Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed t...Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed to understand better the fracture of coating layer of GA steel sheet during plastic deformation. Yield strength of the coating layer was calculated by using a relative difference between hardness of coating layer measured from the nano-indentation test and that of substrate. To measure shearing strength at the interface between substrate and coating layer, shearing test with two specimens attached by an adhesive was carried out. Using the mechanical properties measured, a series of finite element analyses coupled with a failure model was performed. Results reveal that the fracture of coating layer occurs in an irregular manner at the region where compressive deformation is dominant. Meanwhile, a series of vertical cracks perpendicular to material surface are observed at the tensile stressed-region. It is found that 0.26-0.28 of local equivalent plastic strain exists at the coating and substrate at the beginning of failure. The fracture of coating layer depends on ductility of the coating layer considerably as well.展开更多
Both the potential of electric field and the velocity potential of ideal fluid can be expressed with Laplace equation, thus the velocity field of ideal fluid can be simulated by electric field. According to this princ...Both the potential of electric field and the velocity potential of ideal fluid can be expressed with Laplace equation, thus the velocity field of ideal fluid can be simulated by electric field. According to this principle, one simple lab-device is developed. This method can be used to analyze and study the flotation column structure, operation condition such as feed rate, recirculation rate and tailing discharged rate etc. Because this method takes the wall effects of column into consideration in the simulation, it is significance for the scaling-up of flotation column.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0074936)
文摘Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed to understand better the fracture of coating layer of GA steel sheet during plastic deformation. Yield strength of the coating layer was calculated by using a relative difference between hardness of coating layer measured from the nano-indentation test and that of substrate. To measure shearing strength at the interface between substrate and coating layer, shearing test with two specimens attached by an adhesive was carried out. Using the mechanical properties measured, a series of finite element analyses coupled with a failure model was performed. Results reveal that the fracture of coating layer occurs in an irregular manner at the region where compressive deformation is dominant. Meanwhile, a series of vertical cracks perpendicular to material surface are observed at the tensile stressed-region. It is found that 0.26-0.28 of local equivalent plastic strain exists at the coating and substrate at the beginning of failure. The fracture of coating layer depends on ductility of the coating layer considerably as well.
文摘Both the potential of electric field and the velocity potential of ideal fluid can be expressed with Laplace equation, thus the velocity field of ideal fluid can be simulated by electric field. According to this principle, one simple lab-device is developed. This method can be used to analyze and study the flotation column structure, operation condition such as feed rate, recirculation rate and tailing discharged rate etc. Because this method takes the wall effects of column into consideration in the simulation, it is significance for the scaling-up of flotation column.
