MODELING THE FLOW PROCESSES OF A PARTICLE-REINFORCED METAL-MATRIX COMPOSITE DURING MACHINING

This paper reports on a numerical test program to model the micromecha nics associated with the machining of a particle-reinforced metal matr ix composite (PRMMC) The composite material modelled was a 35% by volu me SIC particle-reinforced A356 aluminium alloy. A submodelling approa ch was adopted in order to analyse the micromechanical problem. Simula tion of the metal cutting process was performed using FORGE2, an elast o-visco plastic FEA code. The micromechanical submodelling was perform ed using ANSYS 5.2, an elastoplastic FEA code. The machining model of the aluminium alloy without the reinforcement and the resulting hydros tatic pressure istribution were used as inputs for the ANSYS micromech anical submodels of the composite. The regions modelled included the p rimary shear zone, the machined surface, and the chip-tool contact reg ion, 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 subm odelling agree favourably with those obtained from machined test piece s when observed under a scanning electron microscope (SEM). Particle c lustering has a detrimental effect on the rate of void growth. It was observed that SiC particles under the action of normal loads cause int ense normal stresses at the point of contact between the aluminium mat rix and the tungsten-carbide particles within the cutting tool. Overst raining of the matrix envelopes the SIC particle in contact with the c utting tool. A coarse grade of diamond tool had a superior wear resist ance compared to a fine grade. (C) 1997 Elsevier Science Limited.