Numerical simulation of residual stress field in green power metallurgy compacts by modified Drucker-Prager Cap model

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.

论合作社资本报酬上限的立法设置

迄今为止,中外合作社“资本报酬有限原则”立法的通行模式,是给资本报酬设置一个“数值”上限,但该模式的突出弊端是不利于合作社融资。从应然角度看,由于合作社资本的基本角色是充当合作社生产要素,合作社资本报酬在性质上属于合作社使用这种“生产要素”需要付出的“市场对价”,因此,合作社资本报酬的水平在任何情况下都不可能突破“生产要素使用对价”。这就为立法按“生产要素使用对价”设置资本报酬上限提供了内在根据。进一步看,立法按“生产要素使用对价”设置上限同样可以贯彻“资本报酬有限原则”,方便合作社支付市场化报酬以吸引投资,且一个合作社支付的资本报酬是否高于“生产要素使用对价”也存在有评判的客观标准。基于此,我国合作社“资本报酬有限”原则立法应当以“生产要素使用对价”上限模式取代“数值”上限模式,即限制合作社资本报酬的数额超出合作社使用资本这种“生产要素”需要付出的“市场对价”。