Stress Intensity Factors in Two Bonded Elastic Layers Containing Crack Perpendicular on the Interface with Different Elastic Properties

Abstract

Thin bonded films have many applications (i.e. in information storage and processing systems, and etc.). In many cases, thin bonded films are in a state of residual tension, which can lead to film cracking and crack extension in one layer often accompanies failure in whole systems. In this paper, we analyze a channel crack advanced throughout thickness of an elastic thin film bonded to a dissimilar semi-infinite substrate material via finite element method (FEM). In order to simplify modeling, the problem is idealized as plane strain and a two-dimensional model of a film bonded to an elastic substrate is proposed for simulating channel crack in thin elastic film. Film is modeled by common 4-node and substrate by infinite 4-node meshes. The stress intensity factor (SIF) for cracked thin film has been obtained as a function of elastic mismatch between the substrate and the film. The results indicate that in elastic mismatch state, SIF is more than match state. On the other hand, mismatch state is more sensitive to crack than match state. And SIF has also increased by increasing Young's modulus and Poisson ratio of film.

Investigation of the Near-Tip Stress Field of a Notch Terminating at a Bi-Material Interface

“…Such a defect may appear as a result of the development of voids located in one of the phases of the composite [ 12 , 13 , 14 ]. It is worth noting that a special case of such a sharp corner (notch with a zero-opening angle) is the crack initiated at the interface [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Stress singularities occurring in the tip area of such crack, which is perpendicular to the interface were analysed in [ 15 ].…”

“…Stress singularities occurring in the tip area of such crack, which is perpendicular to the interface were analysed in [15]. GSIFs values, determined for a short crack located in a bi-material with infinite and finite overall dimensions, are presented in [16] and [17][18][19][20][21][22][23], respectively. The problem of local stress concentration, occurring in the vicinity of the crack tip, not perpendicular to the interface, was discussed in [24,25].…”

Asymptotic stress field at tip of notch terminating to interface

“…Other issues, e.g., a notch, which tip is located on the interface have not been investigated sufficiently. Nevertheless, in the literature one can find the results of research for the special case of such a notch (with zero apex angle) -the crack starting at the interface [9][10][11][12][13][14][15]. For such a crack, assuming that it is perpendicular to the interface, the authors of [9] analysed the stress singularities occurring in its tip region.…”

“…In [10] the eigenequation is presented and generalized stress intensity factors (GSIF) for the case of the short crack located in bi-material of infinite dimensions were determined. For the case of a crack located in an element with finite dimensions, the GSIFs were determined by the authors of the work [11][12][13][14][15].…”