FEM Analysis And Experimental Study Of Ultrasonically Assisted Milling Of Particle-reinforced Titanium Matrix Composites

Particle reinforced titanium matrix composites(PTMCs)are a new type of metal matrix composite material using Ti-6Al-4V titanium alloy as the matrix by adding high hardness and high modulus reinforcing phases to it.It has good mechanical and physical characteristics,including high strength,high hardness,and high specific modulus,and it has a wide range of potential uses in the maritime,aerospace,and biomedical industries.However,there are technical problems such as serious tool wear and poor machining surface quality in the actual machining process.Therefore,this paper investigates the machining of particle-reinforced titanium matrix composites by ultrasonic amplitude assisted milling with Ti C_p/Ti-6Al-4V using a combination of simulation and experiment,which is important for the efficient and low loss machining of titanium matrix composites.The main research work completed in this thesis is as follows:(1)Based on ABAQUS/Explicit software,a two-dimensional cutting model was established by combining the motion trajectory of axial ultrasonic vibration processing to model the reinforcing particles and the substrate material in multiple phases,where the particle position parameters were randomly generated using Python code.The cutting forces and cutting temperatures of ultrasonic vibration-assisted milling compared with conventional milling of PTMCs were investigated through thermodynamic coupled cutting simulation.Under various cutting parameters,the variations in cutting force and cutting temperature between the use of axial ultrasonic vibration and conventional cutting methods were examined,and their impacts on cutting force and cutting temperature were investigated.(2)Build a test platform for ultrasonic vibration-assisted milling and conventional milling to conduct side-milling comparison tests on PTMCs.The variation law of machine parameters(spindle speed,feed per tooth and milling width)on milling force and cutting and milling temperature was analyzed,and the effect of the application of ultrasonic vibration on them was also analyzed.To confirm the simulation’s accuracy and give a theoretical foundation for future simulation work,the simulation results and experimental data are also compared.(3)A two-dimensional single-particle cutting simulation model based on ABAQUS/Explicit software was established to study the breaking behavior of particles in two cutting methods under different tool path scenarios,respectively.A two-dimensional multi-particle cutting simulation model based on ABAQUS/Explicit software was established to study the effect of inter-particle stress transfer on particle fragmentation.The effect of the change of cutting force direction on the sprouting and expansion of particle cracks during ultrasonic vibration cutting is analyzed from the perspective of simulated stress evolution to further reveal the suppression of surface defects by ultrasonic vibration-assisted cutting method.(4)The surface roughness and surface defects of the two cutting methods were analyzed by combining laser surface morphometry and scanning electron microscopy.The variation of machined surface roughness under different milling speeds is explained,and the improvement of surface quality by ultrasonic vibration assisted milling is explained.The surface micro-topography further confirmed the inhibition of ultrasonic vibration on surface defects,and found more suitable parameters for ultrasonic vibration cutting,which provided a technical basis for the selection of cutting parameters for PCD tool milling PTMC.