A linear three dimensional finite element (FE) study has been carried out to examine the structural response of a prestressed concrete (PSC) inner containment (IC) dome of reactor building (double containment system) ...A linear three dimensional finite element (FE) study has been carried out to examine the structural response of a prestressed concrete (PSC) inner containment (IC) dome of reactor building (double containment system) of a typical Indian Nuclear Power Plant, having large steam generator (SG) openings with due emphasis on the local behaviour of the steel-concrete interfaces at the SG openings, due to initial prestress transfer. The predominant thrust of the study has been placed on the objective of predicting the possibilities of separation at the steel-concrete interface zones adjacent to the embedded plates (EPs) of the SG openings. Two types of modeling and analysis have been made to study the overall and local behaviour of the structure. Prestressing ducts, passive reinforcements and EPs have been included in the models in certain ways. For the FE analysis, the interface zone has been modeled using interface elements, the properties of which were derived from the results of past experiments conducted on steel plate-concrete inter-face specimens. The FE analysis results have been compared with the results of the past two FE analytical studies on the linear behaviour of the same PSC IC dome. Important observations have been made regarding dome deformation and stresses throughout the structure with special emphasis on the local behaviour of steel-concrete interfaces at and around the SG openings.展开更多
Under the premise of the Earth’s layer structure and mass distribution, the solid inner core cannot be stable in the center of the sphere. Thus, the deviation of the inner core is towards the sphere’s center and the...Under the premise of the Earth’s layer structure and mass distribution, the solid inner core cannot be stable in the center of the sphere. Thus, the deviation of the inner core is towards the sphere’s center and the liquid outer core must have asymmetrical thermal convection. Based on the two suggestions, a concise and self-consistent global motion model can be built. The model consists of the following cycle: an asymmetrical thermal convection structure in the outer core led by the dislocation of the inner core→the plume is in special upwell position because of differential activation→the formation and split of lithosphere→the split plates drift and assemble in a new location, the mass of which causes the inner core to deviate towards this direction again→the new asymmetry is formed. As this circulation continues, a definite and periodical motion emerges/forms. Its nonlinear features result in the Earth’s motion with simple mechanisms but complex behavior. Ultraterrestrial events may disturb or展开更多
Choosing inner door panel of auto as an example, the two stage deep drawing of complex sheet metal was studied. By using CAD software UG and numerical simulation software DYNAFORM, the characteristic of the CAD modeli...Choosing inner door panel of auto as an example, the two stage deep drawing of complex sheet metal was studied. By using CAD software UG and numerical simulation software DYNAFORM, the characteristic of the CAD modeling of the simple workpiece and the complex sheet metal, finite element modeling and the selection of parameters were analyzed. The effects of three important material parameters such as yield stress, strain hardening exponent and normal anisotropic parameter on the formability of the two stage deep drawing of inner door panel of auto were investigated. The results show that the yield stress has large influence on the increase of thickness, while the strain hardening exponent has little effect on the thickness change. Otherwise, larger normal anisotropic parameter can result in a better formability of the sheet.展开更多
文摘A linear three dimensional finite element (FE) study has been carried out to examine the structural response of a prestressed concrete (PSC) inner containment (IC) dome of reactor building (double containment system) of a typical Indian Nuclear Power Plant, having large steam generator (SG) openings with due emphasis on the local behaviour of the steel-concrete interfaces at the SG openings, due to initial prestress transfer. The predominant thrust of the study has been placed on the objective of predicting the possibilities of separation at the steel-concrete interface zones adjacent to the embedded plates (EPs) of the SG openings. Two types of modeling and analysis have been made to study the overall and local behaviour of the structure. Prestressing ducts, passive reinforcements and EPs have been included in the models in certain ways. For the FE analysis, the interface zone has been modeled using interface elements, the properties of which were derived from the results of past experiments conducted on steel plate-concrete inter-face specimens. The FE analysis results have been compared with the results of the past two FE analytical studies on the linear behaviour of the same PSC IC dome. Important observations have been made regarding dome deformation and stresses throughout the structure with special emphasis on the local behaviour of steel-concrete interfaces at and around the SG openings.
基金This work wassupposed by the National Natural Science Foundation of China (Grant No. 49632070) and the Ministry of Land and Resources of China.
文摘Under the premise of the Earth’s layer structure and mass distribution, the solid inner core cannot be stable in the center of the sphere. Thus, the deviation of the inner core is towards the sphere’s center and the liquid outer core must have asymmetrical thermal convection. Based on the two suggestions, a concise and self-consistent global motion model can be built. The model consists of the following cycle: an asymmetrical thermal convection structure in the outer core led by the dislocation of the inner core→the plume is in special upwell position because of differential activation→the formation and split of lithosphere→the split plates drift and assemble in a new location, the mass of which causes the inner core to deviate towards this direction again→the new asymmetry is formed. As this circulation continues, a definite and periodical motion emerges/forms. Its nonlinear features result in the Earth’s motion with simple mechanisms but complex behavior. Ultraterrestrial events may disturb or
文摘Choosing inner door panel of auto as an example, the two stage deep drawing of complex sheet metal was studied. By using CAD software UG and numerical simulation software DYNAFORM, the characteristic of the CAD modeling of the simple workpiece and the complex sheet metal, finite element modeling and the selection of parameters were analyzed. The effects of three important material parameters such as yield stress, strain hardening exponent and normal anisotropic parameter on the formability of the two stage deep drawing of inner door panel of auto were investigated. The results show that the yield stress has large influence on the increase of thickness, while the strain hardening exponent has little effect on the thickness change. Otherwise, larger normal anisotropic parameter can result in a better formability of the sheet.
