共查询到19条相似文献,搜索用时 171 毫秒
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文中以某气浮结构平台为研究对象,基于三维势流理论通过MOSES对气浮体和实浮体在相同波浪下的响应、不同吃水下、不同水深下的下气浮结构的水动力系数进行了研究分析.分析结果表明:气浮体和实浮体在相同波浪条件下的响应是不同的,气浮体垂荡响应大于实浮体,而气浮体的摇摆响应和横荡响应要小于实浮体,气浮体内部气体具有减摇的作用;在相同的扰动波浪周期下,随着水深的增加,气浮体的水动力系数呈下降趋势;在相同的扰动波浪周期下,随着吃水的增加,垂荡的水动力系数呈下降的趋势,而横荡的水动力系数呈上升的趋势,对于纵摇的水动力系数影响不大. 相似文献
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基于理论公式和有限元方法,研究附连水对设备基座机械输入阻抗的影响。根据船体结构在不同的频段内的特性,采用两种简化模型重点研究低频段和中频段里基座的输入阻抗特性。结果显示,当激励频率很低时,船体外附连水对基座机械输入阻抗影响很大,附连水质量越大输入阻抗越大;随着频率的升高,附连水对输入阻抗的影响逐渐变小。 相似文献
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旋转壳体的干,湿模态研究 总被引:1,自引:0,他引:1
何韫如 《华东船舶工业学院学报》1996,10(3):1-7
本文用振动试验建模的方法来探索旋转壳体的干、湿模态参数及其非线性振动特性。还分析了附连水质量与水域大小的关系以及附连水质量对振动特性变化的影响。 相似文献
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应用奇点法计算流体对结构振动的影响以及关于附连水质量的相似关系 总被引:2,自引:0,他引:2
本文把流体力学奇点法与结构有限元法相结合,计算流体对结构振动的影响。这种方法用结构浸水面上的边界元代替流体所占空间内的流体元,可以大大节省计算机容量和减少计算机时。本文还分析了附连水质量计算中的相似关系。文中得出的这些关系使得有可能应用奇点法和有限元法的计算结果为一些较复杂形状的结构得出简便而实用的附连水质量计算公式。文中给出了应用作者所编计算机程序计算附连水质量和水中结构固有振动频率的实际例子——不同浸水情况下的平板、带弹性防挠材的板、实船底部板格以及船舶艉部立体舱段。计算结果与试验结果进行了比较,二者基本符合。 相似文献
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Hideyuki Suzuki Koichiro Yoshida Kazuhiro Iijima 《Journal of Marine Science and Technology》1996,1(5):255-267
The land area of Japan, especially flat land, is very small compared with its economic size. Large-scale floating structures
are one solution to satisfy the demand for space by utilizing the ocean. This paper presents a general view of the dynamic
response characteristics of large-scale floating structures, pontoons and semi-submersibles. For example, it is shown that
the natural frequencies of eigenmodes are higher than the natural frequency of heaving motion. The response of the outer framework
of a structure is shown to be generally larger than the response of the central part. Within the limits of our present understanding
of the general dynamic response characteristics of such structures, the design and analysis of semi-submersible, large-scale
floating structures is discussed. For a pontoon-type large-scale floating structure, a type whose perimeter structure has
been modified to become lighter and more rigid is proposed. With this modification, the dynamic response of the whole structure
is imporved. 相似文献
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《Marine Structures》2000,13(4-5):233-243
Loads acting on large floating structures usually consist of high-frequency and low-frequency loads. The high-frequency loads are associated with the hydroelastic behavior of the structure and excitation of the natural frequency modes. The low-frequency loads are associated with the body motion of the structure and the wave profile. In design analysis, extreme values of these loads must be combined taking into consideration the correlation between them. This paper discusses a methodology for combining the extreme loads, and proposes a simple formulation suitable for use in reliability analysis. A proposed load combination factor K was found to depend on the correlation coefficient of the two loads, the ratio of their standard deviations and the frequency content of the processes from which the loads are determined. The correlation coefficient was found to depend on the complex frequency response functions of the loads and the input wave spectrum. The paper also discusses characteristic extreme values of slightly nonlinear loads acting on large floating structures.Extreme loads may be based on a storm condition with a specified return period. Since very large floating structures are expected to have a long operational lifetime, the return period must be selected carefully. The paper discusses a method for selecting return periods based on the expected operational life of the structure and encounter probability. 相似文献
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Numerical simulation of the spreading dynamic responses of the multibody system with a floating base
To simulate the dynamic responses of the multibody system with a floating base when the upper parts spread with a certain sequence and relative speed, the homogeneous matrix method is employed to model and simulate a four-body system with a floating base and the motions are analyzed when the upper parts are spread sequentially or synchronously. The rolling, swaying and heaving temporal variations are obtained when the multibody system is under the conditions of the static water along with the wave loads and the mean wind loads or the single pulse wind loads, respectively. The moment variations of each joint under the single pulse wind load are also gained. The numerical results showed that the swaying of the floating base is almost not influenced by the spreading time or form when the upper parts spread sequentially or synchronously, while the rolling and the heaving mainly depend on the spreading time and forms. The swaying and heaving motions are influenced significantly by the mean wind loads. The single pulse wind load also has influences on the dynamic responses. The torque of joint 3 and joint 4 in the single pulse wind environment may be twice that in the windless environment when the system spreads with 60 s duration. 相似文献
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《船舶与海洋工程学报》2015,(3)
To simulate the dynamic responses of the multibody system with a floating base when the upper parts spread with a certain sequence and relative speed, the homogeneous matrix method is employed to model and simulate a four-body system with a floating base and the motions are analyzed when the upper parts are spread sequentially or synchronously. The rolling, swaying and heaving temporal variations are obtained when the multibody system is under the conditions of the static water along with the wave loads and the mean wind loads or the single pulse wind loads, respectively. The moment variations of each joint under the single pulse wind load are also gained. The numerical results showed that the swaying of the floating base is almost not influenced by the spreading time or form when the upper parts spread sequentially or synchronously, while the rolling and the heaving mainly depend on the spreading time and forms. The swaying and heaving motions are influenced significantly by the mean wind loads. The single pulse wind load also has influences on the dynamic responses. The torque of joint 3 and joint 4 in the single pulse wind environment may be twice that in the windless environment when the system spreads with 60 s duration. 相似文献
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《船舶与海洋工程学报》2018,(3)
The numerical modelling of the interactions between water waves and floating structures is significant for different areas of the marine sector, especially seakeeping and prediction of wave-induced loads. Seakeeping analysis involving severe flow fluctuations is still quite challenging even for the conventional RANS method. Particle method has been viewed as alternative for such analysis especially those involving deformable boundary, wave breaking and fluid fragmentation around hull shapes. In this paper, the weakly compressible smoothed particle hydrodynamics(WCSPH), a fully Lagrangian particle method, is applied to simulate the symmetric radiation problem for a stationary barge treated as a flexible body. This is carried out by imposing prescribed forced simple harmonic oscillations in heave, pitch and the two-and three-node distortion modes. The resultant,radiation force predictions, namely added mass and fluid damping coefficients, are compared with results from 3-D potential flow boundary element method and 3-D RANS CFD predictions, in order to verify the adopted modelling techniques for WCSPH.WCSPH were found to be in agreement with most results and could predict the fluid actions equally well in most cases. 相似文献
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基于切片法建立物体在静水中浮体上纵向运动时浮体的水动力特征及运动微分方程。物体对浮体的垂向作用力考虑为瞬时压力,采用4阶龙格库塔法求解浮体运动微分方程,并将计算值与试验数据进行比较。 相似文献
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