The phenomenon of ageing structures has focused attention on the problem of multiple-site damage (MSD) and wide spread fatigue damage (WFD). In isolation each ̄aw or crack may be safe. However, the cumulative e€ect of multiple, interacting cracks may signi®cantly degrade the damage tolerance of the structure. This paper presents an overview of a new ®nite element alternating technique algorithm...

We formulate a theoretical model of the shear failure of a thin film tethered to a rigid substrate. The interface between film and substrate is modeled as a cohesive layer with randomly fluctuating shear strength/fracture energy. We demonstrate that, on scales large compared with the film thickness, the internal shear stresses acting on the interface can be approximated by a second-order gradie...

Brittle materials propagate opening cracks under tension. When stress increases beyond a critical magnitude, then quasistatic crack propagation becomes unstable. In the presence of several precracks, a brittle material always propagates only the weakest crack, leading to catastrophic failure. Here, we show that all these features of brittle fracture are fundamentally modified when the material ...

There are few experimental results to date describing the crack-propagation threshold behavior of short fatigue cracks under multiaxial loading conditions. To address this need, in the present study, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat treated to two widely different microstructu...

Coatings subject to residual compression eventually fail by buckle-driven delamination. The phenomenon is most vivid in thermal barrier coatings (TBCs) used in gas turbines. The failure evolution commences with the formation of a large number of small cracks at geometric imperfections near the interface. These cracks spread upon thermal exposure, particularly upon thermal cycling, because of th...

mas·hyy saturated soil liquefaction during earthquakes, shnakhthshdhyy phenomenon that many researchers in the past three decades has attracted. more research on the liquefaction of saturated soils has focused mas·hyy the natural soils are rarely composed of clean sands, and mixed with clay or silt soils, which is why the study has important ghyrkhmyry and paste. despite numerous studies on the...

Fracture assessment of U- and V-notches is important in mechanical engineering. One can use the J-integral as fracture parameter in order to predict the critical fracture load in notches. The critical value of the J-integral in cracks is a function of the material properties. In notches, however, the material properties as well as the notch dimensions affect this critical value (named fracture ...

Two-dimensional weakly-singular Symmetric Galerkin Boundary Elements (SGBEMs) are developed, following the work of [Han and Atluri (2003)], using non-hypersingular integral equations for tractions. Specifically, the present 2D SGBEM is used to compute the stress intensity factors for arbitrary-shaped line cracks, including embedded, edge, branching, and intersecting cracks. The computed stress ...

A study is made of veneer failure by cracking in all-ceramic crown-like layer structures. Model trilayers consisting of a 1 mm thick external glass layer (veneer) joined to a 0.5 mm thick inner stiff and hard ceramic support layer (core) by epoxy bonding or by fusion are fabricated for testing. The resulting bilayers are then glued to a thick compliant polycarbonate slab to simulate a dentin ba...

There are few experimental results to date describing the crack-propagation threshold behavior of short fatigue cracks under multiaxial loading conditions. To address this need, in the present study, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat treated to two widely different microstructu...