This paper presents a finite element formulation of elasticity to model elastic fracture in composites with long aligned fibers. We have employed a B-bar type approach which is applicable to compressible as well as nearly incompressible material systems. An energy approach is undertaken to evaluate the stress intensity factor at the crack tip. The effects of strong intact bridging fibers, fiber...

We develop higher order fi nite element methods for fracture mechanics. The framework is cast within the contextof conforming fi nite elements [1]. The method [2] exploits the a priori knowledge of the singular behavior of thefi elds to construct an alternate regular solution. Solving for the alternate problem yields optimal rates of conver-gence and high order of accuracy. The ...

This is the first in a series of two papers generated from a study on probabilistic meshless analysis of cracks. In this paper (Part I), a Galerkin-based meshless method is presented for predicting first-order derivatives of stress-intensity factors with respect to the crack size in a linear-elastic structure containing a single crack. The method involves meshless discretization of cracked stru...

Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows for a direct correlation between near crack-tip stresses and failure. Predictions are made for both the toughness and average fracture initiation angle of a crack under mixed-mode loading. This is pertinent for composites and is...

The fracture and crack growth of mechanical structures is a usual phenomenon which is due to the application of tensile, cyclic loading or thermal stresses on the structure. So introducing of methods to prevent the crack growth is useful. Afterward, one of the repairing methods of crack growth, consisting to make a hole in the crack tip to elimi-nate the sharp corners, was explained. This metho...

In this work, fracture behavior of multilayered unidirectional graphite/epoxy composite (T800/3900-2) materials is investigated. Rectangular coupons with a single-edged notch are studied under geometrically symmetric loading configurations and impact loading conditions. The notch orientation parallel to or at an angle to the fiber orientation is considered to produce mode-I or mixed-mode (mode-...

Recent studies document linear elastic response of muddy marine sediments to load and deformation on temporal and spatial scales relevant to animal movement, with burrowers making openings for movement in such sediments by fracture. Cracks propagate through linear elastic solids in mode I (opening-mode crack growth) when the stress intensity factor (KI) at the crack tip exceeds the material’s f...

During blasting construction in tunnel engineering, an inclined fissure near the blast hole produces “Z” type of over-excavation and subsequently affects overall effect stability tunnel. In this work, dynamic caustics testing was used to study burst propagation mode penetration form explosive cracks at different positions between holes under double-hole conditions. Results showed that existence...

This paper presents a new method—the Technique of Iterative Local Thresholding (TILT)—for processing 3D X-ray computed tomography (xCT) images for visualization and quantification of rock fractures. The TILT method includes the following advancements. First, custom masks are generated by a fracture-dilation procedure, which significantly amplifies the fracture signal on the intensity histogram ...