In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stre...In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.展开更多
区域生态系统演变影响因素研究是近几十年来新兴的热点领域,对于实现人与自然和谐共生和可持续发展具有重要意义.基于VOSviewer软件,通过关键词共现分析、聚类分析、趋势与热点分析等手段,对中国知网(CNKI)和Web of Science平台的文献...区域生态系统演变影响因素研究是近几十年来新兴的热点领域,对于实现人与自然和谐共生和可持续发展具有重要意义.基于VOSviewer软件,通过关键词共现分析、聚类分析、趋势与热点分析等手段,对中国知网(CNKI)和Web of Science平台的文献进行计可视化计算与分析.研究结果显示:(1)根据文献的时间分布,可以将研究分为摸索发展阶段(1999—2009年)、初步发展阶段(2010—2020年)、快速发展阶段(2021年至今)3个阶段;(2)高产作者少,需要加强合作交流;(3)陆地生态系统、流域生态系统、生境质量、生态系统服务价值、城市群等为当前研究的热点话题,其演变进程与政策的制定具有较强的耦合性.分析结果表明,未来的研究趋势应注重长时间尺度的分析和利用更全面的分析模型.在加强对生态系统演变影响因素的定量分析的基础上,注重多个学科的交融,共同推动该领域的发展.展开更多
基金The research work was financially supported by the National Natural Scientice Foundation of China(Grant No.10142001)by the Shandong Provincial Natural Scientice Foundation(Grant No.Y2006F46)
文摘In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.
文摘区域生态系统演变影响因素研究是近几十年来新兴的热点领域,对于实现人与自然和谐共生和可持续发展具有重要意义.基于VOSviewer软件,通过关键词共现分析、聚类分析、趋势与热点分析等手段,对中国知网(CNKI)和Web of Science平台的文献进行计可视化计算与分析.研究结果显示:(1)根据文献的时间分布,可以将研究分为摸索发展阶段(1999—2009年)、初步发展阶段(2010—2020年)、快速发展阶段(2021年至今)3个阶段;(2)高产作者少,需要加强合作交流;(3)陆地生态系统、流域生态系统、生境质量、生态系统服务价值、城市群等为当前研究的热点话题,其演变进程与政策的制定具有较强的耦合性.分析结果表明,未来的研究趋势应注重长时间尺度的分析和利用更全面的分析模型.在加强对生态系统演变影响因素的定量分析的基础上,注重多个学科的交融,共同推动该领域的发展.
