Finite Element Simulation Of Ultra-precision Machining Of Carbon Nanotubes Reinforced Aluminum Matrix Composites

Carbon nanotubes reinforced aluminum matrix composites not only have excellent mechanical properties,but also have good electrical and thermal conductivity,high temperature stability and wear resistance,etc.,which are the focus of new materials research.Carbon nanotube aluminum matrix composite is a kind of new material which is formed by adding carbon nanotube composite with aluminum or aluminum alloy as matrix through certain preparation technology.Due to the extraordinary properties of carbon nanotube aluminum matrix composites,carbon nanotube aluminum matrix composites can replace ordinary aluminum alloy to produce high-strength and lightweight aerospace components in advanced and sophisticated fields,such as engine guide vane,ultra-light space telescope,etc.The machining accuracy of these parts is usually nanoscale,far higher than the general precision machinery and instruments.Therefore,the ultra-precision machining of carbon nanotube aluminum matrix composites with the accuracy of nanometer to obtain the parts with extremely high surface accuracy,shape accuracy and surface integrity is of certain guiding significance to broaden the application range of ultra-precision machining theory of metal matrix composites and improve the processing technology level.In this paper,based on the two-dimensional orthogonal cutting theory,the twodimensional representative finite element model of carbon nanotubes aluminum matrix composites was established by using the finite element software ABAQUS to study the effects of the aspect ratio,distribution Angle and bending degree of carbon nanotubes on the bonding interface,cutting force and surface residual stress of the composites.The results show that with the increase of the length/diameter ratio of carbon nanotubes,the crack depth of the composite interface increases,and the crack failure degree decreases.At the same time,with the increase of the length/diameter ratio of carbon nanotubes in the composite material,the cutting force in the X direction will increase at the beginning stage.When the cutting force in the X direction increases to the maximum,the cutting force in the X direction gradually decreases with the increase of the length/diameter ratio of carbon nanotubes.On the contrary,the Y direction cutting force has no significant relationship with the length/diameter ratio of CNTs.In addition,with the increase of the aspect ratio of CNTs,the residual compressive stress value of the machined surface gradually increases,indicating that the increase of the aspect ratio of CNTs is conducive to the improvement of the quality of the machined surface.The distribution Angle of carbon nanotubes in the composites has a great influence on the interfacial bonding strength of the composites.With the increase of the distribution Angle of carbon nanotubes,the interface between the matrix and the reinforcement phase in the composites is not easy to crack,and the quality of the machined surface and subsurface is better.In addition,the smaller the distribution Angle of carbon nanotubes in the composites,the greater the fluctuation of cutting forces in X and Y directions.The residual stresses of the machined surface are all compressive stresses and increase with the increase of distribution Angle,which is beneficial to the quality of the machined surface.The bending of carbon nanotubes has a significant effect on the processing characteristics of carbon nanotubes aluminum matrix composites.With the increase of the bending degree of carbon nanotubes,both the crack propagation depth and the failure degree of the composite interface increase,but when the bending degree reaches a certain degree,the crack propagation depth and the failure degree of the machined surface tend to be stable.In addition,with the increase of the bending degree of carbon nanotubes,the cutting force in the X direction gradually decreases,and the change of the cutting force in the Y direction is small.The residual stress of the machined surface is compressive stress,and the compressive stress gradually increases with the increase of the bending degree,which is beneficial to the quality of the machined surface.When the bending degree exceeds a certain value,the residual compressive stress of the machined surface will be greatly reduced.