Fracture analysis of functionally gradient weak/micro-discontinuous interface with finite element method

The main idea of this paper is to study the influence of the discontinuity of mechanical property of FGMs on the stress intensity factors by means of FEM calculations. The FGMs interface is classified into four kinds according to the discontinuity of mechanical properties and their derivatives across it. Mechanical models were established for fracture analysis of the functionally gradient elastic weak/micro-discontinuous interfaces. Finite element method was used to obtain SIFs of the interfacial crack, based on the discussion of which three methods to diminish SIFs were suggested: (a) to increase the sizes of the FGMs plates; (b) to reduce the weak-discontinuity of FGMs interface; (c) to make FGMs interface micro-discontinuous. A simple method to make FGMs interface micro-discontinuous is to make mechanical property of the FGM at one side of the interface to be the lower-rank polynomial truncated from Taylor series of that of the FGM at the other side. The first-rank micro-discontinuity is always enough to reduce SIFs notably, so, it is not necessary to manufacture FGMs interface with higher-rank micro-discontinuity in engineering.