In this paper, effects of ply orientation of adjacent plies with (ϕ//θ) interfaces on mode II critical strain energy release rate (fracture toughness) of multidirectional (MD) laminate has been studied. Ply orientation of adjacent plies is one of the most important parameters affects the mode II critical strain energy release rate () in the initiation of the delamination. To  study this paramet...

The potential hydraulic behaviour of the fracture network in a major Triassic sandstone aquifer in the UK has been evaluated. The properties of the fracture network were determined using results from detailed scan line surveys at 10 sites, television and geophysical borehole logging, and packer testing. Six sets of discontinuities common to all sites were identified and statistically characteri...

The age-related deterioration in the quality (e.g., strength and fracture resistance) and quantity (e.g., bone-mineral density) of human bone, together with increased life expectancy, is responsible for increasing incidence of bone fracture in the elderly. The present study describes ex vivo fracture experiments to quantitatively assess the effect of aging on the fracture toughness properties o...

The energy release rate (ERR) proposed by Irwin based on a theory by Griffith [1, 2] has been extensively used as a fracture criterion in 2D for brittle domains. Under in-plane mixed mode loading (modes I+II), the direction of crack initiation from cracks and sharp V-notches was determined by the orientation at which the ERR attains its maximum. Using the newly developed asymptotic expansion pr...

Australia has a huge resource of hot dry rock, most of which is located in Central Australia. As a first step towards experimental field testing of HDR development in Australia, in-situ stresses and natural fractures in Central Australia are being characterised. Preliminary results indicate that three stress regimes may co-exist in Central Australia, with maximum horizontal in-situ stress being...

The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading. However, it has recently been shown that the toughness of human cortical bone in the transverse (breaking) orientation is actually much lower in shear (mode II) than in tension (mode I); a fact that is physiologically relevant as in vivo bone is invariably loaded multiaxially. Since bo...

In this paper we analyze a two-dimensional discrete model of nearestneighbour Lennard-Jones interactions under the microscopical constraint that points on a lattice triangle maintain their order. This can be understood as a microscopical non-interpenetration constraint and amounts to the positiveness of the determinant of the gradient of the piecewiseaffine interpolations of the discrete displa...

In this study the performance of clay nano-particles on the soil reinforced with Polypropylene fibers (PP-fiber) has been investigated. Also a series of investigations concerning the effect of random orientation of fibers on the engineering behaviour of soil were conducted. Soil mixtures were modified with varying percentages of nanoclay and Fibers. Unconfined compressive strength (UCS), Compac...

Open fractures are of interest in many areas such as ground water contamination, hazardous waste disposal, oil and gas recovery, and geothermal energy extraction. In borehole geophysics and engineering, fractures are usually located by acoustic borehole televiewer logging, however, not all of the observed fractures are permeable. The caliper log, on the other hand, provides the information abou...

The fracture toughness and resistance-curve behavior of relatively coarse-scale, niobium/niobium aluminide (Nb/Nb3Al) laminated composites have been examined and compared to other Nb/Nb3Al composites with (in situ) Nb particulate or microlaminate reinforcements. The addition of high aspectratio Nb reinforcements, in the form of 20 vol. pct of 50to 250-mm-thick layers, was seen to improve the to...