In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending stre...In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.展开更多
采用AFLP技术对平泉县的1个油松-落叶松混交林和2个油松纯林中油松毛虫(Dendrolimus tabulaeformis Tsai et Liu)的135个个体进行了遗传多样性和遗传结构的研究,并调查了3个油松林群落的各种环境条件。结果表明,纯林中油松毛虫种群的遗...采用AFLP技术对平泉县的1个油松-落叶松混交林和2个油松纯林中油松毛虫(Dendrolimus tabulaeformis Tsai et Liu)的135个个体进行了遗传多样性和遗传结构的研究,并调查了3个油松林群落的各种环境条件。结果表明,纯林中油松毛虫种群的遗传多样性高于混交林中的油松毛虫种群;林木生长状况为影响不同油松纯林群落中油松毛虫种群遗传多样性的重要因素;混交林对油松毛虫种群之间的基因流有阻断作用,油松毛虫种群的基因流大小与油松林之间的物种多度呈反相关。展开更多
文摘In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.
文摘采用AFLP技术对平泉县的1个油松-落叶松混交林和2个油松纯林中油松毛虫(Dendrolimus tabulaeformis Tsai et Liu)的135个个体进行了遗传多样性和遗传结构的研究,并调查了3个油松林群落的各种环境条件。结果表明,纯林中油松毛虫种群的遗传多样性高于混交林中的油松毛虫种群;林木生长状况为影响不同油松纯林群落中油松毛虫种群遗传多样性的重要因素;混交林对油松毛虫种群之间的基因流有阻断作用,油松毛虫种群的基因流大小与油松林之间的物种多度呈反相关。
