In this section, we want to model a surface with flaws. We model it as a line from which N parallel cracks progress into the 2D material (see Fig. 2). The ensemble of cracks is submitted to a remote mode I loading p∞ as sketched in Fig. 2, but, because of the interactions between the cracks, each crack i (i = 1, ...N) is submitted locally to both a normal traction pi(x) and a shear traction ti(x).

Three-dimensional enriched finite elements are used to compute mixed-mode stress intensity factors (SIFs) for three-dimensional cracks in elastic functionally graded materials (FGMs) that are subject to general mixed-mode loading. The method, which advantageously does not require special mesh configuration/modifications and post-processing of finite element results, is an enhancement of previou...

DC electric potential technique has been used to monitor crack growth in conductive materials. A constant DC current is passed through these materials and the crack length is measured through the changes in the electrical voltage at the crack mouth. However, this method is not applicable in crack growth measurement in nonconductive materials or adhesively bonded joints. For these materials, a n...

Crack propagation along one of the interfaces between a thin ductile adhesive layer and the elastic substrates it joins is considered. The layer is taken as being elastic-plastic, and the fracture process of the interface is modeled by a traction-separation law, characterized by the peak separation stress 6 and the work of separation per unit area To. Crack growth resistance curves for mode I l...

Recent work (Rice, 1985a) has presented the calculations of the first order variation in an elastic displacement field associated with arbitrary incremental planar advance of the location of the front of a half-plane crack in a loaded elastic full space. That work also indicated the relation of such calculations to a three-dimensional weight function theory for crack analysis and derived an exp...

By partitioning the total stresses in a damaged composite into either mechanical and residual stresses or into initial and perturbation stresses, it was possible to derive several exact results for the energy release rate due to crack growth. These general results automatically include the effects of residual stresses, traction-loaded cracks, and imperfect interfaces. By considering approximate...

A model for mode I fracture in brittle materials is used to elucidate the relationship between characteristics of the fracture process, such as crack roughness, fractal dimension, and fragment size distributions. It is shown that different roughness in local regions of the crack path leads to different mechanisms for the subsequent fracture of those regions. Formation of two robust power laws f...

Mode I steady crack growth was analyzed to determine the toughening due to domain switching in ferroelectric ceramics. A multi-axial, electromechanically coupled, incremental constitutive theory is applied to model the material behavior of the ferroelectric ceramic. The constitutive law is then implemented within the finite element method to study steady crack growth. The effects of mechanical ...

This paper presents a methodology for conducting a 3-D static fracture analysis with applications to a gas turbine compressor blade. An open crack model is considered in the study and crack-tip driving parameters are estimated by using 3-D singular crack-tip elements in ANSYS . The static fracture analysis is verified with a special purpose fracture code (FRANC3D). Once the crack front is perfe...

an epoxy resin was modified by silica nanoparticles and cured with an anhydride. the particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. electron microscopy images showed that the silica particles were well dispersed throughout the resin. tensile test results showed that young’s modulus and tensile strength increased with the vo...