Prediction And Analysis Of Damage Cracks Of Powder Metallurgy Parts In Forming

Powder Metallurgy(PM)has become the preferred manufacturing technology on the key components of aeroengine and automotive manufacture.However,with the increasing demand for complex shaped and high-performance parts,cracking gradually becomes one of the most critical concerns in the PM industry.Currently,the research on the crack prediction of powder compacts are mostly concentrated on the qualitative analysis,as well as the interaction and contact between the all phases during the forming process acquires little attention.Therefore,this study constructed a metal powder compact damage model based on the generalized plastic mechanics and determined the compact fracture parameters by radial and uniaxial compression experiment.The fracture parameters were used as the initial criterion of the extended finite element(XFEM)to simulate the cracks.Quantitative analysis and prediction of the crack in the whole fabrication cycle of complex shape compaction were realized from a combination of the crack propagation criterion based on energy method and an integrated rapid modeling method.The prevention and control method of damage and crack of compacting compaction was put forward,which provided scientific reference for the design of powder metallurgy parts,the design of pressing process and the design of die.The main research contents of this paper are as follows:1.Experimental method and numerical simulation were used respectively to measure the compact strength experiment and measure the related parameters.This provided a foundation for compact tensile strength for subsequent fracture cracks in the process of press forming of powder metallurgy parts in numerical simulation.The feasibility of the model simulation of compact mechanical experiment was confirmed by comparing the draw cohesion model combined with correction of Drucker-Prager Cap.2.Based on the Drucker-Prager Cap constitutive model of density correlation,the damage model of metal powder green compact was derived,and the model was used as the crack initiation criterion of XFEM.In combination with the energy-based crack growth criterion,the crack formation and evolution of metal powder green compact were simulated,verified and analyzed.3.An integrated rapid modeling and simulation method was proposed.Combined with the above extended finite element method,the pressing and forming simulation of typical ?,?,? and ? parts in powder metallurgy industry was carried out.