Papers by Keyword: Linear Elastic Fracture Mechanics

Abstract: Fracture mechanical studies have become a vital aspect of the design of concrete structures. This work aims to analyse/validate the size-effect of structural components in light of principles of Linear Elastic Fracture Mechanics (LEFM). Various models of a quasi-brittle material with different geometries have been analysed for Stress Intensity Factors (SIF) using Abaqus/CAE: a finite element analysis software. The effect of crack-to-depth ratio, span-to-depth ratio and specimen size on SIF values have been studied. Also the variation in SIF values with respect to changing the position of concentrated load application and initial notch on the specimen have been studied. It is found that for a particular notch-to-depth ratio, the SIF increases with a decrease in specimen size. Also, at a constant span-to-depth ratio, SIF increases with increase in the notch-to-depth ratio.

Abstract: The classical two-dimensional solutions of the theory of elasticity provide a framework of Linear Elastic Fracture Mechanics. However, these solutions, in fact, are approximations despite that the corresponding governing equations of the plane theories of elasticity are solved exactly. This paper aims to elucidate the main differences between the approximate (two-dimensional) and exact (three-dimensional) elastic solutions of crack problems. The latter demonstrates many interesting features, which cannot be analysed within the plane theories of elasticity. These features include the presence of scale effects of deterministic nature, the existence of new singular stress states and fracture modes. Furthermore, the deformation and stress fields near the tip of the crack is essentially three-dimensional and do not follow plane stress or plane strain simplifications. Moreover, in certain situations the two-dimensional solutions can provide misleading results; and several characteristic examples are outlined in this paper.

Abstract: Multiple-site Damage (MSD) is a dangerous scenario for aircraft structures due to the interaction of adjacent cracks in one structural element. Despite their excellent fatigue crack growth resistance, Fibre Metal Laminates (FMLs) may also encounter this damage scenario. However, only few studies on fatigue crack growth in presence of MSD in FMLs has been reported. An overview of the relevant methods for predicting the crack propagation properties of MSD in FMLs is given and discussed in this paper. The fatigue crack growth of MSD in FMLs was experimentally studied and is reported in this paper. A new analytical methodology, based on the superposition principle and displacement compatibility method, is proposed.

Abstract: The contribution is focused on estimation of a critical value of generalized stress intensity factor for crack propagation from sharp V-notches. Stress distribution around the tip of the V-notch is described on the base of generalized linear elastic fracture mechanics, because V-notch is a singular stress concentrator with stress singularity exponent different from 0.5 (depending on V-notch opening angle). Then also stability criteria based on strain energy density factor and average critical stress are generalized for the stress singularity different from 0.5. Using FE analysis the critical stresses for crack initiation was estimated and compared with experimental data from the literature.