Numerical Simulation Study On Influence Of Residual Stress Of SiCp/Al Composite On Dimensional Stability

The high volume fraction SiCp/Al composite is a material with high specific strength,high thermal conductivity,low expansion coefficient and good dimensional stability.Nowadays,it has been widely used in aerospace,electronic packaging,precision instruments,etc.,so the thermal conductivity and dimensional stability of SiCp/Al composites are very high.The better the thermal conductivity,when the structural member is heated,it can quickly dissipate heat to reduce the temperature gradient,thereby reducing the amount of heat deformation of the member,which is a component with high dimensional stability and high integration.Degree of electronics is especially important In this paper,the effects of different particle size,volume fraction and double particle size ratio on the thermal conductivity and dimensional stability of SiCp/Al composites were systematically studied by experiments and finite element simulation.Finally,the thermal cycle process was simulated.The influence of dimensional stability reveals the variation of thermal conductivity and dimensional stability of SiCp/Al composites under different influencing factors,It provides theoretical basis and practical significance for the application of SiCp/Al composites in structural instruments of aerospace and other fields.The main research contents and results are as follows:(1)The test prepared by powder metallurgy in a vacuum tube furnace at 750? to prepare a volume fraction of 55%,60%,and the mass ratio of the double particle size was W50?m:W14?m=2:1(W50/W14=2:1),W85?m:W28?m=2:1(W85/W28=2:1)SiCp/Al composite,and using metallographic microscope(OM),scanning electron microscopy(SEM),X-ray diffractometer(XRD),energy spectrum Instruments such as EDS were used to observe and analyze the microstructure and composition of SiCp/AI composites.The thermal conductivity of SiCp/Al composites was measured by laser thermal conductivity meter.The results show that with the increase of volume fraction,the thermal conductivity of W50/W14 SiCp/Al composite increases from 127W/m k to 135W/m·k,and the thermal conductivity of W85/W28 SiCp/Al composite is 131W/m·k is increased to 139W/m k;the larger the particle size at the same volume fraction,the greater the thermal conductivity.(2)Input the performance parameters of SiC particles and A1 matrix in in the modeling software Digimat,and change the size,volume fraction and double particle size ratio of SiC particles to obtain particle size of 14 ? m?28 ? m?50 ?m,85? m,respectively.50%,55%?60%,65%,and two-dimensional finite element model of high volume fraction SiCp/Al composite with particle size grading are 50:14=2:l(55vol%),85:28=2:1(55vol%),50:14=2:1(60vol%)and 85:28=2:1(60vol%).The obtained finite element models are respectively imported into the finite element software ABAQUS,and the analysis steps,boundary conditions and constraints are set in the ABAQUS software according to the requirements,so as to conduct heat conduction simulation and residual stress simulation,which can be calculated according to the cloud image.The thermal conductivity and material dimensional stability of the material are obtained.(3)Based on literature reports,the finite element simulation of thermal conductivity and residual stress of SiCp/Al composites is feasible.The finite element simulation shows that the volume fraction and size of silicon carbide particles have an effect on the thermal conductivity and dimensional stability of the composite.The finite element simulation results show that:a)The thermal conductivity of SiCp/Al composites increases with the increase of particle volume fraction,and the thermal conductivity increases from 165.25 W/m·k to 168.08 W/m·k.The results of simulation and the theory of Maxwell model and experimental values are consistent;the thermal conductivity of SiCp/Al composites increases with particle size,and the thermal conductivity increases from 165.76 W/m·k to 169.92 W/m·k,which is consistent with the experimental results;The grading simulation results are the same as the single particle size.b)With the increase of volume fraction,the residual stress inside the SiCp/Al composite increases,but the dimensional stability first increases and then decreases;as the particle size increases,the interior of the SiCp/Al composite The residual stress is decreasing,and the maximum residual stress is reduced from 1178MPa to 779Mpa,so the dimensional stability is better.The thermal cycle treatment can effectively reduce the residual stress of the SiCp/Al composite and improve the dimensional stability.Increasing,the residual stress is continuously reduced,and the dimensional stability of the material can be basically stabilized after three cycles of thermal cycling.Figure[45]table[12]reference[114].