A ship is constructed by assembling blocks and installing outfits in the assembled ship structure. The measured data of real products and the design data are analyzed to prevent the loss caused by dimensional quality errors in shipbuilding. In recent years, 3D shapes have been used for efficient dimension quality management; however, it is difficult to deal with the large-scale Computer Aided Design (CAD) data required for managing extra-large blocks. A lightweight model is widely used for visualizing and sharing large data in Product Lifecycle Management. This model is mainly composed of triangular elements to minimize the file size and increase visibility. There are no problems with visually confirming the shape based on these triangular elements, but the model has a limitation when numerically calculating the exact position on a curve or a surface. In this article, we propose a method that uses a lightweight model to improve the efficiency of dimensional quality management. Accurate boundary curves are restored from the lightweight model used for visualization. After matching the connectivity of triangular elements, boundary element edges are extracted. Boundary curves are generated by connecting these boundary element edges. In addition, the density for tessellation was evaluated and found to be suitable for the shipbuilding process. The proposed method was tested on several models to demonstrate its feasibility. A ship is designed by dividing it into several blocks, which constitute the hull, and each block is constructed separately and assembled. Blocks are usually made by assembling small parts fabricated by machining steel plates, and the ship is constructed through the assembly of large blocks from the small blocks. For this process to be performed smoothly, errors are calculated between the design dimensions and manufactured dimensions, and then, the errors are used to correct for erroneous portions after constructing each block. In addition, the dimensions for outfitting and the positions of the hull structure are modified in the case of misalignment during the outfitting process such as installing pipes, equipment, and devices on the hull structure. Dimensional quality management is an activity performed to meet the dimensional quality that is required in the shipbuilding process, including at offshore manufacturing plants.
{"title":"Design Point Generation Method from a Lightweight Model for Dimensional Quality Management in Shipbuilding","authors":"K. Kwon","doi":"10.5957/JSPD.08170042","DOIUrl":"https://doi.org/10.5957/JSPD.08170042","url":null,"abstract":"A ship is constructed by assembling blocks and installing outfits in the assembled ship structure. The measured data of real products and the design data are analyzed to prevent the loss caused by dimensional quality errors in shipbuilding. In recent years, 3D shapes have been used for efficient dimension quality management; however, it is difficult to deal with the large-scale Computer Aided Design (CAD) data required for managing extra-large blocks. A lightweight model is widely used for visualizing and sharing large data in Product Lifecycle Management. This model is mainly composed of triangular elements to minimize the file size and increase visibility. There are no problems with visually confirming the shape based on these triangular elements, but the model has a limitation when numerically calculating the exact position on a curve or a surface. In this article, we propose a method that uses a lightweight model to improve the efficiency of dimensional quality management. Accurate boundary curves are restored from the lightweight model used for visualization. After matching the connectivity of triangular elements, boundary element edges are extracted. Boundary curves are generated by connecting these boundary element edges. In addition, the density for tessellation was evaluated and found to be suitable for the shipbuilding process. The proposed method was tested on several models to demonstrate its feasibility.\u0000 \u0000 \u0000 A ship is designed by dividing it into several blocks, which constitute the hull, and each block is constructed separately and assembled. Blocks are usually made by assembling small parts fabricated by machining steel plates, and the ship is constructed through the assembly of large blocks from the small blocks. For this process to be performed smoothly, errors are calculated between the design dimensions and manufactured dimensions, and then, the errors are used to correct for erroneous portions after constructing each block. In addition, the dimensions for outfitting and the positions of the hull structure are modified in the case of misalignment during the outfitting process such as installing pipes, equipment, and devices on the hull structure. Dimensional quality management is an activity performed to meet the dimensional quality that is required in the shipbuilding process, including at offshore manufacturing plants.\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48017231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Curved hull plate forming, the process of forming a flat plate into a curved surface that can fit into the outer shell of a ship's hull, can be achieved through either cold or thermal forming processes, with the latter processes further subcategorizable into line or triangle heating. The appropriate forming process is determined from the plate shape and surface classification, which must be determined in advance to establish a precise production plan. In this study, an algorithm to extract two-dimensional features of constant size from three-dimensional design information was developed to enable the application of machine and deep learning technologies to hull plates with arbitrary polygonal shapes. Several candidate classifiers were implemented by applying learning algorithms to datasets comprising calculated features and labels corresponding to various hull plate types, with the performance of each classifier evaluated using cross-validation. A classifier applying a convolution neural network as a deep learning technology was found to have the highest prediction accuracy, which exceeded the accuracies obtained in previous hull plate classification studies. The results of this study demonstrate that it is possible to automatically classify hull plates with high accuracy using deep learning technologies and that a perfect level of classification accuracy can be approached by obtaining further plate data. The outer shell of a ship is composed of hull plates that are generally formed as curved surfaces. To produce a curved surface from a flat steel plate, a curved hull plate-forming process involving the application of heat or pressure to the plate must be undertaken. Such forming processes can be categorized as either cold forming, in which the plate is bent using physical pressure, or thermal forming, in which bending stress is generated by applying heat to the plate. The former process is generally used to bend plates into cylindrical shapes using a rolling machine, whereas the latter is used to form more complex curved surfaces. In most shipyards, thermal forming is performed by skilled workers who apply direct heat to plates using a torch; accordingly, thermal forming is more difficult and time-consuming than machine-based cold forming and often constitutes a crucial bottleneck process in shipyard operation.
{"title":"Curved Hull Plate Classification for Determining Forming Method using Deep Learning","authors":"Byeong-Eun Kim, S. Son, C. Ryu, J. Shin","doi":"10.5957/JSPD.04180011","DOIUrl":"https://doi.org/10.5957/JSPD.04180011","url":null,"abstract":"Curved hull plate forming, the process of forming a flat plate into a curved surface that can fit into the outer shell of a ship's hull, can be achieved through either cold or thermal forming processes, with the latter processes further subcategorizable into line or triangle heating. The appropriate forming process is determined from the plate shape and surface classification, which must be determined in advance to establish a precise production plan. In this study, an algorithm to extract two-dimensional features of constant size from three-dimensional design information was developed to enable the application of machine and deep learning technologies to hull plates with arbitrary polygonal shapes. Several candidate classifiers were implemented by applying learning algorithms to datasets comprising calculated features and labels corresponding to various hull plate types, with the performance of each classifier evaluated using cross-validation. A classifier applying a convolution neural network as a deep learning technology was found to have the highest prediction accuracy, which exceeded the accuracies obtained in previous hull plate classification studies. The results of this study demonstrate that it is possible to automatically classify hull plates with high accuracy using deep learning technologies and that a perfect level of classification accuracy can be approached by obtaining further plate data.\u0000 \u0000 \u0000 The outer shell of a ship is composed of hull plates that are generally formed as curved surfaces. To produce a curved surface from a flat steel plate, a curved hull plate-forming process involving the application of heat or pressure to the plate must be undertaken. Such forming processes can be categorized as either cold forming, in which the plate is bent using physical pressure, or thermal forming, in which bending stress is generated by applying heat to the plate. The former process is generally used to bend plates into cylindrical shapes using a rolling machine, whereas the latter is used to form more complex curved surfaces. In most shipyards, thermal forming is performed by skilled workers who apply direct heat to plates using a torch; accordingly, thermal forming is more difficult and time-consuming than machine-based cold forming and often constitutes a crucial bottleneck process in shipyard operation.\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41894078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inherent deformation as key parameter plays an essential role in elastic finite element (FE) analysis for welding distortion prediction. In this study, the self-constraints supported by surrounding base material and lateral stiffener were presented, where their influences on magnitudes of inherent deformation components were qualitatively examined. In detail, self-constraint supported by the surrounding base material will distinguish the inherent deformation as an individual physical representation; and self-constraint supported by the lateral stiffener will significantly influence the bending component and final deformed mode. Taking into account fillet welding and orthogonal stiffened welded structure as the application, experiments were conducted for out-of-plane welding distortion measurement. Transient nonlinear thermal elastic-plastic FE analysis of fillet welding was carried out to evaluate inherent deformation after validation with the measured data; then, elastic FE analysis with inherent deformation was carried out to accurately predict the out-of-plane welding distortion and welding buckling behavior in fabrication of an orthogonal stiffened welded structure which is a part of typical ship panel, and there is a good agreement between the predicted and measured welding distortion. Up to now, fusion welding which is considered as a main joining method because of its practical and high productive features is almost employed for component assembly in fabrication of marine structures, automobiles, trains, aircraft, bridges, pressure vessels, and others. However, during the fast heating and cooling processes, a narrow region near the welding line will expand and subsequently shrink because of the constraint of the surrounding base material, and then plastic strains are generated which are the primary cause of welding distortion and residual stress. Therefore, welding-induced distortion is inevitably generated during the welding process, and it will result in loss of dimensional control and structural integrity, trouble of subsequent alignment with the adjacent component, and increment of fabrication cost with straightening such as flame heating (Wang et al. 2015).
{"title":"Accurate FE Computation for Out-of-plane Welding Distortion Prediction of Fillet Welding with Considering Self-Constraint","authors":"Hong Zhou, Jiangchao Wang","doi":"10.5957/JSPD.03180006","DOIUrl":"https://doi.org/10.5957/JSPD.03180006","url":null,"abstract":"Inherent deformation as key parameter plays an essential role in elastic finite element (FE) analysis for welding distortion prediction. In this study, the self-constraints supported by surrounding base material and lateral stiffener were presented, where their influences on magnitudes of inherent deformation components were qualitatively examined. In detail, self-constraint supported by the surrounding base material will distinguish the inherent deformation as an individual physical representation; and self-constraint supported by the lateral stiffener will significantly influence the bending component and final deformed mode. Taking into account fillet welding and orthogonal stiffened welded structure as the application, experiments were conducted for out-of-plane welding distortion measurement. Transient nonlinear thermal elastic-plastic FE analysis of fillet welding was carried out to evaluate inherent deformation after validation with the measured data; then, elastic FE analysis with inherent deformation was carried out to accurately predict the out-of-plane welding distortion and welding buckling behavior in fabrication of an orthogonal stiffened welded structure which is a part of typical ship panel, and there is a good agreement between the predicted and measured welding distortion.\u0000 \u0000 \u0000 Up to now, fusion welding which is considered as a main joining method because of its practical and high productive features is almost employed for component assembly in fabrication of marine structures, automobiles, trains, aircraft, bridges, pressure vessels, and others. However, during the fast heating and cooling processes, a narrow region near the welding line will expand and subsequently shrink because of the constraint of the surrounding base material, and then plastic strains are generated which are the primary cause of welding distortion and residual stress. Therefore, welding-induced distortion is inevitably generated during the welding process, and it will result in loss of dimensional control and structural integrity, trouble of subsequent alignment with the adjacent component, and increment of fabrication cost with straightening such as flame heating (Wang et al. 2015).\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48642480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the last few decades, there have been a significant number of accidents on crude oil tankers, floating production storage and offloading (FPSO) and offshore units due to fire and explosion, which have resulted in loss of lives, assets, and environmental damage. These incidents increase scrutiny and questions on the current level of safety design in hydrocarbon handling spaces and other high-risk spaces in oil tankers and FPSOs. There are many factors which may contribute to these incidents, including; defects of equipment and components, overlook during design, inappropriate maintenance procedure and history, improper workmanship, and lack of company safety procedures and instruction during maintenance and emergency responses. This study is focused on and has discussed all safety aspects and barriers for the enclosed cargo-handling spaces in tankers and offshore units. Various existing regulations, standards, and guidelines have addressed safety design of enclosed cargo-handling spaces. These requirements and guidelines are referred and investigated to identify typical industry gaps in design and to recommend best engineering practices. The proposed key design recommendations may be considered at the early design stage of new building or conversion projects to enhance the overall safety and to reduce the likelihood of critical safety events. The offshore and marine industry face many inherent risks such as failure of equipment and structural integrity, collision, grounding, dropped objects, leakages, fire and explosions. Because of the constant transfer and handling of hydrocarbons in operational profile, oil tankers and floating production storage and offloading (FPSO) units have significant potential fire and explosion risks unless sound safety barriers are considered throughout all phases of the design and the construction. Often a FPSO conversion project, which uses an ageing crude oil tanker, is the preferred choice to provide a functioning FPSO facility to the offshore oil production market in timely manner. When compared with newbuilding FPSOs, a conversion project can provide shorter construction schedule and cost reduction benefits. Considerable number of FPSOs operating in the market apply a conversion-type approach, using existing oil tankers to convert to FPSOs. In a FPSO conversion project, the existing cargo pump room is used for the hydrocarbon cargo handling, transfer and offloading operations. The use of the conventional cargo pump room configuration in newly operating FPSOs has come under scrutiny compared with newbuilding projects, which typically install independent cargo pumps, such as a submergible or deepwell type, within each tank which minimizes the risk of hydrocarbon leaks to other confined spaces. The conventional pump room configuration has always presented high risks and concerns due to confined spaces, many potential leak sources, hydrocarbon handling equipment and piping, where leaks can build an explosiv
{"title":"Enhancement of Safety and Design in Cargo Handling Spaces to Prevent Accidental Fire or Explosion in Oil Tankers and FPSOs","authors":"D. Ok","doi":"10.5957/JSPD.05180018","DOIUrl":"https://doi.org/10.5957/JSPD.05180018","url":null,"abstract":"Over the last few decades, there have been a significant number of accidents on crude oil tankers, floating production storage and offloading (FPSO) and offshore units due to fire and explosion, which have resulted in loss of lives, assets, and environmental damage. These incidents increase scrutiny and questions on the current level of safety design in hydrocarbon handling spaces and other high-risk spaces in oil tankers and FPSOs. There are many factors which may contribute to these incidents, including; defects of equipment and components, overlook during design, inappropriate maintenance procedure and history, improper workmanship, and lack of company safety procedures and instruction during maintenance and emergency responses. This study is focused on and has discussed all safety aspects and barriers for the enclosed cargo-handling spaces in tankers and offshore units. Various existing regulations, standards, and guidelines have addressed safety design of enclosed cargo-handling spaces. These requirements and guidelines are referred and investigated to identify typical industry gaps in design and to recommend best engineering practices. The proposed key design recommendations may be considered at the early design stage of new building or conversion projects to enhance the overall safety and to reduce the likelihood of critical safety events.\u0000 \u0000 \u0000 The offshore and marine industry face many inherent risks such as failure of equipment and structural integrity, collision, grounding, dropped objects, leakages, fire and explosions. Because of the constant transfer and handling of hydrocarbons in operational profile, oil tankers and floating production storage and offloading (FPSO) units have significant potential fire and explosion risks unless sound safety barriers are considered throughout all phases of the design and the construction. Often a FPSO conversion project, which uses an ageing crude oil tanker, is the preferred choice to provide a functioning FPSO facility to the offshore oil production market in timely manner. When compared with newbuilding FPSOs, a conversion project can provide shorter construction schedule and cost reduction benefits. Considerable number of FPSOs operating in the market apply a conversion-type approach, using existing oil tankers to convert to FPSOs. In a FPSO conversion project, the existing cargo pump room is used for the hydrocarbon cargo handling, transfer and offloading operations. The use of the conventional cargo pump room configuration in newly operating FPSOs has come under scrutiny compared with newbuilding projects, which typically install independent cargo pumps, such as a submergible or deepwell type, within each tank which minimizes the risk of hydrocarbon leaks to other confined spaces. The conventional pump room configuration has always presented high risks and concerns due to confined spaces, many potential leak sources, hydrocarbon handling equipment and piping, where leaks can build an explosiv","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45556705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Cilia, D. Bertetta, P. Gualeni, G. Tani, M. Viviani
Additive manufacturing (AM), or three dimensional printing, is a modern way to build objects with possibly a high degree of accuracy and favorable cost/benefit ratio. This approach is widely used by many manufacturing industries and a certain interest for this innovative production technology is also growing in the ship design and production field. To this regard, the experimental activity at the model scale is often necessary for the ship performance assessment in the design phase. In the article, preliminary results of a propeller model for the cavitation tunnel, built with additive technology, are presented, showing the strengths and weaknesses of the printed model. Moreover, as an introductive overview, different AM technologies are briefly described, with the aim to point out potential applicability to ships. Additive Manufacturing (AM), also known as 3D printing, is a well-known process to shape objects by layering materials under numerical control until the completion of the work. It represents an innovative approach because it is based on the addition of material instead of carving material from a block (like CNC—Computer Numerical Control, i.e. a manufacturing approach relying on mills, drills, and other numerically controlled tools). AM is deemed as an outstanding flywheel for innovation in the productive world, and the shipbuilding industry seems to have started realizing the advantages of this technology, already largely used, e.g., in the automotive, aerospace, biomedical, and energy industries (Shahi 2016; Satish Prakasha et al. 2018). In this perspective, an introductive overview of different AM typologies is presented in the article, to possibly understand how it could be used to improve ship design and production. The overview includes the applicable technologies, focusing on the printing process, the materials, and the mechanical properties of the final printed object. A practical example of AM technology application is presented regarding the printing of the blades of a ship's propeller model for experiments in a cavitation tunnel.
增材制造(AM)，或三维打印，是一种现代的方式来建立物体可能具有高度的精度和有利的成本/效益比。这种方法被许多制造行业广泛使用，并且在船舶设计和生产领域对这种创新生产技术的一定兴趣也在增长。为此，在设计阶段进行船舶性能评估，往往需要模型尺度的实验活动。本文介绍了用增材制造技术建立的空化隧道螺旋桨模型的初步结果，并指出了打印模型的优缺点。此外，作为介绍性概述，简要描述了不同的AM技术，目的是指出对船舶的潜在适用性。增材制造(AM)，也称为3D打印，是一种在数控下通过分层材料来塑造物体直到完成工作的众所周知的过程。它代表了一种创新的方法，因为它是基于添加材料而不是从块中雕刻材料(如cnc -计算机数控，即依靠铣床，钻头和其他数控工具的制造方法)。增材制造被认为是生产领域创新的杰出飞轮，造船业似乎已经开始意识到这项技术的优势，已经在汽车、航空航天、生物医学和能源行业得到了广泛应用(Shahi 2016;Satish Prakasha et al. 2018)。从这个角度来看，文章中提出了不同AM类型的介绍性概述，以可能理解如何使用它来改进船舶设计和生产。概述包括适用的技术，重点是打印过程，材料和最终打印对象的机械性能。介绍了利用增材制造技术在空化隧道中打印船舶螺旋桨实验模型叶片的实例。
{"title":"Additive Manufacturing Application to a Ship Propeller Model for Experimental Activity in the Cavitation Tunnel","authors":"T. Cilia, D. Bertetta, P. Gualeni, G. Tani, M. Viviani","doi":"10.5957/JSPD.11170055","DOIUrl":"https://doi.org/10.5957/JSPD.11170055","url":null,"abstract":"Additive manufacturing (AM), or three dimensional printing, is a modern way to build objects with possibly a high degree of accuracy and favorable cost/benefit ratio. This approach is widely used by many manufacturing industries and a certain interest for this innovative production technology is also growing in the ship design and production field. To this regard, the experimental activity at the model scale is often necessary for the ship performance assessment in the design phase. In the article, preliminary results of a propeller model for the cavitation tunnel, built with additive technology, are presented, showing the strengths and weaknesses of the printed model. Moreover, as an introductive overview, different AM technologies are briefly described, with the aim to point out potential applicability to ships.\u0000 \u0000 \u0000 Additive Manufacturing (AM), also known as 3D printing, is a well-known process to shape objects by layering materials under numerical control until the completion of the work. It represents an innovative approach because it is based on the addition of material instead of carving material from a block (like CNC—Computer Numerical Control, i.e. a manufacturing approach relying on mills, drills, and other numerically controlled tools). AM is deemed as an outstanding flywheel for innovation in the productive world, and the shipbuilding industry seems to have started realizing the advantages of this technology, already largely used, e.g., in the automotive, aerospace, biomedical, and energy industries (Shahi 2016; Satish Prakasha et al. 2018).\u0000 In this perspective, an introductive overview of different AM typologies is presented in the article, to possibly understand how it could be used to improve ship design and production. The overview includes the applicable technologies, focusing on the printing process, the materials, and the mechanical properties of the final printed object. A practical example of AM technology application is presented regarding the printing of the blades of a ship's propeller model for experiments in a cavitation tunnel.\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46081043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A mock-up of an offshore structure was prepared by multi-pass welding of several components with different thicknesses, different materials, different grooves, and ultra-long welding lengths. It may be very time consuming to obtain the stress distribution of the mock-up with conventional thermal elastic-plastic (TEP) computational methods. An efficient computation method, i.e. the model separation and stress assembly method, was proposed in the present study to obtain the stress distribution of the mock-up within an acceptable time. The full finite element (FE) model with solid elements was first created and separated into two independent parts, and the stress distribution in each part was obtained by using the TEP FE method. Finally, the full stress distribution in the mock-up was obtained by assembling the stress distributions from each part. The computed results show that the predicted stresses of the mock-up agree with the measured data obtained by using the hole-drilling method and x-ray diffraction method. Therefore, the proposed efficient method for stress simulation in large and complex structures can guarantee the simulation accuracy within an acceptable computation time on a common computer workstation. Because of the intense concentration of heating during fusion welding, the welding seam and its vicinity undergo rapid heating and cooling, generating residual stress in the joint. Welding residual stress can be detrimental to the structure's performance because of fatigue, creep, and plastic collapse (Withers 2007). In addition, it can induce stress corrosion cracking (Dong et al. 1997). Therefore, investigation of welding residual stress distribution is very important to facilitate the structure design and life evaluation of welded structures. The experimental measurement of residual stress has practical limitations. For large and complex structures such as offshore components, it is impossible to obtain the full residual stress distribution from experiments. The finite element (FE) numerical simulation of the welding process can measure the full stress distribution during the welding process with the advantages of being economical, nondestructive, and repeatabile. Therefore, it has been widely applied in many industrial fields to investigate the mechanisms of welding processes, stress and distortion characteristics, and the service life of welded structures (Lindgren 2006).
{"title":"Efficient Computation on Prediction of Welding Residual Stress of a Large and Complex Offshore Structure","authors":"Hongquan Zhao, Jiawei Yang, J. Zou, Chuan Liu","doi":"10.5957/JSPD.04180012","DOIUrl":"https://doi.org/10.5957/JSPD.04180012","url":null,"abstract":"A mock-up of an offshore structure was prepared by multi-pass welding of several components with different thicknesses, different materials, different grooves, and ultra-long welding lengths. It may be very time consuming to obtain the stress distribution of the mock-up with conventional thermal elastic-plastic (TEP) computational methods. An efficient computation method, i.e. the model separation and stress assembly method, was proposed in the present study to obtain the stress distribution of the mock-up within an acceptable time. The full finite element (FE) model with solid elements was first created and separated into two independent parts, and the stress distribution in each part was obtained by using the TEP FE method. Finally, the full stress distribution in the mock-up was obtained by assembling the stress distributions from each part. The computed results show that the predicted stresses of the mock-up agree with the measured data obtained by using the hole-drilling method and x-ray diffraction method. Therefore, the proposed efficient method for stress simulation in large and complex structures can guarantee the simulation accuracy within an acceptable computation time on a common computer workstation.\u0000 \u0000 \u0000 Because of the intense concentration of heating during fusion welding, the welding seam and its vicinity undergo rapid heating and cooling, generating residual stress in the joint. Welding residual stress can be detrimental to the structure's performance because of fatigue, creep, and plastic collapse (Withers 2007). In addition, it can induce stress corrosion cracking (Dong et al. 1997). Therefore, investigation of welding residual stress distribution is very important to facilitate the structure design and life evaluation of welded structures.\u0000 The experimental measurement of residual stress has practical limitations. For large and complex structures such as offshore components, it is impossible to obtain the full residual stress distribution from experiments. The finite element (FE) numerical simulation of the welding process can measure the full stress distribution during the welding process with the advantages of being economical, nondestructive, and repeatabile. Therefore, it has been widely applied in many industrial fields to investigate the mechanisms of welding processes, stress and distortion characteristics, and the service life of welded structures (Lindgren 2006).\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":"1 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41362625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article proposes a variation simulation and diagnosis model for ship block assembly processes considering the effects of welding distortion. The welding process and the deformation pattern affecting the final shape of a block assembly are diagnosed. Prior studies on welding distortion mainly focused on mitigation methodologies. In this research, welding distortion is regarded as the main cause of geometric variation in parts. In addition, how geometric variations are accumulated throughout multiple assembly processes is mathematically modeled. The variation simulation model is based on a state space equation, where variations of previous stages are propagated to the current stage. The diagnosis model predicts the quantitative effect of each variation source on the final assembly's geometrical variation, based on a normal equation and designated component analysis. The proposed model is simulated with FEM (Dassault Systèmes Americas Corp., Waltham, MA) and MATLAB (Mathworks (https://www.mathworks.com/), Massachusetts, United States) replicating a realistic block assembly process for validation. The model can effectively simulate the propagation of welding distortion and quantitatively diagnose variation patterns and welding processes. Analysis, management, and variation diagnostics are some of the important aspects of the production process. These have been mainly studied in mass production processes such as in the automobile industry. Mantripragada and Whitney (1999) and Whitney (2004) proposed a tolerance analysis method for the multistage rigid body assembly using a state space equation. Huang et al. (2006a, 2007) proposed a ship block tolerance model for the single and multiple stage variation propagation of a rigid body model. Liu and Hu (1995,1997) proposed a compliant assembly model using FEM, called the method of influence coefficients (MIC). Govik et al. (2012) proved MIC using an FEM simulation. Variation propagation in a multiple stage process while considering a compliant assembly has been proposed by Camelio et al. (2003, 2002a). Variation propagation models considering the location of data such as in key control characteristics, key product characteristics, and a local coordinate system of parts were proposed by Qu et al. (2016).
{"title":"Variation Simulation and Diagnosis Model of Compliant Block Assembly Considering Welding Deformation","authors":"Junghyun Lee, W. Choi, Min Seok Kang, Hyun Chung","doi":"10.5957/JSPD.02170004","DOIUrl":"https://doi.org/10.5957/JSPD.02170004","url":null,"abstract":"This article proposes a variation simulation and diagnosis model for ship block assembly processes considering the effects of welding distortion. The welding process and the deformation pattern affecting the final shape of a block assembly are diagnosed. Prior studies on welding distortion mainly focused on mitigation methodologies. In this research, welding distortion is regarded as the main cause of geometric variation in parts. In addition, how geometric variations are accumulated throughout multiple assembly processes is mathematically modeled. The variation simulation model is based on a state space equation, where variations of previous stages are propagated to the current stage. The diagnosis model predicts the quantitative effect of each variation source on the final assembly's geometrical variation, based on a normal equation and designated component analysis. The proposed model is simulated with FEM (Dassault Systèmes Americas Corp., Waltham, MA) and MATLAB (Mathworks (https://www.mathworks.com/), Massachusetts, United States) replicating a realistic block assembly process for validation. The model can effectively simulate the propagation of welding distortion and quantitatively diagnose variation patterns and welding processes.\u0000 \u0000 \u0000 Analysis, management, and variation diagnostics are some of the important aspects of the production process. These have been mainly studied in mass production processes such as in the automobile industry. Mantripragada and Whitney (1999) and Whitney (2004) proposed a tolerance analysis method for the multistage rigid body assembly using a state space equation. Huang et al. (2006a, 2007) proposed a ship block tolerance model for the single and multiple stage variation propagation of a rigid body model. Liu and Hu (1995,1997) proposed a compliant assembly model using FEM, called the method of influence coefficients (MIC). Govik et al. (2012) proved MIC using an FEM simulation. Variation propagation in a multiple stage process while considering a compliant assembly has been proposed by Camelio et al. (2003, 2002a). Variation propagation models considering the location of data such as in key control characteristics, key product characteristics, and a local coordinate system of parts were proposed by Qu et al. (2016).\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49362656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhi-Qiang Feng, Ziquan Jiao, Shanben Chen, Junfeng Han, X. Han, R. Yang, Cun-Gen Liu
In shipbuilding, forming plate by line heating is atypical complex manufacturing process involving many uncertain factors, so it is difficult to establish an accurate mathematical model. How to establish a knowledge model that can reflect technological laws is the key to the development of an intelligent decision system for forming plate by line heating. In this article, rough set (RS) theory is applied to the modeling of the line heating process. By defining variable-inclusion RSs, an algorithm of knowledge reduction is proposed, which enhances the noise immunity and fault tolerance of the model, and improves the efficiency of knowledge acquisition. Through introducing fuzzy logic, a method of modeling the line heating process based on RSs and fuzzy logic is proposed, which effectively extracts the technological rules of plate formation. Finally, rapid decision-making for process parameters is implemented by fuzzy inference technology. For some complex manufacturing technologies in modern shipbuilding, such as line heating and welding processes, it is difficult to establish an exact mathematical model because of high nonlinearity, multivariable coupling, and uncertainties of the system. With the development of computer technology and artificial intelligence, soft computing methods such as artificial neural networks, genetic algorithms, fuzzy logic, and rough set (RS) theory have been applied successively in ship manufacturing process modeling, which shows good prospects for intelligent technology in shipbuilding. Shin et al. (1999) at Seoul National University used a single-curvature plate model to simulate the formation of saddle-type shells and deduce the technological parameters of line heating by an artificial neural network. They also proposed a comprehensive algorithm for automatically curving plate by line heating, and further developed an application system that can simulate the deformation of double-curved plates (Shin et al. 2004a, 2004b). Liu et al. (2006) applied a hierarchical genetic algorithm to optimize the technological parameters of an automatic line heating process. In the field of ship welding, fuzzy logic technology has been used to establish a fuzzy model of the relationship between welding variables and weld forming-parameters (Su 2009). Feng (2012) set up a knowledge base of a ship-welding process by a RS method and then implemented ship-welding production design through uncertainty reasoning. Based on RS theory, Chen and Lv (2013) developed a data-driven knowledge base for quality control of ship hull welding.
{"title":"On Rough Set-Based Modeling and with Application to Process Decision for Forming Plate by Line Heating","authors":"Zhi-Qiang Feng, Ziquan Jiao, Shanben Chen, Junfeng Han, X. Han, R. Yang, Cun-Gen Liu","doi":"10.5957/JSPD.09170044","DOIUrl":"https://doi.org/10.5957/JSPD.09170044","url":null,"abstract":"In shipbuilding, forming plate by line heating is atypical complex manufacturing process involving many uncertain factors, so it is difficult to establish an accurate mathematical model. How to establish a knowledge model that can reflect technological laws is the key to the development of an intelligent decision system for forming plate by line heating. In this article, rough set (RS) theory is applied to the modeling of the line heating process. By defining variable-inclusion RSs, an algorithm of knowledge reduction is proposed, which enhances the noise immunity and fault tolerance of the model, and improves the efficiency of knowledge acquisition. Through introducing fuzzy logic, a method of modeling the line heating process based on RSs and fuzzy logic is proposed, which effectively extracts the technological rules of plate formation. Finally, rapid decision-making for process parameters is implemented by fuzzy inference technology.\u0000 \u0000 \u0000 For some complex manufacturing technologies in modern shipbuilding, such as line heating and welding processes, it is difficult to establish an exact mathematical model because of high nonlinearity, multivariable coupling, and uncertainties of the system. With the development of computer technology and artificial intelligence, soft computing methods such as artificial neural networks, genetic algorithms, fuzzy logic, and rough set (RS) theory have been applied successively in ship manufacturing process modeling, which shows good prospects for intelligent technology in shipbuilding. Shin et al. (1999) at Seoul National University used a single-curvature plate model to simulate the formation of saddle-type shells and deduce the technological parameters of line heating by an artificial neural network. They also proposed a comprehensive algorithm for automatically curving plate by line heating, and further developed an application system that can simulate the deformation of double-curved plates (Shin et al. 2004a, 2004b). Liu et al. (2006) applied a hierarchical genetic algorithm to optimize the technological parameters of an automatic line heating process. In the field of ship welding, fuzzy logic technology has been used to establish a fuzzy model of the relationship between welding variables and weld forming-parameters (Su 2009). Feng (2012) set up a knowledge base of a ship-welding process by a RS method and then implemented ship-welding production design through uncertainty reasoning. Based on RS theory, Chen and Lv (2013) developed a data-driven knowledge base for quality control of ship hull welding.\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41587969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu-ping Yang, T. Huang, Harry J. Rucker, C. R. Fisher, Wei Zhang, Michael D. Harbison, S. Scholler, Jennifer K. Semple, R. Dull
Weld residual stress plays an important role in the production and operating performance of ship structures. Various factors such as background noise, vibration, movement during ship construction, a layer of primer on the plate surface, and a layer of paint after ship construction bring challenges to measure weld residual stress in a shipyard. Three large test panels made of DH-36, High-strength low-alloy steel (HSLA), HSLA-65, and HSLA-80 steels were fabricated to examine the feasibility of using commercially available portable x-ray diffraction (XRD) equipment to measure residual stress in a shipyard environment. The measured results show that portable XRD equipment provided reliable measurements, with the shipyard environment effects, on the panels made of DH-36 and HSLA-65. On the other hand, the primer affected the accuracy of measured residual stress on the panel made of HSLA-80, but electropolishing could have been used to remove the primer to achieve a good measurement. Welding is one of the most important manufacturing processes in shipbuilding and inevitably induces residual stress and distortion on ship structures. In addition, flame straightening, often used to remove distortion in the final stage of shipbuilding, can result in even higher residual stress because of higher constraints after ship structures are assembled. It is well known that residual stress affects the buckling strength, fatigue performance, corrosion resistance, and dimensional stability of ship structures. As shipbuilding has been increasingly using thinner and higher strength materials such as HSLA-80 and HSLA-100 to reduce weight and increase mobility, residual stress plays an even more important role in the operating performance of ship structures. Understanding the residual stress evolution from raw material to a completed ship during service is critical to improve the ship's performance. Multiple methods have been developed to measure residual stress which can be classified into three categories: nondestructive techniques, semidestructive techniques, and destructive techniques. The common nondestructive techniques include x-ray diffraction (XRD) (Gou et al. 2015), neutron diffraction (Kartal et al. 2006; Palkowski et al. 2013), magnetic method, ultrasonic methods (Bray & Junghans 1995), and impact-indentation method (Lin et al. 2005; Choi et al. 2010; Zhu et al. 2015). The semidestructive techniques include holedrilling and ring-core methods, and the destructive techniques include block removal, splitting, layering, and contour methods (Tebedge et al. 1973; Leggatt et al. 1996). The U.S. Nuclear Regulatory Commission and the Electric Power Research Institute organized an international round robin program to measure weld residual stress in pressurized water reactor primary cooling loop components containing dissimilar metal welds (Fredette et al. 2011; Rathbun et al. 2011). Neutron diffraction, deep-hole drilling, XRD, surface-hole drilling, ring-core met
焊接残余应力对船舶结构的生产和使用性能有着重要的影响。背景噪声、振动、船舶建造过程中的运动、钢板表面的一层底漆、船舶建造后的一层油漆等各种因素给船厂焊接残余应力的测量带来了挑战。制作了三个由DH-36、高强度低合金钢(HSLA)、HSLA-65和HSLA-80钢制成的大型测试板，以检验使用市售便携式x射线衍射(XRD)设备测量造船厂环境中残余应力的可行性。结果表明，便携式x射线衍射仪对DH-36和HSLA-65板材在船厂环境影响下的测量结果可靠。另一方面，底漆影响了HSLA-80面板上测量残余应力的准确性，但可以使用电抛光去除底漆以获得良好的测量结果。焊接是船舶制造中最重要的工艺之一，不可避免地会对船舶结构产生残余应力和变形。此外，通常用于造船最后阶段消除变形的火焰矫直，由于船舶结构组装后受到更高的约束，可能导致更高的残余应力。众所周知，残余应力影响着船舶结构的屈曲强度、疲劳性能、耐腐蚀性和尺寸稳定性。随着造船行业越来越多地采用HSLA-80、HSLA-100等更薄、更高强度的材料来减轻重量和提高流动性，残余应力对船舶结构的使用性能的影响也越来越大。了解船舶在服役期间从原材料到成品的残余应力演变对提高船舶性能至关重要。测量残余应力的方法多种多样，可分为三大类:非破坏性技术、半破坏性技术和破坏性技术。常用的无损技术包括x射线衍射(XRD) (Gou et al. 2015)、中子衍射(Kartal et al. 2006;Palkowski et al. 2013)、磁法、超声法(Bray & Junghans 1995)和冲击压痕法(Lin et al. 2005;Choi et al. 2010;Zhu et al. 2015)。半破坏性技术包括钻孔和环芯法，破坏性技术包括块体移除、分裂、分层和等高线法(Tebedge et al. 1973;Leggatt et al. 1996)。美国核管理委员会和电力研究所组织了一项国际循环计划，以测量含有不同金属焊缝的压水堆主冷却回路组件的焊缝残余应力(Fredette etal . 2011;Rathbun et al. 2011)。采用中子衍射法、深孔钻孔法、XRD法、面孔钻孔法、环芯法、等高线法等方法测量了该程序的残余应力。对不同测量技术之间的测量结果进行了比较和验证。此外，2012年3月至2013年12月，在欧洲进行了一项循环研究，以研究XRD方法的准确性(GKN & DAkkS 2014)。三十个实验室和公司测定了两个参考样品表面的残余应力。对所有结果进行统计评价，发现XRD方法具有良好的测量精度。鲁棒均值在4.7 ~ 6.3 MPa之间，鲁棒偏差在3.1 ~ 4.0 MPa之间。这些研究极大地改进了残余应力测量技术。
{"title":"Weld Residual Stress Measurement Using Portable XRD Equipment in a Shipyard Environment","authors":"Yu-ping Yang, T. Huang, Harry J. Rucker, C. R. Fisher, Wei Zhang, Michael D. Harbison, S. Scholler, Jennifer K. Semple, R. Dull","doi":"10.5957/JSPD.170056","DOIUrl":"https://doi.org/10.5957/JSPD.170056","url":null,"abstract":"Weld residual stress plays an important role in the production and operating performance of ship structures. Various factors such as background noise, vibration, movement during ship construction, a layer of primer on the plate surface, and a layer of paint after ship construction bring challenges to measure weld residual stress in a shipyard. Three large test panels made of DH-36, High-strength low-alloy steel (HSLA), HSLA-65, and HSLA-80 steels were fabricated to examine the feasibility of using commercially available portable x-ray diffraction (XRD) equipment to measure residual stress in a shipyard environment. The measured results show that portable XRD equipment provided reliable measurements, with the shipyard environment effects, on the panels made of DH-36 and HSLA-65. On the other hand, the primer affected the accuracy of measured residual stress on the panel made of HSLA-80, but electropolishing could have been used to remove the primer to achieve a good measurement.\u0000 \u0000 \u0000 Welding is one of the most important manufacturing processes in shipbuilding and inevitably induces residual stress and distortion on ship structures. In addition, flame straightening, often used to remove distortion in the final stage of shipbuilding, can result in even higher residual stress because of higher constraints after ship structures are assembled. It is well known that residual stress affects the buckling strength, fatigue performance, corrosion resistance, and dimensional stability of ship structures. As shipbuilding has been increasingly using thinner and higher strength materials such as HSLA-80 and HSLA-100 to reduce weight and increase mobility, residual stress plays an even more important role in the operating performance of ship structures. Understanding the residual stress evolution from raw material to a completed ship during service is critical to improve the ship's performance.\u0000 Multiple methods have been developed to measure residual stress which can be classified into three categories: nondestructive techniques, semidestructive techniques, and destructive techniques. The common nondestructive techniques include x-ray diffraction (XRD) (Gou et al. 2015), neutron diffraction (Kartal et al. 2006; Palkowski et al. 2013), magnetic method, ultrasonic methods (Bray & Junghans 1995), and impact-indentation method (Lin et al. 2005; Choi et al. 2010; Zhu et al. 2015). The semidestructive techniques include holedrilling and ring-core methods, and the destructive techniques include block removal, splitting, layering, and contour methods (Tebedge et al. 1973; Leggatt et al. 1996). The U.S. Nuclear Regulatory Commission and the Electric Power Research Institute organized an international round robin program to measure weld residual stress in pressurized water reactor primary cooling loop components containing dissimilar metal welds (Fredette et al. 2011; Rathbun et al. 2011). Neutron diffraction, deep-hole drilling, XRD, surface-hole drilling, ring-core met","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42530361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. R. Fisher, Lori L. Denault, S. Rhodes, Jonathan T. Finley, Y. Gooroochurn
For the U.S. Navy, the use of computational simulations is prevalent for structural finite-element analysis but not for shop floor fabrication during construction. However, prevention and mitigation of welding-induced deformation creates a significant manufacturing challenge during fabrication of major ship assemblies, especially for thin-plate steel construction. The objective of this project was to improve weld sequence planning (WSP) capabilities for major ship assemblies through the development of a quick and user-friendly WSP software tool. An approximately 5× reduction in analysis time (from model setup through solve time) was realized through process automation, development of a weld joint database, and two-step weld sequence optimization algorithms. Physical testing of tank-like structures validated the computational tool, which established high correlation between measured and predicted distortion results. Sequence optimization analysis for an eggcrate structure showed a 43% reduction in maximum distortion from the two-step optimization process within the WSP tool. The end goal of this program is improved confidence in, and use of, computational weld mechanics techniques to more cost-effectively serve the U.S. Navy enterprise. Within shipbuilding, the construction of major ship assemblies (e.g., foundation tanks, bulkheads, and deck plating) can result in significant welding-induced deformation, especially in thin-plate steel construction (Spraragen & Ettinger 1950). Prevention and mitigation of this distortion typically creates a significant manufacturing challenge to the fabrication shop floor in terms of impact to cost and schedule. In addition, the skilled trades do not typically have weld sequence and clamping plans for major structures, instead relying on trade knowledge (i.e., prior experience paired with trial and error) with limited documentation across successive (but corollary) builds. A more rigorous approach using computational weld mechanics (CWM) techniques would involve finite-element analysis (FEA) of the welded component. CWM techniques enable better documentation (possessing a digital component) and sequence optimization for distortion reduction. However, current FEA tools using a transient heat source model and an implicit solver require days, weeks, or even months to prepare the computational model, run the simulation, and analyze the results for major ship assemblies because of their size relative to the size of weld beads. This lengthy calculation time is not feasible for use in a shipyard environment. In addition, the users of the transient heat source FEA tools are typically highly trained, with PhD.-level experience in computational simulation, and are not typically found on the production floor of most shipyards.
{"title":"Computational Tool Development for Weld Sequence Planning in Major Assemblies","authors":"C. R. Fisher, Lori L. Denault, S. Rhodes, Jonathan T. Finley, Y. Gooroochurn","doi":"10.5957/JSPD.11170054","DOIUrl":"https://doi.org/10.5957/JSPD.11170054","url":null,"abstract":"For the U.S. Navy, the use of computational simulations is prevalent for structural finite-element analysis but not for shop floor fabrication during construction. However, prevention and mitigation of welding-induced deformation creates a significant manufacturing challenge during fabrication of major ship assemblies, especially for thin-plate steel construction. The objective of this project was to improve weld sequence planning (WSP) capabilities for major ship assemblies through the development of a quick and user-friendly WSP software tool. An approximately 5× reduction in analysis time (from model setup through solve time) was realized through process automation, development of a weld joint database, and two-step weld sequence optimization algorithms. Physical testing of tank-like structures validated the computational tool, which established high correlation between measured and predicted distortion results. Sequence optimization analysis for an eggcrate structure showed a 43% reduction in maximum distortion from the two-step optimization process within the WSP tool. The end goal of this program is improved confidence in, and use of, computational weld mechanics techniques to more cost-effectively serve the U.S. Navy enterprise.\u0000 \u0000 \u0000 Within shipbuilding, the construction of major ship assemblies (e.g., foundation tanks, bulkheads, and deck plating) can result in significant welding-induced deformation, especially in thin-plate steel construction (Spraragen & Ettinger 1950). Prevention and mitigation of this distortion typically creates a significant manufacturing challenge to the fabrication shop floor in terms of impact to cost and schedule. In addition, the skilled trades do not typically have weld sequence and clamping plans for major structures, instead relying on trade knowledge (i.e., prior experience paired with trial and error) with limited documentation across successive (but corollary) builds.\u0000 A more rigorous approach using computational weld mechanics (CWM) techniques would involve finite-element analysis (FEA) of the welded component. CWM techniques enable better documentation (possessing a digital component) and sequence optimization for distortion reduction. However, current FEA tools using a transient heat source model and an implicit solver require days, weeks, or even months to prepare the computational model, run the simulation, and analyze the results for major ship assemblies because of their size relative to the size of weld beads. This lengthy calculation time is not feasible for use in a shipyard environment. In addition, the users of the transient heat source FEA tools are typically highly trained, with PhD.-level experience in computational simulation, and are not typically found on the production floor of most shipyards.\u0000","PeriodicalId":48791,"journal":{"name":"Journal of Ship Production and Design","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42335068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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