ANALYSIS OF APPROXIMATED CURVED CRACKS IN HOMOGENEOUS AND GRADED MATERIALS

Abstract

In this paper two stages of analysis are studied. In stage I, the influence of crack shape on thecrack-tip stresses, critical loads and subsequent propagation direction is investigated via a simpleanalytical model for cracks in homogeneous materials. This model is verified through finite elementsimulations using ANSYS. It is demonstrated that accurate predictions of mechanical energy releaserate and crack deflection angle may be obtained from a smaller number of crack shape parameters.In stage II, this concept is extended to curved cracks in functionally graded materials (FGMs).It iscommon that analytical and computational models of fracture in FGMs have focused almostextensively on straight cracks. If it can be demonstrated that straight cracks give an adequateapproximation of curved cracks in graded materials, then the existing solutions for straight cracksprovide a sufficient foundation for fracture analysis of FGMs. On the other hand, if straight cracksdo not adequately approximate curved cracks in FGMs, then the development of solutions for nonstraight cracks in graded materials is priority. Three cracks shapes approximations are performed tocompare with the actual crack in isotropic and graded materials. The crack propagation and the SIFswere simulated using finite element method. It was concluded that piecewise linear crack shapesprovide a significantly better approximation than straight crack shapes. Accordingly, analyticalsolutions for piecewise linear cracks in graded materials would be very useful, and should be afocus of future work in this area.