Modelling the flow processes of a particle reinforced metal matrix composite during machining

Abstract

Abstract This paper reports on a numerical test program to model the micromechanics associated with the machining of a particle-reinforced metal matrix composite (PRMMC) The composite material modelled was a 35% by volume SiC particle-reinforced A356 aluminium alloy. A submodelling approach was adopted in order to analyse the micromechanical problem. Simulation of the metal cutting process was performed using FORGE2, an elasto-visco plastic FEA code. The micromechanical submodelling was performed using ANSYS 5.2, an elastoplastic FEA code. The machining model of the aluminium alloy without the reinforcement and the resulting hydrostatic pressure istribution were used as inputs for the ANSYS micromechanical submodels of the composite. The regions modelled included the primary shear zone, the machined surface, and the chip-tool contact region, in both the sticking and sliding regions along the rake face. All FE models were assumed to be plane strain. The results of the FE submodelling agree favourably with those obtained from machined test pieces when observed under a scanning electron microscope (SEM). Particle clustering has a detrimental effect on the rate of void growth. It was observed that SiC particles under the action of normal loads cause intense normal stresses at the point of contact between the aluminium matrix and the tungsten-carbide particles within the cutting tool. Overstraining of the matrix envelopes the SiC particle in contact with the cutting tool. A coarse grade of diamond tool had a superior wear resistance compared to a fine grade.