EFFECT OF A GRADED INTERLAYER ON THE STRESS INTENSITY FACTOR OF CRACKS IN A JOINT UNDER THERMAL LOADING

In a bimaterial joint with and without a graded interlayer, the stress intensity factor of cracks perpendicular to the interface was calcula ted For a thermal loading by a homogeneous change in the temperature. In joints without an interlayer, the stress intensity factor increases to infinity as the crack approaches the interface for the case of the Young's moduli E-1/E-2 > 1 (crack in material 1). Introducing a grade d interlayer with a continuous transition in the material properties b etween the two joined materials leads to a continuous change in the st ress intensity factor if the crack propagates from material 1 into mat erial 2. Results are presented for different transition functions of t he material properties and for different thickness ratios of the layer s. The possible beneficial effect of a graded interlayer is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.