The demand for speeial steel materials such as ultra-thirk high-strength plates and low-temperature resistant high-densily plates has seen explosive growth in recent years following the diversifieation of ship orders ...The demand for speeial steel materials such as ultra-thirk high-strength plates and low-temperature resistant high-densily plates has seen explosive growth in recent years following the diversifieation of ship orders and the iterative upgrading of fuel teehnologies.AI the same time,handheld orders of shipbuilding enterprises are at a historieal high.with some companies'production.schedules extending to 2030.展开更多
This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production ...This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production efficiency.The shipbuilding process involves the complex cutting and arrangement of steel plates,making the optimization of these operations vital for cost-effectiveness and sustainability.Nesting algorithms are broadly classified into four categories:exact,heuristic,metaheuristic,and hybrid.Exact algorithms ensure optimal solutions but are computationally demanding.In contrast,heuristic algorithms deliver quicker results using practical rules,although they may not consistently achieve optimal outcomes.Metaheuristic algorithms combine multiple heuristics to effectively explore solution spaces,striking a balance between solution quality and computational efficiency.Hybrid algorithms integrate the strengths of different approaches to further enhance performance.This review systematically assesses these algorithms using criteria such as material dimensions,part geometry,component layout,and computational efficiency.The findings highlight the significant potential of advanced nesting techniques to improve material utilization,reduce production costs,and promote sustainable practices in shipbuilding.By adopting suitable nesting solutions,shipbuilders can achieve greater efficiency,optimized resource management,and superior overall performance.Future research directions should focus on integrating machine learning and real-time adaptability to further enhance nesting algorithms,paving the way for smarter,more sustainable manufacturing practices in the shipbuilding industry.展开更多
Microstructural evolution features have been systematically investigated for the weld metal of EH36 shipbuilding steel under an in situ confocal scanning laser microscope.The influence of cooling rate on microstructur...Microstructural evolution features have been systematically investigated for the weld metal of EH36 shipbuilding steel under an in situ confocal scanning laser microscope.The influence of cooling rate on microstructural changes during the transformation from austenite to ferrite has been clarified.It is found that ferrite side plates form preceding to acicular ferrites,although the starting temperature of respective component decreases as the cooling rate is raised.In particular,the growth rate of acicular ferrite is measured to increase significantly,rising from 30.4μm/s at a cooling rate of 3 K/s to 109.0μm/s at 15 K/s,driven primarily by an ever-increasing degree of undercooling.These findings highlight the critical role of cooling rate in dictating the sequence and growth rate of microstructural transformations,which is crucial for optimizing welding processes to obtain desired microstructures while avoiding the formation of deleterious components.展开更多
Shipbuilding production management and logistics control are studied so as to find an advanced shipbuilding production logistics management style.The necessity and feasibility to integrate MRP-Ⅱ(manufacture resource ...Shipbuilding production management and logistics control are studied so as to find an advanced shipbuilding production logistics management style.The necessity and feasibility to integrate MRP-Ⅱ(manufacture resource planning)and JIT(just-in-time)are researched properly following the comparison of MRP-Ⅱ and JIT and the analysis of shipbuilding production characteristics.A shipbuilding logistics system combining MRP-Ⅱ with JIT is set up and discussed according to a master production schedule(MPS),MRP and workshop-floor production control.The system is able to simplify the shipbuilding production plan,balance the workshop production,stabilize the supply,and inspire positivity and creativity so as to raise the shipbuilding production management level.展开更多
The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain ...The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain EH36 steel are almost composed of Al-Ca-S-O（-Mn） and undergo negligible changes during the whole process. With Zr addition, a large amount of individually fine MnS precipitates and Zr-containing inclusions are generated. In the rolled EH36-Zr sample, Zr-containing complex inclusions are effective to promote the nucleation of acicular ferrite on the surface, which are hardly found in the simulated welding sample of EH36-Zr steel due to the segregation of soluble Ti and Zr on the grain boundary.展开更多
Heterogeneous microstructure-induced mechanical responses in EH420 shipbuilding steel welded joint by electro-gas welding processed have been systematically studied by scanning electron microscopy,electron backscatter...Heterogeneous microstructure-induced mechanical responses in EH420 shipbuilding steel welded joint by electro-gas welding processed have been systematically studied by scanning electron microscopy,electron backscatter diffraction and mechanical testing.Comparing with the coarse-grained heat-affected zone(CGHAZ),the weld metal presents higher toughness(129.3 J vs.37.3 J)as it contains a large number of acicular ferrites with high-angle grain boundaries(frequency 79.2%)and special grain boundary∑3(frequency 55.3%).Moreover,coarse austenite grains in CGHAZ and slender martensite–austenite constituents between bainite laths may likely facilitate crack propagation.Polygonal ferrites and tempered pearlites formed at the junction of the fine-grained heat-affected zone and the intercritical heat-affected zone induced a softened zone with an average hardness of 185 HV0.5,which is the main reason for the occurrence of tensile fracture.展开更多
The 6-DOF manipulator provides a new option for traditional shipbuilding for its advantages of vast working space,low power consumption,and excellent flexibility.However,the rotation of the end effector along the tool...The 6-DOF manipulator provides a new option for traditional shipbuilding for its advantages of vast working space,low power consumption,and excellent flexibility.However,the rotation of the end effector along the tool axis is functionally redundant when using a robotic arm for five-axis machining.In the process of ship construction,the performance of the parts’protective coating needs to bemachined tomeet the Performance Standard of Protective Coatings(PSPC).The arbitrary redundancy configuration in path planning will result in drastic fluctuations in the robot joint angle,greatly reducing machining quality and efficiency.There have been some studies on singleobjective optimization of redundant variables,However,the quality and efficiency of milling are not affected by a single factor,it is usually influenced by several factors,such as the manipulator stiffness,the joint motion smoothness,and the energy consumption.To solve this problem,this paper proposed a new path optimization method for the industrial robot when it is used for five-axis machining.The path smoothness performance index and the energy consumption index are established based on the joint acceleration and the joint velocity,respectively.The path planning issue is formulated as a constrained multi-objective optimization problem by taking into account the constraints of joint limits and singularity avoidance.Then,the path is split into multiple segments for optimization to avoid the slow convergence rate caused by the high dimension.An algorithm combining the non-dominated sorting genetic algorithm(NSGA-II)and the differential evolution(DE)algorithm is employed to solve the above optimization problem.The simulations validate the effectiveness of the algorithm,showing the improvement of smoothness and the reduction of energy consumption.展开更多
Recently,there have been the increase of ship size and the development of oil and gas in arctic region.These trends have led to the requirements such as high strength,good toughness at low temperature and good weldabi...Recently,there have been the increase of ship size and the development of oil and gas in arctic region.These trends have led to the requirements such as high strength,good toughness at low temperature and good weldability.The high performance structural steels for shipbuilding and arctic offshore structure have been developed by our own micro-alloying and TMCP technologies.M-A constituent was precisely controlled in the both HAZ and base metal to get high toughness at low temperature.Also,the grain growth of austenite at HAZ was effectively suppressed by thermally stable TiN particles,leading to a good HAZ toughness.On the other hand,there has been the key issue of crack arrestability in large size container ship.The effect of joint design on crack arrestability was investigated to prevent a catastrophic failure along the block joint of hatch side coaming.A brittle crack arrest technique was developed without block joint shift,using an arrest weld in the end of hatch side coaming weld line.展开更多
Based on experimental data of line heating, the methods of vector mapping, plane projection, and coordinate converting are presented to establish the spectra for line heating distortion discipline which shows the rela...Based on experimental data of line heating, the methods of vector mapping, plane projection, and coordinate converting are presented to establish the spectra for line heating distortion discipline which shows the relationship between process parameters and distortion parameters of line heating. Back-propagation network （BP-net） is used to modify tile spectra. Mathematical models for optimizing line heating techniques parameters, which include two-objective functions, are constructed. To convert the multi-objective optimization into a single-objective one, the method of changifig weight coefficient is used, and then the individual fitness function is built up, Taking the number of heating lines, distance between the heating lines＇ border （line space）, and shrink quantity of lines as three restrictive conditions, a hierarchy genetic algorithm （HGA） code is established by making use of information provided by the spectra, in which inner coding and outer coding adopt different heredity arithmetic operators in inherent operating, The numerical example shows that the spectra for line heating distortion discipline presented here can provide accurate information required by techniques parameter prediction of line heating process and the technique parameter optimization method based on HGA provided here can obtain good results for hull plate.展开更多
Fused CaF_(2)-TiO_(2) fluxes have been designed,prepared,and applied in the flux cored wires to join EH36 shipbuilding steels under high heat input electro-gas welding.Ensuing microstructural evolution in the weld met...Fused CaF_(2)-TiO_(2) fluxes have been designed,prepared,and applied in the flux cored wires to join EH36 shipbuilding steels under high heat input electro-gas welding.Ensuing microstructural evolution in the weld metals subjected to varied CaF_(2)-TiO_(2) flux cored wires has been fully documented.It has been demonstrated that as the content of TiO2 in the fused fluxes increases,columnar grain size increases,and major constituents in the weld metal change from lath bainite,to granular bainite,and then to acicular ferrite.Such phenomena are elucidated via salient chemical reactions involving oxygen pickup and concurrent titanium transfer.展开更多
This paper compares Chinese, Korean, and Japanese shipyard production technology. Development in the world shipbuilding over recent years has influenced focus areas related to shipyard manufacturing technologies and p...This paper compares Chinese, Korean, and Japanese shipyard production technology. Development in the world shipbuilding over recent years has influenced focus areas related to shipyard manufacturing technologies and product performance. Software systems, information technology, production technology, and local challenges of shipyards are compared with shipbuilding outputs among these three countries. Various technologies developments, shipyard production and the problems in Chinese, Japanese, and Korean shipyards are discussed respectively. Finally, future areas of research are pointed out.展开更多
To manage the complexities of hull module partitions, a new approach to the partitions of hierarchical modules for shipbuilding is proposed. Based on the assembly and manufacture process, the approach determines the h...To manage the complexities of hull module partitions, a new approach to the partitions of hierarchical modules for shipbuilding is proposed. Based on the assembly and manufacture process, the approach determines the hierarchy and basis of the module partition first, and then according to the type of connection between the parts of the block module, the degree of membership for the rational connection is gained and the fuzzy relation matrix between different parts is then established. The fuzzy clustering technique is used to partition the modules, and then the method of fuzzy comprehensive assessment is used to choose a relative reasonable scheme. A case study has been conducted, which proves that the approach is feasible and applicable; Especially it obtains the sub-module partition, which sets up the shipbuilding process at a higher-level assembly and has offered effective tools for the modular ship design.展开更多
The effects of Ca treatment on the particle, microstructure, and toughness of heat-affected zone (HAZ) of shipbuilding steel with Zr-Ti deoxidation after high-heat-input welding were investigated. The simulated weldin...The effects of Ca treatment on the particle, microstructure, and toughness of heat-affected zone (HAZ) of shipbuilding steel with Zr-Ti deoxidation after high-heat-input welding were investigated. The simulated welding at a high-heat-input welding of 200 kJ/cm was carried out using Gleeble-3800 welding simulation. Then, particle characteristics were characterized using an Aztec-Feature automatic particle analysis system. Additionally, an in-situ observation experiment was performed to study the relationships between particle and microstructure by high-temperature confocal laser scanning microscopy (HT-CLSM). The results indicated that the average HAZ toughness at -40 ℃ was increased from 183 to 290 J by adding 0.0026 wt.% Ca. Meanwhile, the formation of acicular ferrite ratio was increased from 49.34% to 60.28% due to the addition of Ca. The scanning electron microscopy results clearly showed that CaO-Al_(2)O_(3)-TiOx-ZrO_(2)-MnS particles could act as effective nucleation sites for the formation of acicular ferrite, which has been verified by the observation of the particle-microstructure relationship under HT-CLSM. Furthermore, particle characterization results show that the cumulative frequency of particles with the size of 1-3 lm was 33.2% in HAZ of Zr-Ti shipbuilding steel but 66.2% in HAZ of Zr-Ti-Ca shipbuilding steel.展开更多
Computer-aided block assembly process planning based on rule-reasoning are developed in order to improve the assembly efficiency and implement the automated block assembly process planning generation in shipbuilding. ...Computer-aided block assembly process planning based on rule-reasoning are developed in order to improve the assembly efficiency and implement the automated block assembly process planning generation in shipbuilding. First, weighted directed liaison graph （WDLG） is proposed to represent the model of block assembly process according to the characteristics of assembly relation, and edge list （EL） is used to describe assembly sequences. Shapes and assembly attributes of block parts are analyzed to determine the assembly position and matched parts of parts used frequently. Then, a series of assembly rules are generalized, and assembly sequences for block are obtained by means of rule reasoning. Final, a prototype system of computer-aided block assembly process planning is built. The system has been tested on actual block, and the results were found to be quite efficiency. Meanwhile, the fundament for the automation of block assembly process generation and integration with other systems is established.展开更多
Based on analysis of green shipping practices of foreign ships manufacturers, ocean carriers ad port countries, their advanced experience was summarized, and its enlightenment to China＇s ＂green shipping＂ was analyz...Based on analysis of green shipping practices of foreign ships manufacturers, ocean carriers ad port countries, their advanced experience was summarized, and its enlightenment to China＇s ＂green shipping＂ was analyzed to realize China＇s dream of becoming ＂ a strong shipping country＂ eady.展开更多
The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grai...The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grain size in the processed zone from 25 μm to about 3 μm, which also caused a remarkable increase in strength values without considerable decrease in formability under uniaxial loading. A coarse-grained （CG） sample before FSP reflected a moderate formability with an Erichsen index （EI） of 2.73 mm. FSP slightly decreased the stretch formability of the sample to 2.66 ram. However, FSP increased the required punch load （FEI） due to the increased strength by grain refinement. FSP reduced considerably the roughness of the free surface of the biaxial stretched samples with reduced orange peel effect. The average roughness value （Ra） decreased from 2.90 in the CG sample down to about 0.65 μm in fine-grained （FG） sample after FSP. It can be concluded that the FG microstructure in low carbon steels sheets or plates used generally in shipbuilding provides a good balance between strength and formability.展开更多
文摘The demand for speeial steel materials such as ultra-thirk high-strength plates and low-temperature resistant high-densily plates has seen explosive growth in recent years following the diversifieation of ship orders and the iterative upgrading of fuel teehnologies.AI the same time,handheld orders of shipbuilding enterprises are at a historieal high.with some companies'production.schedules extending to 2030.
文摘This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production efficiency.The shipbuilding process involves the complex cutting and arrangement of steel plates,making the optimization of these operations vital for cost-effectiveness and sustainability.Nesting algorithms are broadly classified into four categories:exact,heuristic,metaheuristic,and hybrid.Exact algorithms ensure optimal solutions but are computationally demanding.In contrast,heuristic algorithms deliver quicker results using practical rules,although they may not consistently achieve optimal outcomes.Metaheuristic algorithms combine multiple heuristics to effectively explore solution spaces,striking a balance between solution quality and computational efficiency.Hybrid algorithms integrate the strengths of different approaches to further enhance performance.This review systematically assesses these algorithms using criteria such as material dimensions,part geometry,component layout,and computational efficiency.The findings highlight the significant potential of advanced nesting techniques to improve material utilization,reduce production costs,and promote sustainable practices in shipbuilding.By adopting suitable nesting solutions,shipbuilders can achieve greater efficiency,optimized resource management,and superior overall performance.Future research directions should focus on integrating machine learning and real-time adaptability to further enhance nesting algorithms,paving the way for smarter,more sustainable manufacturing practices in the shipbuilding industry.
基金support from the National Natural Science Foundation of China(Grant Nos.U20A20277 and 52350610226)National Key Research and Development Plan of China(Grant No.2022YFE0123300).
文摘Microstructural evolution features have been systematically investigated for the weld metal of EH36 shipbuilding steel under an in situ confocal scanning laser microscope.The influence of cooling rate on microstructural changes during the transformation from austenite to ferrite has been clarified.It is found that ferrite side plates form preceding to acicular ferrites,although the starting temperature of respective component decreases as the cooling rate is raised.In particular,the growth rate of acicular ferrite is measured to increase significantly,rising from 30.4μm/s at a cooling rate of 3 K/s to 109.0μm/s at 15 K/s,driven primarily by an ever-increasing degree of undercooling.These findings highlight the critical role of cooling rate in dictating the sequence and growth rate of microstructural transformations,which is crucial for optimizing welding processes to obtain desired microstructures while avoiding the formation of deleterious components.
基金The National Key Technology R&D Program of China during the 11th Five-Year Plan Period(No.2006BAH02A06)
文摘Shipbuilding production management and logistics control are studied so as to find an advanced shipbuilding production logistics management style.The necessity and feasibility to integrate MRP-Ⅱ(manufacture resource planning)and JIT(just-in-time)are researched properly following the comparison of MRP-Ⅱ and JIT and the analysis of shipbuilding production characteristics.A shipbuilding logistics system combining MRP-Ⅱ with JIT is set up and discussed according to a master production schedule(MPS),MRP and workshop-floor production control.The system is able to simplify the shipbuilding production plan,balance the workshop production,stabilize the supply,and inspire positivity and creativity so as to raise the shipbuilding production management level.
文摘The inclusions evolution behavior in the continuous casting slab, rolled plates, and simulated welding samples of EH36 steels with and without Zr addition has been systematically investigated. The inclusions in plain EH36 steel are almost composed of Al-Ca-S-O（-Mn） and undergo negligible changes during the whole process. With Zr addition, a large amount of individually fine MnS precipitates and Zr-containing inclusions are generated. In the rolled EH36-Zr sample, Zr-containing complex inclusions are effective to promote the nucleation of acicular ferrite on the surface, which are hardly found in the simulated welding sample of EH36-Zr steel due to the segregation of soluble Ti and Zr on the grain boundary.
基金the National Natural Science Foundation of China(Grant Nos.U20A20277,51861130361,51861145312,51850410522,5201101443,and 52011530180)the Newton Advanced Fellowship by Royal Society(Grant No.RP12G0414)+5 种基金the Royal Academy of Engineering(No.TSPC1070)the Special Fund for Key Program of Science and Technology of Liaoning Province(Grant No.2019JH1/101000014)the Research Fund for Central Universities(Grant Nos.N172502004 and N2025025)the Xingliao Talents Program(Nos.XLYC1807024 and XLYC1802024)the Regional Innovation Joint Fund of Liaoning Province(No.2020-YKLH-39)funded in part by the National Research Foundation of South Africa(No.BRICS171211293679)。
文摘Heterogeneous microstructure-induced mechanical responses in EH420 shipbuilding steel welded joint by electro-gas welding processed have been systematically studied by scanning electron microscopy,electron backscatter diffraction and mechanical testing.Comparing with the coarse-grained heat-affected zone(CGHAZ),the weld metal presents higher toughness(129.3 J vs.37.3 J)as it contains a large number of acicular ferrites with high-angle grain boundaries(frequency 79.2%)and special grain boundary∑3(frequency 55.3%).Moreover,coarse austenite grains in CGHAZ and slender martensite–austenite constituents between bainite laths may likely facilitate crack propagation.Polygonal ferrites and tempered pearlites formed at the junction of the fine-grained heat-affected zone and the intercritical heat-affected zone induced a softened zone with an average hardness of 185 HV0.5,which is the main reason for the occurrence of tensile fracture.
文摘The 6-DOF manipulator provides a new option for traditional shipbuilding for its advantages of vast working space,low power consumption,and excellent flexibility.However,the rotation of the end effector along the tool axis is functionally redundant when using a robotic arm for five-axis machining.In the process of ship construction,the performance of the parts’protective coating needs to bemachined tomeet the Performance Standard of Protective Coatings(PSPC).The arbitrary redundancy configuration in path planning will result in drastic fluctuations in the robot joint angle,greatly reducing machining quality and efficiency.There have been some studies on singleobjective optimization of redundant variables,However,the quality and efficiency of milling are not affected by a single factor,it is usually influenced by several factors,such as the manipulator stiffness,the joint motion smoothness,and the energy consumption.To solve this problem,this paper proposed a new path optimization method for the industrial robot when it is used for five-axis machining.The path smoothness performance index and the energy consumption index are established based on the joint acceleration and the joint velocity,respectively.The path planning issue is formulated as a constrained multi-objective optimization problem by taking into account the constraints of joint limits and singularity avoidance.Then,the path is split into multiple segments for optimization to avoid the slow convergence rate caused by the high dimension.An algorithm combining the non-dominated sorting genetic algorithm(NSGA-II)and the differential evolution(DE)algorithm is employed to solve the above optimization problem.The simulations validate the effectiveness of the algorithm,showing the improvement of smoothness and the reduction of energy consumption.
文摘Recently,there have been the increase of ship size and the development of oil and gas in arctic region.These trends have led to the requirements such as high strength,good toughness at low temperature and good weldability.The high performance structural steels for shipbuilding and arctic offshore structure have been developed by our own micro-alloying and TMCP technologies.M-A constituent was precisely controlled in the both HAZ and base metal to get high toughness at low temperature.Also,the grain growth of austenite at HAZ was effectively suppressed by thermally stable TiN particles,leading to a good HAZ toughness.On the other hand,there has been the key issue of crack arrestability in large size container ship.The effect of joint design on crack arrestability was investigated to prevent a catastrophic failure along the block joint of hatch side coaming.A brittle crack arrest technique was developed without block joint shift,using an arrest weld in the end of hatch side coaming weld line.
文摘Based on experimental data of line heating, the methods of vector mapping, plane projection, and coordinate converting are presented to establish the spectra for line heating distortion discipline which shows the relationship between process parameters and distortion parameters of line heating. Back-propagation network （BP-net） is used to modify tile spectra. Mathematical models for optimizing line heating techniques parameters, which include two-objective functions, are constructed. To convert the multi-objective optimization into a single-objective one, the method of changifig weight coefficient is used, and then the individual fitness function is built up, Taking the number of heating lines, distance between the heating lines＇ border （line space）, and shrink quantity of lines as three restrictive conditions, a hierarchy genetic algorithm （HGA） code is established by making use of information provided by the spectra, in which inner coding and outer coding adopt different heredity arithmetic operators in inherent operating, The numerical example shows that the spectra for line heating distortion discipline presented here can provide accurate information required by techniques parameter prediction of line heating process and the technique parameter optimization method based on HGA provided here can obtain good results for hull plate.
基金support from the National Natural Science Foundation of China (Grant Nos.U20A20277,52050410341,52011530180,and 52150610494)Royal Academy of Engineering (TSPC1070)+3 种基金ResearchFund for Central Universities (Grant Nos.N2025025 and N2125016)Regional Innovation Joint Fund of Liaoning Province (2020-YKLH-39)Open Projectof State Key Laboratoryof Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University (SKLASS 2020-09)the Science and Technology Commission of ShanghaiMunicipality (No.19DZ2270200).
文摘Fused CaF_(2)-TiO_(2) fluxes have been designed,prepared,and applied in the flux cored wires to join EH36 shipbuilding steels under high heat input electro-gas welding.Ensuing microstructural evolution in the weld metals subjected to varied CaF_(2)-TiO_(2) flux cored wires has been fully documented.It has been demonstrated that as the content of TiO2 in the fused fluxes increases,columnar grain size increases,and major constituents in the weld metal change from lath bainite,to granular bainite,and then to acicular ferrite.Such phenomena are elucidated via salient chemical reactions involving oxygen pickup and concurrent titanium transfer.
文摘This paper compares Chinese, Korean, and Japanese shipyard production technology. Development in the world shipbuilding over recent years has influenced focus areas related to shipyard manufacturing technologies and product performance. Software systems, information technology, production technology, and local challenges of shipyards are compared with shipbuilding outputs among these three countries. Various technologies developments, shipyard production and the problems in Chinese, Japanese, and Korean shipyards are discussed respectively. Finally, future areas of research are pointed out.
文摘To manage the complexities of hull module partitions, a new approach to the partitions of hierarchical modules for shipbuilding is proposed. Based on the assembly and manufacture process, the approach determines the hierarchy and basis of the module partition first, and then according to the type of connection between the parts of the block module, the degree of membership for the rational connection is gained and the fuzzy relation matrix between different parts is then established. The fuzzy clustering technique is used to partition the modules, and then the method of fuzzy comprehensive assessment is used to choose a relative reasonable scheme. A case study has been conducted, which proves that the approach is feasible and applicable; Especially it obtains the sub-module partition, which sets up the shipbuilding process at a higher-level assembly and has offered effective tools for the modular ship design.
基金supported by the Open Project Program of Bejing Key Laboratory of Pipeline Critical Technology and Equipment forDeepwater Oil&Gas Development(Grant No.BIPT2019001)the Natural Science Foundation of Hebei Province(Grant No.E2021318004)。
文摘The effects of Ca treatment on the particle, microstructure, and toughness of heat-affected zone (HAZ) of shipbuilding steel with Zr-Ti deoxidation after high-heat-input welding were investigated. The simulated welding at a high-heat-input welding of 200 kJ/cm was carried out using Gleeble-3800 welding simulation. Then, particle characteristics were characterized using an Aztec-Feature automatic particle analysis system. Additionally, an in-situ observation experiment was performed to study the relationships between particle and microstructure by high-temperature confocal laser scanning microscopy (HT-CLSM). The results indicated that the average HAZ toughness at -40 ℃ was increased from 183 to 290 J by adding 0.0026 wt.% Ca. Meanwhile, the formation of acicular ferrite ratio was increased from 49.34% to 60.28% due to the addition of Ca. The scanning electron microscopy results clearly showed that CaO-Al_(2)O_(3)-TiOx-ZrO_(2)-MnS particles could act as effective nucleation sites for the formation of acicular ferrite, which has been verified by the observation of the particle-microstructure relationship under HT-CLSM. Furthermore, particle characterization results show that the cumulative frequency of particles with the size of 1-3 lm was 33.2% in HAZ of Zr-Ti shipbuilding steel but 66.2% in HAZ of Zr-Ti-Ca shipbuilding steel.
基金National Natural Science Foundation of China (No.40606018)
文摘Computer-aided block assembly process planning based on rule-reasoning are developed in order to improve the assembly efficiency and implement the automated block assembly process planning generation in shipbuilding. First, weighted directed liaison graph （WDLG） is proposed to represent the model of block assembly process according to the characteristics of assembly relation, and edge list （EL） is used to describe assembly sequences. Shapes and assembly attributes of block parts are analyzed to determine the assembly position and matched parts of parts used frequently. Then, a series of assembly rules are generalized, and assembly sequences for block are obtained by means of rule reasoning. Final, a prototype system of computer-aided block assembly process planning is built. The system has been tested on actual block, and the results were found to be quite efficiency. Meanwhile, the fundament for the automation of block assembly process generation and integration with other systems is established.
文摘Based on analysis of green shipping practices of foreign ships manufacturers, ocean carriers ad port countries, their advanced experience was summarized, and its enlightenment to China＇s ＂green shipping＂ was analyzed to realize China＇s dream of becoming ＂ a strong shipping country＂ eady.
基金supported by “The World Academy of Sciences,Italy(TWAS)” under the Visiting Researchers Program of TWASUNESCO Associateship Scheme(Ref.3240260896)
文摘The stretch formability of a low carbon steel processed by friction stir processing （FSP） was studied under biaxial loading condition applied by a miniaturized Erichsen test. One-pass FSP decreased the ferritic grain size in the processed zone from 25 μm to about 3 μm, which also caused a remarkable increase in strength values without considerable decrease in formability under uniaxial loading. A coarse-grained （CG） sample before FSP reflected a moderate formability with an Erichsen index （EI） of 2.73 mm. FSP slightly decreased the stretch formability of the sample to 2.66 ram. However, FSP increased the required punch load （FEI） due to the increased strength by grain refinement. FSP reduced considerably the roughness of the free surface of the biaxial stretched samples with reduced orange peel effect. The average roughness value （Ra） decreased from 2.90 in the CG sample down to about 0.65 μm in fine-grained （FG） sample after FSP. It can be concluded that the FG microstructure in low carbon steels sheets or plates used generally in shipbuilding provides a good balance between strength and formability.
