This paper proposes an adaptive neural control (ANC) method for the coupled nonlinear model of a novel type of embedded surface morphing aircraft which has a tiltable V-tail. A nonlinear model with six-degrees-of-freedom is established. The first-order sliding mode differentiator (FSMD) is applied to the control scheme to avoid the problem of “differential explosion”. Radial basis function neural networks are introduced to estimate the uncertainty and external disturbance of the model, and an ANC controller is proposed based on this design idea. The stability of the proposed ANC controller is proved using Lyapunov theory, and the tracking error of the closed-loop system is semi-globally uniformly bounded. The effectiveness and robustness of the proposed method are verified by numerical simulations and hardware-in-the-loop (HIL) simulations. © 2022 China Ordnance Society

Based on the high positioning accuracy, low cost and low-power consumption, the ultra-wide-band (UWB) is an ideal solution for indoor unmanned aerial vehicle (UAV) localization and navigation. However, the UWB signals are easy to be blocked or reflected by obstacles such as walls and furniture. A resilient tightly-coupled inertial navigation system (INS)/UWB integration is proposed and implemented for indoor UAV navigation in this paper. A factor graph optimization (FGO) method enhanced by resilient stochastic model is established to cope with the indoor challenging scenarios. To deal with the impact of UWB non-line-of-sight (NLOS) signals and noise uncertainty, the conventional neural net-works (CNNs) are introduced into the stochastic modelling to improve the resilience and reliability of the integration. Based on the status that the UWB features are limited, a ‘two-phase’ CNNs structure was designed and implemented: one for signal classification and the other one for measurement noise prediction. The proposed resilient FGO method is tested on flighting UAV platform under actual indoor challenging scenario. Compared to classical FGO method, the overall positioning errors can be decreased from about 0.60 m to centimeter-level under signal block and reflection scenarios. The superiority of resilient FGO which effectively verified in constrained environment is pretty important for positioning accuracy and integrity for indoor navigation task. © 2022 China Ordnance Society

Gradiently denitrated gun propellant (GDGP) prepared by a “gradient denitration” strategy is obviously superior in progressive burning performance to the traditional deterred gun propellant. Currently, the preparation of GDGP employed a tedious two-step method involving organic solvents, which hinders the large-scale preparation of GDGP. In this paper, GDGP was successfully prepared via a novelty and environmentally friendly one-step method. The obtained samples were characterized by FT-IR, Raman, SEM and XPS. The results showed that the content of nitrate groups gradiently increased from the surface to the core in the surface layer of GDGP and the surface layer of GDGP exhibited a higher compaction than that of raw gun propellant, with a well-preserved nitrocellulose structure. The denitration process enabled the propellant surface with regressive energy density and good progressive burning performance, as confirmed by oxygen bomb and closed bomb test. At the same time, the effects of different solvents on the component loss of propellant were compared. The result showed that water caused the least component loss. Finally, the stability of GDGP was confirmed by methyl-violet test. This work not only provided environmentally friendly, simple and economic preparation of GDGP, but also confirmed the stability of GDGP prepared by this method. © 2023 China Ordnance Society

The weapon transportation support scheduling problem on aircraft carrier deck is the key to restricting the sortie rate and combat capability of carrier-based aircraft. This paper studies the problem and presents a novel solution architecture. Taking the interference of the carrier-based aircraft deck layout on the weapon transportation route and precedence constraint into consideration, a mixed integer formulation is established to minimize the total objective, which is constituted of makespan, load variance and accumulative transfer time of support unit. Solution approach is developed for the model. Firstly, based on modeling the carrier aircraft parked on deck as convex obstacles, the path library of weapon transportation is constructed through visibility graph and Warshall-Floyd methods. We then propose a bi-population immune algorithm in which a population-based forward/backward scheduling technique, local search schemes and a chaotic catastrophe operator are embedded. Besides, the random-key solution representation and serial scheduling generation scheme are adopted to conveniently obtain a better solution. The Taguchi method is additionally employed to determine key parameters of the algorithm. Finally, on a set of generated realistic instances, we demonstrate that the proposed algorithm outperforms all compared algorithms designed for similar optimization problems and can significantly improve the efficiency, and that the established model and the bi-population immune algorithm can effectively respond to the weapon support requirements of carrier-based aircraft under different sortie missions. © 2023 China Ordnance Society

Thermite films are typical energetic materials (EMs) and have great value in initiating explosive devices. However, research in thermite film preparation is far behind that of research in thermite powders. Electrophoretic deposition (EPD) is an emerging, rapid coating method for film fabrication, including of energetic composite films. In this work, a polytetrafluoroethylene (PTFE)/Al/CuO organic-inorganic hybrid energetic film was successfully obtained using the above method for the first time. The addition of lithocholic acid as a surfactant into the electroplating suspension enabled PTFE to be charged. The combustion and energy release were analyzed by means of a high-speed camera and differential scanning calorimetery (DSC). It was found that the combustion process and energy release of PTFE/Al/CuO were much better than that of Al/CuO. The main reason for the excellent combustion performance of the hybrid PTFE/Al/CuO system was that the oxidability of PTFE accelerated the redox reaction between Al and CuO. The prepared PTFE/Al/CuO film was also employed as ignition material to fire a B–KNO3 explosive successfully, indicating considerable potential for use as an ignition material in micro-ignitors. This study sheds light on the preparation of fluoropolymer-containing organic-inorganic hybrid energetic films by one-step electrophoretic deposition. © 2021 China Ordnance Society

In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs (BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element (FE) analysis. Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional (1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs. © 2023 China Ordnance Society

This study elaborates on the effects of matrix rigidity on the high-velocity impact behaviour of UHMWPE textile composites using experimental and numerical methods. Textile composite samples were manufactured of a plain-weave fabric (comprising Spectra® 1000 fibres) and four different matrix materials. High-velocity impact tests were conducted by launching a spherical steel projectile to strike on the prepared samples via a gas gun. The experimental results showed that the textile composites gradually changed from a membrane stretching mode to a plate bending mode as the matrix rigidity and thickness increased. The composites deformed in the membrane stretching mode had higher impact resistance and energy absorption capacity, and it was found that the average energy absorption per ply was much higher in this mode, although the number of broken yarns was smaller in the perforated samples. Moreover, the flexible matrix composites always had higher perforation resistance but larger deformation than the rigid matrix counterparts in the tested thickness and velocity range. A novel numerical modelling approach with enhanced computational efficiency was proposed to simulate textile composites in mesoscale resolution. The simulation results revealed that stress and strain development in the more rigid matrix composite was localised in the vicinity of the impact location, leading to larger local deformation and inferior perforation resistance. © 2022 China Ordnance Society

The properties of the combustion and deflagration to detonation transition (DDT) of Al/Fe2O3/RDX hybrid nanocomposites, a type of potentially novel lead-free primary explosives, were tested in weakly confined conditions, and the interaction of Al/Fe2O3 nanothermite and RDX in the DDT process was studied in detail. Results show that the amount of the Al/Fe2O3 nanothermite has a great effect on the DDT properties of Al/Fe2O3/RDX nanocomposites. The addition of Al/Fe2O3 nanothermite to RDX apparently improves the firing properties of RDX. A small amount of Al/Fe2O3 nanothermite greatly increases the initial combustion velocity of Al/Fe2O3/RDX nanocomposites, accelerating their DDT process. When the contents of Al/Fe2O3 nanothermite are less than 20 wt%, the DDT mechanisms of Al/Fe2O3/RDX nanocomposites follow the distinct abrupt mode, and are consistent with that of RDX, though their DDT processes are different. The RDX added into the Al/Fe2O3 nanothermite increases the latter's peak combustion velocity and makes it generate the DDT when the RDX content is at least 10 wt%. RDX plays a key role in the shock compressive combustion, the formation and the properties of the DDT in the flame propagation of nanocomposites. Compared with RDX, the fast DDT of Al/Fe2O3/RDX nanocomposites could be obtained by adjusting the chemical constituents of nanocomposites. © 2021 China Ordnance Society

Resilience of air & space defense system of systems (SoSs) is critical to national air defense security. However, the research on it is still scarce. In this study, the resilience of air & space defense SoSs is firstly defined and the kill network theory is established by combining super network and kill chain theory. Two cases of the SoSs are considered: (a) The kill chains are relatively homogenous; (b) The kill chains are relatively heterogenous. Meanwhile, two capability assessment methods, which are based on the number of kill chains and improved self-information quantity, respectively, are proposed. The improved self-information quantity modeled based on nodes and edges can achieve qualitative and quantitative assessment of the combat capability by using linguistic Pythagorean fuzzy sets. Then, a resilient evaluation index consisting of risk response, survivability, and quick recovery is proposed accordingly. Finally, network models for regional air defense and anti-missile SoSs are established respectively, and the resilience measurement results are verified and analyzed under different attack and recovery strategies, and the optimization strategies are also proposed. The proposed theory and method can meet different demands to evaluate combat capability and optimize resilience of various types of air & space defense and similar SoSs. © 2023 China Ordnance Society

The active protection system (APS), usually installed on the turret of armored vehicles, can significantly improve the vehicles’ survivability on the battlefield by launching countermeasure munitions to actively intercept incoming threats. However, uncertainty over the launch angle of the countermeasure is increased due to angular disturbances when the off-road armored vehicle is moving over rough terrain. Therefore, accurate and comprehensive angular disturbance prediction is essential to the real-time monitoring of the countermeasure launch angle. In this paper, a deep ensemble learning (DEL)-based approach is proposed to predict the angular disturbances of the countermeasure launcher in the APS based on previous time-series information. In view of the intricate temporal attribute of angular disturbance prediction, the sampling information of historical time series measured by an inertial navigation device is adopted as the input of the developed DEL model. Then, the recursive multi-step (RMS) prediction strategy and multi-output (MO) prediction strategy are combined with the DEL model to perform the final angular disturbance prediction for the countermeasure launcher in the APS of a moving armored vehicle. The proposed DEL model is validated by using the different datasets from real experiments. The results reveal that this approach can be used to accurately predict angular disturbances, with the maximum absolute error of each DOF less than 0.1°. © 2022 China Ordnance Society

Combining the methods of theoretical, numerical and experimental, this research focuses on the jet formation behavior and optimization of trunconical hypercumulation shaped charge structure. With the three-stage division, formation theory of trunconical hypercumulation shaped charge jet is established based on micro element method. By dimensional analysis, main control parameters are identified and their effect on jet formation are analyzed. Through numerical modelling and orthogonal optimization method, influence of the factors and their levels over the indicators of jet tip velocity and jet length as well as order of the significance of each factor and level are obtained. Penetration experiments of trunconical hypercumulation shaped charge based on the orthogonal optimization reveals its advantage over traditional conical shaped charge structure, and finally determines the optimal influence factor level combination. The research and results would provide useful guide for the design and application of trunconical hypercumulation shaped charge structure. © 2022 China Ordnance Society

To investigate the thermal response and initiation behavior of ternary fluoropolymer-matrix PTFE/Al/W reactive materials, a research combining shock loading tests and trans-scale modelling is conducted. On the basis of a good agreement of the numerically simulated and tested shock wave propagation, the significant impact of component ratios and particle sizes on the evolution of mesoscopic temperature, hot-spots and initiation is well characterized and analyzed. Results demonstrate that as the content of W increases, the range of mesoscopic high-temperature area increases and tends to distribute more uniform, while material with smaller W particles causes more intense particle deformation and larger temperature rise. The time to reach the critical temperature shows positive correlation to the content of W, while the critical temperature of hot-spots shows negative correlation to the particle size of W. For PTFE/Al/W of high density, with the increase of W particle size, the reaction rate decrease, however the time to reach the peak reaction rate shortens. © 2022 China Ordnance Society

Automated detection of military people based on the images in different environments plays an important role in accurately completing military missions. With the equipment gradually moving towards intelligence, unmanned aerial vehicles (UAVs) will be widely used for integrated reconnaissance/attack in the future. The lightweight and compact design of the small UAV allows it to travel through dense forests and other environments to capture images with its convenient mobility. However, as the camouflage has been designed to blend in with surroundings, which greatly reduces the probability of the target being discovered. Moreover, the lack of training data on camouflaged people detection will inhibit the training of a deep model. To address these problems, a novel semi-supervised camouflaged military people detection network is proposed to automatically detect the target from the images. In this paper, the camouflaged object detection dataset (COD10K) is first supplemented according to our mission requirements, then the edge attention is utilized to enhance the boundaries based on search identification network. Further, a semi-supervised learning strategy is presented to take advantage of the unlabeled data which can alleviate insufficient data and improve the detection accuracy. Experiments demonstrate that the proposed semi-supervised search identification network (Semi-SINet) performs well in camouflaged people detection compared with other object detection methods. © 2021 China Ordnance Society

The excellent remote sensing ability of synthetic aperture radar (SAR) will be misled seriously when it encounters deceptive jamming which possesses high fidelity and fraudulence. In this paper, the dynamic synthetic aperture (DSA) scheme is used to extract the difference between the true and false targets. A simultaneous deceptive jamming suppression and target reconstruction method is proposed for a single channel SAR system to guarantee remote sensing ability. The system model is formulated as a sparse signal recovery problem with an unknown parametric dictionary to be estimated. An iterative re-weighted method is employed to jointly handle the dictionary parameter learning and target reconstruction problem in an majorization-minimization framework, where a surrogate function majorizing the Gaussian entropy in the objective function is introduced to circumvent its non-convexity. After dictionary parameter learning, the grid mismatching problem in a fixed grid based method is avoided. Therefore, the proposed method can reap a super resolution result. Besides, a simple yet effective DSA section scheme is developed for the SAR data excerpting, in which only two DSAs are required. Experimental results about location error and reconstruction power error reveal that the proposed method is able to achieve a good performance in deceptive jamming suppression. © 2021 China Ordnance Society

To investigate the shock response of cyclotetramethylene tetranitramine (HMX) single crystals at elevated temperatures (below the phase transition point), plate impact experiments at elevated temperatures were designed and conducted. The HMX/window interface particle velocities at temperatures of 300 K, 373 K, and 423 K were measured by the velocity interferometry system for any reflector (VISAR) technique. To further analyze the related mesoscale deformation mechanisms, a nonlinear thermoelastic-viscoplastic model was developed, which considers thermal activation and phonon drag dislocation slip mechanisms. The proposed model could well reproduce the measured thermal hardening behavior of Hugoniot elastic limit (HEL) of HMX single crystals. At elevated temperatures, the reduced dislocation mobility was observed, which stems from both phonon scattering and radiative damping effects. Comparatively speaking, radiative damping contributes less than phonon scattering to thermal hardening behavior. The calibrated model was further used to predict shock response of HMX single crystals with different thicknesses at different initial temperatures. Both the stress relaxation and elastic precursor decrease with thickness are mainly due to the rapid dislocation generation. These insights shed light on the interplay between dislocation motion and dislocation generation in thermal hardening behavior, stress relaxation, and elastic precursor decay, which serves to reveal the mesoscale deformation mechanisms at elevated temperatures. © 2021 China Ordnance Society

Simultaneous Localization and Mapping (SLAM) is the foundation of autonomous navigation for unmanned systems. The existing SLAM solutions are mainly divided into the visual SLAM(vSLAM) equipped with camera and the lidar SLAM equipped with lidar. However, pure visual SLAM have shortcomings such as low positioning accuracy, the paper proposes a visual-inertial information fusion SLAM based on Runge-Kutta improved pre-integration. First, the Inertial Measurement Unit (IMU) information between two adjacent keyframes is pre-integrated at the front-end to provide IMU constraints for visual-inertial information fusion. In particular, to improve the accuracy in pre-integration, the paper uses the Runge-Kutta algorithm instead of Euler integral to calculate the pre-integration value at the next moment. Then, the IMU pre-integration value is used as the initial value of the system state at the current frame time. We combine the visual reprojection error and imu pre-integration error to optimize the state variables such as speed and pose, and restore map points' three-dimensional coordinates. Finally, we set a sliding window to optimize map points' coordinates and state variables. The experimental part is divided into dataset experiment and complex indoor-environment experiment. The results show that compared with pure visual SLAM and the existing visual-inertial fusion SLAM, our method has higher positioning accuracy. © 2023 China Ordnance Society

Herein, we present a thermo-mechanical analyzer (TMA) and dynamic mechanical analyzer (DMA) of composite multi-layered gun propellant, focusing on thermal expansion coefficients and dynamic thermomechanical properties. The linear thermal expansion coefficient of the prepared energetic material is determined as approx. 0.1800 × 10−4 - 0.2081 × 10−4 K−1. According to DMA test and dynamic thermomechanical properties, the glass transition temperature is also obtained. The tested value is within the range of 223.01–223.50 K, which indicates the lower limit of the energetic material. However, DMA tests reveal temperature changes, which occur due to thermal expansion. Moreover, the geometrical factor decreases with increasing temperature. Therefore, thermal expansion significantly affects the storage modulus and loss modulus. Additionally, the thermal expansion coefficient can be used to modify the storage and loss modulus. The results show that the proposed method provides effective and reliable modified results. © 2021 China Ordnance Society

The shielding and corrosion properties of the Alloy 709 advanced austenitic stainless steel have been investigated as a candidate canister material in spent fuel dry casks. The results revealed that the experimental and computational data of the linear and mass attenuation coefficients of the alloy are in good agreement, in which the attenuation coefficient values decreased with increasing photon energy. Alloy 709 was shown to exhibit the highest linear attenuation coefficient against gamma rays when compared to 304 and 316 stainless steels. On the other hand, Alloy 709 exhibited no considerable weight change over a 69-day period in circulating salt brines corrosion testing, while it showed an exponential increase of corrosion current density with temperature in acidic and basic corrosive solutions during electrochemical polarization corrosion testing. Furthermore, Alloy 709 was the least corroded steel compared to other austenitic stainless steels in both acidic and basic solutions. The optimistic results of the shielding and corrosion properties of Alloy 709 due to its chemical composition, suggest utilizing it as a canister material in spent nuclear fuel dry casks. © 2022 China Ordnance Society

Detecting highly-overlapped objects in crowded scenes remains a challenging problem, especially for one-stage detector. In this paper, we extricate YOLOv4 from the dilemma in a crowd by fine-tuning its detection scheme, named YOLO-CS. Specifically, we give YOLOv4 the power to detect multiple objects in one cell. Center to our method is the carefully designed joint prediction scheme, which is executed through an assignment of bounding boxes and a joint loss. Equipped with the derived joint-object augmentation (DJA), refined regression loss (RL) and Score-NMS (SN), YOLO-CS achieves competitive detection performance on CrowdHuman and CityPersons benchmarks compared with state-of-the-art detectors at the cost of little time. Furthermore, on the widely used general benchmark COCO, YOLO-CS still has a good performance, indicating its robustness to various scenes. © 2021 China Ordnance Society

In the present study, the unique three-dimensional graphene coated nickel (Ni/C) foam reinforced silicon carbide (Ni/C@SiC) composites were first obtained via the precursor impregnation and pyrolysis (PIP) processes. The microstructure images indicated that the SiC fillers were successfully prepared in the skeleton pores of the Ni/C foam. The influence of the PIP cycles on the microwave absorption performances was researched, and the results indicated that after the primary PIP process, Ni/C@SiC–I possessed the optimal microwave absorbing performance with a minimum reflection loss(RL) of −25.87 dB at 5.28 GHz and 5.00 mm. Besides, the RL values could be below −10.00 dB from 5.88 GHz to 7.74 GHz when the corresponding matching thickness was 3.85 mm. However, the microwave absorption properties of Ni/C@SiC-II and Ni/C@SiC-III were tremendously degraded as the PIP times increased. At last, the electromagnetic parameter, dielectric loss, attenuation constant as well as impedance matching coefficient were further investigated to analyze the absorbing mechanism, which opened a new path for the certain scientific evaluation of the absorbing materials and had extremely important to the defence technology. © 2021 China Ordnance Society

The conventional case of patch repair involves bonding a patch over single damage/hole in the laminate. This work investigates the effect of interaction of two holes on the tensile behavior patch repaired carbon epoxy woven laminates. The specimens of [0°/45°/45°/0°] laminates were repaired with adhesively bonded two-ply [45°]2 external patches. Three different cases of drilled specimens were produced with different hole arrangements viz. specimens with single central hole (SH), with two holes aligned along the longitudinal axis (LH) and with two holes along transverse axis (TH). The two-hole specimens were repaired with two different types, i.e. single large patches (SP) and with the two smaller patches (DP) of combined bonding area equal to the single large patches. Digital image correlation (DIC) was employed to capture strain contours. The results reveal the difference in the load transfer through the patches depending upon the arrangement of holes. The TH repaired specimen exhibit significant load recovery (SP-32.75%, DP-34.62%) while the LH specimens result in very marginal (SP- 6.11%, DP-4.10%) recovery compared to their drilled case. The TH specimen failed by crack growing through both the holes beneath the patch, while the LH specimens failed by the failure through only one hole. The use of single large patch over multiple holes and multiple small patches individually over each hole has no significant influence on load recovery. © 2022 China Ordnance Society

Behind armour blunt trauma (BABT) is a body injury resulting from the deformation of the back surface of armour as a result of a bullet impact. In the case of textile body armour, the severity of the injury may depend on the material of the fibres, but also on the geometric structure of the fabric. The article focuses on experimental research into injuries of the human body protected by ballistic packets made of biaxial and triaxial fabrics, during a non-penetrating impact from a Parabellum 9 mm × 19 mm Full Metal Jacket (FMJ) bullet, at a speed of 406 ± 5 m/s. In experimental research, the fabrics had a comparable surface weight and were made of the same Kevlar® 29 yarn. The ballistic packages were made of 30 layers. As part of the work, a physical model of the human body was developed. The human body model consisted of a model of the heart, lungs, and skeletal and muscular systems. During the bullet impact, the pressure forces were recorded using sensors located at selected points of the human body. The bullets hit five selected places on the body that were considered critical, from the point of view of maintaining a human's vital functions. It was found that, during firing, pressure increases both at the site of impact and in the internal organs, which can lead to multi-organ damage. As a result of the experimental analysis, it has been shown that the pressures exerted on specific organs are always lower in the case of body protection with a ballistic packet made of triaxial fabrics, compared to a packet made of biaxial fabrics. © 2022 China Ordnance Society

Polymer bonded explosives (PBXs) have high energy density, excellent mechanical properties and better thermal stability. In this study, droplet microfluidic technology was used to successfully prepare HMX/TATB microspheres. The effects of different binder types and binder concentrations on the morphology of the microspheres were studied, and results proved that NC/GAP (1:4) provides particles a regular spherical morphology and good dispersion. Subsequently, the influence of the concentration of the dispersed phase and the flow rate of the continuous phase on the particle size distribution of the microspheres was fully studied. The microspheres had narrow particle size distribution and high spherical shape. Under optimized process conditions, HMX/TATB microspheres were prepared and compared with the physical mixtures. The X-ray diffraction, differential scanning calorimetry, flow properties, bulk density, and mechanical sensitivity of the samples were also studied. Results showed that the crystal form of the microspheres remains unchanged, and the binder maintains good compatibility with explosives. In addition, the fluidity, bulk density, real density and safety performance of the microspheres are remarkably better than the physical mixture. This study provides a new method for preparing PBX with narrow particle size distribution, high spherical shape, excellent dispersion and high bulk density. © 2021 China Ordnance Society

With increasing international and civilian conflicts, developing advanced body armor has become an emerging field in academia and industry. Nanotechnology, by means of, incorporating nanomaterials, is considered a highly effective technique to achieve this goal. It has been widely studied in defense applications owing to high strength-to-weight ratios and excellent energy absorption capability of nanomaterials. Hence, this review encompasses the latest application of nanotechnology involving nanomaterials and nanocomposites in ballistic and anti-impact fields. Additionally, this paper outlines fiber materials utilized, and alternative approaches adopted to develop robust non-metal bullet-proof materials. These approaches include shear thickening fluids (STFs) incorporation, sandwich structures, polymer matrix composites (PMCs), and textile structure optimization. Meanwhile, ballistic-related performances of various materials developed using single or hybrid techniques are collected and compared. © 2022 China Ordnance Society

This study aims at investigating the ballistic resistance and energy absorption in woven E-glass composite panels, considering different projectile nose shapes and oblique incidence angles. To that scope, three-dimensional finite element (FE) models of both projectiles and the laminated target are developed and numerical investigations are carried out using Abaqus Explicit solver. The composite damage model's constitutive law encompasses nonlinear material response, material properties degradation, progressive failure, and an element deletion strategy. The cohesive surface technique is used to represent the interface between two adjacent plies in the laminate, and the traction-separation law is used to characterize the behaviors of interlaminar degradation and failure. Material responses attributable to fiber rupture, matrix cracking, and plasticity caused by micro-matrix cracking due to shear loading are taken into account with suitable damage evolution laws. The computational framework is first validated against the experimental results reported in the literature by performing ballistic impact tests on the target laminate with conical, hemispherical and blunt-ended projectile, and the numerical results showed a good comparison in terms of residual velocity. Subsequently the framework is explored in simulating more complex failure mechanisms, with particular emphasis on the influence of the impact angle of obliquity, a parameter that is not usually analyzed in the literature. In that regard, the effects of normal and oblique impact on the damage morphologies and ballistic behavior of the fabric composite target in terms of energy absorption, impact contact force, and projectile residual velocity are conducted and analyzed, comparatively. The findings showed that the ballistic impact behavior of target composite is substantially influenced by projectile nose shape and incidence angle obliquity. © 2022 China Ordnance Society

To investigate the overall damage characteristics and failure modes of a warship subjected to an underwater non-contact near-field explosion, a hull girder with a trapezoidal cross-section was designed, manufactured, and tested. The design criteria and parameters were determined according to the similarity criterion. Dynamic responses of the girder freely floating on water were obtained under varying conditions, including stand-off distance, charge mass, and position of attack. Damage morphologies of the girder model were obtained. Based on our analysis, basic conditions for sagging damage of the hull girder are proposed. The aim of this study was to determine an efficient method of attack resulting in the most severe damage to the ship hull. The experimental results show that the girder mainly exhibits a first-order response when the first wet frequency of the girder is close to the frequency of the explosion bubble pulsation. The largest deformation was observed when the underwater explosion occurred directly below the midspan of the girder compared to other explosions of the same intensity at different attack positions. When the ratio of stand-off to maximum bubble radius (λ) satisfies 0.7 ≤ λ＜2, the bubble mainly causes sagging damage instead of hogging. As λ decreases (1≤ λ＜2), the sagging damage increases under the same charge mass. However, as λ decreases further (0.7≤ λ＜1), the sagging deformation decreases. This is likely due to the impact of the liquid jet formed by the collapsing bubble, which causes the girder deformation to shift from sagging back to hogging deformation. The initial shock wave excites the high-frequency response of the girder structure but contributes very little to the overall velocity and displacement. However, bubble pulsation typically causes a low-frequency response, which will affect the velocity and displacement of the girder. The low-pressure region of the flow field formed by bubble pulsation and resonant coupling between the girder and the bubble are the predominant causes of damage to the overall girder structure. © 2021 China Ordnance Society

Target maneuver trajectory prediction is an important prerequisite for air combat situation awareness and maneuver decision-making. However, how to use a large amount of trajectory data generated by air combat confrontation training to achieve real-time and accurate prediction of target maneuver trajectory is an urgent problem to be solved. To solve this problem, in this paper, a hybrid algorithm based on transfer learning, online learning, ensemble learning, regularization technology, target maneuvering segmentation point recognition algorithm, and Volterra series, abbreviated as AERTrOS-Volterra is proposed. Firstly, the model makes full use of a large number of trajectory sample data generated by air combat confrontation training, and constructs a Tr-Volterra algorithm framework suitable for air combat target maneuver trajectory prediction, which realizes the extraction of effective information from the historical trajectory data. Secondly, in order to improve the real-time online prediction accuracy and robustness of the prediction model in complex electromagnetic environments, on the basis of the Tr-Volterra algorithm framework, a robust regularized online Sequential Volterra prediction model is proposed by integrating online learning method, regularization technology and inverse weighting calculation method based on the priori error. Finally, inspired by the preferable performance of models ensemble, ensemble learning scheme is also incorporated into our proposed algorithm, which adaptively updates the ensemble prediction model according to the performance of the model on real-time samples and the recognition results of target maneuvering segmentation points, including the adaptation of model weights; adaptation of parameters; and dynamic inclusion and removal of models. Compared with many existing time series prediction methods, the newly proposed target maneuver trajectory prediction algorithm can fully mine the prior knowledge contained in the historical data to assist the current prediction. The rationality and effectiveness of the proposed algorithm are verified by simulation on three sets of chaotic time series data sets and a set of real target maneuver trajectory data sets. © 2022 China Ordnance Society

In this paper, a modified single-degree-of-freedom (SDOF) model of reinforced concrete (RC) beams under close-in explosion is proposed by developing the specific impulse equivalent method and flexural resistance calculation method. The equivalent uniform specific impulse was obtained based on the local conservation of momentum and global conservation of kinetic energy. Additionally, the influence of load uniformity, boundary condition and complex material behaviors (e.g. strain rate effect, hardening/softening and hoop-confined effect) was considered in the resistance calculation process by establishing a novel relationship between external force, bending moment, curvature and deflection successively. The accuracy of the proposed model was verified by carrying out field explosion tests on four RC beams with the scaled distances of 0.5 m/kg1/3 and 0.75 m/kg1/3. The test data in other literatures were also used for validation. As a result, the equivalent load implies that the blast load near the mid-span of beams would contribute more to the maximum displacement, which was also observed in the tests. Moreover, both the resistance model and test results declare that when the blast load becomes more concentrated, the ultimate resistance would become lower, and the compressive concrete would be more prone to softening and crushing. Finally, based on the modified SDOF model, the calculated maximum displacements agreed well with the test data in this paper and other literatures. This work fully proves the rationality of the modified SDOF method, which will contribute to a more accurate damage assessment of RC structures under close-in explosion. © 2022 China Ordnance Society