Numerical Simulation Of Composite Material Properties And The Application Of Self-consistent Method

Composite materials,as one of the mostly potential materials,have been developed rapidly due to their designability and superior physical properties.The effective macro-properties associated with composite materials are closely related to their microstructures,while it is difficult to consider the microstructure comprehensively in theoretical analysis.In this thesis,two-phase continuous composites are mainly concerned.The effective Young's modulus is statistically estimated with the application of finite element analysis based on software ANSYS.The influence of the microscopic morphology(shape,size and random distribution)of the constituent materials on the macroscopic effective properties is taken into account.And a numerical model based on self-consistent theory is proposed to predict the macroscopic effective properties.The main contents of the thesis are as follows.The microstructural models,also named full-size model,of two-phase continuous composites in three-dimension and two-dimension are constructed to simulate the random distribution of each component material.The represent volume element(RVE)of two-phase continuous composite at different volume fractions is predicted by finite element analysis.Then,the estimation of the effective Young 's modulus,Ee,of the material is numerically performed.The effects of Young's modulus ratio,volume fraction,size and shape of its constituents on the effective properties are studied.The simulation results show that the larger the Young's modulus ratio of the constituents is,the larger the RVE is,and the shape and size of the constituent materials have little effect on the effective Young's modulus of the two-phase composite.Based on the main idea of self-consistent theory proposed by Budiansky,the self-consistent numerical model of two-dimensional and three-dimensional two-phase continuous composites is established respectively.In this numerical model,a so-called inclusion having the microstructural properties of the composite material is embedded into the equivalent homogeneous medium with the effective elasticity to be determined.The effective properties of the composites are calculated by iterative method.Numerical results indicates that the effective Young's modulus of the full-size numerical model and the numerical self-consistent model are within the margin of error.The hardware resources and time required for the single iteration calculation of the self-consistent numerical model is much smaller than that of the full-size numerical model.The total time of the iterative computation convergence is increased.It may be concluded that the self-consistent numerical model can reduce the requirement of computing resources at the expense of the computation time.Polycrystalline copper composed of grains with different crystallographic orientation is simulated by the proposed three-dimensional full-size model and self-consistent numerical model,respectively.And prediction of its effective Young's modulus is conducted.The numerical result is compared with the experimental data measured by tensile test,and the correctness of these numerical methods is proved.