Papers by Keyword: Corner Singularity

Abstract: Composite materials or generally materials with interfaces are nowadays used in many varied engineering applications. In comparison with classical engineering materials the existence of material interface causes locally different stress distribution, which can strongly influence behaviour of whole structure and can have an important influence on failure mechanisms of such materials. The paper presented is devoted to the investigation of stress singularity exponents of a crack growing in a bimaterial body perpendicularly to the interface and touching the material interface. Discrepancies between value of stress singularity exponent in the centre of bimaterial body and on the free surface were found. The assumptions of linear elastic fracture mechanics (LEFM) and small scale yielding (SSY) are considered. For numerical calculations finite element analysis was used. Results obtained can contribute to a better understanding of failure of materials with interfaces.

Abstract: The aim of the presentation is to highlight the influence of the kink, developing at the beginning of mixed-mode crack growth, on the propagation behavior of the crack. Le et al. [1] have shown that the variational principle of a body containing a crack results in the principle of maximum energy release rate incorporating the stress intensity factors of the kinked crack. Here the influence of the kink and the kinking angle, resulting in a singular field around the corner, on the crack growth is analyzed. The generalized stress intensity factors at the kinks corner are computed with the help of a FEM strategy. The influence of these on the T-stresses and the plastic energy dissipated at the kink is determined using a small scale yielding approach. The impact of these results on mixed-mode crack propagation is discussed.

Abstract: The influence of corner singularity on the distribution of the stresses around the crack front for a three-dimensional structure is described in this paper. The distribution of stress singularity through the thickness of the middle tension specimen provides us an indication of crack behaviour close to a free surface. An estimation of the region where the change of singularity exponent plays an important role in fatigue crack propagation rate was carried out. A decrease in fatigue crack propagation rate close to the free surface was found. The lower fatigue crack propagation rate in the boundary layer in comparison with the interior of the specimen leads to a change of intersecting angle between crack and free surface and depends on Poisson’s ratio.