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2010年2月14日,虎年大年初一,中共中央总书记、国家主席、中央军委主席胡锦涛同志在福建省委书记孙春兰、省长黄小晶,厦门市委书记于伟国、市长刘赐贵等省市领导的陪同下,专程赴厦门港海天码头视察。 相似文献
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文章提出了基于最大裂纹张口位移计算I型应力强度因子的新方法,该方法适用于复合载荷(均匀拉伸和纯弯曲载荷组合)作用下的具有半椭圆表面裂纹的有限平板模型。首先,理论推导了具有埋藏裂纹的无限大平板受均匀拉伸载荷作用时应力强度因子与裂纹最大张口位移的对应关系,再应用有限元数值模拟技术,考虑了表面效应、模型尺寸效应及载荷形式的影响,然后基于有限元模拟结果,根据多元多次最小二乘法原理拟合出对应修正系数表达式,最终建立了复合载荷作用下有限平板裂纹尖端应力强度因子与最大张口位移的函数关系,实现了由容易获得的最大裂纹张口位移确定应力强度因子的方法。该方法避免了对裂纹尖端的应力场、位移场的分析,为实际应用中应力强度因子的获得提供了新的方法。 相似文献
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Riser long-term fatigue performance is an important design consideration. Although extensive application of irregular sea analysis in time domain with the rainflow counting technique for post-processing is regarded as the most accurate of the approaches for fatigue analysis, it does suffer from some limitations, such as the computational effort. For this reason, two computationally efficient approaches are employed to perform the fatigue analysis of a deepwater top-tensioned riser, based on the Longuet-Higgins distribution and time domain scaling respectively. With Longuet-Higgins distribution irregular wave sea states are expanded into their individual wave bins. These regular wave simulations are of short duration and consequently run quickly. Using the time domain scaling technique, the number of irregular wave runs can be performed for a comparatively small number of load cases and hence reduces the calculation time. The results showed a reasonable accuracy and significant efficiency for both approaches, compared with those from the equivalent rainflow analysis. With much less computational effort and disk storage requirement, the approaches outlined in this paper can therefore be used for the fatigue assessment of deepwater risers in industry practice. 相似文献
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发动机上有些小孔,由于位置不同,所起作用各异,在维修、保养过程中应保持其畅通.否则,不仅缩短零部件的使用寿命,而且还会产生种种不良后果. 相似文献