| Si Cp/Al composites have excellent physical and mechanical properties.It has the characteristics of high specific strength,good wear and fatigue resistance,low coefficient of thermal expansion and so on.It has great application prospects in aerospace equipment,military weapons,electronic packaging and other manufacturing fields.The brittleness of Si C particles and the plasticity of aluminum alloy matrix make it difficult to obtain better surface processing quality and be further applied.This paper presents research on the grinding process of Si Cp/Al composites with medium and high-volume fraction(≥ 45%).The research is based on the combination of finite element simulation technology and experiment verification,intended to supplement,and improve the grinding removal mechanism,providing theoretical guidance for the high-quality machining and the design of corresponding cutting tools for Si Cp/Al.The main contents of the research are as follows:(1)A parametric modeling method of Si Cp/Al composites is proposed.Based on the secondary development method of ABAQUS,a parametric cutting simulation system including model establishment,tool design,tool position adjustment,setting contact and boundary conditions and remeshing module are developed to make the cutting simulation process more accurate and efficient.(2)First,based on the developed parametric cutting simulation system,the multi-scale(millimeter and micron scale)single diamond grit cutting simulation model with variable cutting depth for Si Cp/Al composites with medium and high volume fraction is established.In the millimeter scale cutting model,the factors that have important effects on the material removal process are taken in to consideration,such as the diameter,volume fraction,shape and characteristic of random distribution of Si C particle.Second,considering the important influence of Si C particles on the removal mechanism,brittle fracture(BF)and Johnson Holmquist model(JH2)constitutive models are used to model the removal process of Si C particles in models with different scales.Finally,based on the multi-scale and multi constitutive cutting simulation models of Si Cp/Al composites,the grinding removal processes of Si Cp/Al composites with different volume fractions are compared.The overall removal characteristics of Si Cp/Al composites with a variety of volume fractions such as surface defect types and formation mechanism,sub surface damage,cutting force,secondary cutting phenomenon of Si C particles and so on are studied;the local removal characteristics of materials such as coating phenomenon of matrix,pit formation process,deformation process and crack formation process of Si C particle and so on are further analyzed.The grinding removal mechanisms of Si Cp/Al composites are revealed.Considering the randomness during the generation process of Si C particle in the modeling method,a random modeling for the millimeter scale cutting simulation model was conducted for five times,intended to draw conclusions which reflect the general rules.(3)A cutting experiment scheme is designed to make a single abrasive particle contact with the material only once in the process of cutting in to cutting out and the experimental parameters are in line with the actual grinding conditions.The single diamond grit cutting experiment is carried out on 2A12 aluminum alloy,Si Cp/Al composites with different volume fractions(45% and 65%)and Si C ceramics respectively.On the one hand,the effectiveness of multi-scale cutting simulation analysis for Si Cp/Al composites in this study is verified based on the cutting force,specific grinding energy,micro morphology and longitudinal profile morphology obtained from the cutting experiment.On the other hand,the grinding mechanisms of Si Cp/Al composites are further improved and supplemented based on the real data obtained from the cutting experiment. |
