Pub Date : 2026-02-01Epub Date: 2025-09-16DOI: 10.1016/j.dt.2025.09.022
Yifan Yuan , Xiaohong Shen , Lin Sun , Ke He , Yongsheng Yan , Haiyan Wang
Cascading failures pose a serious threat to the survivability of underwater unmanned swarm networks (UUSNs), significantly limiting their service ability in collaborative missions such as military reconnaissance and environmental monitoring. Existing failure models primarily focus on power grids and traffic systems, and don't address the unique challenges of weak-communication UUSNs. In UUSNs, cascading failure present a complex and dynamic process driven by the coupling of unstable acoustic channels, passive node drift, adversarial attacks, and network heterogeneity. To address these challenges, a directed weighted graph model of UUSNs is first developed, in which node positions are updated according to ocean-current–driven drift and link weights reflect the probability of successful acoustic transmission. Building on this UUSNs graph model, a cascading failure model is proposed that integrates a normal–failure–recovery state-cycle mechanism, multiple attack strategies, and routing-based load redistribution. Finally, under a five-level connectivity UUSNs scheme, simulations are conducted to analyze how dynamic topology, network load, node recovery delay, and attack modes jointly affect network survivability. The main findings are: (1) moderate node drift can improve survivability by activating weak links; (2) based-energy routing (BER) outperform based-depth routing (BDR) in harsh conditions; (3) node self-recovery time is critical to network survivability; (4) traditional degree-based critical node metrics are inadequate for weak-communication UUSNs. These results provide a theoretical foundation for designing robust survivability mechanisms in weak-communication UUSNs.
{"title":"Cascading failure modeling and survivability analysis of weak-communication underwater unmanned swarm networks","authors":"Yifan Yuan , Xiaohong Shen , Lin Sun , Ke He , Yongsheng Yan , Haiyan Wang","doi":"10.1016/j.dt.2025.09.022","DOIUrl":"10.1016/j.dt.2025.09.022","url":null,"abstract":"<div><div>Cascading failures pose a serious threat to the survivability of underwater unmanned swarm networks (UUSNs), significantly limiting their service ability in collaborative missions such as military reconnaissance and environmental monitoring. Existing failure models primarily focus on power grids and traffic systems, and don't address the unique challenges of weak-communication UUSNs. In UUSNs, cascading failure present a complex and dynamic process driven by the coupling of unstable acoustic channels, passive node drift, adversarial attacks, and network heterogeneity. To address these challenges, a directed weighted graph model of UUSNs is first developed, in which node positions are updated according to ocean-current–driven drift and link weights reflect the probability of successful acoustic transmission. Building on this UUSNs graph model, a cascading failure model is proposed that integrates a normal–failure–recovery state-cycle mechanism, multiple attack strategies, and routing-based load redistribution. Finally, under a five-level connectivity UUSNs scheme, simulations are conducted to analyze how dynamic topology, network load, node recovery delay, and attack modes jointly affect network survivability. The main findings are: (1) moderate node drift can improve survivability by activating weak links; (2) based-energy routing (BER) outperform based-depth routing (BDR) in harsh conditions; (3) node self-recovery time is critical to network survivability; (4) traditional degree-based critical node metrics are inadequate for weak-communication UUSNs. These results provide a theoretical foundation for designing robust survivability mechanisms in weak-communication UUSNs.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 66-82"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-19DOI: 10.1016/j.dt.2025.09.027
Xiaoke Liu , Kejing Yu , Pengwan Chen
Flexible materials play a crucial role in protecting against behind armour blunt trauma (BABT). However, their compliance complicates the understanding of failure mechanisms and energy absorption. This study used a combined experimental and numerical approach to investigate the response and failure modes of a flexible ultra-high-molecular-weight polyethylene (UHMWPE) foam protective sandwich structure (UFPSS) under low-velocity impact (LVI). A finite element (FE) model, accounting for nonlinear large deformation and strain-rate-dependent material behavior, was developed for a woven-UFPSS (featuring a plain-woven fabric structure) subjected to a 50 J impact. Experimental and numerical results showed strong agreement in peak force (error < 5%), maximum displacement (error < 6%), and buffer time (error < 8%). The impact's kinetic energy was mainly converted into internal energy of the fabric and foam materials (∼50%), viscous dissipation in the foam core (12%–15%), frictional work at the contact interfaces (5%–6%), and work by the pneumatic fixture clamping force (∼38%). This study provides the first investigation of the LVI performance of sandwich structures with all soft material layers, offering significant insights for the application of compliant materials in protective fields.
{"title":"Energy absorption properties and failure modes of flexible UHMWPE foam protective sandwich structure subjected to low-velocity impact","authors":"Xiaoke Liu , Kejing Yu , Pengwan Chen","doi":"10.1016/j.dt.2025.09.027","DOIUrl":"10.1016/j.dt.2025.09.027","url":null,"abstract":"<div><div>Flexible materials play a crucial role in protecting against behind armour blunt trauma (BABT). However, their compliance complicates the understanding of failure mechanisms and energy absorption. This study used a combined experimental and numerical approach to investigate the response and failure modes of a flexible ultra-high-molecular-weight polyethylene (UHMWPE) foam protective sandwich structure (UFPSS) under low-velocity impact (LVI). A finite element (FE) model, accounting for nonlinear large deformation and strain-rate-dependent material behavior, was developed for a woven-UFPSS (featuring a plain-woven fabric structure) subjected to a 50 J impact. Experimental and numerical results showed strong agreement in peak force (error < 5%), maximum displacement (error < 6%), and buffer time (error < 8%). The impact's kinetic energy was mainly converted into internal energy of the fabric and foam materials (∼50%), viscous dissipation in the foam core (12%–15%), frictional work at the contact interfaces (5%–6%), and work by the pneumatic fixture clamping force (∼38%). This study provides the first investigation of the LVI performance of sandwich structures with all soft material layers, offering significant insights for the application of compliant materials in protective fields.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 32-48"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-29DOI: 10.1016/j.dt.2025.09.038
Wei Han , Changjiu Li , Xichao Su , Yong Zhang , Fang Guo , Tongtong Yu , Xuan Li
The highly dynamic nature, strong uncertainty, and coupled multiple safety constraints inherent in carrier aircraft recovery operations pose severe challenges for real-time decision-making. Addressing bolter scenarios, this study proposes an intelligent decision-making framework based on a deep long short-term memory Q-network. This framework transforms the real-time sequencing for bolter recovery problem into a partially observable Markov decision process. It employs a stacked long short-term memory network to accurately capture the long-range temporal dependencies of bolter event chains and fuel consumption. Furthermore, it integrates a prioritized experience replay training mechanism to construct a safe and adaptive scheduling system capable of millisecond-level real-time decision-making. Experimental demonstrates that, within large-scale mass recovery scenarios, the framework achieves zero safety violations in static environments and maintains a fuel safety violation rate below 10% in dynamic scenarios, with single-step decision times at the millisecond level. The model exhibits strong generalization capability, effectively responding to unforeseen emergent situations—such as multiple bolters and fuel emergencies—without requiring retraining. This provides robust support for efficient carrier-based aircraft recovery operations.
{"title":"Real-time decision support for bolter recovery safety: Long short-term memory network-driven aircraft sequencing","authors":"Wei Han , Changjiu Li , Xichao Su , Yong Zhang , Fang Guo , Tongtong Yu , Xuan Li","doi":"10.1016/j.dt.2025.09.038","DOIUrl":"10.1016/j.dt.2025.09.038","url":null,"abstract":"<div><div>The highly dynamic nature, strong uncertainty, and coupled multiple safety constraints inherent in carrier aircraft recovery operations pose severe challenges for real-time decision-making. Addressing bolter scenarios, this study proposes an intelligent decision-making framework based on a deep long short-term memory Q-network. This framework transforms the real-time sequencing for bolter recovery problem into a partially observable Markov decision process. It employs a stacked long short-term memory network to accurately capture the long-range temporal dependencies of bolter event chains and fuel consumption. Furthermore, it integrates a prioritized experience replay training mechanism to construct a safe and adaptive scheduling system capable of millisecond-level real-time decision-making. Experimental demonstrates that, within large-scale mass recovery scenarios, the framework achieves zero safety violations in static environments and maintains a fuel safety violation rate below 10% in dynamic scenarios, with single-step decision times at the millisecond level. The model exhibits strong generalization capability, effectively responding to unforeseen emergent situations—such as multiple bolters and fuel emergencies—without requiring retraining. This provides robust support for efficient carrier-based aircraft recovery operations.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 184-205"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-04DOI: 10.1016/j.dt.2025.09.009
Hongyu Han, Zhaohui Dang
This paper proposes a threat assessment framework for non-cooperative satellites by analyzing their motion characteristics, developing a quantitative evaluation methodology, and demonstrating its effectiveness via representative scenarios with neural network acceleration. The framework first establishes a threat evaluation model that integrates three core parameters: capability, opportunity, and hidden values. Subsequently, this research systematically investigates the critical role of transfer windows in threat quantification and introduces a transfer window-based threat assessment approach. The proposed methodology is validated through multiple representative scenarios, with simulation results demonstrating superior performance compared to conventional methods relying solely on optimal transfer windows or minimum distance metrics, enabling more nuanced threat ranking in scenarios where traditional techniques prove inadequate. To address computational demands, a neural network-based approximation system is implemented to achieve a 25,200 × speedup (0.005 s vs. baseline 126 s per 1000-sample batch) through parallel processing, maintaining 99.3% accuracy. Finally, the study explores the framework's extensibility to diverse NCS objectives. It identifies discrepancies between intention inference models and threat evaluation paradigms, providing methodological insights for next-generation space domain awareness systems.
{"title":"Threat assessment of non-cooperative satellites in interception scenarios: A transfer window perspective","authors":"Hongyu Han, Zhaohui Dang","doi":"10.1016/j.dt.2025.09.009","DOIUrl":"10.1016/j.dt.2025.09.009","url":null,"abstract":"<div><div>This paper proposes a threat assessment framework for non-cooperative satellites by analyzing their motion characteristics, developing a quantitative evaluation methodology, and demonstrating its effectiveness via representative scenarios with neural network acceleration. The framework first establishes a threat evaluation model that integrates three core parameters: capability, opportunity, and hidden values. Subsequently, this research systematically investigates the critical role of transfer windows in threat quantification and introduces a transfer window-based threat assessment approach. The proposed methodology is validated through multiple representative scenarios, with simulation results demonstrating superior performance compared to conventional methods relying solely on optimal transfer windows or minimum distance metrics, enabling more nuanced threat ranking in scenarios where traditional techniques prove inadequate. To address computational demands, a neural network-based approximation system is implemented to achieve a 25,200 × speedup (0.005 s vs. baseline 126 s per 1000-sample batch) through parallel processing, maintaining 99.3% accuracy. Finally, the study explores the framework's extensibility to diverse NCS objectives. It identifies discrepancies between intention inference models and threat evaluation paradigms, providing methodological insights for next-generation space domain awareness systems.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 172-183"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-12DOI: 10.1016/j.dt.2025.09.019
Qiangqiang Xiao, Zhengxiang Huang, Xudong Zu, Xin Jia, Bin Ma
<div><div>The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect, while at low velocities, the strength effect becomes predominant. In the latter regime, material strength dictates the resistance to plastic deformation and flow, a contrast to the shockwave-dominated interactions where compressibility is key. This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets. An integrated approach where the axial and radial dynamics are coupled has been proposed, influencing each other through shared physical principles rather than being treated as separate, empirically linked phenomena. The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine–Hugoniot relation. These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface, providing a robust physical basis for the penetration model. Notably, it considers the target material's compressibility, which elevates the pressure at the jet-target interface beyond that observed with incompressible materials. This pressure increase is directly proportional to the target's degree of compressibility. As such, this model of compressible penetration reorients the analytical approach: rather than merely estimating penetration resistance, it determines this value from the target material's specific compressibility and yield strength. This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power, particularly for novel target materials or engagement conditions outside established experimental datasets. This investigation establishes a quantitative link between the material's yield strength and its penetration resistance. The accuracy of this penetration resistance value is paramount, as it significantly influences the predicted crater diameter; indeed, the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination. Ultimately, by integrating the yield strength of the target material, this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet. The theory's validation involved two experimental sets: the first focused on shaped charge jet penetration into 45# steel at varied stand-offs, while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete (RPC) with differing strength characteristics. These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys, where plastic flow is significant, and advanced quasi-brittle cementitious composites, presenting a broad spectrum of material responses and penetration challenges. Resulting hole profiles derived from
{"title":"The effects of compressibility and target strength on shaped charge jet penetration","authors":"Qiangqiang Xiao, Zhengxiang Huang, Xudong Zu, Xin Jia, Bin Ma","doi":"10.1016/j.dt.2025.09.019","DOIUrl":"10.1016/j.dt.2025.09.019","url":null,"abstract":"<div><div>The penetration of shaped charge jets into targets at high velocities is significantly influenced by the compressibility effect, while at low velocities, the strength effect becomes predominant. In the latter regime, material strength dictates the resistance to plastic deformation and flow, a contrast to the shockwave-dominated interactions where compressibility is key. This paper presents a self-consistent compressible penetration theory that considers both the axial penetration and radial crater growth of shaped charge jets into targets. An integrated approach where the axial and radial dynamics are coupled has been proposed, influencing each other through shared physical principles rather than being treated as separate, empirically linked phenomena. The presented theory is rooted in the compressible Bernoulli equation and the linear Rankine–Hugoniot relation. These foundational equations are employed to accurately model the high-pressure shock state and subsequent material flow at the jet-target interface, providing a robust physical basis for the penetration model. Notably, it considers the target material's compressibility, which elevates the pressure at the jet-target interface beyond that observed with incompressible materials. This pressure increase is directly proportional to the target's degree of compressibility. As such, this model of compressible penetration reorients the analytical approach: rather than merely estimating penetration resistance, it determines this value from the target material's specific compressibility and yield strength. This shift from empirical correlations to a physics-based derivation of penetration resistance enhances the model's predictive power, particularly for novel target materials or engagement conditions outside established experimental datasets. This investigation establishes a quantitative link between the material's yield strength and its penetration resistance. The accuracy of this penetration resistance value is paramount, as it significantly influences the predicted crater diameter; indeed, the crater diameter's sensitivity to this resistance underscores the necessity for its precise determination. Ultimately, by integrating the yield strength of the target material, this framework enables the prediction of both the penetration depth and the resultant crater diameter from a shaped charge jet. The theory's validation involved two experimental sets: the first focused on shaped charge jet penetration into 45# steel at varied stand-offs, while the second utilized targets of high-to ultrahigh-strength steel-fiber reactive powder concrete (RPC) with differing strength characteristics. These experimental campaigns were specifically chosen to test the theory against both ductile metallic alloys, where plastic flow is significant, and advanced quasi-brittle cementitious composites, presenting a broad spectrum of material responses and penetration challenges. Resulting hole profiles derived from ","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 244-253"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-11DOI: 10.1016/j.dt.2025.09.018
Zhipeng Liu , Wenbin Yang , Zhijian Yang , Guansong He
The interfacial structure and its regulation play a crucial role in determining the overall performance of advanced functional composites. Weak interfacial interactions between carbon fibers and the matrix present a critical challenge limiting the general performance and functional applications of carbon fiber-reinforced composites. In this paper, a novel strategy for bioinspired root-soil interfacial structure was presented to enhance the mechanical properties of polymer bonded explosives. A multiscale nanowire heterostructure was constructed through the in-situ growth of morphologically controllable zinc oxide nanowires on the carbon fiber surface via a facile hydrothermal method, with polydopamine as the interfacial reinforcement layer. This structure emulated the function of the "root", and combined with a network-distributed polymer binder representing the "soil", formed a robust root-soil interlocking interfacial structure within the polymer bonded explosives. Due to the multiscale interfacial reinforcement structure, the tensile strength of the polymer bonded explosives was visibly increased by 41%, the strain at the break by 110%, and the creep resistance by 51% with only 0.4 wt% filler adopted. The thermal stress resistance was improved by 57% owing to the synergistic enhancement of thermal conductivity and mechanical properties. This study provides new perspectives and insights for designing and constructing high-performance polymer bonded explosives and other functional composites.
{"title":"Bioinspired interface design for enhancing the mechanical properties of energetic composites by developing a root-soil interlocked structure","authors":"Zhipeng Liu , Wenbin Yang , Zhijian Yang , Guansong He","doi":"10.1016/j.dt.2025.09.018","DOIUrl":"10.1016/j.dt.2025.09.018","url":null,"abstract":"<div><div>The interfacial structure and its regulation play a crucial role in determining the overall performance of advanced functional composites. Weak interfacial interactions between carbon fibers and the matrix present a critical challenge limiting the general performance and functional applications of carbon fiber-reinforced composites. In this paper, a novel strategy for bioinspired root-soil interfacial structure was presented to enhance the mechanical properties of polymer bonded explosives. A multiscale nanowire heterostructure was constructed through the in-situ growth of morphologically controllable zinc oxide nanowires on the carbon fiber surface via a facile hydrothermal method, with polydopamine as the interfacial reinforcement layer. This structure emulated the function of the \"root\", and combined with a network-distributed polymer binder representing the \"soil\", formed a robust root-soil interlocking interfacial structure within the polymer bonded explosives. Due to the multiscale interfacial reinforcement structure, the tensile strength of the polymer bonded explosives was visibly increased by 41%, the strain at the break by 110%, and the creep resistance by 51% with only 0.4 wt% filler adopted. The thermal stress resistance was improved by 57% owing to the synergistic enhancement of thermal conductivity and mechanical properties. This study provides new perspectives and insights for designing and constructing high-performance polymer bonded explosives and other functional composites.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 1-13"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-02DOI: 10.1016/j.dt.2025.09.003
Yu Luan, Jiayi Du, Teng Ren, Chengkai Pu, Zhenggang Xiao
Step ladder-structured nitrocellulose (LNC) is a novel energetic binder prepared by chemically modifying nitrocellulose (NC) with the introduction of flexible polyethylene glycol (PEG-400) chain segments, with a regular structure and good performance of bonding. The step ladder-structured addresses critical limitations of NC-based propellants, including low-temperature brittleness and high sensitivity, while enhancing process safety. Although the structural, thermal, and other properties of LNC have been investigated in our previous research, there is a lack of systematic studies on the rheological properties during solution and gelatinization. The study of the relationship between the structural features and rheological properties of LNC is a key factor in guiding its gelatinization and improving the properties of LNC-based propellants. Steady-state rheology flow experiments revealed that LNC exhibited shear thinning in different solutions, which decreased with increasing concentration. It has desirable solubility and dispersion in N, N-dimethylformamide (DMF) solvent. The effect of solvents on the entanglement or orientation of LNC molecular chains may be reduced. These results can be quantitatively demonstrated using the Herschel-Bulkley model. Dynamic viscoelastic studies identified a critical point of concentration-frequency of 2.5 rad/s. This particular frequency point is a turning point in the law of the effect of concentration on the loss factor (tanδ). For gelatinized systems, increasing the solvent content reduces the temperature sensitivity of the gelatinized materials. The viscosity-temperature correlation based on the Arrhenius equation allowed the optimization of the solvent content through the derived equilibrium relationship. These structure-rheological performance relationships establish basic guidelines for the precision gelatinization of LNC-based propellant, provide theoretical support for the replacement of conventional NC by LNC, and guide the gelatinization process to improve the performance of gun propellants.
{"title":"Rheological behaviors of step ladder-structured nitrocellulose in solution and gelatinization process","authors":"Yu Luan, Jiayi Du, Teng Ren, Chengkai Pu, Zhenggang Xiao","doi":"10.1016/j.dt.2025.09.003","DOIUrl":"10.1016/j.dt.2025.09.003","url":null,"abstract":"<div><div>Step ladder-structured nitrocellulose (LNC) is a novel energetic binder prepared by chemically modifying nitrocellulose (NC) with the introduction of flexible polyethylene glycol (PEG-400) chain segments, with a regular structure and good performance of bonding. The step ladder-structured addresses critical limitations of NC-based propellants, including low-temperature brittleness and high sensitivity, while enhancing process safety. Although the structural, thermal, and other properties of LNC have been investigated in our previous research, there is a lack of systematic studies on the rheological properties during solution and gelatinization. The study of the relationship between the structural features and rheological properties of LNC is a key factor in guiding its gelatinization and improving the properties of LNC-based propellants. Steady-state rheology flow experiments revealed that LNC exhibited shear thinning in different solutions, which decreased with increasing concentration. It has desirable solubility and dispersion in N, N-dimethylformamide (DMF) solvent. The effect of solvents on the entanglement or orientation of LNC molecular chains may be reduced. These results can be quantitatively demonstrated using the Herschel-Bulkley model. Dynamic viscoelastic studies identified a critical point of concentration-frequency of 2.5 rad/s. This particular frequency point is a turning point in the law of the effect of concentration on the loss factor (tan<em>δ</em>). For gelatinized systems, increasing the solvent content reduces the temperature sensitivity of the gelatinized materials. The viscosity-temperature correlation based on the Arrhenius equation allowed the optimization of the solvent content through the derived equilibrium relationship. These structure-rheological performance relationships establish basic guidelines for the precision gelatinization of LNC-based propellant, provide theoretical support for the replacement of conventional NC by LNC, and guide the gelatinization process to improve the performance of gun propellants.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 110-124"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-13DOI: 10.1016/j.dt.2025.09.014
Shijie Deng, Yingxin Kou, You Li, An Xu, Bincheng Wen, Juntao Zhang, Ling Ma
This study addresses the maneuver evasion problem for medium-to-long-range air-to-air missiles by proposing a KAN--PPO-based evasion algorithm. The algorithm introduces Kolmogorov-Arnold Networks (KAN) to mitigate the catastrophic forgetting issue of Multilayer Perceptrons (MLP) in continual learning, while incorporating -return to resolve sparse reward challenges in evasion scenarios. First, we model the evasion problem with -return and present the KAN--PPO algorithm. Subsequently, we establish game environments based on the segmented ballistic characteristics of medium and long range missiles. During training, a joint reward function is designed by combining the miss distance and positional advantages to train the agent. Experiments evaluate four dimensions: (1) Performance comparison between KAN and MLP in value function approximation; (2) Catastrophic forgetting mitigation of KAN--PPO in dual-task scenarios; (3) Continual learning capabilities across multiple evasion scenarios; (4) Quantitative analysis of agent strategy evolution and positional advantages. Empirical results demonstrate that KAN improves value function approximation accuracy by an order of magnitude compared with traditional MLP architectures. In continual learning tasks, the KAN--PPO scheme exhibits significant knowledge retention, achieving performance improvements of 32.7% and 8.6% over MLP baselines in Task1→2 and Task2→3 transitions, respectively. Furthermore, the learned maneuver strategies outperform High-G Barrel Rolls(HGB) and S-maneuver tactics in securing positional advantages while accomplishing evasion.
{"title":"Avoidance method for medium-to-long-range air-to-air missile based on the kan-λ-ppo algorithm","authors":"Shijie Deng, Yingxin Kou, You Li, An Xu, Bincheng Wen, Juntao Zhang, Ling Ma","doi":"10.1016/j.dt.2025.09.014","DOIUrl":"10.1016/j.dt.2025.09.014","url":null,"abstract":"<div><div>This study addresses the maneuver evasion problem for medium-to-long-range air-to-air missiles by proposing a KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO-based evasion algorithm. The algorithm introduces Kolmogorov-Arnold Networks (KAN) to mitigate the catastrophic forgetting issue of Multilayer Perceptrons (MLP) in continual learning, while incorporating <span><math><mrow><mi>λ</mi></mrow></math></span>-return to resolve sparse reward challenges in evasion scenarios. First, we model the evasion problem with <span><math><mrow><mi>λ</mi></mrow></math></span>-return and present the KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO algorithm. Subsequently, we establish game environments based on the segmented ballistic characteristics of medium and long range missiles. During training, a joint reward function is designed by combining the miss distance and positional advantages to train the agent. Experiments evaluate four dimensions: (1) Performance comparison between KAN and MLP in value function approximation; (2) Catastrophic forgetting mitigation of KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO in dual-task scenarios; (3) Continual learning capabilities across multiple evasion scenarios; (4) Quantitative analysis of agent strategy evolution and positional advantages. Empirical results demonstrate that KAN improves value function approximation accuracy by an order of magnitude compared with traditional MLP architectures. In continual learning tasks, the KAN-<span><math><mrow><mi>λ</mi></mrow></math></span>-PPO scheme exhibits significant knowledge retention, achieving performance improvements of 32.7% and 8.6% over MLP baselines in Task1→2 and Task2→3 transitions, respectively. Furthermore, the learned maneuver strategies outperform High-G Barrel Rolls(HGB) and S-maneuver tactics in securing positional advantages while accomplishing evasion.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 352-366"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-13DOI: 10.1016/j.dt.2025.09.021
Yiming Zhang , Hanqing Xia , Kangyu Ji , Ningfei Wang , Ke Li , Sen Chen , Yi Wu
An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion. This study investigated the dynamic responses of single ammonium perchlorate (AP)/octogen (HMX) particles embedded in a hydroxyl-terminated polybutadiene (HTPB) binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar (SHPB) system. The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured. During compression, transverse cracks developed within the AP particles, and their propagation led to particle fracturing, resulting in ductile fracturing. Unlike AP, HMX generated numerous short cracks within the internal and edge regions simultaneously, leading to fragmentation and brittle fracturing. Moreover, particle damage reduced the modulus of the sample, shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation. A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles. The simulation results agreed with the experimental observations. These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface, which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.
{"title":"Real-time visualization and numerical investigation of the dynamic compression response behaviours of single AP/HMX particles embedded in an HTPB binder","authors":"Yiming Zhang , Hanqing Xia , Kangyu Ji , Ningfei Wang , Ke Li , Sen Chen , Yi Wu","doi":"10.1016/j.dt.2025.09.021","DOIUrl":"10.1016/j.dt.2025.09.021","url":null,"abstract":"<div><div>An in-depth understanding of the behaviours of solid propellants under low-velocity impact loads is crucial for enhancing their safety in applications such as aerospace propulsion. This study investigated the dynamic responses of single ammonium perchlorate (AP)/octogen (HMX) particles embedded in a hydroxyl-terminated polybutadiene (HTPB) binder under dynamic compression loading via real-time synchrotron-based X-ray phase contrast imaging and a modified split Hopkinson pressure bar (SHPB) system. The compression of the viscoelastic binder and subsequent dynamic fracturing of the AP/HMX particles were captured. During compression, transverse cracks developed within the AP particles, and their propagation led to particle fracturing, resulting in ductile fracturing. Unlike AP, HMX generated numerous short cracks within the internal and edge regions simultaneously, leading to fragmentation and brittle fracturing. Moreover, particle damage reduced the modulus of the sample, shifting its dynamic stress response from nonlinear elasticity to strain softening and further strain hardening as the binder exhibited plastic deformation. A compression simulation incorporating a real particle microscopic structure was established to study the mechanical response of the interface and particles. The simulation results agreed with the experimental observations. These results indicate that the shear stress at the HTPB-AP interface is greater than that at the HTPB-HMX interface, which is a factor influencing the differences in the mesoscale damage mechanisms of the particles.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 254-269"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-09-13DOI: 10.1016/j.dt.2025.09.020
Hao Wang, Xiangyu Li, Yong Peng, Zhandong Tian, Fangyun Lu
Reinforced concrete (RC) columns are often subjected to off-central explosion due to the uncertainty of blast locations. However, few studies have focused on the dynamic response of RC columns under off-central explosions. A field blast experiment was conducted under close-in explosion with varying detonation offset distances (0 m, 0.5 m, and 1 m), the overpressure load and dynamic responses of the full-scale RC columns were measured. Compared with the centrally detonated condition, a relative offset distance of 1.67 decreases the maximum and residual deflections of the RC column by 16.8% and 21.4%, respectively, while increasing the maximum and residual support rotations by 24.7% and 17.8%. Based on the experimental results, a theoretical model was proposed that considers the detonation location and charge mass, boundary conditions, axial compression ratio and material properties. The theoretical model exhibited good agreement with the experimental results, with prediction errors below 10% for both maximum and residual deflection. The effects of parameters were analyzed, and it indicated that an increase in offset distance results in decreased maximum and residual deflections but an increased support angle, thereby exacerbating damage. Higher axial load ratio, span-depth ratio, and longitudinal reinforcement ratio reduce both deflections and support angle. Additionally, a rapid method to predict the maximum and residual deflection of RC columns under off-central blast loading was also proposed based on the Generalized Regression Neural Network (GRNN). Eleven features which related to the RC column properties and the blast characteristics were used in the training process of GRNN, and accurate predictions were achieved with prediction errors within 20%. This study fills the gap in predicting the dynamic response of RC columns under off-central explosion, providing valuable references for blast-resistant design.
{"title":"Dynamic response of RC columns under off-central explosions: Experimental, theoretical studies and neural network prediction","authors":"Hao Wang, Xiangyu Li, Yong Peng, Zhandong Tian, Fangyun Lu","doi":"10.1016/j.dt.2025.09.020","DOIUrl":"10.1016/j.dt.2025.09.020","url":null,"abstract":"<div><div>Reinforced concrete (RC) columns are often subjected to off-central explosion due to the uncertainty of blast locations. However, few studies have focused on the dynamic response of RC columns under off-central explosions. A field blast experiment was conducted under close-in explosion with varying detonation offset distances (0 m, 0.5 m, and 1 m), the overpressure load and dynamic responses of the full-scale RC columns were measured. Compared with the centrally detonated condition, a relative offset distance of 1.67 decreases the maximum and residual deflections of the RC column by 16.8% and 21.4%, respectively, while increasing the maximum and residual support rotations by 24.7% and 17.8%. Based on the experimental results, a theoretical model was proposed that considers the detonation location and charge mass, boundary conditions, axial compression ratio and material properties. The theoretical model exhibited good agreement with the experimental results, with prediction errors below 10% for both maximum and residual deflection. The effects of parameters were analyzed, and it indicated that an increase in offset distance results in decreased maximum and residual deflections but an increased support angle, thereby exacerbating damage. Higher axial load ratio, span-depth ratio, and longitudinal reinforcement ratio reduce both deflections and support angle. Additionally, a rapid method to predict the maximum and residual deflection of RC columns under off-central blast loading was also proposed based on the Generalized Regression Neural Network (GRNN). Eleven features which related to the RC column properties and the blast characteristics were used in the training process of GRNN, and accurate predictions were achieved with prediction errors within 20%. This study fills the gap in predicting the dynamic response of RC columns under off-central explosion, providing valuable references for blast-resistant design.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"56 ","pages":"Pages 314-336"},"PeriodicalIF":5.9,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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