Wenyu Wu, Xiaodong Li, Wenjie Liu, Penglin Kang, Dongqian Fan, Lu Xu, Shuangqi Hu
Improving the energy density and safety of explosives are crucial for developing composite energetic materials. In this study, a facile and continuous spray drying granulation technique was used to obtain NTO/HMX composite explosives with insensitive NTO as coating material. The micro‐morphology, particle size, crystallographic structure, exothermic decomposition, impact sensitivity, and detonation performance of NTO/HMX composite explosives with different NTO contents were investigated by various experimental methods. The test results indicate that the higher the NTO content, the better the crystal integrity of HMX and the lower the mechanical sensitivity of NTO/HMX composite explosives. When the mass ratio of NTO and HMX is 25 : 75, NTO/HMX composite explosives have a good spherical density structure formed by the aggregation of nanoparticles, small particle sizes with a median size of 1.22 μm, and a uniform distribution of particle sizes in the range of 0.3–2.8 μm. The addition of NTO not only enhances the thermal decomposition of HMX but also significantly decreases mechanical sensitivity. The composite explosives had not altered the raw NTO and HMX crystallographic structures (β‐type). With the same ratio (25 : 75), NTO/HMX composite explosives (25 : 75) possess higher impact energy and friction force, better safety, and better thermal stability than physical mixtures. Additionally, the high‐energy insensitive composite microspheres preserve the important high‐energy properties of HMX while effectively enhancing its safety characteristics, which have the advantages of controllable crystallographic micromorphology, high energy, and excellent impact sensibility and could be broadly applicable in the field of munitions.
{"title":"Fabrication and performance characterization of NTO/HMX spherical composite explosives with improved safety performance.","authors":"Wenyu Wu, Xiaodong Li, Wenjie Liu, Penglin Kang, Dongqian Fan, Lu Xu, Shuangqi Hu","doi":"10.1002/prep.202400079","DOIUrl":"https://doi.org/10.1002/prep.202400079","url":null,"abstract":"Improving the energy density and safety of explosives are crucial for developing composite energetic materials. In this study, a facile and continuous spray drying granulation technique was used to obtain NTO/HMX composite explosives with insensitive NTO as coating material. The micro‐morphology, particle size, crystallographic structure, exothermic decomposition, impact sensitivity, and detonation performance of NTO/HMX composite explosives with different NTO contents were investigated by various experimental methods. The test results indicate that the higher the NTO content, the better the crystal integrity of HMX and the lower the mechanical sensitivity of NTO/HMX composite explosives. When the mass ratio of NTO and HMX is 25 : 75, NTO/HMX composite explosives have a good spherical density structure formed by the aggregation of nanoparticles, small particle sizes with a median size of 1.22 μm, and a uniform distribution of particle sizes in the range of 0.3–2.8 μm. The addition of NTO not only enhances the thermal decomposition of HMX but also significantly decreases mechanical sensitivity. The composite explosives had not altered the raw NTO and HMX crystallographic structures (β‐type). With the same ratio (25 : 75), NTO/HMX composite explosives (25 : 75) possess higher impact energy and friction force, better safety, and better thermal stability than physical mixtures. Additionally, the high‐energy insensitive composite microspheres preserve the important high‐energy properties of HMX while effectively enhancing its safety characteristics, which have the advantages of controllable crystallographic micromorphology, high energy, and excellent impact sensibility and could be broadly applicable in the field of munitions.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"102 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141885950","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}
Hybrid rockets have many attractive properties but have not yet been used in any high performance applications, mainly due to the low regression rate of the solid fuels used. In this work, a number of crystalline organic fillers were assessed with the aim to increase the regression rate and density of HTPB‐based fuels. Hexamine, which was the most promising filler, catalyses the HTPB/isocyanate crosslinking reaction leading to unacceptable short pot life. However, it was found that the pot life could be substantially prolonged by the use of less reactive brands of HTPB, added plasticizer and reduced NCO/OH ratio. Fuel formulations containing 75 % hexamine were easy to cast and the cured slabs were of good quality, free from bubbles or voids, with a density 30 % higher than plain HTPB. The tensile strength of the fuels were similar to typical solid propellants but the elasticity might need to be improved. Hexamine decompose at substantially lower temperature than HTPB. This, and its high density, makes it promising for use in hybrid rocket fuels.
{"title":"Formulation of Hexamine‐based Fuels for Hybrid Rockets","authors":"Niklas Wingborg","doi":"10.1002/prep.202400064","DOIUrl":"https://doi.org/10.1002/prep.202400064","url":null,"abstract":"Hybrid rockets have many attractive properties but have not yet been used in any high performance applications, mainly due to the low regression rate of the solid fuels used. In this work, a number of crystalline organic fillers were assessed with the aim to increase the regression rate and density of HTPB‐based fuels. Hexamine, which was the most promising filler, catalyses the HTPB/isocyanate crosslinking reaction leading to unacceptable short pot life. However, it was found that the pot life could be substantially prolonged by the use of less reactive brands of HTPB, added plasticizer and reduced NCO/OH ratio. Fuel formulations containing 75 % hexamine were easy to cast and the cured slabs were of good quality, free from bubbles or voids, with a density 30 % higher than plain HTPB. The tensile strength of the fuels were similar to typical solid propellants but the elasticity might need to be improved. Hexamine decompose at substantially lower temperature than HTPB. This, and its high density, makes it promising for use in hybrid rocket fuels.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"71 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141612504","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}
Dennis Christensen, Geir Petter Novik, Erik Unneberg
Accurate estimates of sensitivities of energetic materials are crucial for ensuring safe production, transport, usage and destruction of explosives. When estimating sensitivities, researchers most commonly follow the NATO standard guidelines (STANAGs), in which the Bruceton method is imposed. Introduced in 1948, this method contains (i) an experimental design for choosing which stimulus levels to measure at and (ii) a recipe for computing sensitivity estimates. Although the former experimental design is supported by both theory and simulations, few modern researchers are aware that the latter recipe was only intended as a pen‐and‐paper approximation of the maximum likelihood estimates, which are easy to compute today. The persistent use of this outdated approximation has led to many unfortunate misconceptions amongst users of the Bruceton method, including the rejection of many perfectly valid data sets and neglect of uncertainty assessments via confidence intervals. This is both dangerous and unnecessarily wasteful. This paper sets the record straight and explains how researchers should estimate sensitivity via maximum likelihood estimation and how to construct confidence intervals. It also shows explicitly how wasteful said approximation is via both simulations and with real data.
{"title":"Estimating sensitivity with the Bruceton method: Setting the record straight","authors":"Dennis Christensen, Geir Petter Novik, Erik Unneberg","doi":"10.1002/prep.202400022","DOIUrl":"https://doi.org/10.1002/prep.202400022","url":null,"abstract":"Accurate estimates of sensitivities of energetic materials are crucial for ensuring safe production, transport, usage and destruction of explosives. When estimating sensitivities, researchers most commonly follow the NATO standard guidelines (STANAGs), in which the Bruceton method is imposed. Introduced in 1948, this method contains (i) an experimental design for choosing which stimulus levels to measure at and (ii) a recipe for computing sensitivity estimates. Although the former experimental design is supported by both theory and simulations, few modern researchers are aware that the latter recipe was only intended as a pen‐and‐paper approximation of the maximum likelihood estimates, which are easy to compute today. The persistent use of this outdated approximation has led to many unfortunate misconceptions amongst users of the Bruceton method, including the rejection of many perfectly valid data sets and neglect of uncertainty assessments via confidence intervals. This is both dangerous and unnecessarily wasteful. This paper sets the record straight and explains how researchers should estimate sensitivity via maximum likelihood estimation and how to construct confidence intervals. It also shows explicitly how wasteful said approximation is via both simulations and with real data.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"46 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141577913","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}
Mahesh S. Ingole, Kumar Nagendra, P. A. Ramakrishna
This paper addresses the combustion of ammonium perchlorate (AP) near adiabatic conditions at high pressures and higher initial temperatures. The AP pellets were coated with a thin layer of silica grease to simulate the near adiabatic condition. The experiments were performed at initial temperatures of 30 and 70 °C in the pressure range of 2.5–30 MPa for coated and bare pellets. The bare pellets were found to exhibit mesa burning as reported in the literature. However, the coated pellets did not exhibit mesa burning. The burn rates of coated AP pellets increased linearly for the entire pressure range of 2.5–30 MPa with 0.64 pressure index. Further, the experiments were carried out for the first time at an initial temperature of 90 °C for 14–30 MPa pressure range, wherein, AP combustion did not display any characteristics of mesa burning (pressure index of 0.33). The surface morphology of quenched samples of both bare and coated pellets of AP were studied, by quenching (rapid depressurization technique) pellets at 6, 12, and 18 MPa pressures. The surface structure of quenched samples for near adiabatic conditions was similar for all three pressures. However, for bare pellets the changes in surface structure were observed with change in pressure, similar to the literature. Mesa burning was found to be an effect of convective heat loss from the periphery of the pellets and it was not observed when heat loss was reduced or initial temperature was higher than the critical initial temperature.
{"title":"Combustion of ammonium perchlorate fo near adiabatic condition at high pressures and elevated Initial temperature","authors":"Mahesh S. Ingole, Kumar Nagendra, P. A. Ramakrishna","doi":"10.1002/prep.202400010","DOIUrl":"https://doi.org/10.1002/prep.202400010","url":null,"abstract":"This paper addresses the combustion of ammonium perchlorate (AP) near adiabatic conditions at high pressures and higher initial temperatures. The AP pellets were coated with a thin layer of silica grease to simulate the near adiabatic condition. The experiments were performed at initial temperatures of 30 and 70 °C in the pressure range of 2.5–30 MPa for coated and bare pellets. The bare pellets were found to exhibit mesa burning as reported in the literature. However, the coated pellets did not exhibit mesa burning. The burn rates of coated AP pellets increased linearly for the entire pressure range of 2.5–30 MPa with 0.64 pressure index. Further, the experiments were carried out for the first time at an initial temperature of 90 °C for 14–30 MPa pressure range, wherein, AP combustion did not display any characteristics of mesa burning (pressure index of 0.33). The surface morphology of quenched samples of both bare and coated pellets of AP were studied, by quenching (rapid depressurization technique) pellets at 6, 12, and 18 MPa pressures. The surface structure of quenched samples for near adiabatic conditions was similar for all three pressures. However, for bare pellets the changes in surface structure were observed with change in pressure, similar to the literature. Mesa burning was found to be an effect of convective heat loss from the periphery of the pellets and it was not observed when heat loss was reduced or initial temperature was higher than the critical initial temperature.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"20 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141574879","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‐Chao Wang, Jie Yao, Feng‐Wei Guo, Shuang Li, Yi‐Long Xu, Jun‐Hui Liu, Chen Shen, Xue‐Yong Guo, Shi Yan, Jian‐Xin Nie
Understanding the mechanical response characteristics and determining the optimized process conditions is critical to mitigate crystal impacts during resonant acoustic mixing (RAM). Therefore, high‐melting explosive (HMX) crystal collisions with container walls under different RAM accelerations were investigated through simulations and experiments. The HMX crystal damages after RAM were assessed using microscopic imaging, small‐angle X‐ray scattering, and Brunauer–Emmett–Teller tests. Results show that crystal fractures observed in steel containers can be prevented by using low‐modulus polytetrafluoroethylene containers. Rough containers reduce internal damage but increase surface abrasion. Lower RAM accelerations, shorter RAM durations, and low‐modulus containers can mitigate HMX crystal damage.
{"title":"Mechanical response characteristics of HMX crystals under resonant acoustic mixing","authors":"Zi‐Chao Wang, Jie Yao, Feng‐Wei Guo, Shuang Li, Yi‐Long Xu, Jun‐Hui Liu, Chen Shen, Xue‐Yong Guo, Shi Yan, Jian‐Xin Nie","doi":"10.1002/prep.202400095","DOIUrl":"https://doi.org/10.1002/prep.202400095","url":null,"abstract":"Understanding the mechanical response characteristics and determining the optimized process conditions is critical to mitigate crystal impacts during resonant acoustic mixing (RAM). Therefore, high‐melting explosive (HMX) crystal collisions with container walls under different RAM accelerations were investigated through simulations and experiments. The HMX crystal damages after RAM were assessed using microscopic imaging, small‐angle X‐ray scattering, and Brunauer–Emmett–Teller tests. Results show that crystal fractures observed in steel containers can be prevented by using low‐modulus polytetrafluoroethylene containers. Rough containers reduce internal damage but increase surface abrasion. Lower RAM accelerations, shorter RAM durations, and low‐modulus containers can mitigate HMX crystal damage.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"13 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141516871","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}
The Gibbs Free energy is a driving force for equilibrium crystal shapes and the formation of crystal facets in molecular crystals. Orientation dependence of interfacial properties is linked to surface free energy (SFE). Prediction of orientation‐dependent properties such as thermal stability, mechanical response, and compatibility with binders require a systematic approach to the quantification of SFE. In molecular crystals, entropy has a much larger contribution among all ordered crystalline materials. In this paper, we extend our previously developed method to quantify SFE and entropy of β‐HMX to other common energetic materials–TATB, α‐RDX, and PETN. Two complimentary approaches, Nonequilibrium Thermodynamic Integration (NETI) and Steered Molecular Dynamics (SMD) methods are used to obtain insight into interfacial phenomena along with surface free energy estimates. We discuss the relevance of surface free energy and the importance of surface entropy for facetted molecular crystals in understanding crystal properties, activation of slip planes, and potential pathways for fracture. These values allow us to predict theoretical crystal shape using Wulff Construction, better understand the effect of hydrogen bonding on SFE, and the diversity of bonding environment in energetic crystals. In particular, in crystals with low stacking fault energy, the SMD values can be inconclusive due to the triggering of slip plane motions. In cases where SMD simulations lead to large deformations and high uncertainty, the NETI approach can still provide SFE estimates.
{"title":"Insight into material behavior via surface free energy calculations for common energetic materials","authors":"Janki Brahmbhatt, Santanu Chaudhuri","doi":"10.1002/prep.202300230","DOIUrl":"https://doi.org/10.1002/prep.202300230","url":null,"abstract":"The Gibbs Free energy is a driving force for equilibrium crystal shapes and the formation of crystal facets in molecular crystals. Orientation dependence of interfacial properties is linked to surface free energy (SFE). Prediction of orientation‐dependent properties such as thermal stability, mechanical response, and compatibility with binders require a systematic approach to the quantification of SFE. In molecular crystals, entropy has a much larger contribution among all ordered crystalline materials. In this paper, we extend our previously developed method to quantify SFE and entropy of β‐HMX to other common energetic materials–TATB, α‐RDX, and PETN. Two complimentary approaches, Nonequilibrium Thermodynamic Integration (NETI) and Steered Molecular Dynamics (SMD) methods are used to obtain insight into interfacial phenomena along with surface free energy estimates. We discuss the relevance of surface free energy and the importance of surface entropy for facetted molecular crystals in understanding crystal properties, activation of slip planes, and potential pathways for fracture. These values allow us to predict theoretical crystal shape using Wulff Construction, better understand the effect of hydrogen bonding on SFE, and the diversity of bonding environment in energetic crystals. In particular, in crystals with low stacking fault energy, the SMD values can be inconclusive due to the triggering of slip plane motions. In cases where SMD simulations lead to large deformations and high uncertainty, the NETI approach can still provide SFE estimates.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"8 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507180","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}
Shane A. Oatman, August A. Caito, Daniel J. Klinger, James N. Cooper, Tim D. Manship, Steven F. Son
Burning rate as a function of pressure is one of the primary evaluation metrics of solid propellants. Most solid propellant burning rate measurements are made at a nearly constant pressure using a variety of measurement approaches. This type of burning rate data is highly discretized and requires many tests to accurately determine the burning rate response to pressure. It would be more efficient to measure burning rate dynamically as pressures are varied. Techniques used to make transient burning rate measurements are reviewed briefly and initial results using a microwave interferometry (MI) technique are presented. The MI method used in tandem with a closed bomb enables nearly continuous measurement of burning rates for self‐pressurizing burns, capturing burning rate data over a wide range of pressures. This approach is especially useful for characterization of propellants with complex burning behaviors (e. g., slope breaks or mesa burning). The burning rates of three research propellants were characterized over a pressure range of 0.101–24.14 MPa (14–3500 psi). One research propellant exhibited a slope break at a pressure of 6.63 MPa (960 psi). Using MI in a closed pressure vessel, 14 propellant strand burns resulted in a nearly continuous burning rate curve over a pressure range of 0.41–24.13 MPa (60–3500 psi) that reasonably matched conventional burning rate measurements. The development of this technique provides an opportunity to quickly characterize the burning rate curve of solid propellants with greater fidelity and efficiency than traditional quasi‐static pressure testing techniques.
{"title":"Closed vessel burning rate measurements of composite propellants using microwave interferometry","authors":"Shane A. Oatman, August A. Caito, Daniel J. Klinger, James N. Cooper, Tim D. Manship, Steven F. Son","doi":"10.1002/prep.202400072","DOIUrl":"https://doi.org/10.1002/prep.202400072","url":null,"abstract":"Burning rate as a function of pressure is one of the primary evaluation metrics of solid propellants. Most solid propellant burning rate measurements are made at a nearly constant pressure using a variety of measurement approaches. This type of burning rate data is highly discretized and requires many tests to accurately determine the burning rate response to pressure. It would be more efficient to measure burning rate dynamically as pressures are varied. Techniques used to make transient burning rate measurements are reviewed briefly and initial results using a microwave interferometry (MI) technique are presented. The MI method used in tandem with a closed bomb enables nearly continuous measurement of burning rates for self‐pressurizing burns, capturing burning rate data over a wide range of pressures. This approach is especially useful for characterization of propellants with complex burning behaviors (e. g., slope breaks or mesa burning). The burning rates of three research propellants were characterized over a pressure range of 0.101–24.14 MPa (14–3500 psi). One research propellant exhibited a slope break at a pressure of 6.63 MPa (960 psi). Using MI in a closed pressure vessel, 14 propellant strand burns resulted in a nearly continuous burning rate curve over a pressure range of 0.41–24.13 MPa (60–3500 psi) that reasonably matched conventional burning rate measurements. The development of this technique provides an opportunity to quickly characterize the burning rate curve of solid propellants with greater fidelity and efficiency than traditional quasi‐static pressure testing techniques.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"181 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507182","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}
Yao Xu, Siyue Gao, Jianzhong Zhang, Yanlei Liu, Weibin Zhang, Jun Wang, Hui Wang, Shujing Wang, Zhiqiang Ma, Pengwan Chen, Rui Liu
Pressed 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB)‐based polymer‐bonded explosive (PBX) exhibits significant anisotropic and irreversible expansion characteristics during temperature cycling, resulting in both safety and service issues. The anisotropic and irreversible expansion properties of PBX have shown to be closely related to the microstructures, including explosive crystals, binders, micro voids, el. Fiber Bragg grating (FBG) technology has advantages of high reliability, accuracy, and sensitivity, which is more conducive to real‐time capture of the changes in strain throughout the temperature cycling. In this study, temperature cycling strain monitoring experiments of PBX pressed under different thermal–mechanical coupling loading conditions were studied using FBG technology. The effect of the pressing parameters on the anisotropic and irreversible expansion characteristics of the PBX's during temperature cycling was measured and analyzed, taking into account potential microstructural factors such as crystal orientation, binders, and porosity. The results indicated that the strain on the side and top of PBX cylinders were distributed with increasing strain in the direction of higher density. The strain stratification was significant during the high‐temperature stage of temperature cycling and was not obvious during the low‐temperature stage. The degree of strain stratification decreased with an increase in temperature cycling cycles and increased with higher pressing temperatures. The anisotropic expansion of PBX cylinders increased with an increase in temperature during cycling and decreased with a reduction in temperature. The axial expansion degree of PBX cylinders pressed under different compression conditions in the later cycles of temperature cycling is consistent with the different crystal orientations intensity inside them.
{"title":"Using a fiber Bragg grating technique to investigate temperature cycling strain of pressed TATB‐based polymer‐bonded explosives","authors":"Yao Xu, Siyue Gao, Jianzhong Zhang, Yanlei Liu, Weibin Zhang, Jun Wang, Hui Wang, Shujing Wang, Zhiqiang Ma, Pengwan Chen, Rui Liu","doi":"10.1002/prep.202400032","DOIUrl":"https://doi.org/10.1002/prep.202400032","url":null,"abstract":"Pressed 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB)‐based polymer‐bonded explosive (PBX) exhibits significant anisotropic and irreversible expansion characteristics during temperature cycling, resulting in both safety and service issues. The anisotropic and irreversible expansion properties of PBX have shown to be closely related to the microstructures, including explosive crystals, binders, micro voids, el. Fiber Bragg grating (FBG) technology has advantages of high reliability, accuracy, and sensitivity, which is more conducive to real‐time capture of the changes in strain throughout the temperature cycling. In this study, temperature cycling strain monitoring experiments of PBX pressed under different thermal–mechanical coupling loading conditions were studied using FBG technology. The effect of the pressing parameters on the anisotropic and irreversible expansion characteristics of the PBX's during temperature cycling was measured and analyzed, taking into account potential microstructural factors such as crystal orientation, binders, and porosity. The results indicated that the strain on the side and top of PBX cylinders were distributed with increasing strain in the direction of higher density. The strain stratification was significant during the high‐temperature stage of temperature cycling and was not obvious during the low‐temperature stage. The degree of strain stratification decreased with an increase in temperature cycling cycles and increased with higher pressing temperatures. The anisotropic expansion of PBX cylinders increased with an increase in temperature during cycling and decreased with a reduction in temperature. The axial expansion degree of PBX cylinders pressed under different compression conditions in the later cycles of temperature cycling is consistent with the different crystal orientations intensity inside them.","PeriodicalId":20800,"journal":{"name":"Propellants, Explosives, Pyrotechnics","volume":"346 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507181","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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