＂Until very recently, 12-year-old Li Xioling drank the spring water that originated from the Longmen Shan, orthe Dragon＇s Gate Mountains of the Tibetan Plateau. Sitting in a makeshift house set up on the bank of ...＂Until very recently, 12-year-old Li Xioling drank the spring water that originated from the Longmen Shan, orthe Dragon＇s Gate Mountains of the Tibetan Plateau. Sitting in a makeshift house set up on the bank of the Yanhe River outside her home town Bailu Township of Pengzhou city, Sichuan Province, Li says, ＂It tastes a little sweet. We used itto cook and to bathe.＂展开更多
Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stre...Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stress concentration coefficient Kt at weld toe and fatigue life N were studied based on the finite element software ABAQUS/FE-SAFE,and the parametric equations were founded based on regression analysis of Origin software.The results show that weld edge transition arc radius r plays the most important role in stress concentration coefficient Kt as well as weld toe inclination angle 0.For the same inclination angle θ,stress concentration coefficient Kt decreases gradually with transition arc radius r increasing.With inclination angle θ increases,the effect of transition arc radius r on stress concentration factor Kt is increasing continuously,also the effect of change in stress concentration coefficient Kt caused by r on fatigue life N is increasing continuously.While in the case of same weld edge transition arc radius r,stress concentration coefficient Kt increases with inclination angle θincreasing.With transition arc radius r increases,the effect of inclination angle θ on stress concentration factor Kt is decreasing constantly,the effect of change in stress concentration coefficient Kt caused by θ on fatigue life N is decreasing constantly.The associated parametric equations have important instructive significance for the improvement of stress concentration degree and fatigue life of welded butt joint for train bogie.展开更多
A method of estimating the safe storage life （τ）, self-accelerating decomposition temperature （TsADT） and critical temperature of thermal explosion （Tb） of double-base propellant using isothermal and non-isothe...A method of estimating the safe storage life （τ）, self-accelerating decomposition temperature （TsADT） and critical temperature of thermal explosion （Tb） of double-base propellant using isothermal and non-isothermal decomposition behaviours is presented. For double-base propellant composed of 56±1wt% of nitrocellulose （NC）, 27±0.5wt% of nitroglycerine （NG）, 8.15±0.15wt% of dinitrotoluene （DNT）, 2.5±0.1wt% of methyl centralite, 5.0±0.15wt% of catalyst and 1.0±0.1wt% of other, the values of r of 49.4 years at 40℃, of TSAOT of 151.35℃ and of Tb of 163.01℃ were obtained.展开更多
Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the...Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the 28-inch submarine pipeline in the East China Sea, the pipeline was segmented according to the similarity, considering the factors of pipe assembly, typhoon, current, wave and seabed topography. The effects of span length on natural frequency in each section of submarine pipeline were analyzed by finite element model. The maximum safe span length allowed by each pipeline section was verified by fatigue cumulative damage theory, and the fatigue life of each pipeline section were predicted. The results showed that each order natural frequency of the pipeline decreased with the increase of span length. The calculated results of empirical formulas were much smaller than those of the FEM analysis. The increase of the gap between the suspended pipeline and the seabed was beneficial to enhance the fatigue life of the suspended pipeline.展开更多
以某型现役汽车起重机底架钢结构为研究对象,建立起重机虚拟样机模型及有限元静力学模型,分析并获得五个载荷步下的名义应力谱;基于FE-SAFE(durability analysis software for finite element models)耐久性分析软件,用多轴临界平面疲...以某型现役汽车起重机底架钢结构为研究对象,建立起重机虚拟样机模型及有限元静力学模型,分析并获得五个载荷步下的名义应力谱;基于FE-SAFE(durability analysis software for finite element models)耐久性分析软件,用多轴临界平面疲劳损伤模型,采用Brown-Miller准则建立寿命损伤模型,对底架结构的疲劳寿命进行预算。预算结果表明该型起重机底架结构工作约3 062个循环时出现肉眼可见裂纹,而其使用寿命约为70 555个工作循环。其疲劳寿命预算分析为某型现役起重机的实际设计和使用检修提供有价值的参考。展开更多
为研究由多构件构成的输电线耐张串金具在外部荷载作用下的疲劳寿命,提出了以多个静力组合荷载构成的工况计算疲劳寿命的方法.首先在Abaqus中建立输电线耐张串金具有限元模型,分别求解在随机风荷载作用下的动力分析和由不同组合荷载组...为研究由多构件构成的输电线耐张串金具在外部荷载作用下的疲劳寿命,提出了以多个静力组合荷载构成的工况计算疲劳寿命的方法.首先在Abaqus中建立输电线耐张串金具有限元模型,分别求解在随机风荷载作用下的动力分析和由不同组合荷载组成多工况静力分析的应力解.将其导入Fe-Safe中,计算动力工况和不同静力工况的疲劳寿命.以FOS(Factors of Strength)强度因子为评估指标,对比动力与静力工况的疲劳寿命结果的区别,探究不同静力工况的应力解对疲劳寿命结果的影响.结果表明:该方法可有效地提高此类结构的计算效率;非线性较强的U形挂环和球头挂环受初始应力影响较大,会产生较大的相对误差;但在实际载荷分量变化范围以内,各构件静力与动力工况的疲劳寿命预测结果相差不大.展开更多
文摘＂Until very recently, 12-year-old Li Xioling drank the spring water that originated from the Longmen Shan, orthe Dragon＇s Gate Mountains of the Tibetan Plateau. Sitting in a makeshift house set up on the bank of the Yanhe River outside her home town Bailu Township of Pengzhou city, Sichuan Province, Li says, ＂It tastes a little sweet. We used itto cook and to bathe.＂
基金supported by the National Natural Science Foundation of China(No.51365014)Natural Science Foundation of Jiangxi Province(No.20151BAB206007)
文摘Stress concentration has a significant effect on fatigue properties of welded butt joint of bogie.The influences of joint geometric parameters {weld edge transition arc radius r,weld toe inclination angle θ） on stress concentration coefficient Kt at weld toe and fatigue life N were studied based on the finite element software ABAQUS/FE-SAFE,and the parametric equations were founded based on regression analysis of Origin software.The results show that weld edge transition arc radius r plays the most important role in stress concentration coefficient Kt as well as weld toe inclination angle 0.For the same inclination angle θ,stress concentration coefficient Kt decreases gradually with transition arc radius r increasing.With inclination angle θ increases,the effect of transition arc radius r on stress concentration factor Kt is increasing continuously,also the effect of change in stress concentration coefficient Kt caused by r on fatigue life N is increasing continuously.While in the case of same weld edge transition arc radius r,stress concentration coefficient Kt increases with inclination angle θincreasing.With transition arc radius r increases,the effect of inclination angle θ on stress concentration factor Kt is decreasing constantly,the effect of change in stress concentration coefficient Kt caused by θ on fatigue life N is decreasing constantly.The associated parametric equations have important instructive significance for the improvement of stress concentration degree and fatigue life of welded butt joint for train bogie.
基金We are grateful to the National Natural Science Foundation of China （No. 20573098）
文摘A method of estimating the safe storage life （τ）, self-accelerating decomposition temperature （TsADT） and critical temperature of thermal explosion （Tb） of double-base propellant using isothermal and non-isothermal decomposition behaviours is presented. For double-base propellant composed of 56±1wt% of nitrocellulose （NC）, 27±0.5wt% of nitroglycerine （NG）, 8.15±0.15wt% of dinitrotoluene （DNT）, 2.5±0.1wt% of methyl centralite, 5.0±0.15wt% of catalyst and 1.0±0.1wt% of other, the values of r of 49.4 years at 40℃, of TSAOT of 151.35℃ and of Tb of 163.01℃ were obtained.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.11802168 and 51575331)project funded by China Postdoctoral Science Foundation(No.2019M661458)
文摘Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the 28-inch submarine pipeline in the East China Sea, the pipeline was segmented according to the similarity, considering the factors of pipe assembly, typhoon, current, wave and seabed topography. The effects of span length on natural frequency in each section of submarine pipeline were analyzed by finite element model. The maximum safe span length allowed by each pipeline section was verified by fatigue cumulative damage theory, and the fatigue life of each pipeline section were predicted. The results showed that each order natural frequency of the pipeline decreased with the increase of span length. The calculated results of empirical formulas were much smaller than those of the FEM analysis. The increase of the gap between the suspended pipeline and the seabed was beneficial to enhance the fatigue life of the suspended pipeline.
文摘以某型现役汽车起重机底架钢结构为研究对象,建立起重机虚拟样机模型及有限元静力学模型,分析并获得五个载荷步下的名义应力谱;基于FE-SAFE(durability analysis software for finite element models)耐久性分析软件,用多轴临界平面疲劳损伤模型,采用Brown-Miller准则建立寿命损伤模型,对底架结构的疲劳寿命进行预算。预算结果表明该型起重机底架结构工作约3 062个循环时出现肉眼可见裂纹,而其使用寿命约为70 555个工作循环。其疲劳寿命预算分析为某型现役起重机的实际设计和使用检修提供有价值的参考。
文摘为研究由多构件构成的输电线耐张串金具在外部荷载作用下的疲劳寿命,提出了以多个静力组合荷载构成的工况计算疲劳寿命的方法.首先在Abaqus中建立输电线耐张串金具有限元模型,分别求解在随机风荷载作用下的动力分析和由不同组合荷载组成多工况静力分析的应力解.将其导入Fe-Safe中,计算动力工况和不同静力工况的疲劳寿命.以FOS(Factors of Strength)强度因子为评估指标,对比动力与静力工况的疲劳寿命结果的区别,探究不同静力工况的应力解对疲劳寿命结果的影响.结果表明:该方法可有效地提高此类结构的计算效率;非线性较强的U形挂环和球头挂环受初始应力影响较大,会产生较大的相对误差;但在实际载荷分量变化范围以内,各构件静力与动力工况的疲劳寿命预测结果相差不大.
