Pub Date : 2024-01-03DOI: 10.2174/0126659980278013231127103015
Yinhui Rao, Yuanming Chen, Xiaobin Hong, Xiaodong Lin
Compared to single unmanned boat, multi unmanned boats have more flexible mobility and efficient task completion capabilities, which can effectively expand the types of tasks. However, the traditional independent path planning and obstacle avoidance methods of unmanned boats are difficult to meet the requirements of collaborative operation among multiple unmanned boats due to the lack of information exchange. According to the actual demand of multi unmanned boats cooperative operation, a method of multi unmanned boats cooperative obstacle avoidance based on 5G edge computing is proposed to realize the unified planning and scheduling of multi unmanned boats. Firstly, 5G technology and Kubeedge edge computing tools are used to build a multi unmanned boat collaborative obstacle avoidance system based on cloud, edge and end collaboration, and the Kubeedge edge computing platform was optimized by optimizing communication strategies, building a highly available Kubeedge cluster, building a Harbor image center, and using Web management interfaces to further improve the reliability and stability of the system. Secondly, the YOLOR-Deepport multi target recognition and tracking algorithm based on cloud, edge and end collaborative network is used to complete the recognition and tracking tasks of obstacle targets, and a set of EECBS path planning methods based on Kubedge centralized control platform is designed to plan collision free and efficient paths for each unmanned boat in real-time. Finally, the effectiveness of the system was verified through simulation experiments. The experimental results show that compared to the traditional autonomous planning obstacle avoidance method for unmanned boats, the collaborative planning obstacle avoidance method proposed in this paper can exhibit excellent performance in dense and narrow scenarios, with a more reasonable navigation path, a range reduction of 20% - 50%, and higher safety. The results show that the cooperative obstacle avoidance system based on 5G edge computing designed in the paper is feasible, and it can effectively realize the cooperative path planning and obstacle avoidance of multi unmanned boats.
{"title":"Design and Simulation of Multi Unmanned Boat Cooperative Obstacle\u0000Avoidance System Based on 5G Edge Computing","authors":"Yinhui Rao, Yuanming Chen, Xiaobin Hong, Xiaodong Lin","doi":"10.2174/0126659980278013231127103015","DOIUrl":"https://doi.org/10.2174/0126659980278013231127103015","url":null,"abstract":"\u0000\u0000Compared to single unmanned boat, multi unmanned boats have more flexible mobility and efficient task completion capabilities, which can effectively expand the types of tasks. However, the traditional independent path planning and obstacle avoidance methods of unmanned boats are difficult to meet the requirements of collaborative operation among multiple unmanned boats due to the lack of information exchange.\u0000\u0000\u0000\u0000According to the actual demand of multi unmanned boats cooperative operation, a method of multi unmanned boats cooperative obstacle avoidance based on 5G edge computing is proposed to realize the unified planning and scheduling of multi unmanned boats.\u0000\u0000\u0000\u0000Firstly, 5G technology and Kubeedge edge computing tools are used to build a multi unmanned boat collaborative obstacle avoidance system based on cloud, edge and end collaboration, and the Kubeedge edge computing platform was optimized by optimizing communication strategies, building a highly available Kubeedge cluster, building a Harbor image center, and using Web management interfaces to further improve the reliability and stability of the system. Secondly, the YOLOR-Deepport multi target recognition and tracking algorithm based on cloud, edge and end collaborative network is used to complete the recognition and tracking tasks of obstacle targets, and a set of EECBS path planning methods based on Kubedge centralized control platform is designed to plan collision free and efficient paths for each unmanned boat in real-time. Finally, the effectiveness of the system was verified through simulation experiments.\u0000\u0000\u0000\u0000The experimental results show that compared to the traditional autonomous planning obstacle avoidance method for unmanned boats, the collaborative planning obstacle avoidance method proposed in this paper can exhibit excellent performance in dense and narrow scenarios, with a more reasonable navigation path, a range reduction of 20% - 50%, and higher safety.\u0000\u0000\u0000\u0000The results show that the cooperative obstacle avoidance system based on 5G edge computing designed in the paper is feasible, and it can effectively realize the cooperative path planning and obstacle avoidance of multi unmanned boats.\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"3 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139389622","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 : 2022-04-30DOI: 10.2174/2665998002999220430124428
A. Yakubu, S. Abdullahi, S. Sahabi, G. Sani
Introduction Microwave devices and communication devices produce electric fields which may be dangerous to surrounding applications. These field can be shielded using conductive shells that are closed on all sides. These close conductive shells are often designed using thin metal foils. However, for many applications these enclosures can add significant cost and weight to a product and a minute gap in the enclosure can completely damage the benefits of the enclosure. Moreso, the metal foil are not flexible to complex geometry. The solution to the gap identified is to use a material that is light, flexible and durable which can shield unwanted electromagnetic wave (EM) waves. For this work, treated and untreated corn husk powder (CHP) was produced from agricultural waste residues by grinding into powder form, while polycaprolactone (PCL) was commercially obtained. Method The composites of the materials were synthesized using melt blending technique. The dielectric property of the produced materials were investigated using open ended coaxial probe technique. The dielectric constant values was used in the computational study of the composites using finite element method. Result Results indicates that the dielectric property of the treated was greater than the untreated composites. The alkali treatment affected the value of the dielectric constant, shielding effectiveness, and transmission coefficients of the composites. The highest dielectric property obtained was 3.42 for the 30 % filler with a loss factor of 0.47. The filler played significant role in the values of shielding effectiveness (SE) obtained, where the highest filler was able to shield radiation by up to -4.21 dB at the frequency range measured. Conclusion From the electric field intensity, it was observed that the highest filler had the minimum transmitted intensity of 2185.87 v/m. Due to the high loss factor of 0.47 obtained for the 30 % filler content, waveguide terminators and other microwave components can be produced from this composite.
{"title":"Computational Study of Treated and Untreated Corn Husk Powder and Polycaprolactone for Microwave Shielding Using Finite Element Method","authors":"A. Yakubu, S. Abdullahi, S. Sahabi, G. Sani","doi":"10.2174/2665998002999220430124428","DOIUrl":"https://doi.org/10.2174/2665998002999220430124428","url":null,"abstract":"\u0000\u0000Introduction\u0000Microwave devices and communication devices produce electric fields which may be dangerous to surrounding applications. These field can be shielded using conductive shells that are closed on all sides. These close conductive shells are often designed using thin metal foils. However, for many applications these enclosures can add significant cost and weight to a product and a minute gap in the enclosure can completely damage the benefits of the enclosure. Moreso, the metal foil are not flexible to complex geometry. The solution to the gap identified is to use a material that is light, flexible and durable which can shield unwanted electromagnetic wave (EM) waves. For this work, treated and untreated corn husk powder (CHP) was produced from agricultural waste residues by grinding into powder form, while polycaprolactone (PCL) was commercially obtained. \u0000\u0000Method\u0000The composites of the materials were synthesized using melt blending technique. The dielectric property of the produced materials were investigated using open ended coaxial probe technique. The dielectric constant values was used in the computational study of the composites using finite element method. \u0000\u0000Result\u0000Results indicates that the dielectric property of the treated was greater than the untreated composites. The alkali treatment affected the value of the dielectric constant, shielding effectiveness, and transmission coefficients of the composites. The highest dielectric property obtained was 3.42 for the 30 % filler with a loss factor of 0.47. The filler played significant role in the values of shielding effectiveness (SE) obtained, where the highest filler was able to shield radiation by up to -4.21 dB at the frequency range measured. \u0000\u0000Conclusion\u0000From the electric field intensity, it was observed that the highest filler had the minimum transmitted intensity of 2185.87 v/m. Due to the high loss factor of 0.47 obtained for the 30 % filler content, waveguide terminators and other microwave components can be produced from this composite.\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117003055","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 : 2022-01-28DOI: 10.2174/2665998002666220128154727
Andrew YT Leung
Electric hand dryers are more environmentally friendly than hand towels to eliminate solid waste and reduce maintenance of refilling. Hand dryers can attract microbes from the floor or wall. Likewise, hand towel attracts microbes from the environment. We present a two stages (ozone and plasma) disinfection electric hand dryer to dry hands by viral free air. Ozone can disinfect dryers’ wet internal surfaces and air but can be dangerous in high concentrations and for a long time. We use it for two seconds to disable microbes by 90%. In air exhaust reaching hands, there are a pair of plasma generators deactivating the remaining microbes and ozone at the air outlet. With the combination use of ozone and plasma, 99.9% of microbes were disabled. Plasma accelerates the neutralization of ozone to oxygen at the outlet
{"title":"Disinfection Electrical Hand Dryer Using Plasma and Ozone","authors":"Andrew YT Leung","doi":"10.2174/2665998002666220128154727","DOIUrl":"https://doi.org/10.2174/2665998002666220128154727","url":null,"abstract":"\u0000\u0000Electric hand dryers are more environmentally friendly than hand towels to eliminate solid waste and reduce maintenance of refilling. Hand dryers can attract microbes from the floor or wall. Likewise, hand towel attracts microbes from the environment. We present a two stages (ozone and plasma) disinfection electric hand dryer to dry hands by viral free air. Ozone can disinfect dryers’ wet internal surfaces and air but can be dangerous in high concentrations and for a long time. We use it for two seconds to disable microbes by 90%. In air exhaust reaching hands, there are a pair of plasma generators deactivating the remaining microbes and ozone at the air outlet. With the combination use of ozone and plasma, 99.9% of microbes were disabled. Plasma accelerates the neutralization of ozone to oxygen at the outlet\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131189270","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 : 2022-01-14DOI: 10.2174/2665998002666220114145027
Qutaiba Ibrahim Ali, F. Alsharbaty
Power grid is one of the most important manifestations of the modern civilization and the engine of it where it is described as a digestive system of the civil life. It is a structure has three main functions: generation, transmission lines, distribution. This concept was appropriate for a century. However, the beginning of the twenty-first century brought dramatic changes on different domains: media, human growth, economic, environmental, political, and technical etc. Smart grid is a sophisticated structure including cyber and physical bodies hence it reinforces the sustainability, the energy management, the capability of integration with microgrids, and exploiting the renewable energy resources. The quantum leap of smart grid is related to the advanced communication networks that deal with the cyber part. Moreover, the communication networks of smart grid offer attractive capabilities such as monitoring, control, and protection at the level of real time. The wireless communication techniques in integration frame are promised solution to compensate the requirements of smart grid designing such as wireless local area networks, worldwide interoperability for microwave access, long term evolution, and narrowband- internet of things. These technologies could provide high capacity, flexibility, low-cost maintenance for smart grid. However, the multi-interfaces in smart grid may exploit by persons or agencies to implement different types of cyber-attacks may lead to dangerous damage. This research paper reviews the up-to-date researches in the field of smart grid to handle the new trends and topics in one frame in order to offer integration vision in this vital section. It concentrates on the section of communication networks the mainstay of smart grid. This paper discusses the challenging and requirements of adopting the wireless communication technologies and delves deeply into literature review to devise and suggest solutions to compensate the impairments efficiently. Moreover, it explores the cyber security that representing the real defiant to implement the concept of smart grid safely.
{"title":"Challenges, Trends and Solutions for Communication Networks and Cyber-Security in Smart Grid.","authors":"Qutaiba Ibrahim Ali, F. Alsharbaty","doi":"10.2174/2665998002666220114145027","DOIUrl":"https://doi.org/10.2174/2665998002666220114145027","url":null,"abstract":"\u0000\u0000Power grid is one of the most important manifestations of the modern civilization and the engine of it where it is described as a digestive system of the civil life. It is a structure has three main functions: generation, transmission lines, distribution. This concept was appropriate for a century. However, the beginning of the twenty-first century brought dramatic changes on different domains: media, human growth, economic, environmental, political, and technical etc. Smart grid is a sophisticated structure including cyber and physical bodies hence it reinforces the sustainability, the energy management, the capability of integration with microgrids, and exploiting the renewable energy resources. The quantum leap of smart grid is related to the advanced communication networks that deal with the cyber part. Moreover, the communication networks of smart grid offer attractive capabilities such as monitoring, control, and protection at the level of real time. The wireless communication techniques in integration frame are promised solution to compensate the requirements of smart grid designing such as wireless local area networks, worldwide interoperability for microwave access, long term evolution, and narrowband- internet of things. These technologies could provide high capacity, flexibility, low-cost maintenance for smart grid. However, the multi-interfaces in smart grid may exploit by persons or agencies to implement different types of cyber-attacks may lead to dangerous damage. This research paper reviews the up-to-date researches in the field of smart grid to handle the new trends and topics in one frame in order to offer integration vision in this vital section. It concentrates on the section of communication networks the mainstay of smart grid. This paper discusses the challenging and requirements of adopting the wireless communication technologies and delves deeply into literature review to devise and suggest solutions to compensate the impairments efficiently. Moreover, it explores the cyber security that representing the real defiant to implement the concept of smart grid safely.\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123482976","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 : 2021-12-06DOI: 10.2174/2665998002666211206104809
Jiaying Huang, Wangqiang Niu, Xiaotong Wang
In wind power generation, the power curve can reflect the overall power generation performance of a wind turbine. How to make the power curve have high precision and be easy to interpret is a hot research topic. Because the current power curve modeling method is not comprehensive in feature selection, the simplified model and state curve of a wind turbine are introduced to avoid feature selection and make the model interpret easily. A power modeling method based on different working conditions is proposed. The wind turbine system is simplified into three physical models of blades, mechanical transmission and generator, and the energy transfer is expressed by mathematical expressions. The operation process of the wind turbine is divided into three phases: constant power (CP), constant speed (CS), and maximum power point tracking (MPPT), and the power expression of each phase is given after the analysis of state curves. The effectiveness of the proposed method is verified by the supervisory control and data acquisition (SCADA) data of a 2MW wind turbine. The experimental results show that the mean absolute percentage error (MAPE) index of the proposed power modeling method based on state curve analysis is 11.56%, which indicates that the power prediction result of this method is better than that of the sixth-order polynomial regression method, whose MAPE is 13.88%. The results show that the proposed method is feasible with high transparency and is interpreted easily.
{"title":"Output Power Modeling of Wind Turbine Based on State Curve Analysis","authors":"Jiaying Huang, Wangqiang Niu, Xiaotong Wang","doi":"10.2174/2665998002666211206104809","DOIUrl":"https://doi.org/10.2174/2665998002666211206104809","url":null,"abstract":"\u0000\u0000 In wind power generation, the power curve can reflect the overall power generation performance of a wind turbine. How to make the power curve have high precision and be easy to interpret is a hot research topic.\u0000\u0000\u0000\u0000\u0000Because the current power curve modeling method is not comprehensive in feature selection, the simplified model and state curve of a wind turbine are introduced to avoid feature selection and make the model interpret easily.\u0000\u0000\u0000\u0000\u0000A power modeling method based on different working conditions is proposed. The wind turbine system is simplified into three physical models of blades, mechanical transmission and generator, and the energy transfer is expressed by mathematical expressions. The operation process of the wind turbine is divided into three phases: constant power (CP), constant speed (CS), and maximum power point tracking (MPPT), and the power expression of each phase is given after the analysis of state curves.\u0000\u0000\u0000\u0000\u0000The effectiveness of the proposed method is verified by the supervisory control and data acquisition (SCADA) data of a 2MW wind turbine. The experimental results show that the mean absolute percentage error (MAPE) index of the proposed power modeling method based on state curve analysis is 11.56%, which indicates that the power prediction result of this method is better than that of the sixth-order polynomial regression method, whose MAPE is 13.88%.\u0000\u0000\u0000\u0000\u0000The results show that the proposed method is feasible with high transparency and is interpreted easily.\u0000\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124505239","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 : 2021-09-07DOI: 10.2174/2665998001666210907102634
Guo-Qiang Wei, S. Ji, Wenya Mao, Wen-Da Wang
Post-earthquake fire is one of the secondary disasters caused by the earthquake; many earthquakes around the world have brought about severe fires and led to enormous losses. It is of great significance to study the fire resistance of structures after earthquake to improve the level of urban disaster prevention and reduce the fire loss. A nonlinear finite element model of composite joints subjected to post-earthquake fires is established based on ABAQUS software. The state after the earthquake damage is imported into the thermal-stress analysis model through the restart request in ABAQUS, and considered as the initial state of the thermal-stress analysis model. It is noticed that when the damage index is less than 0.517, the damage level shows significant effect on the fire resistance, but the influence is no longer significant when the damage index reaches 0.781. When only the column is exposed to fire, the column showed obvious local buckling and overall bending deformation. Meanwhile, when the joint area below the concrete slab is exposed to fire, the joint shows a mixed failure mode of the excessive vertical displacement of beam end and column instability. The fire resistance of the composite joint decreases gradually with the increase of seismic damage level. The fire condition has a significant effect on the fire resistance of the composite joints; with the increase of fire area, the fire resistance of composite joints with same damage degrees decreases gradually.
{"title":"Study on the fire resistance of concrete-filled steel tubular column to composite beam joints after earthquake damage","authors":"Guo-Qiang Wei, S. Ji, Wenya Mao, Wen-Da Wang","doi":"10.2174/2665998001666210907102634","DOIUrl":"https://doi.org/10.2174/2665998001666210907102634","url":null,"abstract":"\u0000\u0000 Post-earthquake fire is one of the secondary disasters caused by the earthquake; many earthquakes around the world have brought about severe fires and led to enormous losses. It is of great significance to study the fire resistance of structures after earthquake to improve the level of urban disaster prevention and reduce the fire loss. \u0000\u0000\u0000\u0000\u0000A nonlinear finite element model of composite joints subjected to post-earthquake fires is established based on ABAQUS software. The state after the earthquake damage is imported into the thermal-stress analysis model through the restart request in ABAQUS, and considered as the initial state of the thermal-stress analysis model. \u0000\u0000\u0000\u0000\u0000It is noticed that when the damage index is less than 0.517, the damage level shows significant effect on the fire resistance, but the influence is no longer significant when the damage index reaches 0.781. When only the column is exposed to fire, the column showed obvious local buckling and overall bending deformation. Meanwhile, when the joint area below the concrete slab is exposed to fire, the joint shows a mixed failure mode of the excessive vertical displacement of beam end and column instability. \u0000\u0000\u0000\u0000\u0000 The fire resistance of the composite joint decreases gradually with the increase of seismic damage level. The fire condition has a significant effect on the fire resistance of the composite joints; with the increase of fire area, the fire resistance of composite joints with same damage degrees decreases gradually.\u0000\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125801999","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 : 2021-06-03DOI: 10.2174/266599800101210409114514
Jinde Cao
{"title":"Meet the Editor-in-Chief","authors":"Jinde Cao","doi":"10.2174/266599800101210409114514","DOIUrl":"https://doi.org/10.2174/266599800101210409114514","url":null,"abstract":"","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120889789","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 : 1969-12-31DOI: 10.2174/2665998001999200614170038
S. Du, Huijie Liu, Yanying Hu, Tengfei Yang
Partial metallurgical bond (namely 'hook') is formed between the overlapped metal sheets during friction stir spot welding (FSSW). The geometry of hook is found to significantly affect the mechanical performance of FSSWed joints, while that how to adjust hook geometry to a better state remains to be studied. The conventional FSSW joints under different plunge depths and dwelling time were obtained. The cross-sectional morphology of each spot weld was investigated to clarify the material flow behavior and deduce the formation mechanism of hook. The tensile shear strength and fracture features were examined to reveal the effect of hook geometry on the mechanical properties. The weld geometry affects the tensile shear strength of FSSWed joints by determining their fracture modes. The formation mechanism of hook is deduced by a material flow model. In the tool-plunging stage, the faying interface is broken by upward-flowing materials, hook is therefore initiated and driven up gradually. During the tool-dwelling stage, hook continues to migrate to the low-pressure zone, surrounding the stir zone. The uncertainty of crack-propagating endpoint along hook makes it difficult to ensure the mechanical properties of welds. If the hook endpoint has not yet reached the low-pressure zone at the end of welding process, welds with ideal hook geometry can be obtained. Target friction stir spot welds were produced by the use of a tool possessing smaller pin diameter.
{"title":"An approach to improving the mechanical properties of friction stir spot welded joints on the basis of hook formation mechanism","authors":"S. Du, Huijie Liu, Yanying Hu, Tengfei Yang","doi":"10.2174/2665998001999200614170038","DOIUrl":"https://doi.org/10.2174/2665998001999200614170038","url":null,"abstract":"\u0000\u0000Partial metallurgical bond (namely 'hook') is formed between the overlapped metal sheets during\u0000friction stir spot welding (FSSW). The geometry of hook is found to significantly affect the mechanical\u0000performance of FSSWed joints, while that how to adjust hook geometry to a better state remains to be studied.\u0000\u0000\u0000\u0000 The conventional FSSW joints under different plunge depths and dwelling time were obtained. The\u0000cross-sectional morphology of each spot weld was investigated to clarify the material flow behavior and deduce\u0000the formation mechanism of hook. The tensile shear strength and fracture features were examined to reveal the\u0000effect of hook geometry on the mechanical properties.\u0000\u0000\u0000\u0000The weld geometry affects the tensile shear strength of FSSWed joints by determining their fracture\u0000modes. The formation mechanism of hook is deduced by a material flow model. In the tool-plunging stage, the\u0000faying interface is broken by upward-flowing materials, hook is therefore initiated and driven up gradually.\u0000During the tool-dwelling stage, hook continues to migrate to the low-pressure zone, surrounding the stir zone.\u0000\u0000\u0000\u0000The uncertainty of crack-propagating endpoint along hook makes it difficult to ensure the\u0000mechanical properties of welds. If the hook endpoint has not yet reached the low-pressure zone at the end of\u0000welding process, welds with ideal hook geometry can be obtained. Target friction stir spot welds were produced\u0000by the use of a tool possessing smaller pin diameter.\u0000","PeriodicalId":269903,"journal":{"name":"Current Chinese Engineering Science","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1969-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122963308","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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