Numerical Simulation Of Strengthening And Fracture Behavior Of Cu Matrix Composites Reinforced By TiB_2P/TiB_w

Hybrid reinforced copper matrix composites are obtained ideal composite propertics by adjusti ng the type,morphology,size,distribution and quantity of in-situ reinforcment.However,it is difficult to obtain the effect of each reinforcement paranieter on the mechanical properties of composites.In this study,finite element models of TiB/Cu,TiB₂/Cu and(TiB₂+TiB)/Cu composites were built according to the ture microstructurce(TiB₂+TiB)/Cu composites.The effects of particles and whiskers on the mechanical properties of composites were studied.The interface damge thcory,matrix ductile fracture theory and reinforced brittle fracture thcory are introduced into the composite model.The mechanical behaviors of elastic deformation,plastic deformation and fracture damage of composite were simulated under uniaxial tensile loading on the software platform.Comparing with experimental data,the stability and reliabitity of the composite model are verified.It was quantitatively analyzed to the e ffect of TiB whisker(volume fraction,length,diameter),TiB₂ particle(volume fraction,size,smoothness)and hybrid(volume fraction,proportion)on the stress-strain,the stress distribution of reinforcement,the matrix strain distribution and the fracture style of the composites during uniaxial tensile.Combined with the results of conductivit prediction model,a unified strength-conductivity prcdiction model is built.Research indicates:(1)The whisker length and diameter have a great effect on the mechanical properies and the whisker stress distribution of the composites.When the whisker is long and fine,it is easy to break the middle part of the whisker.When the whiskers are short and thick,it is prone to outcrop or pull out.When the whisker length is 6d and the whisker diameter is 0.25?m,the optimal mechanical properties of TiB/Cu composites are obtained.(2)During the tensile process of TiB₂/Cu composites,the average stress of particles increases with the increase of particle volume fraction,and the average stress of particles with particle volume fraction of 80%is the largest.The stress concentration at the sharp angle decreases with the increase of particle roundness,and the increase of particle roundness effectively improve the stress distribution state on the particle.The average stress of particles decreases with the increase of particle size,and the average stress of particles with a diameter of 2?m is the smallest.(3)The of simulation results show that there are three damage modes of TiB/Cu composite:ductile damage of Cu matrix,interface damage and brittle fracture of TiB whisker.The main fracture modes of the composites with short and coarse whiskers are the first two,while those with long and thin whiskers are the three.There are three damage modes in TiB₂/Cu under tensile load:ductile damage of Cu matrix,interface damage and brittle fracture of TiB₂ particle sharp angle.(4)Based on the unified prediction model of strength and electricity,the volume fraction and the proportion of reinforcement were caculated.Using M-?2p as the evaluation criterion for the comprehensive properties of(TiB₂+TiB)/Cu composites,the best comprehensive properties were obtained when the volume fraction of reinforcement was 12%and the proportion of whisker:particle=5:1.