| Particle-reinforced metal matrix composites(PRMMCs)are used in many industries,such as automotive manufacturing,aerospace,and underwater structures,among many others,due to their unique material properties such as high strength ratios and good damage limits,where SiC/Al composites pose a great challenge to the actual processing process due to the significant difference in hardness between the two phases of the material.Conventional machining of SiC/Al composites results in high cutting forces and severe frictional heating due to frequent contact between the three phases of toolparticle-matrix,which affects the quality of the machined surface as well as the remaining tool life.Therefore,this thesis investigates the machining mechanism of SiC/Al composites under these conditions one by one by adding corresponding auxiliary machining methods based on ABAQUS simulation software for numerical simulation,as follows:(1)Based on ABAQUS software,a microscopic orthogonal cutting simulation model of SiC/Al composites is established,and the Johnson-Cook principal structure as well as the Johnson-Cook damage criterion are used to describe the deformation failure of the Al matrix during the cutting simulation,and the SiC particles are described by the brittle crack criterion due to their hard and brittle properties,and the one-dimensional x and y directions are added on top of the constructed model Ultrasonic vibration-assisted machining(UVC),the cutting mechanism was studied in depth,emphasizing the relationship between it and the vibration parameters used,and the simulation results showed that high-frequency vibration in the x and y directions significantly reduces the average cutting force and the average cutting temperature at the tool tip.However,as the amplitude increases,all unidirectional vibration cutting causes an increase in the average cutting temperature,and the maximum cutting temperature at the tool tip varies with the ultrasonic vibration parameters with a similar trend.(2)Using the Coupled-Eulerian-Lagrange method(CEL),a high-pressure water jet model based on Eulerian lattice(Eulerian)is added on top of the established microscopic orthogonal cutting model of SiC/Al composites to realize the heat exchange between the cutting process and the water jet.The results show that the combination of thermal and impact effects of high-pressure water jet can significantly reduce the cutting temperature for different volume fractions of SiC particles.And with the increase of water jet velocity,the equivalent plastic strain region of the workpiece gradually decreases and the average cutting force decreases.(3)Combine the above two auxiliary methods to study the ultrasonic vibrationassisted cutting of SiC/Al composites under high-pressure water jets.The results show that the combined aid of high-pressure water jet and ultrasonic vibration will significantly reduce the cutting temperature,and the chip is easy to break,making the cutting force lower,in addition,the increase of particle content in these two combined aid methods will cause excessive machining stress and high temperature.(4)The removal mechanism of machining SiC/Al composites was investigated by building a 3D micro-turning and micro-milling non-homogeneous model with spherical SiC particles,also with 1D ultrasonic vibration on the 3D turning model and ultrasonic torsional vibration on the milling model,to demonstrate its superiority in cutting optimisation.Then,related experiments were carried out to compare the chip produced by turning and the machined surface morphology produced by milling with the simulation results,and a good consistency was obtained. |
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