Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.05.013
Norliza Ismail , Wan Yusmawati Wan Yusoff , Azuraida Amat , Nor Azlian Abdul Manaf , Nurazlin Ahmad
Solder joint, crucial component in electronic systems, face significant challenges when exposed to extreme conditions during applications. The solder joint reliability involving microstructure and mechanical properties will be affected by extreme conditions. Understanding the behaviour of solder joints under extreme conditions is vital to determine the durability and reliability of solder joint. This review paper aims to comprehensively explore the underlying failure mechanism affecting solder joint reliability under extreme conditions. This study covers an in-depth analysis of effect extreme temperature, mechanical stress, and radiation conditions towards solder joint. Impact of each condition to the microstructure including solder matrix and intermetallic compound layer, and mechanical properties such as fatigue, shear strength, creep, and hardness was thoroughly discussed. The failure mechanisms were illustrated in graphical diagrams to ensure clarity and understanding. Furthermore, the paper highlighted mitigation strategies that enhancing solder joint reliability under challenging operating conditions. The findings offer valuable guidance for researchers, engineers, and practitioners involved in electronics, engineering, and related fields, fostering advancements in solder joint reliability and performance.
{"title":"A review of extreme condition effects on solder joint reliability: Understanding failure mechanisms","authors":"Norliza Ismail , Wan Yusmawati Wan Yusoff , Azuraida Amat , Nor Azlian Abdul Manaf , Nurazlin Ahmad","doi":"10.1016/j.dt.2024.05.013","DOIUrl":"10.1016/j.dt.2024.05.013","url":null,"abstract":"<div><div>Solder joint, crucial component in electronic systems, face significant challenges when exposed to extreme conditions during applications. The solder joint reliability involving microstructure and mechanical properties will be affected by extreme conditions. Understanding the behaviour of solder joints under extreme conditions is vital to determine the durability and reliability of solder joint. This review paper aims to comprehensively explore the underlying failure mechanism affecting solder joint reliability under extreme conditions. This study covers an in-depth analysis of effect extreme temperature, mechanical stress, and radiation conditions towards solder joint. Impact of each condition to the microstructure including solder matrix and intermetallic compound layer, and mechanical properties such as fatigue, shear strength, creep, and hardness was thoroughly discussed. The failure mechanisms were illustrated in graphical diagrams to ensure clarity and understanding. Furthermore, the paper highlighted mitigation strategies that enhancing solder joint reliability under challenging operating conditions. The findings offer valuable guidance for researchers, engineers, and practitioners involved in electronics, engineering, and related fields, fostering advancements in solder joint reliability and performance.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 134-158"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.06.006
Hanshan Li, Xiaoqian Zhang
Aiming at the requirement of damage testing and evaluation of equivalent target plate based on the explosion of intelligent ammunition, this paper proposes a novel method for damage testing and evaluation method of circumferential equivalent target plate. Leveraging the dispersion characteristics parameters of fragment, we establish a calculation model of the fragment power situation and the damage calculation model under the condition of fragment ultimate penetration equivalent target plate. The damage model of equivalent target plate involves the fragment dispersion density, the local perforation damage criterion, the tearing damage model, and the damage probability. We use the camera to obtain the image of the equivalent target plate with fragment perforation, and research the algorithm of fragment distribution position recognition and fragment perforation area calculation method on the equivalent target plate by image processing technology. Based on the obtained parameters of the breakdown position and perforation area of fragments on equivalent target plate, we apply to damage calculation model of equivalent target plate, and calculate the damage probability of each equivalent target plate, and use the combined probabilistic damage calculation method to obtain the damage evaluation results of the circumferential equivalent target plate in an intelligent ammunition explosion experiment. Through an experimental testing, we verify the feasibility and rationality of the proposed damage evaluation method by comparison, the calculation results can reflect the actual damage effect of the equivalent target plate.
{"title":"An equivalent target plate damage probability calculation mathematics model and damage evaluation method","authors":"Hanshan Li, Xiaoqian Zhang","doi":"10.1016/j.dt.2024.06.006","DOIUrl":"10.1016/j.dt.2024.06.006","url":null,"abstract":"<div><div>Aiming at the requirement of damage testing and evaluation of equivalent target plate based on the explosion of intelligent ammunition, this paper proposes a novel method for damage testing and evaluation method of circumferential equivalent target plate. Leveraging the dispersion characteristics parameters of fragment, we establish a calculation model of the fragment power situation and the damage calculation model under the condition of fragment ultimate penetration equivalent target plate. The damage model of equivalent target plate involves the fragment dispersion density, the local perforation damage criterion, the tearing damage model, and the damage probability. We use the camera to obtain the image of the equivalent target plate with fragment perforation, and research the algorithm of fragment distribution position recognition and fragment perforation area calculation method on the equivalent target plate by image processing technology. Based on the obtained parameters of the breakdown position and perforation area of fragments on equivalent target plate, we apply to damage calculation model of equivalent target plate, and calculate the damage probability of each equivalent target plate, and use the combined probabilistic damage calculation method to obtain the damage evaluation results of the circumferential equivalent target plate in an intelligent ammunition explosion experiment. Through an experimental testing, we verify the feasibility and rationality of the proposed damage evaluation method by comparison, the calculation results can reflect the actual damage effect of the equivalent target plate.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 82-103"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.07.008
Jong-Hwan Kim , Seungwon Baik , Jirui Fu , Joon-Hyuk Park
This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio (PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.
{"title":"Ballistic limit velocity of small caliber projectiles against SS400 steel plates: Live fire experiments and empirical models","authors":"Jong-Hwan Kim , Seungwon Baik , Jirui Fu , Joon-Hyuk Park","doi":"10.1016/j.dt.2024.07.008","DOIUrl":"10.1016/j.dt.2024.07.008","url":null,"abstract":"<div><div>This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio (PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 22-34"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141844759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.06.004
Haoyu Zhang , Yuxin Xu , Lihan Xiao , Canjie Zhen
The accurate prediction of peak overpressure of explosion shockwaves is significant in fields such as explosion hazard assessment and structural protection, where explosion shockwaves serve as typical destructive elements. Aiming at the problem of insufficient accuracy of the existing physical models for predicting the peak overpressure of ground reflected waves, two physics-informed machine learning models are constructed. The results demonstrate that the machine learning models, which incorporate physical information by predicting the deviation between the physical model and actual values and adding a physical loss term in the loss function, can accurately predict both the training and out-of-training dataset. Compared to existing physical models, the average relative error in the predicted training domain is reduced from 17.459%–48.588% to 2%, and the proportion of average relative error less than 20% increased from 0% to 59.4% to more than 99%. In addition, the relative average error outside the prediction training set range is reduced from 14.496%–29.389% to 5%, and the proportion of relative average error less than 20% increased from 0% to 71.39% to more than 99%. The inclusion of a physical loss term enforcing monotonicity in the loss function effectively improves the extrapolation performance of machine learning. The findings of this study provide valuable reference for explosion hazard assessment and anti-explosion structural design in various fields.
{"title":"Physics-informed machine learning model for prediction of ground reflected wave peak overpressure","authors":"Haoyu Zhang , Yuxin Xu , Lihan Xiao , Canjie Zhen","doi":"10.1016/j.dt.2024.06.004","DOIUrl":"10.1016/j.dt.2024.06.004","url":null,"abstract":"<div><div>The accurate prediction of peak overpressure of explosion shockwaves is significant in fields such as explosion hazard assessment and structural protection, where explosion shockwaves serve as typical destructive elements. Aiming at the problem of insufficient accuracy of the existing physical models for predicting the peak overpressure of ground reflected waves, two physics-informed machine learning models are constructed. The results demonstrate that the machine learning models, which incorporate physical information by predicting the deviation between the physical model and actual values and adding a physical loss term in the loss function, can accurately predict both the training and out-of-training dataset. Compared to existing physical models, the average relative error in the predicted training domain is reduced from 17.459%–48.588% to 2%, and the proportion of average relative error less than 20% increased from 0% to 59.4% to more than 99%. In addition, the relative average error outside the prediction training set range is reduced from 14.496%–29.389% to 5%, and the proportion of relative average error less than 20% increased from 0% to 71.39% to more than 99%. The inclusion of a physical loss term enforcing monotonicity in the loss function effectively improves the extrapolation performance of machine learning. The findings of this study provide valuable reference for explosion hazard assessment and anti-explosion structural design in various fields.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 119-133"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The load-bearing capacity of reinforced concrete (RC) beams primarily relies on internal reinforced bars. However, limited research has been conducted on the dynamic response of these bars. To address this gap, this study has established an analytical model using dimensional analysis for calculating the deformation of reinforced bars within RC beams subjected to contact explosion. Comparison with experimental data reveals that the model has a relative error of 5.22%, effectively reflecting the deformation of reinforced bars. Additionally, based on this model, the study found that while concrete does influence the deformation of reinforced bars, this influence can be disregarded in comparison to the material properties of the bars themselves. The findings of this study have implications for calculating the residual load-bearing capacity of damaged RC beams, evaluating the extent of damage to RC beams after blast loading, and providing guidance for the blast-resistant design of RC structures.
{"title":"Analysis model for damage of reinforced bars in RC beams under contact explosion","authors":"Chaozhi Yang , Zhengxiang Huang , Xin Jia , Wei Shang , Jian Zhang","doi":"10.1016/j.dt.2024.03.003","DOIUrl":"10.1016/j.dt.2024.03.003","url":null,"abstract":"<div><div>The load-bearing capacity of reinforced concrete (RC) beams primarily relies on internal reinforced bars. However, limited research has been conducted on the dynamic response of these bars. To address this gap, this study has established an analytical model using dimensional analysis for calculating the deformation of reinforced bars within RC beams subjected to contact explosion. Comparison with experimental data reveals that the model has a relative error of 5.22%, effectively reflecting the deformation of reinforced bars. Additionally, based on this model, the study found that while concrete does influence the deformation of reinforced bars, this influence can be disregarded in comparison to the material properties of the bars themselves. The findings of this study have implications for calculating the residual load-bearing capacity of damaged RC beams, evaluating the extent of damage to RC beams after blast loading, and providing guidance for the blast-resistant design of RC structures.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 104-118"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140791696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A philosophy for the design of novel, lightweight, multi-layered armor, referred to as Composite Armor Philosophy (CAP), which can adapt to the passive protection of light-, medium-, and heavy-armored vehicles, is presented in this study. CAP can serve as a guiding principle to assist designers in comprehending the distinct roles fulfilled by each component. The CAP proposal comprises four functional layers, organized in a suggested hierarchy of materials. Particularly notable is the inclusion of a ceramic-composite principle, representing an advanced and innovative solution in the field of armor design. This paper showcases real-world defense industry applications, offering case studies that demonstrate the effectiveness of this advanced approach. CAP represents a significant milestone in the history of passive protection, marking an evolutionary leap in the field. This philosophical approach provides designers with a powerful toolset with which to enhance the protection capabilities of military vehicles, making them more resilient and better equipped to meet the challenges of modern warfare.
{"title":"Composite armor philosophy (CAP): Holistic design methodology of multi-layered composite protection systems for armored vehicles","authors":"Evangelos Ch. Tsirogiannis , Foivos Psarommatis , Alexandros Prospathopoulos , Georgios Savaidis","doi":"10.1016/j.dt.2024.07.009","DOIUrl":"10.1016/j.dt.2024.07.009","url":null,"abstract":"<div><div>A philosophy for the design of novel, lightweight, multi-layered armor, referred to as Composite Armor Philosophy (CAP), which can adapt to the passive protection of light-, medium-, and heavy-armored vehicles, is presented in this study. CAP can serve as a guiding principle to assist designers in comprehending the distinct roles fulfilled by each component. The CAP proposal comprises four functional layers, organized in a suggested hierarchy of materials. Particularly notable is the inclusion of a ceramic-composite principle, representing an advanced and innovative solution in the field of armor design. This paper showcases real-world defense industry applications, offering case studies that demonstrate the effectiveness of this advanced approach. CAP represents a significant milestone in the history of passive protection, marking an evolutionary leap in the field. This philosophical approach provides designers with a powerful toolset with which to enhance the protection capabilities of military vehicles, making them more resilient and better equipped to meet the challenges of modern warfare.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 181-197"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141851970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.05.005
Pooja Naresh Bhatt , Rashmi Pandhare
The study projects a flexible and compact wearable pear-shaped Super High Frequency (SHF) antenna that can provide detailed location recognition and tracking applicable to defense beacon technology. This mini aperture with electrical dimensions of 0.12λ0 × 0.22λ0 × 0.01λ0 attains a vast bandwidth over 3.1–34.5 GHz Super High Frequency (SHF) frequency band at S11 ≤ −10 dB, peak gain of 7.14 dBi and proportionately homogeneous radiation pattern. The fractional bandwidth (% BW) acquired is 168% that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military operations. The proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is accomplished. The Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety standards. The flexibility is proven by analyzing the full electromagnetic simulations for various bending conditions. Time response analysis is attained with its Fidelity Factor and Group Delay. Communication excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 m. Prototype is fabricated along with experimental validation. All the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.
{"title":"A tensile wearable SHF antenna with efficient communication in defense beacon technology","authors":"Pooja Naresh Bhatt , Rashmi Pandhare","doi":"10.1016/j.dt.2024.05.005","DOIUrl":"10.1016/j.dt.2024.05.005","url":null,"abstract":"<div><div>The study projects a flexible and compact wearable pear-shaped Super High Frequency (SHF) antenna that can provide detailed location recognition and tracking applicable to defense beacon technology. This mini aperture with electrical dimensions of 0.12<em>λ</em><sub>0</sub> × 0.22<em>λ</em><sub>0</sub> × 0.01<em>λ</em><sub>0</sub> attains a vast bandwidth over 3.1–34.5 GHz Super High Frequency (SHF) frequency band at S<sub>11</sub> ≤ −10 dB, peak gain of 7.14 dBi and proportionately homogeneous radiation pattern. The fractional bandwidth (% BW) acquired is 168% that envelopes diversified frequency spectrum inclusive of X band specifically targeted to all kinds of defense and military operations. The proposed antenna can be worn on a soldier's uniform and hence the Specific Absorption Rate simulation is accomplished. The Peak SAR Value over 1 g of tissue is 1.48 W/kg and for 10 g of tissue is 0.27 W/kg well under the safety standards. The flexibility is proven by analyzing the full electromagnetic simulations for various bending conditions. Time response analysis is attained with its Fidelity Factor and Group Delay. Communication excellence is determined using Link Budget Analysis and it is seen that margin at 100 Mbps is 62 m and at 200 Mbps is 59 m. Prototype is fabricated along with experimental validation. All the results show harmony in shaping the antenna to provide critical situational awareness and data sharing capabilities required in defense beacon technology for location identification.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 198-210"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141032947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.dt.2024.05.015
G. Murali , Anoop Kallamalayil Nassar , Madhumitha Swaminathan , Parthiban Kathirvel , Leong Sing Wong
Solid waste recycling is an economically sound strategy for preserving the environment, safeguarding natural resources, and diminishing the reliance on raw material consumption. Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials. This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete (UHPGC). In total, 18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder, ranging from 10% to 40%. Similarly, for each of the mixtures above, steel fibre was added at a dosage of 1.5% to address the inherent brittleness of UHPGC. The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders. The specimens were subjected to drop-weight impact testing, wherein an examination was carried out to evaluate various parameters, including flowability, density at fresh and hardened state, compressive strength, impact numbers indicative of cracking and failure occurrences, ductility index, and analysis of failure modes. Additionally, the variations in the impact test outcomes were analyzed using the Weibull distribution, and the findings corresponding to survival probability were offered. Furthermore, the microstructure of UHPGC was scrutinized through scanning electron microscopy. Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume, with reductions ranging from 18.63% to 34.31%. Similarly, failure impact number values decreased from 8.26% to 28.46% across glass powder contents. The maximum compressive and impact strength was recorded in UHPGC, comprising 10% silica fume with fibres.
{"title":"Effect of silica fume and glass powder for enhanced impact resistance in GGBFS-based ultra high-performance geopolymer fibrous concrete: An experimental and statistical analysis","authors":"G. Murali , Anoop Kallamalayil Nassar , Madhumitha Swaminathan , Parthiban Kathirvel , Leong Sing Wong","doi":"10.1016/j.dt.2024.05.015","DOIUrl":"10.1016/j.dt.2024.05.015","url":null,"abstract":"<div><div>Solid waste recycling is an economically sound strategy for preserving the environment, safeguarding natural resources, and diminishing the reliance on raw material consumption. Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials. This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete (UHPGC). In total, 18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder, ranging from 10% to 40%. Similarly, for each of the mixtures above, steel fibre was added at a dosage of 1.5% to address the inherent brittleness of UHPGC. The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders. The specimens were subjected to drop-weight impact testing, wherein an examination was carried out to evaluate various parameters, including flowability, density at fresh and hardened state, compressive strength, impact numbers indicative of cracking and failure occurrences, ductility index, and analysis of failure modes. Additionally, the variations in the impact test outcomes were analyzed using the Weibull distribution, and the findings corresponding to survival probability were offered. Furthermore, the microstructure of UHPGC was scrutinized through scanning electron microscopy. Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume, with reductions ranging from 18.63% to 34.31%. Similarly, failure impact number values decreased from 8.26% to 28.46% across glass powder contents. The maximum compressive and impact strength was recorded in UHPGC, comprising 10% silica fume with fibres.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"41 ","pages":"Pages 59-81"},"PeriodicalIF":5.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.dt.2024.04.014
In this paper, high cis-1,4 content hydroxyl-terminated polybutadiene (cis-HTPB) with different molecular weights was prepared through the oxidative cracking process using cis-butadiene rubber as raw material. Firstly, this article comprehensively compared the differences between cis-HTPB and conventional I-HTPB in terms of molecular weight distribution, functionality, viscosity, molecular polarity, and other physicochemical properties, which provided effective data support for its subsequent application. In addition, the reaction kinetics study showed that cis-HTPB with isocyanate curing agent has high reactivity, allowing it to be rapidly cured at low temperatures, and the cured elastomers had excellent mechanical properties, with tensile strength and elongation up to 1.89 MPa and 1100%, respectively. It was also found that cis-HTPB has extremely excellent low-temperature resistance, and the glass transition temperature (Tg) of its cured elastomer is as low as −101 °C. Based on the above studies, cis-HTPB is applied as a binder in composite solid propellants for the first time to investigate its practical performance, and the results indicated that cis-HTPB-based propellants have excellent process and mechanical properties.
{"title":"Properties of high cis-1,4 content hydroxyl-terminated polybutadiene and its application in composite solid propellants","authors":"","doi":"10.1016/j.dt.2024.04.014","DOIUrl":"10.1016/j.dt.2024.04.014","url":null,"abstract":"<div><div>In this paper, high <em>cis</em>-1,4 content hydroxyl-terminated polybutadiene (<em>cis</em>-HTPB) with different molecular weights was prepared through the oxidative cracking process using <em>cis</em>-butadiene rubber as raw material. Firstly, this article comprehensively compared the differences between <em>cis</em>-HTPB and conventional I-HTPB in terms of molecular weight distribution, functionality, viscosity, molecular polarity, and other physicochemical properties, which provided effective data support for its subsequent application. In addition, the reaction kinetics study showed that <em>cis</em>-HTPB with isocyanate curing agent has high reactivity, allowing it to be rapidly cured at low temperatures, and the cured elastomers had excellent mechanical properties, with tensile strength and elongation up to 1.89 MPa and 1100%, respectively. It was also found that <em>cis</em>-HTPB has extremely excellent low-temperature resistance, and the glass transition temperature (<em>T</em><sub>g</sub>) of its cured elastomer is as low as −101 °C. Based on the above studies, <em>cis</em>-HTPB is applied as a binder in composite solid propellants for the first time to investigate its practical performance, and the results indicated that <em>cis</em>-HTPB-based propellants have excellent process and mechanical properties.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 199-209"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140765286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.dt.2024.05.001
Protection of urban critical infrastructures (CIs) from GPS-denied, bomb-carrying kamikaze drones (G-B-KDs) is very challenging. Previous approaches based on drone jamming, spoofing, communication interruption and hijacking cannot be applied in the case under examination, since G-B-KDs are uncontrolled. On the other hand, drone capturing schemes and electromagnetic pulse (EMP) weapons seem to be effective. However, again, existing approaches present various limitations, while most of them do not examine the case of G-B-KDs. This paper, focuses on the aforementioned under-researched field, where the G-B-KD is confronted by two defensive drones. The first neutralizes and captures the kamikaze drone, while the second captures the bomb. Both defensive drones are equipped with a net-gun and an innovative algorithm, which, among others, estimates the locations of interception, using a real-world trajectory model. Additionally, one of the defensive drones is also equipped with an EMP weapon to damage the electronics equipment of the kamikaze drone and reduce the capturing time and the overall risk. Extensive simulated experiments and comparisons to state-of-art methods, reveal the advantages and limitations of the proposed approach. More specifically, compared to state-of-art, the proposed approach improves: (a) time to neutralize the target by at least 6.89%, (b) maximum number of missions by at least 1.27% and (c) total cost by at least 5.15%.
{"title":"A novel framework to intercept GPS-denied, bomb-carrying, non-military, kamikaze drones: Towards protecting critical infrastructures","authors":"","doi":"10.1016/j.dt.2024.05.001","DOIUrl":"10.1016/j.dt.2024.05.001","url":null,"abstract":"<div><div>Protection of urban critical infrastructures (CIs) from GPS-denied, bomb-carrying kamikaze drones (G-B-KDs) is very challenging. Previous approaches based on drone jamming, spoofing, communication interruption and hijacking cannot be applied in the case under examination, since G-B-KDs are uncontrolled. On the other hand, drone capturing schemes and electromagnetic pulse (EMP) weapons seem to be effective. However, again, existing approaches present various limitations, while most of them do not examine the case of G-B-KDs. This paper, focuses on the aforementioned under-researched field, where the G-B-KD is confronted by two defensive drones. The first neutralizes and captures the kamikaze drone, while the second captures the bomb. Both defensive drones are equipped with a net-gun and an innovative algorithm, which, among others, estimates the locations of interception, using a real-world trajectory model. Additionally, one of the defensive drones is also equipped with an EMP weapon to damage the electronics equipment of the kamikaze drone and reduce the capturing time and the overall risk. Extensive simulated experiments and comparisons to state-of-art methods, reveal the advantages and limitations of the proposed approach. More specifically, compared to state-of-art, the proposed approach improves: (a) time to neutralize the target by at least 6.89%, (b) maximum number of missions by at least 1.27% and (c) total cost by at least 5.15%.</div></div>","PeriodicalId":58209,"journal":{"name":"Defence Technology(防务技术)","volume":"40 ","pages":"Pages 225-241"},"PeriodicalIF":5.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141038220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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