Grinding Removal Mechanism And Processes For SiCp/Al Composites With High Volume Fraction

Si Cp/Al composite is one of typical particle-reinforced composites and an important lightweight material in the aerospace and automotive fields.The surface cavity generated in the grinding process of Si Cp/Al composite directly affects the ground surface quality and the friction performance.The ground surface of Si Cp/Al composite consists of plastic aluminum alloy and brittle silicon carbide,and the surface cavity results from the crushing and shedding of silicon carbide particles,the characteristic of which is closely related to the grinding process parameters.The research on the grinding removal mechanism and processes of Si Cp/Al composites has important theoretical significance and practical value for controlling ground surface quality.A mixed linear cohesion-slip constitutive model of the weak interface layer has been established.The "soft matrix-weak interface-hard particle" microcosmic grinding model was proposed,with the grinding removal mechanism of Si Cp/Al composite revealed.The grinding force and the grinding temperature prediction models of Si Cp/Al composites were established and verified.At the same time,a new method was proposed to indicate the surface quality by using the relation curve between the projected area proportion and the contour height,and the ground surface quality including surface cavity could be predicted.The principal work content is as follows:A mixed linear cohesion-slip constitutive model of the weak interface layer has been established.Firstly,the material property parameters of Si Cp/Al composites were determined through the basic performance test.Secondly,the quasi-static compression test and high-speed impact Hopkins pressure bar test of Si Cp/Al composites are carried out respectively to present a "soft matrix-weak interface-hard particle" microscopic geometric model.Finally,the mixed linear cohesion-slip constitutive model parameters of the weak interface layer were determined by the high-speed impact Hopkins pressure bar test and simulation results.A "soft matrix-weak interface-hard particle" microscopic grinding model has been proposed,with the grinding removal mechanism of Si Cp/Al composites revealed.Based on the single abrasive grain grinding tests of Si Cp/Al composites,the "soft matrix-weak interface-hard particle" microscopic grinding model was established to study the plastic removal mechanism of aluminum alloys and the brittle removal mechanism of silicon carbide particles.The influence of the abrasive grain angle on the grinding force was investigated to establish the single abrasive grain grinding force prediction model.Furthermore,a multi-abrasive grain grinding force prediction model of Si Cp/Al composites was established on the basis of the improved particle swarm optimization support vector machine algorithm.A grinding temperature prediction model of Si Cp/Al composites was established to reveal the main factors affecting the grinding temperature and its distribution field.The power and distribution density of the wire heat source were obtained with the grinding force.The grinding temperature prediction model was established based on the linear heat source transfer theory to reveal the reason for the lower grinding temperature of Si Cp/Al composites and the main factors affecting the rise velocity of grinding temperature.By means of the digital simulation technique,the grinding temperature field distribution of Si Cp/Al composites with different grinding process parameters was revealed.A new method was proposed to indicate the surface quality by using the relationship curve between the projected area proportion and contour height.By the abrasive grain movement analysis and grinding simulation technique of Si Cp/Al composites,the mechanism of surface cavity generation was revealed.Moreover,a characterization technique and evaluation indexes of ground surface quality including surface cavity feature were proposed to predict the ground surface quality of Si Cp/Al composites with different grinding process parameters.The optimization of the grinding process parameters of Si Cp/Al composites was conducted,with the optimized grinding process parameters ascertained.The influence of surface quality on the friction coefficients under dry friction conditions was investigated,and the friction coefficient prediction model was established under different grinding process parameters.Finally,with the surface roughness and grinding efficiency as the objective function,the friction coefficient,grinding force and grinding temperature as the constraint conditions,the grinding process parameters were optimized by means of the NSGA-Ⅱ multi-objective optimization algorithm.The research on the grinding mechanism and processes of high volume fraction Si Cp/Al composites has accumulated experience for the investigation on the grinding process of particle reinforced composites.This research methodology has theoretical significance and practical value for accelerating the engineering applications of high volume fraction Si Cp/Al composites.Besides,this research achievement can be extended and applied to the grinding process of other particle reinforced composites.