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With the increasing applications of composite materials in various engineering structures,failure analysis on crack induced fracture problems in composite materials has attracted more and more attention among researchers.Fracture behavior studies based on the linear elastic fracture mechanic theories are not accurate enough when yielding occurs around crack tips.In the current study,we introduce two approaches of plastic zone correction to evaluate the plastic deformation ahead crack tips in composite materials.The first one is the mixed-mode Dugdale model and the second one is the generalized Irwin model.By applying the Von Mises yielding criterion,the plastic zone size and crack tip opening displacement can be connected to the stress field ahead each crack tip through the two models.The Dugdale model is suitable for all crack problems as its advantage,but the calculation process is complex.The Irwin model can only be used when the crack is located in one material (matrix cracking) so that stress oscillation can be avoided.Based on the two models,the problem of a crack lying at the interface of a circular inclusion and matrix,and crack-coated inclusion interaction have been studied as examples.Numerical analysis are given to show the influence of different kinds of parameters on the plastic zone size and crack tip opening displacement of each problem.It is found that the mixed-mode loading conditions usually induce higher plastic zone size and crack tip opening displacement than pure mode Ⅰ problem in multiphase composite materials.For the circular interface crack,the property of interface and matrix material has a strong effect on the plastic zone size.The introduction of plastic zone correction can greatly improve the accuracy of fracture prediction for fiber-reinforced composite materials with ductile matrix (such as metal matrix composites).