共查询到19条相似文献,搜索用时 250 毫秒
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基于势流理论和格林函数,探索五体船在不规则波中运动的波浪载荷响应函数,并且运用波谱分析法,采用北大西洋波浪散布图,对船体的几个典型剖面作波浪载荷的长期预报。分析不同航速、不同浪向角下典型剖面上的弯矩和剪力,研究五体船在波浪中运动时剖面载荷的分布规律。 相似文献
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随着船舶尺度的增大,船体结构刚度变得越来越小,这意味着波浪激励频率和船体振动固有频率更加接近。准确地评估船体受到的波浪载荷及运动响应对船舶设计和安全性评估有重要意义。论文基于CFD-FEM耦合方法对一艘集装箱船建立水弹性模型并进行了数值计算。通过结构的升沉、纵摇,以及截面弯矩的数值计算和试验结果的比较,验证了该方法的准确性。与传统的势流水弹性方法相比,基于CFD-FEM方法能够充分考虑流场与结构相互作用过程中的非线性因素。对于一定的波长-船长比,当船体梁的固有频率较低时,波浪载荷的非线性强弱对船体梁垂向弯矩响应有较大的影响。 相似文献
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液舱中液体晃荡不仅对液舱结构产生内载荷作用,同时也通过与船体运动的耦合对LNG船的波浪载荷产生影响.文章通过某大型LNG船自航模型在波浪中的带液舱运动和波浪载荷试验,研究液舱中液体晃荡特性及其对总体波浪载荷的影响.同时对液舱有水(30%H)状态下的液舱中液体运动周期进行了试验研究,结果发现:在相同排水量和重量分布下,液舱中液体的存在对船体梁垂向振动频率和船体横摇周期都有影响;液舱中液体的运动周期不仅与液舱本身的形状和液面高度有关,还与船模航行时遭遇的浪向以及航速有关;虽然船舶浪向和航速是液舱内液体晃荡对总体波浪载荷产生影响的敏感参数,但总体影响不显著. 相似文献
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波激弹振和砰击颤振是集装箱船运营中极易出现的两种现象,分析其对船舶运动和剖面载荷的影响,对船舶设计和强度评估具有重要意义。采用黏性流体-柔性结构双向耦合方法对集装箱船模型在不同波长工况下的运动和响应进行求解,其中计算流体力学用于模拟流场的冲击和上浪等非线性现象并得到船体外载荷,然后通过有限元法求解船体运动和变形,两者在流固交界面进行隐式信息交换。计算捕捉到船体的非线性波激振动和颤振,分析结果发现,波激振动和颤振对整体运动影响较小,但会显著增大船体中垂的弯矩幅值,艏、艉区域垂向加速度受颤振的影响较大,当遭遇波浪的倍频成分接近船体湿频率时也会激发船体一定程度的弹振。与文献结果的比较表明,该耦合方法有望成为处理船舶水弹性问题的一种有效手段。 相似文献
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《中国舰船研究》2016,(6)
针对某千吨级三体船母型船,在保持排水量不变的前提下,调查长宽比对运动和载荷的影响,并通过船型变换得到长宽比在12~19之间的6种系列派生船型;应用三维时域Rankine方法软件WASIM对不同长宽比系列船体的纵向运动和波浪载荷进行频响计算,并进一步结合海浪谱分别计算4~6级海况下船体纵摇和升沉运动统计值以及船体剖面弯矩和剪力沿船长单位的分布。分析发现,当主体长宽比从12.27增加至19.16时,纵摇和升沉的最大峰值分别下降了近60%和35%,但剪力和弯矩的峰值则分别增大了2倍和3.5倍。进一步将直接计算的总纵弯矩和剪力与英国劳氏规范相比较,发现6级海况下剖面剪力有义值的计算结果已超过规范的规定。结果表明:主船体的长宽比对耐波性和波浪载荷具有相反的影响,即主体越瘦长,运动响应越小,耐波性越好;但主体越瘦长,总纵弯矩和剪力会大幅增加,对船体结构产生不利影响。因此,在设计之初确定瘦长三体船的主尺度,特别是瘦长度时,应兼顾考虑船体运动响应与波浪载荷的影响。 相似文献
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《船舶标准化工程师》2016,(4)
本文通过船舶三维运动程序进行了船舶运动与波浪载荷分析,运用波谱理论进行了长期波浪载荷分析。利用动态载荷法与ANSYS软件相结合计算了一艘5 500 TEU集装箱船在各种波浪载荷下船体结构的受力和应力分布状况,并与现行船级社规范进行了综合比较,可为船体结构的设计提供参考。 相似文献
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《Marine Structures》2000,13(2):107-128
The paper aims at quantifying the changes in notional reliability levels that result from redesigning a traditional single-hull bulk carrier to become a double-hull structure. The probability of failure is calculated using a first-order reliability method. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out. The still water loads are defined on the basis of a statistical analysis that accounts for the ship type. The ultimate collapse bending moment of the midship cross section is used as the basis for the reliability formulation. It is shown that by introducing the double-hull in the bulk carriers their level of structural safety can be increased up to values typical of tankers. Additionally, the time-dependent degrading effect of corrosion on the ultimate moment is also taken into account in the reliability assessment of bulk carriers. 相似文献
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A time-domain technique for estimating wave-induced ship hull bending moment from ship motion measurements is presented. This technique is developed to improve hull response monitoring systems. Artificial neural networks are used to model the time-domain relationship between the wave-induced vertical bending moment and the coupled heave and pitch motions. The application of the proposed technique is validated using experimental data. 相似文献
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Assessment of the ultimate longitudinal strength of hull girders under combined waveloads can be of particular importance especially for ships with large deck openings and low torsional rigidity. In such cases the horizontal and torsional moments may approach or exceed the vertical bending moment when a vessel progresses in oblique seas. This paper presents a direct calculation methodology for the evaluation of the ultimate strength of a 10,000 TEU container ship by considering the combined effects of structural non-linearities and steady state wave induced dynamic loads on a mid ship section cargo hold. The strength is evaluated deterministically using non-linear nite element analysis. The design extreme values of principal global wave-induced load components and their combinations in irregular seaways are predicted using a cross-spectral method together with short-term and long-term statistical formulations. Consequently, the margin of safety between the ultimate capacity and the maximum expected moment is established. 相似文献
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《船舶与海洋工程学报》2018,(3)
The ship motions and wave-induced loads of a new type of river-to-sea ship are investigated experimentally and numerically. A river-to-sea ship is an unconventional type of container ship characterized by high breadth to draft ratio and low length to breadth ratio, which makes it more prone to hydroelasticity than conventional ships of the same size. A segmented model was tested under two loading conditions, namely, ballast and loaded conditions, to determine the vertical motions and wave-induced loads under each condition. Results are compared with numerical simulations in the frequency domain. The wave-induced responses are calculated by a nonlinear time domain code at each time step. The response amplitude operators of vertical ship responses in regular waves are analyzed, and the wave-induced responses are consistent with the experimental results. 相似文献
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MVNakhodka collapsed and broke in two on January 2, 1997 in the Sea of Japan, giving rise to a serious and disastrous oil spill on the
coastline of Japan. During the inquiry into the cause of the accident, one of the main tasks of the inquiry committee was
to identify the external loads which made the ship structure collapse. Among the several possible scenarios for the accident,
after careful examination, the wave loads in the heavy weather at the time of the accident were taken to be the most plausible
cause. The results of that research are described in two papers, and the present paper deals with the way in which wave loads
on theNakhodka at the moment of the accident were estimated. We first describe the details of the accident such as the location, the sea
condition, the loading condition, and the ship's heading speed. Then the static loads resulting from the distribution of the
cargo weight and the buoyancy are given to show that the static bending moment at the time of the accident caused extreme
sagging. Next the wave loads in the irregular waves, calculated by the nonlinear time domain simulation program SRSLAM, are
presented. It is shown that the bending moment in the waves reaches 1 087 800 KN*m at maximum SS 6.9, which is where the hull girder collapse took place. It was concluded that the ship broke in two because
the bending moment exceeded the hull girder strength which had been reduced due to corrosion, taking into account conclusions
derived from the research dealing with the structural strength aspect. We also discuss the stochastic significance of the
estimated value and nonlinear nature of the peak distribution, in addition to the effects of the ship speed and wave heading
on the wave load estimation.
This article is based on an article that appeared in Japanese in the Journal of the Society of Naval Architects of Japan,
vol. 183 (1998). 相似文献
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利用三维势流理论和简单格林函数计算了迎浪航行时不同航速和不同水深组合下的波浪运动响应和载荷传递函数,研究不同水深和航速组合对三体船的波浪运动响应和波浪载荷的影响,并对船舯垂向弯矩和舯后1/4船长处剪力进行了长期预报.将预报值与规范值进行比较,结果令人满意.计算结果表明三体船在不同水深下航行时,水深对其运动响应和波浪载荷都会产生显著影响. 相似文献