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船舶结构钢海洋环境点蚀模型研究之二:实船蚀坑形态与径深比时变模型 总被引:1,自引:0,他引:1
文章基于点蚀生长原理与实船蚀坑形态检测数据,对船舶受点蚀构件的两类主要蚀坑的形态、形成机制及其随船龄演化情况作了大致描述.认为遭受点蚀船舶构件的蚀坑形态与其所处位置、服役时间等密切相关;两类蚀坑形态差异的原因在于其各自点蚀进程中的具体控制因素及相应的影响程度存在较大区别.论述证明将点蚀蚀坑径深比处理成随时间变化的函数是有理论和事实依据的;并与点蚀深度模型相结合,依据Yamamoto实测散货船货舱区肋骨蚀坑数据建立了相应的蚀坑径深比时变模型. 相似文献
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新型耐海水用钢0Cr17Ni12Mo3Cu3及其点蚀行为的显微研究 总被引:1,自引:0,他引:1
采用金相显微镜、X射线衍射,扫描电子显微镜(SEM)及扫描隧道显微镜(STM)研究了新型耐海水用钢的显微组织及其点蚀行为。试验结果表明,该钢经1050℃,保温2h固溶处理后,可得到单相的奥氏体组织,具有良好的抗点蚀性能。并通过STM的观测,得到了新型钢的超高分辨三维点蚀形貌图象,为该钢的开发应用奠定了技术基础。 相似文献
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采用金相显微镜、X射线衍射、扫描电子显微镜(SEM)及扫描隧道显微镜(STM)研究了新型耐海水用钢的显微组织及其点蚀行为。试验结果表明,该钢经1050℃、保温2h固溶处理后,可得到单相的奥氏体组织,具有良好的抗点蚀性能。并通过STM的观测,得到了新型钢的超高分辨三维点蚀形貌图象,为该钢的开发应用奠定了技术基础。 相似文献
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点蚀损伤船体结构板的极限剪切屈曲强度研究 总被引:1,自引:0,他引:1
腐蚀损伤导致船体结构板的极限承载能力大幅度下降。文章采用腐蚀体积描述板的点蚀损伤程度,模拟船体结构板的点蚀损伤形态,在点蚀损伤板模型中变化板的厚度、点蚀数目、点蚀直径以及点蚀分布等要素,实施系列有限元数值模拟计算,在进行理论分析的基础上,采用统计学方法,建立了点蚀损伤板极限剪切屈曲强度的评估方法,得到了点蚀损伤板极限剪切屈曲强度的计算公式。从而确立了基于腐蚀体积的点蚀损伤船体结构板极限剪切屈曲强度的评价技术,可为在役海船点蚀损伤后的安全性评估提供有效的技术手段。 相似文献
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腐蚀疲劳点蚀演化及腐蚀疲劳裂纹成核机制研究 总被引:1,自引:0,他引:1
作为一种不可逆的热力学过程,腐蚀疲劳的点蚀演化伴随着体系能量的耗散。文章基于热力学原理,对腐蚀疲劳点蚀演化过程中的能量问题进行探索性研究。引入双变量点蚀模型,建立点蚀演化过程中体系热力学势函数,推导了点蚀形状参数在演化过程中的变化方程,并分析了体系应变能、表面能和电化学能对点蚀演化形貌的影响机制及规律。根据裂纹成核位错机理建立了腐蚀疲劳裂纹成核临界条件的能量准则,并与应力强度因子准则进行比较,分析结果验证了能量准则的合理性。 相似文献
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《江苏科技大学学报(社会科学版)》2017,(4)
点蚀损伤常发生于船体结构,将会造成结构的局部缺失而影响船舶结构的安全性.针对船体结构的基本构件加筋板,采用非线性有限元法研究轴向压力下点蚀损伤对其极限强度的影响,考虑点蚀位置、直径、数目、深度、点蚀损失体积等影响因素,分析船体加筋板极限应力和屈曲失效模式,获得结构的极限强度,拟合影响因素和加筋板极限强度的关系曲线,定性分析了点蚀损伤对加筋板的破坏.结果表明,点蚀损伤削减了加筋板极限强度;点蚀影响因素(点蚀直径、数目、深度、损失体积)对含点蚀损伤加筋板极限强度的影响近似呈现非线性的二次单调函数关系. 相似文献
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The galvanic corrosion behaviour of aluminium 3004 and copper with different area ratios were studied in the tropical marine atmosphere at Tuticorin harbour over a period of 426 days. The area ratios of AAl : ACu, studied were 1:1, 1:2, 1:4, 1:8, 2:1, 4:1 8:1. The galvanic corrosion behaviour of metals was studied in terms of relative increase in the corrosion rate of aluminium due to galvanic coupling with copper, relative decrease in the corrosion rate of copper due to galvanic coupling with aluminium, and the susceptibility of aluminium to pitting owing to galvanic coupling with copper. The galvanic potential and galvanic current of the system were monitored. Pits of different dimensions ranging from mild etchings to perforations were experienced on the borders and the surfaces of the interface of aluminium in contact with copper. The weathering parameters and the environmental pollutants which have a major role in influencing the galvanic corrosion of metals were also monitored. The corrosion products resulting from galvanic corrosion were analysed using XRD and the pitting on aluminium resulting from galvanic corrosion has been highlighted in terms of pit depth, size and density of pit, using a high resolution microscope. 相似文献
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Maintenance is playing an important role in integrity management of marine assets such as ship structures, offshore renewable energy platforms and subsea oil and gas facilities. The service life of marine assets is heavily influenced by the involvement of numerous material degradation processes (such as fatigue cracking, corrosion and pitting) as well as environmental stresses that vary with geographic locations and climatic factors. The composition of seawater constituents (e.g. dissolved oxygen, salinity, temperature content, etc.) is one of the major influencing factors in degradation of marine assets. Improving the efficiency and effectiveness of maintenance management strategies can have a significant impact on operational availability and reliability of marine assets. Many research studies have been conducted over the past few decades to predict the degradation behaviour of marine structures operating under different environmental conditions. The utilisation of structural degradation data – particularly on marine corrosion – can be very useful in developing a reliable, risk-free and cost-effective maintenance strategy. This paper presents an overview of the state-of-the-art and future trends in asset maintenance management strategies applied to corroded steel structures in extreme marine environments. The corrosion prediction models as well as industry best practices on maintenance of marine steel structures are extensively reviewed and analysed. Furthermore, some applications of advanced technologies such as computerized maintenance management system (CMMS), artificial intelligence (AI) and Bayesian network (BN) are discussed. Our review reveals that there are significant variations in corrosion behaviour of marine steel structures and their industrial maintenance practices from one climatic condition to another. This has been found to be largely attributed to variation in seawater composition/characteristics and their complex mutual relationships. 相似文献
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Galvanic corrosion behaviour of aluminium 3004 and copper in tropical marine atmosphere 总被引:1,自引:0,他引:1
The galvanic corrosion behaviour of aluminium 3004 and copper with different area ratios were studied in the tropical marine atmosphere at Tuticorin harbour over a period of 426 days. The area ratios OfAAI: Acu, studied were l:l, 1:2, l:4, 1:8, 2:1, 4:1 & 8:1. The galvanic corrosion behaviour of metals was studied in terms of relative increase in the corrosion rate of aluminium due to galvanic coupling with copper, relative decrease in the corrosion rate of copper due to galvanic coupling with aluminium, and the susceptibility of aluminium to pitting owing to galvanic coupling with copper, The galvanic potential and galvanic current of the system were monitored. Pits of different dimensions ranging from mild etchings to perforations were experienced on the borders and the surfaces of the interface of aluminium in contact with copper. The weathering parameters and the environmental pollutants which have a major role in influencing the galvanic corrosion of metals were also monitored. The corrosion products resulting from galvanic corrosion were analysed using XRD and the pitting on aluminium resulting from galvanic corrosion has been highlighted in terms of pit depth, size and density of pit, using a high resolution microscope. 相似文献
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考虑腐蚀影响的船舶结构可靠性研究现状与展望 总被引:6,自引:4,他引:2
对近年来考虑腐蚀影响的船舶结构可靠性计算各主要研究层面的研究现状做了介绍与评述.通过这一综述可以发现:此领域研究工作重心已由考虑线性、非线性均匀腐蚀的影响逐步向局部腐蚀尤其是点腐蚀方向转变.今后的研究重点为以下三个方面,即:①发展符合基本腐蚀机理、与实测腐蚀数据较为吻合的点腐蚀多指标模型;②确定蚀点几何参数在各类荷载条件下对构件强度的影响;③深入评估腐蚀与疲劳的相互作用对结构可靠性计算的影响. 相似文献
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The objective of this study was to estimate the strength and deformability of corroded steel plates under quasi-static uniaxial
tension. In order to accurately simulate this problem, we first estimated the true stress–strain relationship of a flat steel
plate by introducing a vision sensor system to the deformation measurements in tensile tests. The measured true stress–stain
relationship was then applied to a series of nonlinear implicit three-dimensional finite element analyses using commercial
code LS-DYNA. The strength and deformability of steel plates with various pit sizes, degrees of pitting intensity, and general
corrosion were estimated both experimentally and numerically. The failure strain in relation to the finite element mesh size
used in the analyses was clarified. Two different steels having yield ratios of 0.657 and 0.841 were prepared to examine the
material effects on corrosion damage. The strength and deformability did not show a clear dependence on the yield ratios of
the present two materials, whereas a clear dependence was shown with respect to the surface configuration such as the minimum
cross-sectional area of the specimens, the maximum depth of the pit cusp from the mean corrosion diminution level, and pitting
patterns. Empirical formulae for the reduction of deformability and the reduction of energy absorption of pitted plates were
proposed which may be useful in strength assessment when examining the structural integrity of aged corroded structures. 相似文献
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针对船用冷凝器的主要失效模式-冷却管点蚀穿孔,用Gumbel分布拟合冷凝器冷却管最大腐蚀深度的概率分布,用长磨合期磨损速度公式拟合呈指数衰减形式的冷却管腐蚀速度,通过对最早泄漏时间预测值时刻的可靠度赋值,得到满足期望可靠度的最大腐蚀深度估计值及腐蚀剩余寿命.基于积累的腐蚀数据和船用冷凝器剖管分析报告,进行了实例计算.该方法是对腐蚀数据统计分析理论及腐蚀寿命预测理论的合理补充,且在确定设备检修时间及报废时间方面具有一定的应用价值. 相似文献