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101.
Weicheng Cui 《Journal of Marine Science and Technology》2002,7(1):43-56
Metals are the most widely used materials in engineering structures, and one of the most common failure modes of metal structures
is fatigue failure. Although metal fatigue has been studied for more than 160 years, many problems still remain unsolved.
In this article, a state-of-the-art review of metal fatigue is carried out, with particular emphasis on the latest developments
in fatigue life prediction methods. All factors which affect the fatigue life of metal structures are grouped into four categories:
material, structure, loading, and environment. The effects of these factors on fatigue behavior are also addressed. Finally,
potential problems to be resolved in the near future are pointed out.
Received: January 7, 2002 / Accepted: March 25, 2002 相似文献
102.
Y. Sumi 《Journal of Marine Science and Technology》1998,3(2):102-112
The fitness for serviceability of structural members of marine structures in which fatigue cracks might be found during in-service
inspection is investigated in order to prevent instantaneous failures of ships, as well as a loss of serviceability such as
the oil- and/or watertightness of critical compartments. The essential features of fatigue crack propagation and the remaining
life assessment are discussed in the first part of the paper, where the effects of weldment, complicated stress distributions
including stress biaxialities at three-dimensional structural joints, structural redundancy, and crack curving are found to
be of primary importance. The second part of the paper contains a discussion of an advanced numerical simulation method for
the remaining life assessment, in which the above-mentioned effects of fatigue crack propagation are taken into account. The
simulated crack paths and the fatigue crack propagation lives are found to be in fairly good agreement with the experimental
results. 相似文献
103.
104.
传统的疲劳问题一般都是采用S—N曲线及Miner累计损伤理论进行的,文章在基于断裂力学的基础上,通过权函数法来计算应力沿裂纹面的非线性效应力强度因子,鉴于船舶在海洋环境中受到载荷的随机性,充分考虑加载次序、过载峰和应力比等对裂纹扩展的影响,给出了船舶结构疲劳裂纹在随机载荷下的扩展寿命的计算过程。 相似文献
105.
文章研究了静水压力下功能梯度圆柱壳的稳定性特性.该文在Flügge理论的基础上,通过变换轴向波数,先后采用波动法和牛顿迭代法得到不同边界条件下FG圆柱壳的固有频率值.最后利用线性拟合方法得到水下FG圆柱壳的临界压力.在经过与各向同性圆柱壳的分析结果进行对比,验证了文中研究的有效性和正确性的基础上,讨论了水下FG圆柱壳的临界压力.通过算例,分析了材料组分、体积分数、边界条件、壳体尺寸等因素对水下FG圆柱壳临界压力的影响. 相似文献
106.
107.
Iván Cáceres Rabionet Vicente Gracia García Montserrat Rubio Galindo 《Coastal management》2013,41(3):254-273
Artificial islands have been constructed next to large cities due to the need for extra space in highly populated areas. These emerged structures have been used by many countries as platforms for developing infrastructure (airports, harbors, highways, etc.), rebuilding ecological areas, and creating new spaces for tourism or residential areas. In this study, two state-of-the-art numerical models for wave propagation and nearshore circulation are used to simulate the effects of an emerged artificial island on the Barcelona coast. Several sea indicators (wave height, intensity and direction of currents, and mean water level) are analyzed to assess the changes likely to be induced by an artificial island. Three different situations are studied and the indicators are compared across the different tests to obtain information that can be used in the planning process of these structures. In two-meter wave conditions, the tests show that wave height is generally reduced in the sheltered area, which leads to improved safety for beach users (bathing is prohibited when wave height exceeds the two-meter threshold). However, the numerical models also reveal that velocities in the sheltered area usually decrease, which must be controlled to prevent stagnation in the bathing area. 相似文献
108.
利用CGWAVE波浪数值模型探讨波浪入射角度不同时航道水深对波浪传播的影响,得出航道与两侧岸滩不同水深比条件下的波浪临界入射角。通过与物理模型试验的对比验证该数值模型的可信度,并将其应用于曹妃甸中心渔港一期工程项目中,本研究的相关成果可用于指导航道工程设计和建设。 相似文献
109.
铁道货车车轮产生损伤失效的主要原因是承受了复杂的热载荷和机械载荷的联合作用,而高温低循环疲劳是车轮踏面区域产生损伤的重要机理之一.针对铁道货车车轮CL60钢进行了450℃时的高温低循环疲劳实验.研究发现:在整个循环过程中,应力-应变关系曲线的变化趋势基本一致;随着循环周次的进行,拉压应力峰值呈现出连续的降低态势,压应力峰值减幅略大于拉应力峰值减幅,表现了低循环疲劳的典型特性;试样断口上出现了较为严重的氧化现象,断口裂纹扩展以穿晶为主. 相似文献
110.
A study of maneuvering control for an air cushion vehicle based on back propagation neural network 总被引:1,自引:0,他引:1
A back propagation (BP) neural network mathematical model was established to investigate the maneuvering control of an air cushion vehicle (ACV). The calculation was based on four-freedom-degree model experiments of hydrodynamics and aerodynamics. It is necessary for the ACV to control the velocity and the yaw rate as well as the velocity angle at the same time. The yaw rate and the velocity angle must be controlled correspondingly because of the whipping, which is a special characteristic for the ACV. The calculation results show that it is an efficient way for the ACV's maneuvering control by using a BP neural network to adjust PID parameters online. 相似文献