Numerical Simulation Of Rate-dependence Deformation Behavior Of Bulk Metallic Glass Matrix Composites

Bulk metallic glass matrix composites show high strength and good toughness,and have broad application prospects.Considering the complex service environment of metallic glass matrix composites in practical engineering applications,it is necessary to study the rate-dependence deformation behavior of metallic glass matrix composites.At present,the research on rate-dependence behavior of metallic glass matrix composites is mostly focus on the experimental research.However,due to the influence of alloy composition,material microstructure,experimental environment and so on,the experimental data is scattered,and it is not adequate for systematically and comprehensively study of metallic glass matrix composites.In this thesis,the rate-dependence deformation behavior of metallic glass matrix composites at room temperature and low strain rate is numerically simulated by finite element method.The deformation mechanism and influencing factors of rate-dependence deformation behavior are discussed.Then the meso-viscoplastic constitutive model is established by homogenization method to describe the mechanical behavior of the composites at different strain rates.It provides a reference for the preparation and engineering application of bulk metallic glass matrix composites.Main research work in this thesis are as follows:1.The thermo-mechanical coupled constitutive equation is implemented into the finite element software ABAQUS by the user material subroutine(UMAT),which is used to describe the deformation behavior of metallic glass in the process of finite element simulation.The deformation of pure metallic glass under different strain rates is simulated by finite element method.And the simulation result is compared with the experimental data.It is verified that the constitutive model can reasonably describe the rate-dependence deformation behavior of metallic glass.2.The rate-dependence deformation behavior and deformation mechanism of metallic glass matrix composites at room temperature and low strain rate are investigated by finite element method.Firstly,the rationality of the geometric model and the constitutive model are verified,and then the effect of rate-dependence behavior of toughening phase and microstructure on the rate-dependence deformation behavior of metallic glass matrix composites are further considered.The result shows that the rate-dependence of metallic glass matrix composites is determined by both the rate-dependence of the matrix and the toughening phase.Whether or not the toughening phase exhibits rate-dependence,the shear band expands is accelerated in matrix and the temperature increment in the shear band is faster when the strain rate increases,and the failure of metallic glass matrix composites will be more easily.Compared with the non-performance rete-dependence of toughening phase,the macro-plastic deformation ability of composites is improved when the toughening phase exhibits rate-dependence.The volume fraction of toughening phase has a significant effect on the rate-dependence deformation behavior and mechanical properties of metallic glass matrix composites,and the smaller the volume fraction,the greater the rate-dependence coefficient of composites.The shape of toughening phase also has an effect on the rate-dependence deformation behavior and mechanical properties of metallic glass matrix composites,and the larger the aspect ratio,the greater the rate-dependence coefficient of composites.3.Based on the Eshelby's equivalence inclusion theory and the generalized incremental affine linearization method,the meso-viscoplastic constitutive model of bulk metallic glass matrix composites is established by the extended Mori-Tanaka's homogenization method,and its numerical implementation is carried out.The simulation result is compared with the experimental result.The result shows that the meso-constitutive model can reasonably describe the monotonic tensile and monotonic compression deformation behaviors of metallic glass matrix composites,and the rate-dependence deformation behavior at low strain rate is also well described.