Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_489
H. Gu, M. Kitamura
It is found that the accuracy of recovered stress at central area of bilinear quadrilateral element by previous SPR methods 1-3) is inferior. Sometimes, the recovered stress is even worse than the raw result of FEA at that area. This may be due to only recovering the nodal stresses and using them to interpolate the stress elsewhere. To overcome this, the recovery procedure is modified by considering additional nodes located at middle point of element edges and the central point of elements and introducing a weighted average procedure to determine the recovered result at some nodes. Numerical analysis of three examples demonstrates the capability of the new procedure to improve the accuracy of recovery at the central area, and the contribution of the weighted average procedure to the stability of recovery at boundary area.
{"title":"A Modified Recovery Procedure to Improve the Accuracy of Stress at Central Area of Bilinear Quadrilateral Element","authors":"H. Gu, M. Kitamura","doi":"10.2534/JJASNAOE1968.2000.188_489","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_489","url":null,"abstract":"It is found that the accuracy of recovered stress at central area of bilinear quadrilateral element by previous SPR methods 1-3) is inferior. Sometimes, the recovered stress is even worse than the raw result of FEA at that area. This may be due to only recovering the nodal stresses and using them to interpolate the stress elsewhere. To overcome this, the recovery procedure is modified by considering additional nodes located at middle point of element edges and the central point of elements and introducing a weighted average procedure to determine the recovered result at some nodes. Numerical analysis of three examples demonstrates the capability of the new procedure to improve the accuracy of recovery at the central area, and the contribution of the weighted average procedure to the stability of recovery at boundary area.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":" 736","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131978236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_311
K. Masuda, K. Sano, H. Maeda, C. Rheem, T. Ikoma
The objectives of present. paper are to develop the estimation method for the hydrodynamic forces on very large floating structures in the vicinity of a breakwater and to clarify the characteristics of elastic response on the very large floating structures (VLFS).In the present paper. the source distribution method was applied to prediction of by hydrodynamic forces on VLFS and the elastic responses of VLFS were computed by model analysis. From the results of numerical calculation, the effects of breakwater on the elastic response of VLFS and the characteristics of elastic responses on the phase two model of VLFS were made clear.
{"title":"Study on Characteristic of Hydroelastic Responses for Ver Large Floating Structure in the vicinity of a Breakwater","authors":"K. Masuda, K. Sano, H. Maeda, C. Rheem, T. Ikoma","doi":"10.2534/JJASNAOE1968.2000.188_311","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_311","url":null,"abstract":"The objectives of present. paper are to develop the estimation method for the hydrodynamic forces on very large floating structures in the vicinity of a breakwater and to clarify the characteristics of elastic response on the very large floating structures (VLFS).In the present paper. the source distribution method was applied to prediction of by hydrodynamic forces on VLFS and the elastic responses of VLFS were computed by model analysis. From the results of numerical calculation, the effects of breakwater on the elastic response of VLFS and the characteristics of elastic responses on the phase two model of VLFS were made clear.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122064273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_1
S. Rhee, T. Hino
Laminar and turbulent separated flows around a 6 : 1 prolate spheroid are investigated using an unstructured grid CFD method. The RANS equations are solved for incompressible viscous flows. The artificial compressibility is introduced in the continuity equation and cell-centered finite-volume method on unstructured grid is used for spatial discretization. The Spalart-Allmaras one-equation turbulence model is employed for the Reynolds stress. The computational results are compared with experimental data and the physics of three-dimensional turbulent flow separation is confirmed. A range of Reynolds numbers and angles of attack is considered and the effects are investigated. The modification of the Spalart-Allmaras model is added to improve the performance and examine the effects of turbulence model on the vortical flow structure.
{"title":"Computational Investigation of 3D Turbulent Flow Separation around a Spheroid using an Unstructured Grid Method","authors":"S. Rhee, T. Hino","doi":"10.2534/JJASNAOE1968.2000.188_1","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_1","url":null,"abstract":"Laminar and turbulent separated flows around a 6 : 1 prolate spheroid are investigated using an unstructured grid CFD method. The RANS equations are solved for incompressible viscous flows. The artificial compressibility is introduced in the continuity equation and cell-centered finite-volume method on unstructured grid is used for spatial discretization. The Spalart-Allmaras one-equation turbulence model is employed for the Reynolds stress. The computational results are compared with experimental data and the physics of three-dimensional turbulent flow separation is confirmed. A range of Reynolds numbers and angles of attack is considered and the effects are investigated. The modification of the Spalart-Allmaras model is added to improve the performance and examine the effects of turbulence model on the vortical flow structure.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125199554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_669
T. Niwa, M. Toyosada
In the previous paper, we developed a simulation model of fatigue crack opening and closing phenomena for predicting RPG load under an arbitrary stress distribution field. By using the simulation model, effects of stress ratio and residual stress distribution on fatigue crack propagation rate are quantitatively assessed. However, it became clear that the estimated fatigue life is longer than experimental one under decreased maximum load while keeping minimum load and a overload condition.In this paper, we considered the plastic shrinkage at an immediate generation of new crack surface for the purpose of solving the above problem and modified the above simulation model. And then, we carried out fatigue crack propagation analyses under various conditions and compared the estimated RPG loads and crack growth curves with the experimantal ones. As a result, it is confirmed that modified simulation model is appreciable to various amplitude fatigue loading tests.
{"title":"A Study on Plastic Shrinkage Coefficient of Crack Opening/Closing Model at a Crack Extension","authors":"T. Niwa, M. Toyosada","doi":"10.2534/JJASNAOE1968.2000.188_669","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_669","url":null,"abstract":"In the previous paper, we developed a simulation model of fatigue crack opening and closing phenomena for predicting RPG load under an arbitrary stress distribution field. By using the simulation model, effects of stress ratio and residual stress distribution on fatigue crack propagation rate are quantitatively assessed. However, it became clear that the estimated fatigue life is longer than experimental one under decreased maximum load while keeping minimum load and a overload condition.In this paper, we considered the plastic shrinkage at an immediate generation of new crack surface for the purpose of solving the above problem and modified the above simulation model. And then, we carried out fatigue crack propagation analyses under various conditions and compared the estimated RPG loads and crack growth curves with the experimantal ones. As a result, it is confirmed that modified simulation model is appreciable to various amplitude fatigue loading tests.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"132 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124252484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_135
R. Zhu, Kimio Saito
In this paper, the tank sloshing and the vibration of the internal structure in contact with the water are discussed by extending the Boundary Element Method (BEM). The BEM has been widely used to solve the nonlinear fluid motions in a tank as well as the potential flow past an obstacle. However, when a tank is fitted with the thin internal structure, the basic BEM will give a numerical error due to the thickness of the plate in the evaluation of the pressure acting on the internal structure. Nishino et al. solved this problem by introducing the Thin Plate Boundary Element Method (TPBEM) with some manipulation of the formula.The basic BEM, in this paper, is extended to the Multiple Domain Boundary Element Method (MDBEM) by dividing the whole fluid domain into several sub-domains. The computer program has been developed and applied to the sloshing of two-dimensional (2D) tank with internal structure and also to the vibration of the internal structure in a tank. Some of the computational results are compared with the ones in the published papers. It shows that they agree well each other and the present method is effective.
本文通过扩展边界元法(BEM)，讨论了水箱晃动和内部结构与水接触时的振动问题。边界元法已被广泛应用于求解槽内非线性流体运动和过障势流。然而，当储罐内部结构较薄时，在计算作用于内部结构的压力时，由于板的厚度，基本边界元法会产生数值误差。Nishino等人通过引入薄板边界元法(Thin Plate Boundary Element Method, TPBEM)并对公式进行一些修改，解决了这一问题。本文将基本边界元法扩展为多域边界元法(MDBEM)，将整个流体域划分为若干子域。开发了计算机程序，并将其应用于具有内部结构的二维水箱的晃动和水箱内部结构的振动。部分计算结果与已发表的论文进行了比较。结果表明，二者吻合良好，本方法是有效的。
{"title":"Multiple Domain Boundary Element Method Applied to Fluid Motions in a Tank with Internal Structure","authors":"R. Zhu, Kimio Saito","doi":"10.2534/JJASNAOE1968.2000.188_135","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_135","url":null,"abstract":"In this paper, the tank sloshing and the vibration of the internal structure in contact with the water are discussed by extending the Boundary Element Method (BEM). The BEM has been widely used to solve the nonlinear fluid motions in a tank as well as the potential flow past an obstacle. However, when a tank is fitted with the thin internal structure, the basic BEM will give a numerical error due to the thickness of the plate in the evaluation of the pressure acting on the internal structure. Nishino et al. solved this problem by introducing the Thin Plate Boundary Element Method (TPBEM) with some manipulation of the formula.The basic BEM, in this paper, is extended to the Multiple Domain Boundary Element Method (MDBEM) by dividing the whole fluid domain into several sub-domains. The computer program has been developed and applied to the sloshing of two-dimensional (2D) tank with internal structure and also to the vibration of the internal structure in a tank. Some of the computational results are compared with the ones in the published papers. It shows that they agree well each other and the present method is effective.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"76 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128367828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_191
K. Kijima, Y. Furukawa, T. Kishimoto
Marine disasters which cause serious environmental pollution occur frequently. Disabled ships due to marine disasters must be removed from the sea route as soon as possible. Generally disabled ships are towed by tugboats. Concerning the towing problems with tugtowed ships systems, some factors such as the length of the towing ropes, the location of the towing point and the condition of the disabled ships, etc. should be considered. However, these important factors have been left to the knowledge and the experience of towing operators up to the present time. In order to tow disabled ships safely, we need to develop the optimum method of towing systems from the viewpoint of navigational safety.As the first stage of this research, we carried out captive model tests to measure the hydrodynamic forces acting on disabled ships. For the conditions of the disabled ships, we considered the ship which has immersed bow due to large trim angle.Finally, applying the results of the captive model tests, we calculated the manoeuvring motions of tug and towed ships, then estimated the course stability in towing conditions.
{"title":"On the Towing System for Disabled Ships","authors":"K. Kijima, Y. Furukawa, T. Kishimoto","doi":"10.2534/JJASNAOE1968.2000.188_191","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_191","url":null,"abstract":"Marine disasters which cause serious environmental pollution occur frequently. Disabled ships due to marine disasters must be removed from the sea route as soon as possible. Generally disabled ships are towed by tugboats. Concerning the towing problems with tugtowed ships systems, some factors such as the length of the towing ropes, the location of the towing point and the condition of the disabled ships, etc. should be considered. However, these important factors have been left to the knowledge and the experience of towing operators up to the present time. In order to tow disabled ships safely, we need to develop the optimum method of towing systems from the viewpoint of navigational safety.As the first stage of this research, we carried out captive model tests to measure the hydrodynamic forces acting on disabled ships. For the conditions of the disabled ships, we considered the ship which has immersed bow due to large trim angle.Finally, applying the results of the captive model tests, we calculated the manoeuvring motions of tug and towed ships, then estimated the course stability in towing conditions.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114907935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_617
K. Matsuoka, I. Takahashi, S. Uematsu, M. Ushijima
{"title":"Effect of load history on fatigue life of welded joint","authors":"K. Matsuoka, I. Takahashi, S. Uematsu, M. Ushijima","doi":"10.2534/JJASNAOE1968.2000.188_617","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_617","url":null,"abstract":"","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"39 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130043431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_173
H. Masuda, A. Wada, M. Enomoto, H. Yamato, S. Shirayama
There is no doubt that a motorboat driver's motion during its turn has a large influence in its speed and stability. Nevertheless, this mechanism has not yet been solved. In this paper, we present a novel system to analyze three dimensional motion of a driver based upon three dimensional measurement with multiple CCD cameras. Using this system, we can calculate the centre of gravity and moment of inertia of a motorboat driver in its turn.
{"title":"Three Dimensional Measurement of a Motorboat Driver's Motion","authors":"H. Masuda, A. Wada, M. Enomoto, H. Yamato, S. Shirayama","doi":"10.2534/JJASNAOE1968.2000.188_173","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_173","url":null,"abstract":"There is no doubt that a motorboat driver's motion during its turn has a large influence in its speed and stability. Nevertheless, this mechanism has not yet been solved. In this paper, we present a novel system to analyze three dimensional motion of a driver based upon three dimensional measurement with multiple CCD cameras. Using this system, we can calculate the centre of gravity and moment of inertia of a motorboat driver in its turn.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117067972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_465
N. Fukuchi, T. Shinoda, Takahiro Ono
The man-machine systems on the marine safety, such as a ship navigation system, should be designed to consider the fact that the thinking faculty and operating ability of ship operators tend to be affected by their mental work-load under the pressure from navigation environment. For this purpose, it is desirable that the relation between stress degrees of operators and human errors during operating a man-machine systems is clarified by analyzing the state-transition gotten to a marine accident.This paper about this problem consists of (1) the analysis of state-transition by the stochastic process model based on Markov chains using the accident incident probability estimated by the fault tree analysis, and (2) the prediction of effectiveness to reduce the risk by taking countermeasures in specified functional system. As a practical example, the stochastic state-transition analyses and the suitable measures for preventing from “the ship collision” are investigated using the proposed method.
{"title":"A Stochastic State-transition and Safety Assessment for Marine Accidents Based on Human Factors","authors":"N. Fukuchi, T. Shinoda, Takahiro Ono","doi":"10.2534/JJASNAOE1968.2000.188_465","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_465","url":null,"abstract":"The man-machine systems on the marine safety, such as a ship navigation system, should be designed to consider the fact that the thinking faculty and operating ability of ship operators tend to be affected by their mental work-load under the pressure from navigation environment. For this purpose, it is desirable that the relation between stress degrees of operators and human errors during operating a man-machine systems is clarified by analyzing the state-transition gotten to a marine accident.This paper about this problem consists of (1) the analysis of state-transition by the stochastic process model based on Markov chains using the accident incident probability estimated by the fault tree analysis, and (2) the prediction of effectiveness to reduce the risk by taking countermeasures in specified functional system. As a practical example, the stochastic state-transition analyses and the suitable measures for preventing from “the ship collision” are investigated using the proposed method.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127269028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2000-12-01DOI: 10.2534/JJASNAOE1968.2000.188_479
M. Fujikubo, P. Kaeding
An ISUM rectangular plate element with new shape functions for its lateral deflection under longitudinal/transverse thrust has been developed in the 1st Report. In this report, the ISUM plate element is combined with beam-column elements to model stiffened plates, and its applicability is extended to biaxial thrust. The fundamental collapse behaviour of stiffened plates is investigated by FEM analyses. The ISUM approach is formulated considering the collapse characteristics. A new modelling technique to evaluate overall buckling of stiffeners with attached plating as well as local plate buckling is proposed. Results for longitudinal and biaxial thrust show the applicability and accuracy of this approach.
{"title":"ISUM Rectangular Plate Element with New Lateral Shape Functions (2nd Report) - Stiffened Plates under Biaxial Thrust -","authors":"M. Fujikubo, P. Kaeding","doi":"10.2534/JJASNAOE1968.2000.188_479","DOIUrl":"https://doi.org/10.2534/JJASNAOE1968.2000.188_479","url":null,"abstract":"An ISUM rectangular plate element with new shape functions for its lateral deflection under longitudinal/transverse thrust has been developed in the 1st Report. In this report, the ISUM plate element is combined with beam-column elements to model stiffened plates, and its applicability is extended to biaxial thrust. The fundamental collapse behaviour of stiffened plates is investigated by FEM analyses. The ISUM approach is formulated considering the collapse characteristics. A new modelling technique to evaluate overall buckling of stiffeners with attached plating as well as local plate buckling is proposed. Results for longitudinal and biaxial thrust show the applicability and accuracy of this approach.","PeriodicalId":321056,"journal":{"name":"Journal of the Society of Naval Architects of Japan","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133788470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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