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1.
波浪弯矩设计值与长期预报理论计算值的比较   总被引:5,自引:1,他引:5  
本文分析了国际船级社协会(IACS)纵向强度标准S1中,波浪弯矩值成采用IACSWP/S委员会推荐的海浪谱和海况统计资料条件下的长期预报理论计算值的关系,大量计算实践表明后者总体上要比前者大1.5倍。文中建议为了把长期技术应用于船体波浪弯的直接设计计算,对上述预报过程可取10概率水平时地长期预报值作为船体波浪湾矩设计值。  相似文献   

2.
Longitudinal stresses due to combined horizontal and vertical bending moments in ships, corresponding to a return period of 20 years, are estimated by linear response analysis. In principle, the stress should be obtained by combining the stress in all sea states that can occur over a long-term period. A method to determine the desired long-term extreme stress by considering only a few short-term sea states is presented. The sea states have a certain probability of occurrence, and are each identified by a contour line in the (H s, T p)-plane. This approach makes it possible to estimate the extreme loads on the vessel in a practical and accurate manner. Moreover, it is shown that the long-term stress can be estimated by combining the individual long-term extreme stresses due to vertical and horizontal bending moments by using the sum-of-squares approach and accounting for the correlation between stresses. It was found that the correlation coefficient can be taken as the largest of the ones calculated along the contour line. It is shown that this correlation coefficient can even be approximated by the normalized phase angle at the wave length where the dominant response has its peak value. A comparison with the results obtained using well-known combination rules is presented. While linear analysis has been used here, it is believed that the approach can be generalized to stresses with nonlinear behavior, and hence represent a significant improvement in calculation efficiency. Received: September 18, 2001 / Accepted: December 18, 2001  相似文献   

3.
根据设计船舶的具体要求确定设计变量、目标函数及约束条件,构造出描述船舶优化设计的数学模型。运用有约束条件的非线性规划问题的罚函数算法、多目标决策问题的分层序列算法,结合MATLAB Optimization Toolbox进行优化计算。计算结果表明,优化船型与非优化船型相比,营运性能将有所提高。  相似文献   

4.
    
In this previous study, a consistent theoretical formula was established in single hull structure, taking account of all the structural components affecting the load share of each member, in combination with the combined load effect of direct force from the longitudinal stiffener and shear force on the primary supporting member. What's more, it has been known qualitatively that the bending moment at the root of the web stiffener in double hull structure is less than that in single hull structure. However, the difference between double hull and single hull structures has not been achieved. In this study, the authors develop a theoretical formulation to represent the stresses at the root of the web stiffener due to the load from both the longitudinal stiffener and the shear force on the primary supporting member in the double hull structure. Then, the results calculated by the derived formulae are compared with the results obtained by finite element analysis, and good accuracy of the proposed formula was verified. Finally, the calculated stresses were compared between double hull and single hull structures. On one hand, the share of loading born by the web stiffener is almost comparable between the double hull and single hull structures. On the other hand, the bending moment at the root of the web stiffener is smaller in the double hull structure than in single hull structure, and therefore, the maximum stress is smaller.  相似文献   

5.
介绍了非线性动力学理论在船舶横甩研究中的应用,总结了近年来横甩研究的主要方法和结论,最后指出了横甩问题尚需深入研究的几个方面。  相似文献   

6.
船用装载仪软件的设计和实现   总被引:4,自引:1,他引:4  
本文就装载软件设计中的有关计算方法:稳性、纵倾、总纵程度的计算,作了详细的介绍。重点介绍了强度计算时的可变重量分布的计算方法、纵倾调整、静水剪力及弯曲矩计算以及校核点剪力和弯矩的插值方法(Akima算法)。  相似文献   

7.
三弯矩方程的改进及在船舶轴系动态校中中的应用   总被引:10,自引:0,他引:10  
针对船舶轴系静态校中计算的缺点,对船舶轴系动态校中计算进行了理论分析,并对传统的连续梁三弯矩方程进行了改进,提出了对轴系同时进行垂直平面和水平平面校中计算的方法;同时,利用改进的三弯矩方程,开发了基于VB的计算软件,通过对实船轴系的校中计算与测试,证明是完全正确的。  相似文献   

8.
船-桥碰撞力学问题研究现状及非线性有限元仿真   总被引:4,自引:0,他引:4  
归纳研究了船舶与桥梁碰撞力学的几种典型计算方法,并对各自的特点进行了分析。文中借助DYTRAN非线性有限元程序,以一艘4万吨级的油船与长江上某一斜拉索桥发生正向碰撞为例,演示了有限元法仿真计算船-桥碰撞问题的一般过程。反映了船-桥碰撞过程中船艏、桥梁承合、桥面和拉索的力与变形的时间历程,得到了具有指导意义的结论。  相似文献   

9.
本文利用非线性切片理论,以两条不同类型的船舶为例,具体分析了现行规范中关于波浪弯矩、砰击振动弯矩以及弯矩迭加计算时存在的一些问题;指出了在确定计算载荷时应当计及船舶在波浪中的失速,所谓的谐振波不一定就是最危险的规则子波,按动量冲击理论计算以底部砰击为主的船舶是不合适的,不应把波浪弯矩和砰击报动弯矩的最大值简单相加来确定合成弯矩。  相似文献   

10.
This study proposes a new procedure for the estimation of stranding forces and their contact positions. The method is based on the measurement of a few characteristic on-site parameters, i.e., the draughts and bending moments acting on a stranded ship. A procedure that estimates penetration into the ship bottom based on knowledge of the resistance versus penetration relationship is also presented. The seabed topology is parameterized by a paraboloid. This geometry can, in principle, characterize a wide range of obstructions, from sharp rocks to large shoals. Nonlinear finite element analysis is used to simulate various stranding situations and to generate the corresponding resistance versus penetration curves. The present method provides insight into the identification of real stranding scenarios in terms of the location of obstructions, their possible shapes and the corresponding resistance-penetration curves. The proposed methodology represents a first step towards a tool for quick decision making during salvage operations. The ultimate goal is to allow near real-time prediction of the risk of penetration into cargo tanks and hull girder failure. To demonstrate the effectiveness of the proposed method, it is applied to a simulated trial stranding scenario.  相似文献   

11.
船舶动力定位系统的一增广非线性观测器设计   总被引:3,自引:1,他引:2  
滤波和状态估计在动力定位系统中起着非常重要的作用。本文在文献[1]的基础上,为船舶动力定位系统设计了一增广非线性状态观测器,其稳定性通过李亚普诺夫方法得到了证明。该非线性观测器的性能通过对一动力定位船舶模型的仿真得到了验证。  相似文献   

12.
波浪对船舶非线性横摇阻尼的影响   总被引:4,自引:0,他引:4  
横摇非线性阻尼通常是在静水中进行横摇衰减试验确定。本文通过在波浪水池中进行不规则波的船模横摇衰减试验,研究了波浪对非线性横摇阻尼的影响。研究发现波浪的存在使横摇阻尼线性部分减少,非线性部分增加;采用随机减量法得到非线性横摇阻尼时,门槛值不同所得到的阻尼也不相同,一般说来,门槛值越大,阻尼非线性成分增加,而线性成分减少。  相似文献   

13.
船舶参数激励非线性横摇运动方程   总被引:3,自引:0,他引:3  
讨论了船舶在海浪上运动时参数激励产生的机理,建立了船舶参数激励和波浪激励非线性横摇运动方程。本文工作为研究倾覆机理奠定了基础。  相似文献   

14.
船用非线性碟簧动力吸振器的参数研究   总被引:1,自引:0,他引:1  
李俊  金咸定 《中国造船》2001,42(1):39-44
采用有限元法、改善的动力缩减法和数值积分法,讨论了耦合非线性碟簧动力吸振器的船体结构动力响应的计算,并通过数值优化法参数,研究了非线性碟簧动力吸振器的线性刚度、粘性阻尼、Coulomb阻尼、刚度非线性和弹簧组合系数与抑振带宽的关系,得到了若干有意义的结论,可作为船用非线性碟簧动力吸振器宽带优化设计的指导原则。  相似文献   

15.
采用有限元法、改善的动力缩减法和数值积分法研究了减小船体艉部振动的非线性碟簧动力吸振器的宽带数值优化设计,通过结合具体的应用实例系统讨论了非线性碟簧动力吸振器的线性刚度、粘性阻尼、Coulomb阻尼、刚度非线性和弹簧组合系数与抑振带宽的关系,试图对船体梁这类复杂结构的非线性动力吸振器的理论和研究方法予以创新和发展。  相似文献   

16.
大开口型船舶波浪诱导载荷研究   总被引:5,自引:1,他引:4  
通过对某5万t级大开口型船舶的各种波浪诱导载荷长期预报,详细讨论了不同波浪散布图、装载工况、航速、水动力计算理论和短峰波对波浪诱导载荷长期预报极值的影响,指出了一些值得注意的问题,以期对类似船型的液体波浪诱导载荷预报提供有用的参考。  相似文献   

17.
肘板连接的极限强度分析   总被引:2,自引:1,他引:2  
为比较各种肘板连接的强度特征,本文用非线性有限元方法计算了4种肘板连接的极限强度。计算中考虑了大位移、材料塑性和装配误差等影响。计算结果表明,按照同一规范设计的4种肘板连接对于正常载荷均具有足够的强度,但相对而言,对接连接比搭接连接具有较高的极限强度。  相似文献   

18.
船舶减摇鳍不确定非线性系统的变结构鲁棒控制   总被引:2,自引:0,他引:2  
船舶减摇鳍非线性系统延模中存在参数的不确定性,和由于系统状态变化而引起参数变化大外界干扰等所产生的不确定性。本文提出了一个变结构鲁棒控制算法。经仿真试验表明,该算法对于船舶减摇鳍控制系统十分有效,特别是鲁棒性能令人满意。  相似文献   

19.
本文讨论了文献[1]给出的计算船体失效概率公式在原理及数值结果方面存在的问题,进而导得了相应的正确表达式。该式可用于分析各个海况对船体安全性的影响,为船体可靠性长期分析,提供了一个有效途径。  相似文献   

20.
移动式近海基地是一个大型的、浮动的、自行驱动的、由三至五个模块组成的海洋结构.其中的每个模块均能在风、浪、流作用力下实现长期定位.本文首先讨论了针对移动式近海基地的控制架构.然后针对近海基地中的单独模块设计了一个非线性带前馈的比例微分(PD)控制器,并将其应用到多个模块的运动控制中.文中同时给出了所设计的控制系统的仿真结果.  相似文献   

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