Making use of the method of obtaining regional vertical strain rate from regional preciseleveling data and gaining dynamic pattern combining with deformation data on spanningfaults, the regional vertical strain dynami...Making use of the method of obtaining regional vertical strain rate from regional preciseleveling data and gaining dynamic pattern combining with deformation data on spanningfaults, the regional vertical strain dynamic evolution characteristics of several moderatelystrong earthquakes such as Lijiang (M_s 7.0) and Menyuan (M_s 6.4) earthquakes occurredin crustal deformation monitoring areas located in the western Yunnan and Qilianshan-Hexiregion. Based on the above-mentioned facts, by studying the time-space nonhomogeneity andstrain energy accumulation status, some criteria for judging the medium. and short-termstrong seismic risk regions according to the regional vertical strain rate dynamic informationare proposed.展开更多
As metallic foams used for energy absorption in the automotive and aerospace industries, recently invented lotus-type porous metals are viewed as potential energy absorbers. Yet, solid conclusion on their eligibility ...As metallic foams used for energy absorption in the automotive and aerospace industries, recently invented lotus-type porous metals are viewed as potential energy absorbers. Yet, solid conclusion on their eligibility as energy absorbers is still in question, particularly when compression is in the direction perpendicular to the axial orientation of cylindrical pores. In this work, the energy absorption of lotus-type porous coppers in the perpendicular direction is investigated at strain rates from 0.001 s^（-1） to^2400 s^（-1）. The energy absorption capacity and the energy absorption efficiency are calculated to be4–16 k J/kg and 0.32–0.7, respectively, slightly inferior to metal foams and the same porous solid compressed in the parallel direction due to the shortened extent of the plateau stress region. The deformation mechanism is examined experimentally in conjunction with finite element modeling. Both suggest that gradual squeeze and collapse of pores are the mechanisms accommodating the energy absorption. The deformation is generally evenly distributed over pore ligaments and independent of strain rate.展开更多
基金This research was sponsored by the National Key Basic Research Project (G1998040703) and China Seismological Burear (95-04-04-01-01).
文摘Making use of the method of obtaining regional vertical strain rate from regional preciseleveling data and gaining dynamic pattern combining with deformation data on spanningfaults, the regional vertical strain dynamic evolution characteristics of several moderatelystrong earthquakes such as Lijiang (M_s 7.0) and Menyuan (M_s 6.4) earthquakes occurredin crustal deformation monitoring areas located in the western Yunnan and Qilianshan-Hexiregion. Based on the above-mentioned facts, by studying the time-space nonhomogeneity andstrain energy accumulation status, some criteria for judging the medium. and short-termstrong seismic risk regions according to the regional vertical strain rate dynamic informationare proposed.
基金financial support from the National Natural Science Foundation of China (Grant No. 50904004)
文摘As metallic foams used for energy absorption in the automotive and aerospace industries, recently invented lotus-type porous metals are viewed as potential energy absorbers. Yet, solid conclusion on their eligibility as energy absorbers is still in question, particularly when compression is in the direction perpendicular to the axial orientation of cylindrical pores. In this work, the energy absorption of lotus-type porous coppers in the perpendicular direction is investigated at strain rates from 0.001 s^（-1） to^2400 s^（-1）. The energy absorption capacity and the energy absorption efficiency are calculated to be4–16 k J/kg and 0.32–0.7, respectively, slightly inferior to metal foams and the same porous solid compressed in the parallel direction due to the shortened extent of the plateau stress region. The deformation mechanism is examined experimentally in conjunction with finite element modeling. Both suggest that gradual squeeze and collapse of pores are the mechanisms accommodating the energy absorption. The deformation is generally evenly distributed over pore ligaments and independent of strain rate.
