and the critical angle of approach, which will determine the ricochet conditions. The article presents the results of the calculated determination of the penetration capacity of the ready-made damage element, taking into account the contact surface of the interaction of the damage element with the obstacle, which are obtained as a result of the calculation modelling in the Ansys Autodyn software complex. Ways to determine the penetration capacity of ready-made destruction elements of fragmentation and high-explosive warhead, taking into account their true geometric shape and excess kinetic energy are proposed in the article. The proposed technique can be used to create the penetration nomograms of the elements of the lesion. The application of computational modeling of the determination of nonograms of penetration ability will allow to abandon a large number of experimental studies with real undermining of the warhead, thereby reducing the cost and speeding up the process of creating, refining and adopting the newest samples of defeat equipment.

Ballistic Protection of Military Shelters from Mortar Fragmentation and Blast Effects using a Multi layer Structure

In addition to its usage as a top attack ammunition in the battle field against troops, 120 mm mortar bomblethas been recently used in the terror attacks against military shelters and civil constructions. This research studiesthe protection of vehicle and personnel military shelters against mortar fragmentation warhead projectile and it’sdestroying effects. The mortar warhead threat combines both blast load and ballistic fragment penetration effects. Composite structure layers are proposed herein to be integrated with concertina walls to achieve full protection against the mortar projectile destroying effects. The current paper investigates the ability of the proposed layers to stop the mortar’s fragments and to mitigate its blast load. The velocity and the mass distribution of the produced projectile fragments were estimated using Split-X software. Besides, the ability of the proposed protection layers to stop the fragments and mitigate the blast wave was evaluated using AUTODYN hydrocode. A static firing test was then performed to validate the theoretical results and verify the effectiveness of the proposed protection added layers. The current study showed that the proposed composite layers are sufficient to protect the military shelters from the mortar’s destroying ballistic effects.