Research On Fracture Behaviors Of Particle Reinforced Composite Materials Based On XFEM

Due to the specific strength and specific stiffness,particle reinforced composites are widely used in many fields, such as aerospace, nuclear energy,construction industry, etc. In the application of particle reinforced composites, fracture is one of the most common failure modes,which significantly influences the service lives of the composites materials. Therefore, it is especially important to understand the fracture behavior of these types of composites.The numerical simulate calculation of the stress intensity factors are performance for the particle reinforced composites by using the extended finite element method(XFEM) in this thesis. The main contents are given as follows:Firstly, the basic methods and research status of fracture mechanics of particle reinforced composites are reviewed. The characteristics of the crack tip fields are emphasized when the crack interacts with the material interface. Secondly, we focus on the related numerical methods and their applications. The advantages and disadvantages of numerical method are discussed.Finally, the XFEM is briefly introduced and the possible improvements of this method are also pointed out.The several basic theory of fracture mechanics and the method of stress intensity factors(SIFs) are introduced, implementations formulation of interaction integrals are suggested to compute compound crack SIFs in XFEM. Some critical problem of programming have solved,such as the location of crack, the quadrature scheme and the enriched node of crack tip.In XFEM, a standard displacement-based approximation is enriched near a crack by incorporating both discontinuous fields and the near tip asymptotic fields based on partition of unity method. The elementary theory of XFEM and the improved XFEM are introduced.Implementation procedures and formulations of XFEM are described in detail.The interaction integrals still valid even when the integral in this thesis can be used to material interfaces.As a result, the interaction integral accurately when the crack tip tends to evaluate fracture parameters accurately when the crack tip tends to material interfaces.The several different forms of composite crack intensity factor is calculated by ANSYS and programming, the effect on the stress intensity factor when the crack happens to the matrix, as well as the volume ratio, radius, modulus ration on crack intensity factor are analyze.Particle reinforced composites containing crack stress of crack propagation behavior to carry on the numerical simulation, analysis of matrix and particle modulus ratio on the track of crack propagation and the influence of the energy release rate.