Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi＇s three-dimensional velocity field of rolling was analyzed and an anal...Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi＇s three-dimensional velocity field of rolling was analyzed and an analytical expression of rolling torque and single force was obtained. Through redoing the same experiment of rolling pure lead as Sims, the calculated results by the above expression were compared with those of Kobayashi and Sims formulae. The results show that the twin shear stress yield criterion is available for rolling analysis and the calculated results by the new formula are a little higher than those by Kobayashi and Sims ones if the reduction ratio is less than 30%.展开更多
Lattice-strained Si thin films grown onto SiGe(110)/Si(110) are attracting because of their potential to realize high-speed transistors. In this study we observe surface morphology of Si/SiGe/Si(110) using scanning el...Lattice-strained Si thin films grown onto SiGe(110)/Si(110) are attracting because of their potential to realize high-speed transistors. In this study we observe surface morphology of Si/SiGe/Si(110) using scanning electron microscopy and we also observe microstructure of the identical position using cross-sectional transmission electron microscopy. These results reveal that crossing of stress-induced twins causes remarkable surface roughness. We propose using vicinal substrate to avoid this phenomenon and our successive experimental results are shown in this paper.展开更多
Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is...Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.展开更多
A dynamic material model of Mg-4.51Al-1.19Zn-0.5Mn-0.5Ca(AZ41,mass fraction,%)magnesium alloy was put forward.The results show that the dynamic material model can characterize the deformation behavior and microstructu...A dynamic material model of Mg-4.51Al-1.19Zn-0.5Mn-0.5Ca(AZ41,mass fraction,%)magnesium alloy was put forward.The results show that the dynamic material model can characterize the deformation behavior and microstructure evolution and describe the relations among flow stress,strain,strain rates and deformation temperatures.Statistical analysis shows the validity of the proposed model.The model predicts that lower deformation temperature and higher strain rate cause the sharp strain hardening. Meanwhile,the flow stress curve turns into a steady state at high temperature and lower strain rate.The moderate temperature of 350 ℃and strain rate of 0.01 s-1 are appropriate to this alloy.展开更多
The Ms6.2 Dayao, Yunnan, earthquake occurred on July 21, 2003, followed by a major Ms6.1 earthquake about 88 days later in the same region. Hypocenters of the two earthquakes are almost in the same place. Based on the...The Ms6.2 Dayao, Yunnan, earthquake occurred on July 21, 2003, followed by a major Ms6.1 earthquake about 88 days later in the same region. Hypocenters of the two earthquakes are almost in the same place. Based on the P wave first motion polarities of the two aftershock sequences recorded by temporary stations, we have studied the stress field in the aftershock zone and obtained the two stress field directions in Dayao region using the new version of PKU_Grid^Test Software provided by Chunquan Yu. Assuming that the rotation of the stress field is caused by the second main shock, we estimated the crustal stress value in the focal region by using the stress value calculation method proposed by Yongge Wan. The estimated maximum, intermediate and minimum principal stresses are 166.3 MPa, 158.7 MPa and 151 MPa, respectively, before the second main shock. The normal and shear stresses projected on the fault plane of the second main shock before it occurred are 157.3 MPa, 7.4 MPa, and are 158.8 MPa, 0.2 MPa after it occurred, respectively. The perturbed input parameters experiments attest the stability of the solution. The result shows that the preseismic shear stress is larger than the post-seismic one, and their difference corresponds to the stress drop approximately. The estimated compressive stress level is very high, but the differential stress is low. The result is helpful for friction coefficient estimation, plate motion simulation and related studies.展开更多
基金ItemSponsored by National Natural Science Foundation of China (50474015)
文摘Using the twin shear stress yield criterion, the surface integral of the co-line vectors, and the integration depending on upper limit, Kobayashi＇s three-dimensional velocity field of rolling was analyzed and an analytical expression of rolling torque and single force was obtained. Through redoing the same experiment of rolling pure lead as Sims, the calculated results by the above expression were compared with those of Kobayashi and Sims formulae. The results show that the twin shear stress yield criterion is available for rolling analysis and the calculated results by the new formula are a little higher than those by Kobayashi and Sims ones if the reduction ratio is less than 30%.
文摘Lattice-strained Si thin films grown onto SiGe(110)/Si(110) are attracting because of their potential to realize high-speed transistors. In this study we observe surface morphology of Si/SiGe/Si(110) using scanning electron microscopy and we also observe microstructure of the identical position using cross-sectional transmission electron microscopy. These results reveal that crossing of stress-induced twins causes remarkable surface roughness. We propose using vicinal substrate to avoid this phenomenon and our successive experimental results are shown in this paper.
文摘Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far field uniform uniaxial tensile or compressive stress.
基金Project(Y2008F27)supported by the Natural Science Foundation of Shandong Province,China
文摘A dynamic material model of Mg-4.51Al-1.19Zn-0.5Mn-0.5Ca(AZ41,mass fraction,%)magnesium alloy was put forward.The results show that the dynamic material model can characterize the deformation behavior and microstructure evolution and describe the relations among flow stress,strain,strain rates and deformation temperatures.Statistical analysis shows the validity of the proposed model.The model predicts that lower deformation temperature and higher strain rate cause the sharp strain hardening. Meanwhile,the flow stress curve turns into a steady state at high temperature and lower strain rate.The moderate temperature of 350 ℃and strain rate of 0.01 s-1 are appropriate to this alloy.
基金supported by the National Natural Science Foundation of China (40874022,41074072)Public Utility Research Project (200808053)973 program (2008CB425703)
文摘The Ms6.2 Dayao, Yunnan, earthquake occurred on July 21, 2003, followed by a major Ms6.1 earthquake about 88 days later in the same region. Hypocenters of the two earthquakes are almost in the same place. Based on the P wave first motion polarities of the two aftershock sequences recorded by temporary stations, we have studied the stress field in the aftershock zone and obtained the two stress field directions in Dayao region using the new version of PKU_Grid^Test Software provided by Chunquan Yu. Assuming that the rotation of the stress field is caused by the second main shock, we estimated the crustal stress value in the focal region by using the stress value calculation method proposed by Yongge Wan. The estimated maximum, intermediate and minimum principal stresses are 166.3 MPa, 158.7 MPa and 151 MPa, respectively, before the second main shock. The normal and shear stresses projected on the fault plane of the second main shock before it occurred are 157.3 MPa, 7.4 MPa, and are 158.8 MPa, 0.2 MPa after it occurred, respectively. The perturbed input parameters experiments attest the stability of the solution. The result shows that the preseismic shear stress is larger than the post-seismic one, and their difference corresponds to the stress drop approximately. The estimated compressive stress level is very high, but the differential stress is low. The result is helpful for friction coefficient estimation, plate motion simulation and related studies.
基金supported by National Natural Science Foundation of China(Nos.51975146,52205344)the Natural Science Foundation of Shandong Province,China(No.ZR2020QE171)+1 种基金the Key Research and Development Plan in Shandong Province,China(No.2019JZZY010364)the National Defense Basic Scientific Research of China(No.JCK2018603C017)。
