Seawater Corrosion Fatigue of Welded Joints Under Random Variable Amplitude Loading     

Xue Yinian  Xu Jilin Li Yanping Li He Professor  Solid Mechanics Division 《中国海洋工程》1993,(2)

- Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine environment, random variable amplitude fatigue tests have been carried out on welded plate joints in sea water. The tests have been conducted under the conditions of loading frequency of 0.2 Hz, stress ratio of -1, seawater temperature of about 20℃ and cathodic protection with the potential about -850 mV, SCE. The test results have been compared with the seawater corrosion fatigue life under constant amplitude loading. Miner's linear cumulative damage summation rule has been used to predict the corrosion fatigue life under variable amplitude loading. The predicted life is in good agreement with the test data.  相似文献   

Numerical Study on the Probability of Fatigue Failure of a Semi-Submerged Platform Structure     

Yu Jianxing  Hu Yunchang  Wang Yehong  YuHongjie Associate Professor  Tianjin University  Tianjin  Professor  Tianjin University  Tianjin  Postgraduate for Master Degree  Tianjin University  Tianjin 《中国海洋工程》1994,(4)

On the basis of Miner's linear cumulative damage theorem, random variables are introduced to evaluate objectively the fatigue damage of a semi-submerged platform structure and a method is presented to analyze the fatigue reliability of the structure in its design life. The reliability of the method is verified through numerical examples and some conclusions are drawn, which have certain guiding and reference value for design and inspection.  相似文献   

冰区自升式平台桩腿动强度的安全评估     

张剑波 《海洋通报》2006,25(6):63-68

应用ANSYS软件建立了自升式平台和冰相互作用的数学仿真模型,对自升式平台进行了动力分析和桩腿的极限强度和疲劳强度校核。应用本模型对渤海某自升式平台桩腿进行的强度校核和不同海冰参数下平台桩腿的冰激疲劳损伤实例分析表明,本文的研究结果为自升式平台冰激疲劳设计提供了一个有效的方法,并为自升式平台在冰区的使用提供了依据。  相似文献   

疲劳模型评价海底粉土不稳定性的应用   总被引：1，自引：0，他引：1  

杨少丽  叶银灿  冯秀丽 《中国海洋大学学报(自然科学版)》2002,32(1):115-119

该文探讨疲劳模型在评价海底粉土不稳定性中的应用。研究表明以超孔压为疲劳参数 ,以 Ψ 作为孔压产生率的疲劳模型可用于预测海底粉土中超孔压的产生和累积。基于已有的疲劳模型 ,借鉴以孔压作为疲劳参数 ,运用包含有周期循环数的公式来预测超孔压的累积的思路 ,将粉土的动三轴孔压累积曲线用一条渐进线来代表 ,从而用一种新的且较简单的疲劳模型可预测超孔压的均值。  相似文献   

随机载荷作用下平台结构疲劳寿命预测     

张剑波 《海洋通报》2006,25(5):50-56

海洋等工程结构物在服役过程中的受载历程是一个随机过程。研究裂纹在谱载荷作用下的扩展规律对可靠预报平台等结构物的疲劳寿命具有十分重要的意义。提出了一个由应力比和裂纹尖端约束及塑性区尺寸为主要参数计算裂纹张开比,来考查载荷相互作用下疲劳裂纹扩展寿命的计算模型。用该模型对几种谱载荷作用下疲劳实验结果进行了预测,将预测结果与不考虑裂纹闭合的线性损伤模型及疲劳计算程序FASTRAN的预测结果进行了比较,表明本模型能较好地预测谱载荷作用下的疲劳裂纹扩展。  相似文献   

Effect of Band Width on Fatigue Life under Random Stress Response     

Wu Yisheng Associate Professor 《中国海洋工程》1992,(2)

A fatigue life estimation method for offshore structures under random stress response is studied in this paper. The method of broad band cumulative frequency number is used to determine the effect of band width of stress frequency spectra on fatigue. A formula of correction factor for fatigue under broad band stress spectra is suggested and compared with that given by P. H. Wirsching.  相似文献   

圆形网箱框架用PE管材的弯曲疲劳试验   总被引：1，自引：0，他引：1  

关长涛  陆光炯  林德芳  杨长厚  徐斌  黄滨 《中国海洋大学学报(自然科学版)》2006,36(2):236-240

网箱框架在风、浪、流单一载荷或其复合载荷的作用下,始终处于动态变化中,在这样的工况条件下,很容易发生疲劳破坏。本文通过对网箱框架工况条件的分析,认为网箱框架在沿直径方向的弯曲疲劳为主要因素,且在弯曲过程中周长保持不变。以圆形框架在直径方向产生20%的压缩变形为极端条件,通过几点假设,将工况条件向试验条件进行转化,提出1种圆形网箱框架用PE管材的弯曲疲劳试验方法。采用此方法对3种改性配方的聚乙烯管材样品进行了弯曲疲劳试验。结果表明,经10万次弯曲试验,3种配方的试样表面均无开裂等破坏现象,各配方的最大应力水平分别下降了14.3%,9.4%和16.9%。  相似文献   

Analysis of Wave Loads on A Semi-Submersible Platform   总被引：10，自引：0，他引：10  

QIAN  Kun 《中国海洋工程》2002,16(3):395-406

For the global and structural fatigue strength analysis of a semi-submersible platform, wave loads under design conditions are calculated by use of the three-dimensional boundary element method. Methods for calculating the forward-speed free-surface Green function are discussed and a computer program with this Green function is developed. According to the special rules, the wave loads under several typical design conditions of the platform are calculated. The maximum vertical bending moment, torsion moment and horizontal split force are determined from a series of contour maps of wave loads for the wave period of 5 to 18 seconds at a certain interval and the wave phase of 0°to 360°at a certain interval. The wave height is determined by the function of wave period with a given exceedance probability. The maximum wave loads under the combination of wave parameters are used as the input of hydrodynamic pressure in the three-dimensional finite element analysis process. The transfer functions of wave loads  相似文献   

基于剩余强度衰减的混凝土疲劳寿命估算方法   总被引：4，自引：0，他引：4  

朱劲松  宋玉普 《海洋工程》2003,21(3):78-82

从疲劳过程中材料静载强度不断退化的本质出发，提出一个混凝土剩余强度衰减模型，模型的参数可简单地由试验S—N曲线确定。将模型应用于复杂多级疲劳荷载作用下的混凝土剩余疲劳寿命估算时，可以得到令人满意的结果。  相似文献   

内流对海底管线涡致振动与疲劳寿命的影响   总被引：2，自引：0，他引：2  

申仲翰  赵强 《海洋工程》1995,(3)

在复杂的海洋环境条件下，管道的动力学特性受到内外部流体的作用而呈现出新的特点。本文通过对处在海底平稳流动作用下的悬跨管道的涡致振动进行分析，特别地考虑到管道内部流动的作用，给出了内流速度对管道响应幅度的影响，进而指出其对管道疲劳的意义。  相似文献