本文基于AREM（Advanced Regional Eta Model）模式，结合中国气象局成都高原气象研究所西南低涡加密观测科学试验得到的探空观测第一手资料，通过对2012年7月3～4日四川区域性暴雨天气过程（20120703过程）进行数值模拟分析，结果表明...本文基于AREM（Advanced Regional Eta Model）模式，结合中国气象局成都高原气象研究所西南低涡加密观测科学试验得到的探空观测第一手资料，通过对2012年7月3～4日四川区域性暴雨天气过程（20120703过程）进行数值模拟分析，结果表明：（1）降水雨带的分布主要取决于西南低涡移动路径，不同初值会使得低涡路径在磨合协调期产生强摆动，稳定后则在此基础上，随着环境流场继续移动发展。（2）引入4个加密探空站点资料会对整个大气物理量场造成一定影响，最大差值分布在这些站点附近，热力和动力物理量场最大偏差中心并不重合。时间演变直观地说明了初值对局地大气状态的影响时段有限，主要集中在前期，与模式自身调整期相重叠。（3）初始的大气状态必然会随着模式的磨合过程进行调整，不同初值在调整期能对中小尺度低涡系统的位置及强度产生影响，形成各自稳定的低涡系统初态。（4）低涡中心所对应的散度、涡度、垂直速度关系非常密切，但三者强度和发展高度的演变并非完全一致。展开更多
Various microstructure-level finite element models were generated according to the real microstructure of DP590 steel to capture the mechanical behavior and fracture mode.The failure mode of the dual-phase(DP)steels,m...Various microstructure-level finite element models were generated according to the real microstructure of DP590 steel to capture the mechanical behavior and fracture mode.The failure mode of the dual-phase(DP)steels,mainly resulting from microstructure-level inhomogeneity and initial geometrical imperfection,was predicted using the plastic strain localization theory.In addition,dog-bone-type tensile test specimens with different edge qualities were prepared and the deformation processes were recorded using a digital image correlation system.When the steel exhibited no initial geometrical imperfection,void initiation was triggered by decohesion between martensite and ferrite which was predicted based on the severe strain concentration,or tensile stress in areas where stress triaxiality and strain values were high.Final failure was caused by shear localization in the vicinity.Moreover,the initial geometrical imperfections severely affected the overall ductility and failure mode of the DP590steel.When initial geometrical imperfections were deeply ingrained,an incipient crack began at the site of initial geometrical imperfection,and then caused progressive damage throughout the microstructure,from the area of shear localization to the final fracture.Overall,the depth of the geometrical imperfection was the critical factor in determining whether internal decohesion or a local crack plays a dominant role.展开更多
文摘本文基于AREM（Advanced Regional Eta Model）模式，结合中国气象局成都高原气象研究所西南低涡加密观测科学试验得到的探空观测第一手资料，通过对2012年7月3～4日四川区域性暴雨天气过程（20120703过程）进行数值模拟分析，结果表明：（1）降水雨带的分布主要取决于西南低涡移动路径，不同初值会使得低涡路径在磨合协调期产生强摆动，稳定后则在此基础上，随着环境流场继续移动发展。（2）引入4个加密探空站点资料会对整个大气物理量场造成一定影响，最大差值分布在这些站点附近，热力和动力物理量场最大偏差中心并不重合。时间演变直观地说明了初值对局地大气状态的影响时段有限，主要集中在前期，与模式自身调整期相重叠。（3）初始的大气状态必然会随着模式的磨合过程进行调整，不同初值在调整期能对中小尺度低涡系统的位置及强度产生影响，形成各自稳定的低涡系统初态。（4）低涡中心所对应的散度、涡度、垂直速度关系非常密切，但三者强度和发展高度的演变并非完全一致。
基金supported by the National Natural Science Foundation of China(Grant No.51105250)
文摘Various microstructure-level finite element models were generated according to the real microstructure of DP590 steel to capture the mechanical behavior and fracture mode.The failure mode of the dual-phase(DP)steels,mainly resulting from microstructure-level inhomogeneity and initial geometrical imperfection,was predicted using the plastic strain localization theory.In addition,dog-bone-type tensile test specimens with different edge qualities were prepared and the deformation processes were recorded using a digital image correlation system.When the steel exhibited no initial geometrical imperfection,void initiation was triggered by decohesion between martensite and ferrite which was predicted based on the severe strain concentration,or tensile stress in areas where stress triaxiality and strain values were high.Final failure was caused by shear localization in the vicinity.Moreover,the initial geometrical imperfections severely affected the overall ductility and failure mode of the DP590steel.When initial geometrical imperfections were deeply ingrained,an incipient crack began at the site of initial geometrical imperfection,and then caused progressive damage throughout the microstructure,from the area of shear localization to the final fracture.Overall,the depth of the geometrical imperfection was the critical factor in determining whether internal decohesion or a local crack plays a dominant role.
