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Finite Element Numerical Method for Nonlinear Interaction Response Analysis of Offshore Jacket Affected by Environment Marine Forces
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作者 Seyyed Mahmood Ghassemi Zadeh Reza Shojayee Baghdar Seyyed Mohammad Saleh Vaziri Kang Olia 《Open Journal of Marine Science》 2015年第4期422-442,共21页
In this paper a nonlinear response of a fixed offshore platform under the combined forces of waves, wind and sea currents is presented. Wave force acting on the elements is calculated using Morison equation. Hydrodyna... In this paper a nonlinear response of a fixed offshore platform under the combined forces of waves, wind and sea currents is presented. Wave force acting on the elements is calculated using Morison equation. Hydrodynamic loads on horizontal and vertical tubular members and the dynamic response of offshore fixed platform coupled with distribution of displacement, axial force, and bending moment along the base of the platform for regular and severe cases have been investigated. The structure must be able maintain production in a one-year wave return period condition and also to be able to continue with one hundred-year storm return period. The results of this study show that bending moment values with a one-year wave return period condition for the base platform and junction of platform to deck are 70 percent and 59 percent, respectively more than bending moment with a one-year wave return period. The direction of wave and wind hit has significant effects on the shift platform response, also nonlinear response is important for the safe design and operation of offshore structures. 展开更多
关键词 Fixed JACKET Platform Finite Element Method STOKES Wave Theory Nonlinear Response of Structure
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焊接结构学中的热–力耦合问题简析 被引量:5
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作者 王苹 刘永 +1 位作者 常荷茜 董平沙 《焊接学报》 EI CAS CSCD 北大核心 2019年第7期6-11,I0002,共7页
针对热加工制造中的热力耦合基础问题,借助基本力学理论,分别研究了一维刚性约束杆、二维平板及满足刚性约束的3-Bar模型在升降温过程中的应力应变演化规律.结果表明,3-Bar模型中加热条带的宽度即为焊接塑性区的宽度;焊接塑性区的纵向... 针对热加工制造中的热力耦合基础问题,借助基本力学理论,分别研究了一维刚性约束杆、二维平板及满足刚性约束的3-Bar模型在升降温过程中的应力应变演化规律.结果表明,3-Bar模型中加热条带的宽度即为焊接塑性区的宽度;焊接塑性区的纵向残余应力接近材料屈服强度;塑性区大小,塑性区尺寸及其所在位置为焊后变形控制及焊接接头设计关键所在,焊缝塑性区应尽可能接近并对称于结构中性轴分布,以避免产生附加变形;将加热温度峰值与加热宽度输入3-Bar模型,可预测火焰调修控制变形效果.火焰调修时自第二个热循环作用起,残余应力与塑性应变均无法发生改变,调修中反复加热同一区域为无用功. 展开更多
关键词 焊接残余应力 塑性区 3-Bar模型 火焰调修
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Emerging and Innovative Materials for Hydropower Engineering Applications:Turbines,Bearings,Sealing,Dams and Waterways,and Ocean Power 被引量:3
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作者 Emanuele Quaranta Peter Davies 《Engineering》 SCIE EI 2022年第1期148-158,共11页
The hydropower sector is currently experiencing several technological developments.New technologies and practices are emerging to make hydropower more flexible and more sustainable.Novel materials have also been recen... The hydropower sector is currently experiencing several technological developments.New technologies and practices are emerging to make hydropower more flexible and more sustainable.Novel materials have also been recently developed to increase performance,durability,and reliability;however,no systematic discussions can be found in the literature.Therefore,in this paper,novel materials for hydropower applications are presented,and their performance,advantages,and limitations are discussed.For example,composites can reduce the weight of steel equipment by 50%to 80%,polymers and superhydrophobic materials can reduce head losses by 4%to 20%,and novel bearing materials can reduce bearing wear by 6%.These improvements determine higher efficiencies,longer life span,waste reduction,and maintenance needs,although the initial cost of some materials is not yet competitive with respect to the costs of traditional materials.The novel materials are described here based on the following categories:novel materials for turbines,dams and waterways,bearings,seals,and ocean hydropower. 展开更多
关键词 Bearing Composite Dam HYDROPOWER Material Ocean SEAL TURBINE
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Preparation and Properties of Embeddable Ag/Ag Cl Gelling Reference Electrode for Rebars Corrosion Monitoring in Concrete 被引量:1
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作者 汤雁冰 王胜年 +1 位作者 陈龙 范志宏 《China Ocean Engineering》 SCIE EI CSCD 2015年第6期925-932,共8页
Reference electrodes are a key part for corrosion monitoring and measurement of rebars in concrete. A reference electrode that can be buried in concrete is fabricated by using Ag/Ag Cl electrode and methyl cellulose g... Reference electrodes are a key part for corrosion monitoring and measurement of rebars in concrete. A reference electrode that can be buried in concrete is fabricated by using Ag/Ag Cl electrode and methyl cellulose gelling electrolyte. The stability, repeatability and anti-polarization of the reference electrode are investigated; the influences of the inner electrolyte loss, exterior OH- contamination, and temperature on the potential of the reference electrode are also investigated in this paper. The results show that the reference electrode has good stability, repeatability, and antipolarization. The influences of inner electrolyte loss, exterior OH- contamination, and temperature on the potential of the reference electrode are minimal. Therefore, it can be used for corrosion monitoring and measurement of rebars in concrete. 展开更多
关键词 reference electrode methyl cellulose gelling electrolyte Ag/AgCl electrode corrosion monitoring rebarsconcrete
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Comparison of the Effect of Tetrapod Block and Armor X block on Reducing Wave Overtopping in Breakwaters 被引量:2
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作者 Omid Nourani Mehdi Behdarvandi Askar 《Open Journal of Marine Science》 2017年第4期472-484,共13页
As the Armor shape has a significant effect on the reduction of wave overtopping, this study compares the performance of various shapes of concrete armored blocks of X block and Tetrapod as the most suitable armors. I... As the Armor shape has a significant effect on the reduction of wave overtopping, this study compares the performance of various shapes of concrete armored blocks of X block and Tetrapod as the most suitable armors. In this study, a three-dimensional numerical model was used for simulation of the effects of waves on the armors of Tetrapod and X Block breakwaters. In this regard, in order to calibrate the numerical model, a sample of conventional stone armor has been selected and using available experimental data on the design of armor such as wave overtopping, wave height, period of waves and energy density of the required spectral range of wave verification was conducted on a numerical model. In this regard, it is necessary to calibrate all the conditions of the model including boundary conditions, numerical modeling, initial conditions, numerical solvers and other parameters in the numerical model and simulation error rate is determined. The maximum error of the numerical model for the relative height values of the impact waves on the structure of breakwater is 7.87% for different conditions. Accordingly, the maximum error of the numerical model in determining overtopping values is 7.81%. The average fluctuation value of overtopping in the X block armor has dropped by about 31% compared to the tetrapod armor. 展开更多
关键词 WAVE OVERTOPPING Numerical Model TETRAPOD X BLOCK Flow3D 10.1 WAVE Collision
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Investigation of Hydroelastic Ship Responses of An ULOC in Head Seas 被引量:1
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作者 汪雪良 Pandeli TEMAREL +1 位作者 胡嘉骏 顾学康 《China Ocean Engineering》 SCIE EI CSCD 2016年第5期687-702,共16页
Investigation of hydroelastic ship responses has been brought to the attention of the scientific and engineering world for several decades. There are two kinds of high-frequency vibrations in general ship responses to... Investigation of hydroelastic ship responses has been brought to the attention of the scientific and engineering world for several decades. There are two kinds of high-frequency vibrations in general ship responses to a large ocean-going ship in its shipping line, so-called springing and whipping, which are important for the determination of design wave load and fatigue damage as well. Because of the huge scale of an ultra large ore cartier (ULOC), it will suffer seldom slamming events in the ocean. The resonance vibration with high frequency is springing, which is caused by continuous wave excitation. In this paper, the wave-induced vibrations of the ULOC are addressed by experimental and numerical methods according to 2D and 3D hydroelasticity theories and an elastic model under full-load and ballast conditions. The influence of loading conditions on high-frequency vibration is studied both by numerical and experimental results. Wave-induced vibrations are higher under ballast condition including the wave frequency part, the multiple frequencies part, the 2-node and the 3-node vertical bending parts of the hydroelastic responses. The predicted results from the 2D method have less accuracy than the 3D method especially under ballast condition because of the slender-body assumption in the former method. The applicability of the 2D method and the further development of nonlinear effects to 3D method in the prediction of hydroelastic responses of the ULOC are discussed. 展开更多
关键词 hydroelastic ship response EXPERIMENT wave-induced vibration ultra large ore carrier
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Modeling of the Changes in Flow Velocity on Seawalls under Different Conditions Using FLOW-3D Software 被引量:5
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作者 Maryam Deilami-Tarifi Mehdi Behdarvandi-Askar +1 位作者 Vahid Chegini Sadegh Haghighi-Pour 《Open Journal of Marine Science》 2016年第2期317-322,共6页
Seawalls are among protective structures that are constructed for decreasing the level of wave force and/or protecting from other structures. In this regard, more accurate investigation of these structures takes great... Seawalls are among protective structures that are constructed for decreasing the level of wave force and/or protecting from other structures. In this regard, more accurate investigation of these structures takes great importance from different perspectives. This research investigates the change of the velocity on seawall crown by considering the obstacles in different layouts and slopes. FLOW-3D has been used in this research for modeling. The results of the modeling show that the existence of obstacles has a determinative role in decreasing flow rate in the crown of seawalls. Also, as it was expected, the slope factor on upstream seawalls is very determinative in decreasing this rate such that the lowest velocity on the wall occurs in D-state layout and the slope of 45°. 展开更多
关键词 Flow Velocity Seawall Crown MODELING FLOW-3D
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Analyzing Factors Affecting Erosion and Sedimentary Deposits Using the Empirical Method of PSIAC 被引量:1
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作者 Abdolreza Alijani Armita Alijani +1 位作者 Nader Kohansal Ghadimvand Mohsen Aleali 《Open Journal of Geology》 2017年第8期1078-1093,共16页
PSIAC empirical method is considered as one of the methods calculating and estimating the amount of erodibility and sedimentation of sedimentary deposits in sedimentary basins and dams’ reservoirs. This method is bas... PSIAC empirical method is considered as one of the methods calculating and estimating the amount of erodibility and sedimentation of sedimentary deposits in sedimentary basins and dams’ reservoirs. This method is based on analyzing nine influential factors including: surface geology, solid, weather, runoff, unpaved area, limited plant coverage, land usage, high lands erosion, river erosion and sediment transportation. These factors are rated according to their level of importance. The case study of this research is Lali Water Catchment, Khuzestan, Iran. The amount and intensity of adorability will be ranked as low, moderate and high. This research is based on field work, laboratorial studies and analyzing results obtained from statistics. Results indicated that the unpaved area and high land erosion are identified as the most effective factors, respectively. In contrast, runoff and surface geology are considered as the lowest rate. Other factors reflect moderate effects. Since any significant studies have not been done in this regard, the current research can present a new method to scrutinize the empirical effects of these factors. It is noteworthy to highlight that different methods are compared with each other in order to scrutinize the amount of erodibility in most studies, but the present study has analyzed the influential factors of the sub-methods of one major method. This essay focuses on the affectability of each one of the nine factors, independently. In conclusion, the outcomes of this research can contribute to identify and determine suitable alternatives to stabilize sedimentary basins and increase the life span of dams and watershed management projects and also reduce the destructive effects of floods. Additionally, it contributes civil projects in such lands. 展开更多
关键词 ERODIBILITY SEDIMENTATION PSIAC Empirical Method SEDIMENTARY BASINS Dams’ Reservoir
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船舶复合材料强度极限状态与设计方法方面的近来工业进展
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作者 Beatrice Barsotti Marco Gaiotti Cesare Mario Rizzo 《Journal of Marine Science and Application》 CSCD 2020年第4期553-566,共14页
To further exploit the potential of marine composites applications in building ship hulls,offshore structures,and marine equipment and components,design approaches should be improved,facing the challenge of a more com... To further exploit the potential of marine composites applications in building ship hulls,offshore structures,and marine equipment and components,design approaches should be improved,facing the challenge of a more comprehensive and explicit assessment of appropriately defined limit states.The structure ultimate/limit conditions shall be verified in principle within the whole structural domain and throughout the ship service life.What above calls for extended and reliable materials characterization on the one hand and for accurate and wide-ranging procedures in structural analyses.This paper presents an overview of recent industrial developments of marine composites limit states assessments and design approaches,as available in open literature,focusing on pleasure crafts and yachts as well as navy ships and thus showing a starting point to fill the gap in this respect.After a general introduction about composites characterization techniques,current design practice and rule requirements are briefly summarized.Both inter-ply and intra-ply failure modes and corresponding limit states are then presented along with recently proposed assessment approaches.Three-dimensional aspects in failure modes and manufacturing methods have been identified as the main factors influencing marine composite robustness.Literature review highlighted also fire resistance and hybrid joining techniques as significant issues in the use of marine composites. 展开更多
关键词 Marine composites Navy ships Pleasure crafts YACHTS FEM Material characterization Limit state design Ultimate strength
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Durability of Concrete with Different Improvement Measures and Its Ser-vice Life Prediction in Island and Reef Environment
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作者 GONG Wei YU Hong-fa +2 位作者 MA Hai-yan WANG Nan ZHU Hai-wei 《China Ocean Engineering》 SCIE EI CSCD 2022年第6期947-958,共12页
To solve the durability of island and reef concrete engineering in the harsh environment of high temperature,high salt,high humidity and windy,the strength grade of concrete and the type of corrosion inhibitor were us... To solve the durability of island and reef concrete engineering in the harsh environment of high temperature,high salt,high humidity and windy,the strength grade of concrete and the type of corrosion inhibitor were used as the influence factors,while the relative dynamic elastic modulus was used as the evaluation index.In addition,the law and time variability of the deterioration of concrete,the size effect,environmental similarity and the service life model were studied.The results showed that improving the strength grade of concrete could improve the durability of concrete,and corrosion inhibitor could slightly improve the durability of concrete.Time-varying law of the deterioration of concrete conformed to the univariate quadratic polynomial.Combined with the concrete damage equivalent theory,a size effect model based on the relative dynamic elastic modulus was proposed and verified,and the size effect coefficient was also given.An environmental similarity model between simulated and practical island and reef environment was proposed.Combined with the reliability theory and the first order second moment method,a new service life model of concrete structure was proposed.The authors were convinced that the research will be advantageous to researchers. 展开更多
关键词 island and reef environment relative dynamic elastic modulus size effect environmental similarity service life model
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Standardization of the Main Dimensions of Design Container Ships in Ports—A Case Study
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作者 Soheil Radfar Amir Taherkhani Roozbeh Panahi 《World Journal of Engineering and Technology》 2017年第4期51-61,共11页
Ports are crucial element in the export and import chains of each country. Therefore, sufficient and efficient designing of ports is of great importance to increase the safety of operations and to lower the constructi... Ports are crucial element in the export and import chains of each country. Therefore, sufficient and efficient designing of ports is of great importance to increase the safety of operations and to lower the construction costs. Their design procedure is iterative and specifications of the design ship are of the most important inputs in this regard. The design ship is characterized with its length (L), breadth (B), and draft (d). In this research a regression analysis has been carried out in the southern coasts of Iran (Persian Gulf) to obtain these specifications. The results have shown under- and over-estimations of the main dimensions. Hence, this supports the idea that it is worth performing individual regression analysis, especially in restricted waterways and in the regions with specific fleet for the sake of verification of recommended values by standard technical guidelines. 展开更多
关键词 Length BREADTH Draft DEAD WEIGHT TONNAGE TERMINAL
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Investigation of sediment transport pattern and beach morphology in the vicinity of submerged groyne (case study: Dahane Sar Sefidrood) 被引量:4
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作者 H. Afsoos BIRIA M. A. Lashteh NESHAEI +1 位作者 A. GHABRAEI M. A. MEHRDAD 《Frontiers of Structural and Civil Engineering》 CSCD 2015年第1期82-90,共9页
Marine structures, such as Groynes, Sea walls and Detached Breakwaters, are constructed in coast of area to improve coast stability against bed erosions due to changing wave and current pattern. Marine mechanisms and ... Marine structures, such as Groynes, Sea walls and Detached Breakwaters, are constructed in coast of area to improve coast stability against bed erosions due to changing wave and current pattern. Marine mechanisms and interaction with the hydraulic structures need to be intensively studied. Groynes are one of the most prominent structures that are used in shore protection and littoral sediment. The main hydraulic function of the groyne is to control the long shore current and littoral sediment transport. This structure can be submerged and provide the necessary beach protection without negative aesthetic impact. However, for submerged structures adopted for beach protection, the shoreline response to these structures is not well understood. The objective of this study is to predict sediment transport in the vicinity of submerged groyne and comparison with non-submerged groyne focusing on a part of the coast at Dahane Sar Sefidrood, Guilan Province, Iran, where serious coast erosion has been occurred. The simulations were designed using a one-line model which can be used as a first approximation of shoreline prediction in the vicinity of groyne. The results of the proposed model are compared with experimental data to determine the shape of the coast. The results of predicted beach deformation show that when submerged groyne construct in the beach, sediment accumulation will be slightly less than the non-submerged groyne; because transfer coefficient for the submerged groyne is more than non-submerged groyne. This result will cause more sediment passing on submerged groyne. Finally, the result of the present study show that using submerged groyne is an efficient way to control the sediment and beach erosion without causing severe environmental effect on the coast. 展开更多
关键词 submerged groyne non-submerged groyne beach morphology Dahane Sar Sefidrood sediment transport
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