Dynamic behavior of a cylindrical crack in a functionally graded interlayer under torsional loading

In this paper the problem of a cylindrical crack located in a functionally graded material (FGM) interlayer between two coaxial elastic dissimilar hom ogeneous cylinders and subjected to a torsional impact loading is considere d. The shear modulus and the mass density of the FGM interlayer are assumed to vary continuously between those of the two coaxial cylinders. This mixe d boundary value problem is first reduced to a singular integral equation w ith a Cauchy type kernel in the Laplace domain by applying Laplace and Four ier integral transforms. The singular integral equation is then solved nume rically and the dynamic stress intensity factor (DSIF) is also obtained by a numerical Laplace inversion technique. The DSIF is found to rise rapidly to a peak and then reduce and tend to the static value almost without oscil lation. The influences of the crack location, the FGM interlayer thickness and the relative magnitudes of the adjoining material properties are examin ed. It is found among others that, by increasing the FGM gradient, the DSIF can be greatly reduced. (C) 2001 Elsevier Science Ltd. All rights reserved .