Finite Element Simulation Of Nanoindentation Of C/SiC Composites

C/SiC composite material has the function of deflection crack,stress conduction and oxidation protection,which can overcome the brittleness of traditional ceramics.It also has the characteristics of high specific strength,high specific stiffness,low density and high temperature resistance.It has become the most scientific research potential application material on the aviation and defense equipment in the past 20 years.The researches on the mechanical properties of the interface and in situ mechanical properties have a key role on the preparation method,manufacturing process and field application.The reinforcement and interface of the composites are in the micro-nano scale,and the influence factors of the micro mechanical properties of the composite materials are combined by simulation and experiment.This work is a part of the project “Grinding mechanism of fiber-reinforced ceramic matrix composites based on interface micromechanics”,which is National Natural Science Foundation of China(Number: 51275346).This paper mainly contains the following contents:Using ABAQUS software,the 2D axis symmetric model is established to simulate the nanoindentation of C/SiC composite material,and the simulation results are analyzed based on Oliver-Pharr theory.Nanoindentation experiment of C/SiC material is done by the “Nanoindenter G200”.The experimental results and the simulation results show that the maximum error is 4%,so the model is correct.The maximum load,material hardness and elastic modulus of the indentation test were positive correlation with the interface strength and the interface thickness.Simulation method is used to study how the residual stress,thermal expansion coefficient,pressure head tip radius of the spherical surface and the contact point influence the nanoindentation experiments.The influence factors of the in situ mechanical properties of the composites were studied by establishing the displacement control model of the indentation point.The results show that the mechanical properties of the materials are changed due to the interface phase.The hardness and elastic modulus of carbon fiber material near the interface are increased by 30%,whereas the hardness and elastic modulus of the substrate near the interface are decreased by 14%.In summary,this paper studies the micromechanical properties of C/SiC composites by nanoindentation method and analyzes the related factors,which provide the theoretical basis for the preparation,engineering application and processing and removal mechanism of C/SiC composite materials.