Analysis Of Fracture Stress Intensity Factors Of The Three Dimensional ModeⅠCracks And Mixed-modeⅠ/ⅡCracks

The strength of crack tip’s stress strain field is characterized by stress intensity factor, which is the significant parameter in the linear elastic fracture mechanics. It is simulated and calculated on finite element software of ANSYS by the interactive integral method that stress intensity factors of center inclined crack of rectangular plate, compact tension specimen and compact tension shear specimen. Comparing the result of finite element analysis with theoretical value and the result of experiment, some beneficial conclusion is gained. The main contents are as follows:1.The fundamental principle of the interactive integral method and the numerical method for calculating 2 dimension and 3 dimension stress intensity factors are introduced. Firstly Building 2 dimension finite element model of center inclined crack of rectangular plate, which is divided using three different mesh density. Then calculating its stress intensity factor, which is calculated and compared with the result of the handbook of stress intensity factor to prove the result by the way of finite element accurate. And analysis on the feature of interactive integral method calculating stress intensity factor.2.Based on the geometric shape and mechanical characteristics of compact tension specimen,the 3 dimension straight crack model of 1/4 specimen is built. It is analyzed how stress intensity factor is distributed along the thickness in plane strain state and 3 dimension state. The effects of several important factors such as the dimension and angle of singular element on the tip of crack, the size of integration domain, load value and length of crack on the stress intensity factor of specimen are investigated. Then, these finite element results of compact tension specimen are compared with testing, and the difference between them is analyzed.3.To calculate conveniently compact tension shear specimen which has I/II complex fracture and special loading device by finite element, the hypothesis that a model of specimen of 3 dimension inclined crack is recombination of compact tension shear specimen and loading device. When the special loading angles are simulated and calculated, stress intensity factor KI,KII,Keff and equivalent angle uploading βeq are analyzed, which are compared with the results of literatures which are already existed. The distribution of stress intensity factor KI,KII along specimen thickness is researched by numerical calculation, when Poisson’s ratio changes. Meanwhile, stress intensity factor KI,KII,Keff and equivalent loading angle βeq are researched when Poisson’s ratio and loading angle change.