Numerical simulation of intergranular mesomotion of tungsten copper powder explosion compaction
The process of explosive compaction of powder into a dense body and the formation of bonding is mainly the microscopic movement process of the collapse and closure of pores between particles in porous materials.Since smooth particle dynamics(SPH)does not rely on grids to calculate the flow problem of large deformation of structures in Lagrangian coordinates,this paper uses SPH method to numerically model and simulate the closing process of typical micro pores in explosive compaction of tungsten copper powder,and theoretically analyzes the mechanism of energy deposition in explosive compaction of powder.Firstly,the closed motion of the regular triangular and inverted triangular pores in the powder dense sphere model is loaded with a fixed impact velocity boundary.According to the simulated pore closure deformation movement diagram and temperature nephogram,it can be concluded that micro explosive welding,large plastic deformation,micro pore closure,supersonic collision,micro friction welding,jet penetration and liquid phase sintering occurred in the process of pore closure.By comparing the jet shape and pore closure state of W-Cu particles in different arrangement modes,it can be seen that when the triangular pore is closed,the tungsten copper jet flows to the tungsten side,the copper side is continuous jet,and the tungsten side is intermittent jet,during the collision of cone top of the copper tungsten particles and the jet ocurring.It can be seen that micro Explosion welding has greater self-cleaning effect on the surface of copper particles than the tungsten side.When the copper particles are below,the lower copper is significantly squeezed and protruding during the triangular pores close.When the tungsten particles are below,the deformation in the same area is relatively small.When the inverted triangle pore is closed,the pore closure morphology is relatively regular and the plastic deformation of the lower surface of the tungsten particles at the upper end is relatively small at the condition of that the tungsten particles are above.When the copper particles are above,the final morphology of pore closure shows an irregular state,with the pore closure leaning towards tungsten particles and copper particles exhibiting significant plastic deformation.Under different arrangements,the final closure state and particle morphology of pores vary.The energy deposition mechanism generated by different pore closure methods is consistent with the theoretical analysis.
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