Study On3D-Fracture Behavior In CTS-Specimen With Inclined Crack

Study on3D mixed-mode fracture problems at home and abroad so far is still imperfect.Some regular-shaped through cracks and surface cracks have been investigated in the currentstudy of3D mixed mode crack, while little study on the irregular-shaped cracks can not meetthe actual needs of the project. In the paper an in-depth study on the brittle fracturecharacteristics and crack propagation of CTS-specimen with inclined crack is presented. Twokinds of irregular-shaped3D mixed-mode cracks are built by improving CTS-specimendesigned by Richard. The computational analysis is based on the numerically highly effectivemodified virtual crack closure integral method and the commercially available FE-codeANSYS.3D model of CTS-specimen with finite thickness was built firstly on the basis of2Dmodel. Fracture behavior of specimen was investigated with3D Boundary conditions undermode-I and mode-II simple loading respectively. The presented numerical solutions showedthat3D effect was the main reason of leading CTS-specimen to produce mixed-mode fractureunder pure shear loading. The quantitative analysis on out-of-plane stress constrain near cracktip field of CTS specimen directly showed the range of3D effect. Meanwhile, the effect ofloading angles and material poisson’s ratio on3D fracture behavior was also investigated.On the basis of fracture studies on3D CTS-specimen, MCTS-specimen with mixed-modecrack was built thought inclining crack front of CTS-specimen by model deformationtechnology of HYPERMESH software. Fracture characteristic of oblique through crack wasinvestigated under in-plane different loading conditions which were achieved by specialloading device designed by Richard. The main factors which leaded to mixed-mode fracture ofspecimen were revealed. On the basis of these numerical analyses, initial crack expansionbehavior of MCTS-specimen was analyzed according to Richard criterion under differentloading conditions. By changing the inclined angle of crack front, the fracture law of obliquethrough cracks with different inclined angles was summarized under mode-and mode-simple loading, and the change of complex stress intensity factor along crack front with thevariation of inclined angle was discussed.Calculation model of MCTS-specimen with inclined crack plane was built by applying the same method. Combining with special loading device designed by Richard, fracturecharacteristic of through crack with inclined crack plane was investigated under in-planedifferent loading conditions. The main factors which leaded to mixed-mode fracture ofspecimen were revealed. On the basis of these studies, initial crack expansion behavior ofMCTS-specimen was analyzed according to Richard criterion under different loadingconditions. By changing the inclined angle of crack plane, the relationship between complexstress intensity factor along crack front and inclined angle of crack plane was set up undermode-I and mode-II simple loading respectively, and summarizing the fracture law of thecrack.In order to verify the presented numerical calculation, MCTS-specimen with45inclined crack plane and APDL programming language of ANSYS software were applied.Computational simulation of crack propagation path and feature in the specimen whichsubjected to mode-I and mode-II loading respectively was completed by the aid of MVCCImethod and equivalent transformation relations between energy release rate and stress intensityfactor. Meanwhile the experiment of MCTS-specimen with45inclined crack plane whichwas made using transparent plexiglass material was presented under mode-I and mode-IIloading respectively. The actual expansion of the crack was obtained. The results showed thatexperimental findings of cracking and crack expansion characteristics were in good agreementwith simulated results of cracking and crack expansion characteristics, which verified thecomputational analyses of this article.The presented study enriches the contents of3D fracture investigation, makes contributionfor further research on3D mixed-mode fracture, and provides reference for assess safety ofcomponents with similar crack in practical engineering.