A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the v...A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the values of the Cockcroft-Latham equation were calculated by the corresponding finite element numerical algorithm developed.A concept about damage incremental ratio in plastic deformation was defined as the ratio of damage increment at one step to the accumulated value.A method of finding the intersection of incremental ratio varying curve and simulation step axis was brought forward to make the fracture step certain. Then,the effects of temperature and strain rate on critical damage value were achieved.The results show that the critical damage value is not a constant but changes in a range of 0.021 8-0.378 0.It decreases significantly with the increase of strain rate at a certain temperature.While under a certain strain rate,the critical damage value has little change with the increase of temperature.展开更多
The uniaxial tensile tests were carried out at temperature ranging from room temperature(RT)to 523 K under strain rates of 0.001,0.010 and 0.100 s^(-1) to obtain the flow stress of AZ31 B magnesium alloy.The tensile t...The uniaxial tensile tests were carried out at temperature ranging from room temperature(RT)to 523 K under strain rates of 0.001,0.010 and 0.100 s^(-1) to obtain the flow stress of AZ31 B magnesium alloy.The tensile tests were simulated by the finite element method(FEM)to calculate the critical damage values(Dc)of the CockcroftLatham criterion to predict the occurrence of fracture defects.Finally,the effects of temperature and strain rate on Dc were analyzed to predict the critical damage value’s evolution.The results demonstrate that the critical damage value changes in the range of 0.188-0.718.It increases as strain rate decreases at constant temperature,and increases with the increase of temperature under certain strain rate,but is more sensitive to the temperature.展开更多
The environmental risk of chemical spills near coastal zones threatens abundant marine ecological resources. By appraising the ecological damage value of the environmental risk of marine chemical spills, we can facili...The environmental risk of chemical spills near coastal zones threatens abundant marine ecological resources. By appraising the ecological damage value of the environmental risk of marine chemical spills, we can facilitate decision-making for the development of a coastal zone and establishment of economic policy on coastal zone management. In this study, the ecological effect of the environmental risk of a chemical spill in the Haicang chemical industrial park in Xiamen was identified, after which its impact was forecasted and its ecological damage value was assessed. The information generated in this study will be useful in future studies evaluating marine ecological compensation based on environmental risk analysis.展开更多
The sources of marine oil spills are mainly from accidents of marine oil tankers or freighters, marine oil-drilling platforms, marine oil pipelines, marine oilfields, terrestrial pollution, oil-bearing atmosphere, and...The sources of marine oil spills are mainly from accidents of marine oil tankers or freighters, marine oil-drilling platforms, marine oil pipelines, marine oilfields, terrestrial pollution, oil-bearing atmosphere, and offshore oil production equipment. It is concluded upon analysis that there are two main reasons for marine oil spills: (I) The motive for huge economic benefits of oil industry owners and oil shipping agents far surpasses their sense of ecological risks. (II) Marine ecological safety has not become the main concern of national security. Oil spills are disasters because humans spare no efforts to get economic benefits from oil. The present paper draws another conclusion that marine ecological damage caused by oil spills can be roughly divided into two categories: damage to marine resource value (direct value) and damage to marine ecosystem service value (indirect value). Marine oil spills cause damage to marine biological, fishery, seawater, tourism and mineral resources to various extents, which contributes to the lower quality and value of marine resources.展开更多
基金Projects(CSTC,cstc2009aa3012-1)supported by Science and Technology Committee of Chongqing,ChinaProject(20100470813)supported by China Postdoctoral Science FoundationProject(2010011511)supported by Sharing Fund of Chongqing University’s Large-scale Equipment
文摘A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the values of the Cockcroft-Latham equation were calculated by the corresponding finite element numerical algorithm developed.A concept about damage incremental ratio in plastic deformation was defined as the ratio of damage increment at one step to the accumulated value.A method of finding the intersection of incremental ratio varying curve and simulation step axis was brought forward to make the fracture step certain. Then,the effects of temperature and strain rate on critical damage value were achieved.The results show that the critical damage value is not a constant but changes in a range of 0.021 8-0.378 0.It decreases significantly with the increase of strain rate at a certain temperature.While under a certain strain rate,the critical damage value has little change with the increase of temperature.
基金financially supported by the National Great Theoretic Research Project(No.2013CB632200)the National Science&Technology Support Project(No.2011BAE 22B01-3)+1 种基金the International Cooperation Project(No.2010DFR 50010)the Sharing Fund of Chongqing University’s Large-Scale Equipment。
文摘The uniaxial tensile tests were carried out at temperature ranging from room temperature(RT)to 523 K under strain rates of 0.001,0.010 and 0.100 s^(-1) to obtain the flow stress of AZ31 B magnesium alloy.The tensile tests were simulated by the finite element method(FEM)to calculate the critical damage values(Dc)of the CockcroftLatham criterion to predict the occurrence of fracture defects.Finally,the effects of temperature and strain rate on Dc were analyzed to predict the critical damage value’s evolution.The results demonstrate that the critical damage value changes in the range of 0.188-0.718.It increases as strain rate decreases at constant temperature,and increases with the increase of temperature under certain strain rate,but is more sensitive to the temperature.
基金supported by Marine Science Fund of SOA for Young Scholars (No.2008121)
文摘The environmental risk of chemical spills near coastal zones threatens abundant marine ecological resources. By appraising the ecological damage value of the environmental risk of marine chemical spills, we can facilitate decision-making for the development of a coastal zone and establishment of economic policy on coastal zone management. In this study, the ecological effect of the environmental risk of a chemical spill in the Haicang chemical industrial park in Xiamen was identified, after which its impact was forecasted and its ecological damage value was assessed. The information generated in this study will be useful in future studies evaluating marine ecological compensation based on environmental risk analysis.
基金supported by the Academy of Ocean of China (No. AOCQN200812)part of the results of the scientific research project entitled ‘The Legal Issues on the Ecological Damage Caused by Marine Oil Spills
文摘The sources of marine oil spills are mainly from accidents of marine oil tankers or freighters, marine oil-drilling platforms, marine oil pipelines, marine oilfields, terrestrial pollution, oil-bearing atmosphere, and offshore oil production equipment. It is concluded upon analysis that there are two main reasons for marine oil spills: (I) The motive for huge economic benefits of oil industry owners and oil shipping agents far surpasses their sense of ecological risks. (II) Marine ecological safety has not become the main concern of national security. Oil spills are disasters because humans spare no efforts to get economic benefits from oil. The present paper draws another conclusion that marine ecological damage caused by oil spills can be roughly divided into two categories: damage to marine resource value (direct value) and damage to marine ecosystem service value (indirect value). Marine oil spills cause damage to marine biological, fishery, seawater, tourism and mineral resources to various extents, which contributes to the lower quality and value of marine resources.
