Crack spacing effect on the brittle fracture characteristics of semi-infinite functionally graded materials with periodic edge cracks

The effect of crack spacing on the brittle fracture characteristics of a se mi-infinite functionally graded material (FGM) with periodic edge cracks is discussed. The incompatible eigenstrain induced in the material due to mis match in the coefficients of thermal expansion is considered in the analysi s. The nonhomogeneity of the material is simulated by an equivalent eigenst rain. whereby the problem is reduced to that of a cracked homogeneous mater ial with incompatible and equivalent eigenstrains. A method is then formula ted to calculate the stress intensity factor of periodic edge cracks in suc h a semi-infinite homogeneous medium and applied to calculate apparent frac ture toughness of a semi-infinite FGM from its prescribed composition profi le. Inverse calculation is also carried out to compute composition profile from prescribed apparent fracture toughness of the semi-infinite FGM. Numer ical calculations are carried out for semi-infinite TiC/Al2O3 FGM and the r esults are shown in the figures.