The role of grain bridging in affecting the initial rising portion of the R-curve and the transient, non-steady-state behavior of short cracks during (cyclic) fatigue-crack propagation has been quantitatively examined in a 99.5% pure alumina. Fatigue-crack growth properties for both long and short ( af < 2 mm) cracks emanating from machined notches (root radius, 15–150 m) were investigated, whe...

The fatigue growth of multiple cracks, of arbitrary lengths, emanating from a row of fastener holes in a bonded, riveted, lap joint in a pressurized aircraft fuselage is studied. The effects of residual stresses due to a rivet misfit, and of plastic deformation near the hole, are included. A Schwartz Neumann alternating method which uses the analytical solution for a row of multiple colinear cr...

The relationship between the crack nucleation and stress-induced martensitic transformation in the retained massive austenites (RM’s) of austempered ductile irons (ADIs) was examined in detail by carrying out tensile tests and scanning electron microscope (SEM) observations for an ADI material. The SEM observations revealed that cracks were not nucleated in the peripheral regions of graphite no...

We present numerical simulations of the fall of a two dimensional (2D) model granular material in a rectangular container and study the decompactionof this granular assembly consisting of non-cohesive particles. During the fall we observe the occurrence of cracks splitting the initial pile into pieces. Cracks preferentially occur in the lower part of the array, an eeect also observed experiment...

* Corresponding author; Email: [email protected] ABSTRACT An important task in mixed-mode fracture analysis and prediction is the simulation of crack growth under mixed-mode conditions. To complete such a task, one must have (a) a computer code capable of handling the kinematics of general crack growth and determining the stress and deformation states during crack growth, and (b) a fracture crit...

We have considered the problem of elastic wave velocities in a matrix containing aligned ellipsoidal fluid-filled cracks. This problem is relevant o a variety of geophysical pplications, including crustal and mantle seismology and the behavior of stressed and dilatant rock. When the cracks are ellipsoids of revolution, the composite is transversely isotropic and is describable with five elastic...

In this study, (Gd0.9Yb0.1)2Zr2O7 (GYbZ)/yttria-stabilized zirconia (YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were prepared by plasma spray-physical vapor deposition (PS-PVD). The microstructure, mechanical performance, and shock behavior of with spraying distances 600, 800, 1000 mm investigated. GYbZ coating a distance 600 showed closely packed columnar structure. Howeve...

This paper investigates the efficiency of Ultrasonic Pulse Velocity (UPV) method in detecting cracks and flaws inside the concrete. A series of concrete beams and slab specimens were cast and damaged to simulate the different mechanisms possible in a reinforced concrete deck due to mechanical loading. Two types of simulated cracks, namely, cracks perpendicular and cracks parallel to axis of bea...

The problem of N cracks interaction in an isotropic elastic solid is decomposed into a subproblem of a homogeneous solid without crack and N subproblems with each having a single crack subjected to unknown tractions on the two crack faces. The unknown tractions, namely pseudo tractions on each crack are expanded into polynomials with unknown coefficients, which have to be determined by the cons...