The Experimental Investigation And Numerical Simulation Of Fatigue Crack In Functionally Graded Materials

As a kind of typical non-homogeneous composite materials, functionallygraded materials(FGMs) are designed to meet the harsh requirements of manyimportant industrial fields. Significant experimental, theoretical and mumericalresearch efforts on FGMs in nowadays are devoted to this subject. Due to thelimitation of condition and high cost, experimental observations could bring usmany difficulties. Theoretical analysis needs rigid assumptions and cannot easilysovle problems with complicated properties and boundary conditions. Owing tothe ability to solve problems of any materials, loads and structures, numericalmethods become an important tool to investigate the fracture behaviors. Thepresent article addresses the numerical simulation of mixed-mode crackpropagation in FGMs by using the extended finite element method(XFEM).Fatigue fracture is the main reason to result in failures of structuralmember,especially in the servo actuator of flight control system.Once the actuatorcrack because of its own defects, crack propagation will lead to structure failureseven if under low alternate loading.So,it is particularly important to do theresearch of crack propagation rate and the residual life prediction of specimen.In this paper, powder metallurgy method according to a certain mass ratiowas prepared ZrO2/NiCr system functionally graded materials and the preparedmaterial cut and polished into the same size three-point bend specimens, and thenpressure-pressure amplitude cyclic loading fatigue experiments, cracks parallel tothe direction of the gradient material. With fatigue testing machine and relatedauxiliary equipment, a three-point bending test were investigated during thefatigue crack growth of type I and I-II-type situation of fatigue crack growthsituation. In view of functionally graded materials preparation process as well asthe difference between the different material components of materials of variousparameters would bring a big difference, while conducting fatigue crack growthsimulation time and require these parameters is essential, but this article weredesigned experimental measurements of the three point bending test by the elasticmodulus and fracture toughness. And then by means of extended finite elementmethod and two-dimensional case to simulate the interaction integral I and I-IIhybrid fatigue crack growth, and to compare the results with the experimental.