Youcai Xiao, Kelei Pei, Yu Zou, Yong Han, Tianyuan Gong, Xiangdong Xiao, Yi Sun
The accidental ignition of polymer‐bonded explosives (PBXs) caused by hot spots has been the focus of domestic and international research. Micro‐crack friction plays a crucial role in the formation these hot spots. In this study, confined tests were conducted to investigate the ignition response of PBX under impact loading. The experimental results revealed that the PBX underwent ignition under the given conditions of a pressure load with a pulse width of 50 μs and an amplitude of 638 MPa. The viscoelastic statistical cracking model (Visco‐SCRAM) and hot‐spot ignition model were used to describe the damage behaviors and ignition responses of the PBX. The simulation results revealed that more severe damage occurs at the center of the impact face and its vicinity under confined impact conditions, which is consistent with the observed post‐test samples. Additionally, simulation results also predict a trapezoidal shape for the severely damaged region within the PBX. The findings of this study provide insights for understanding the damage behavior and the critical ignition of PBX under impact loading.
{"title":"Dynamic damage and non‐shock ignition behavior of polymer bonded explosive under lower velocity impact","authors":"Youcai Xiao, Kelei Pei, Yu Zou, Yong Han, Tianyuan Gong, Xiangdong Xiao, Yi Sun","doi":"10.1002/prep.202300016","DOIUrl":"https://doi.org/10.1002/prep.202300016","url":null,"abstract":"The accidental ignition of polymer‐bonded explosives (PBXs) caused by hot spots has been the focus of domestic and international research. Micro‐crack friction plays a crucial role in the formation these hot spots. In this study, confined tests were conducted to investigate the ignition response of PBX under impact loading. The experimental results revealed that the PBX underwent ignition under the given conditions of a pressure load with a pulse width of 50 μs and an amplitude of 638 MPa. The viscoelastic statistical cracking model (Visco‐SCRAM) and hot‐spot ignition model were used to describe the damage behaviors and ignition responses of the PBX. The simulation results revealed that more severe damage occurs at the center of the impact face and its vicinity under confined impact conditions, which is consistent with the observed post‐test samples. Additionally, simulation results also predict a trapezoidal shape for the severely damaged region within the PBX. The findings of this study provide insights for understanding the damage behavior and the critical ignition of PBX under impact loading.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"21 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ch Devi Vara Prasad, P. Kanakaraju, R. Vinu, Abhijit P. Deshpande
HTPB (hydroxyl‐terminated polybutadiene) is a well‐established binder in the composite solid propellant owing to its excellent compatibility with ammonium perchlorate (AP) and aluminium (Al) particles in giving rise to optimal ballistic and mechanical properties. Efforts are being made to improve the ballistic properties further, such as specific impulse. One way of increasing the specific impulse is to hydrogenate HTPB, which decreases the molecular mass of the combustion product gases. This paper is a summary of efforts in synthesizing hydrogenated HTPB (HHTPB) using copper chromite (CC) as a catalyst. A novel synthesis methodology is developed for HHTPB using a temperature‐programmed batch reactor with a variable speed stirrer and an instrumentation system to maintain the desired liquid reactant temperature. A process cycle is developed that includes addition sequence and reaction time. The product is analyzed using 1H‐NMR and FTIR to estimate the degree of hydrogenation and the geometrical isomers respectively. The estimated apparent equilibrium rate constants from the degree of hydrogenation values are respectively 74 and 2034 L/(mol MPa) for non‐catalyzed and catalyzed systems, indicating the effectiveness of the catalyst. This is also substantiated by the reduction in Gibbs free energy (ΔG), to an extent of 4.48 kJ/mol. Thermogravimetry examination indicates that the decomposition temperature of HHTPB produced by the catalytic method is marginally higher compared to HTPB. DSC curves indicate that the decomposition enthalpy of HHTPB is higher than that of HTPB. In summary, this paper proposed and validated a novel method in the preparation of HHTPB using copper chromite.
{"title":"Synthesis of HHTPB by partial hydrogenation of HTPB using copper chromite as a catalyst","authors":"Ch Devi Vara Prasad, P. Kanakaraju, R. Vinu, Abhijit P. Deshpande","doi":"10.1002/prep.202300339","DOIUrl":"https://doi.org/10.1002/prep.202300339","url":null,"abstract":"HTPB (hydroxyl‐terminated polybutadiene) is a well‐established binder in the composite solid propellant owing to its excellent compatibility with ammonium perchlorate (AP) and aluminium (Al) particles in giving rise to optimal ballistic and mechanical properties. Efforts are being made to improve the ballistic properties further, such as specific impulse. One way of increasing the specific impulse is to hydrogenate HTPB, which decreases the molecular mass of the combustion product gases. This paper is a summary of efforts in synthesizing hydrogenated HTPB (HHTPB) using copper chromite (CC) as a catalyst. A novel synthesis methodology is developed for HHTPB using a temperature‐programmed batch reactor with a variable speed stirrer and an instrumentation system to maintain the desired liquid reactant temperature. A process cycle is developed that includes addition sequence and reaction time. The product is analyzed using <jats:sup>1</jats:sup>H‐NMR and FTIR to estimate the degree of hydrogenation and the geometrical isomers respectively. The estimated apparent equilibrium rate constants from the degree of hydrogenation values are respectively 74 and 2034 L/(mol MPa) for non‐catalyzed and catalyzed systems, indicating the effectiveness of the catalyst. This is also substantiated by the reduction in Gibbs free energy (ΔG), to an extent of 4.48 kJ/mol. Thermogravimetry examination indicates that the decomposition temperature of HHTPB produced by the catalytic method is marginally higher compared to HTPB. DSC curves indicate that the decomposition enthalpy of HHTPB is higher than that of HTPB. In summary, this paper proposed and validated a novel method in the preparation of HHTPB using copper chromite.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"15 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ki T. Wolf, Joel T. Clemmer, Michael L. Hobbs, Michael Kaneshige, Dan S. Bolintineanu, Judith A. Brown
Exploding bridgewire (EBW) detonators are used to rapidly and reliably initiate energetic reactions by exploding a bridgewire via Joule heating. While the mechanisms of EBW detonators have been studied extensively in nominal conditions, comparatively few studies have addressed thermally damaged detonator operability. We present a mesoscale simulation study of thermal damage in a representative EBW detonator, using discrete element method (DEM) simulations that explicitly account for individual particles in the pressed explosive powder. We use a simplified model of melting, where solid spherical particles undergo uniform shrinking, and fluid dynamics are ignored. The subsequent settling of particles results in the formation of a gap between the solid powder and the bridgewire, which we study under different conditions. In particular, particle cohesion has a significant effect on gap formation and settling behavior, where sufficiently high cohesion leads to coalescence of particles into a free‐standing pellet. This behavior is qualitatively compared to experimental visualization data, and simulations are shown to capture several key changes in pellet shape. We derive a minimum and maximum limit on gap formation during melting using simple geometric arguments. In the absence of cohesion, results agree with the maximum gap size. With increasing cohesion, the gap size decreases, eventually saturating at the minimum limit. We present results for different combinations of interparticle cohesion and detonator orientations with respect to gravity, demonstrating the complex behavior of these systems and the potential for DEM simulations to capture a range of scenarios.
起爆桥丝（EBW）雷管通过焦耳加热起爆桥丝，从而快速可靠地引发高能反应。虽然对 EBW 雷管在额定条件下的机理进行了广泛研究，但针对热损伤雷管可操作性的研究相对较少。我们采用离散元素法 (DEM) 模拟，明确考虑了压制炸药粉末中的单个颗粒，对具有代表性的 EBW 雷管中的热损伤进行了中尺度模拟研究。我们使用了一个简化的熔化模型，其中固体球形颗粒发生均匀收缩，流体动力学被忽略。颗粒随后的沉降导致固体粉末和桥丝之间形成间隙，我们在不同条件下对其进行了研究。特别是，颗粒的内聚力对间隙的形成和沉降行为有显著影响，足够高的内聚力会导致颗粒凝聚成一个独立的颗粒。我们将这种行为与实验可视化数据进行了定性比较，结果表明模拟捕捉到了颗粒形状的几个关键变化。我们利用简单的几何参数推导出熔化过程中间隙形成的最小和最大限制。在没有内聚力的情况下，结果与最大间隙大小一致。随着内聚力的增加，间隙减小，最终在最小极限处达到饱和。我们展示了颗粒间内聚力和雷管相对于重力方向的不同组合的结果，证明了这些系统的复杂行为以及 DEM 模拟捕捉各种情况的潜力。
{"title":"Investigation of thermal damage in explosive bridgewire detonators via discrete element method simulations","authors":"Ki T. Wolf, Joel T. Clemmer, Michael L. Hobbs, Michael Kaneshige, Dan S. Bolintineanu, Judith A. Brown","doi":"10.1002/prep.202300305","DOIUrl":"https://doi.org/10.1002/prep.202300305","url":null,"abstract":"Exploding bridgewire (EBW) detonators are used to rapidly and reliably initiate energetic reactions by exploding a bridgewire via Joule heating. While the mechanisms of EBW detonators have been studied extensively in nominal conditions, comparatively few studies have addressed thermally damaged detonator operability. We present a mesoscale simulation study of thermal damage in a representative EBW detonator, using discrete element method (DEM) simulations that explicitly account for individual particles in the pressed explosive powder. We use a simplified model of melting, where solid spherical particles undergo uniform shrinking, and fluid dynamics are ignored. The subsequent settling of particles results in the formation of a gap between the solid powder and the bridgewire, which we study under different conditions. In particular, particle cohesion has a significant effect on gap formation and settling behavior, where sufficiently high cohesion leads to coalescence of particles into a free‐standing pellet. This behavior is qualitatively compared to experimental visualization data, and simulations are shown to capture several key changes in pellet shape. We derive a minimum and maximum limit on gap formation during melting using simple geometric arguments. In the absence of cohesion, results agree with the maximum gap size. With increasing cohesion, the gap size decreases, eventually saturating at the minimum limit. We present results for different combinations of interparticle cohesion and detonator orientations with respect to gravity, demonstrating the complex behavior of these systems and the potential for DEM simulations to capture a range of scenarios.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"228 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Huanhuan Gao, Fang Wang, Hui Liu, Yukun Chen, Jianzhong Liu
The agglomeration of aluminum during the combustion of solid propellants considerably impacts engine operation and has been widely studied in recent years. The characteristics of aluminum agglomeration in aluminum‐based composite propellants have been studied via experiments and simulations. In this study, the agglomeration process and the characteristics of agglomerated particles are summarized. Agglomeration models and simulation methods have garnered considerable attention because they are not influenced by experimental conditions, are economical, and have minimal restrictions. Therefore, five agglomeration models and four simulation methods are introduced herein to investigate agglom eration in aluminum‐based composite propellants. By analyzing the advantages and disadvantages of these models and methods, deeper agglomeration mechanisms can be explored and new directions for suppressing agglomeration can be identified to mitigate agglomeration issues. These efforts can support and guide the design of solid rocket propellants and the safe operation of rocket engines.
{"title":"Research progress and prospects on agglomeration models and simulation methods of aluminum particles in aluminum‐based composite propellants","authors":"Huanhuan Gao, Fang Wang, Hui Liu, Yukun Chen, Jianzhong Liu","doi":"10.1002/prep.202400056","DOIUrl":"https://doi.org/10.1002/prep.202400056","url":null,"abstract":"The agglomeration of aluminum during the combustion of solid propellants considerably impacts engine operation and has been widely studied in recent years. The characteristics of aluminum agglomeration in aluminum‐based composite propellants have been studied via experiments and simulations. In this study, the agglomeration process and the characteristics of agglomerated particles are summarized. Agglomeration models and simulation methods have garnered considerable attention because they are not influenced by experimental conditions, are economical, and have minimal restrictions. Therefore, five agglomeration models and four simulation methods are introduced herein to investigate agglom eration in aluminum‐based composite propellants. By analyzing the advantages and disadvantages of these models and methods, deeper agglomeration mechanisms can be explored and new directions for suppressing agglomeration can be identified to mitigate agglomeration issues. These efforts can support and guide the design of solid rocket propellants and the safe operation of rocket engines.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"211 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuhong Yuan, Yinsheng Huang, Mingcheng Ge, Ye Zhong, Zhimin Li
To explore combustion catalysts for solid propellants, four novel energetic coordination compounds were prepared with the anion of nitrocyanamide (NCA) as the ligand and 1‐allyl‐imidazole (AIM) as the ligand, and transition metals Mn, Co, Ni, and Cu as the central ions. The structures of these compounds were [Mn(AIM)4] (NCA)2 (1), [Co(AIM)4](NCA)2 (2), [Ni(AIM)4](NCA)2 (3), [Cu(AIM)4](NCA)2 (4). The results showed that all of the compounds possessed high energy density, and compound 2 had a mass energy density (Eg) of 17.9 kJ g−1 and a volume energy density (Ev) of 25.59 kJ cm−3. The catalytic effect of these compounds on the thermal decomposition of ammonium perchlorate (AP) was studied using DSC. The addition of 5 % catalyst to AP samples advanced the high‐temperature decomposition temperature and significantly increased the heat release. Compound 4 exhibited the best catalytic performance, with an increased heat release of 1739 J g−1, decomposition temperature advanced by 88.2 °C, and activation energy reduced to 74.74 kJ mol−1. These results demonstrate the potential of these compounds as combustion catalysts for solid propellants.
{"title":"Energetic transition metal complexes based on 1‐allylimidazole and nitrocyanamide: Syntheses, characterizations and catalytic performances on the thermal decomposition of ammonium perchlorate","authors":"Yuhong Yuan, Yinsheng Huang, Mingcheng Ge, Ye Zhong, Zhimin Li","doi":"10.1002/prep.202300342","DOIUrl":"https://doi.org/10.1002/prep.202300342","url":null,"abstract":"To explore combustion catalysts for solid propellants, four novel energetic coordination compounds were prepared with the anion of nitrocyanamide (NCA) as the ligand and 1‐allyl‐imidazole (AIM) as the ligand, and transition metals Mn, Co, Ni, and Cu as the central ions. The structures of these compounds were [Mn(AIM)<jats:sub>4</jats:sub>] (NCA)<jats:sub>2</jats:sub> (1), [Co(AIM)<jats:sub>4</jats:sub>](NCA)<jats:sub>2</jats:sub> (2), [Ni(AIM)<jats:sub>4</jats:sub>](NCA)<jats:sub>2</jats:sub> (3), [Cu(AIM)<jats:sub>4</jats:sub>](NCA)<jats:sub>2</jats:sub> (4). The results showed that all of the compounds possessed high energy density, and compound 2 had a mass energy density (<jats:italic>E<jats:sub>g</jats:sub></jats:italic>) of 17.9 kJ g<jats:sup>−1</jats:sup> and a volume energy density (<jats:italic>E<jats:sub>v</jats:sub></jats:italic>) of 25.59 kJ cm<jats:sup>−3</jats:sup>. The catalytic effect of these compounds on the thermal decomposition of ammonium perchlorate (AP) was studied using DSC. The addition of 5 % catalyst to AP samples advanced the high‐temperature decomposition temperature and significantly increased the heat release. Compound 4 exhibited the best catalytic performance, with an increased heat release of 1739 J g<jats:sup>−1</jats:sup>, decomposition temperature advanced by 88.2 °C, and activation energy reduced to 74.74 kJ mol<jats:sup>−1</jats:sup>. These results demonstrate the potential of these compounds as combustion catalysts for solid propellants.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"42 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zi‐Jun Chen, Hong‐Hao Ma, Qing‐Tao Xu, Ze He, Zhao‐Wu Shen, Lu‐Qing Wang
In this paper, a launching system with a novel charge structure was proposed to improve the interior ballistic performance. According to the working characteristics of the novel launching system, a lumped‐parameter model was established. The parameters of the propellant and the interior ballistic characteristics of the launching system were obtained by experiments. According to the experimental results, the accuracy of the lumped‐parameter model was verified by code. The simulated results were in good agreement with the experimental results. Based on the lumped‐parameter model, the propellant parameters, such as the impetus, the burning rate, the web thickness, and the charge mass, were investigated to understand the interior ballistic performances of the launching system. An optimization method was proposed to design the propellant parameters of the launching system. The results show that the optimal scheme can increase the velocity of the projectile by 9.54 %. Compared with the traditional launching method, the velocity of the projectile is increased by 37.09 % while the peak pressure in the barrel has no change.
{"title":"Numerical simulation and optimized design of a launching system with a novel charge structure","authors":"Zi‐Jun Chen, Hong‐Hao Ma, Qing‐Tao Xu, Ze He, Zhao‐Wu Shen, Lu‐Qing Wang","doi":"10.1002/prep.202300326","DOIUrl":"https://doi.org/10.1002/prep.202300326","url":null,"abstract":"In this paper, a launching system with a novel charge structure was proposed to improve the interior ballistic performance. According to the working characteristics of the novel launching system, a lumped‐parameter model was established. The parameters of the propellant and the interior ballistic characteristics of the launching system were obtained by experiments. According to the experimental results, the accuracy of the lumped‐parameter model was verified by code. The simulated results were in good agreement with the experimental results. Based on the lumped‐parameter model, the propellant parameters, such as the impetus, the burning rate, the web thickness, and the charge mass, were investigated to understand the interior ballistic performances of the launching system. An optimization method was proposed to design the propellant parameters of the launching system. The results show that the optimal scheme can increase the velocity of the projectile by 9.54 %. Compared with the traditional launching method, the velocity of the projectile is increased by 37.09 % while the peak pressure in the barrel has no change.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"2012 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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