Compaction process simulation and residual stress prediction of green PM compact were carried out with elasto-plastic 3D FEA based on the modified Drueker-Prager Cap model in Abaqus. The model parameters of the invest...Compaction process simulation and residual stress prediction of green PM compact were carried out with elasto-plastic 3D FEA based on the modified Drueker-Prager Cap model in Abaqus. The model parameters of the investigated powder Distaloy AE were determined as functions of relative density through typical mechanical property tests of powder. The model was implemented as a user subroutine USDFLD. Single sided compaction of a d20 ram^5 mm disk green compact of Distaloy AE was simulated, and the residual stress of the disk after ejection was predicted with FEA. The FEA results of the compaction process and the residual stress of the disk show good agreement with compaction experiments and X-ray diffraction measurements, which validates the model and its parameters. The results indicate that the compressive residual stresses exist mainly in a thin layer on the side surface, but the residual stresses are very small on the top and bottom surfaces.展开更多
This study established a 3D finite element model for 15# hydropower house of the Three Gorges Project (TGP) and performed a nonlinear dynamic analysis under pressure fluctuation. In this numerical model, the stiffness...This study established a 3D finite element model for 15# hydropower house of the Three Gorges Project (TGP) and performed a nonlinear dynamic analysis under pressure fluctuation. In this numerical model, the stiffness degradation in tension for concrete was considered on the basis of the continuum isotropic damage theory. Natural vibration frequencies of the damaged and undamaged structures were compared after static water pressure was applied. Then a study was further conducted on forced vibration of the powerhouse with pre-existing damages under pressure fluctuation that acts on the flow passage; displacement, velocity and acceleration of the important structural members were afterwards presented and checked. Numerical results show that tensile damages in concrete surrounding the spiral case only exert significant impact upon the dynamic characteristics of substructure but show little effect on the superstructure. Nevertheless vibrations of the powerhouse are still under the recommended vibration limits.展开更多
基金Project(2009ZX04004-031-04) supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China
文摘Compaction process simulation and residual stress prediction of green PM compact were carried out with elasto-plastic 3D FEA based on the modified Drueker-Prager Cap model in Abaqus. The model parameters of the investigated powder Distaloy AE were determined as functions of relative density through typical mechanical property tests of powder. The model was implemented as a user subroutine USDFLD. Single sided compaction of a d20 ram^5 mm disk green compact of Distaloy AE was simulated, and the residual stress of the disk after ejection was predicted with FEA. The FEA results of the compaction process and the residual stress of the disk show good agreement with compaction experiments and X-ray diffraction measurements, which validates the model and its parameters. The results indicate that the compressive residual stresses exist mainly in a thin layer on the side surface, but the residual stresses are very small on the top and bottom surfaces.
基金Project (No. 50809013) supported by the National Natural Science Foundation of China
文摘This study established a 3D finite element model for 15# hydropower house of the Three Gorges Project (TGP) and performed a nonlinear dynamic analysis under pressure fluctuation. In this numerical model, the stiffness degradation in tension for concrete was considered on the basis of the continuum isotropic damage theory. Natural vibration frequencies of the damaged and undamaged structures were compared after static water pressure was applied. Then a study was further conducted on forced vibration of the powerhouse with pre-existing damages under pressure fluctuation that acts on the flow passage; displacement, velocity and acceleration of the important structural members were afterwards presented and checked. Numerical results show that tensile damages in concrete surrounding the spiral case only exert significant impact upon the dynamic characteristics of substructure but show little effect on the superstructure. Nevertheless vibrations of the powerhouse are still under the recommended vibration limits.
