We investigate the feasibility of cohesive theories of fracture, in conjunction with the direct simulations of shear-load dominated fracture, to numerically reproduce the inter-sonic crack propagation in unidirectional graphite-epoxy composite plates [1]. The particular configuration contemplated in this study refers to the experiments performed by Coker and Rosakis [2, 3]. The numerical simula...

Crack propagation of PMMA in some liquid environments is described for various testing conditions, such as fixed load, fixed displacement and monotonically increasing displacement. Fracture mechanics concepts have been used successfully in analysing the results. When continuous stable cracking is achieved, values of fracture toughness (R) for PMMA under these loading conditions are obtained as ...

The slow motion of a crack line is studied via an experiment in which sheets of paper are split into two halves in a "peel-in-nip" (PIN) geometry under a constant load, in creep. The velocity-force relation is exponential. The dynamics of the fracture line exhibits intermittency, or avalanches, which are studied using acoustic emission. The energy statistics is a power law, with the exponent be...

Tight-binding molecular dynamics simulations shed light into the fracture mechanisms and the ideal strength of tetrahedral amorphous carbon and of nanocomposite carbon containing diamond crystallites, two of the hardest materials. It is found that fracture in the nanocomposites, under tensile or shear load, occurs intergrain and so their ideal strength is similar to the pure amorphous phase. Th...

Treatment of intertrochanteric hip fracture is based on patient medical condition, preexisting degenerative arthritis, bone quality, and the biomechanics of the fracture configuration. A critical review of the evidence-based literature demonstrates a preference for surgical fixation in patients who are medically stable. Stable fractures can be successfully treated with plate-and-screw implants ...

This letter demonstrates a method for fabricating single-crystal Si nanolines, with rectangular cross sections and nearly atomically flat sidewalls. The high quality of these nanolines leads to superb mechanical properties, with the strain to fracture measured by nanoindentation tests exceeding 8.5% for lines of 74 nm width. A large displacement burst before fracture was observed, which is attr...

Three separate impact events were simulated (LS-DYNA ® ) based on experimental tests previously conducted [2] (i.e., the appropriate impact velocities assigned to the model projectile): i) a pre-fracture event (2.1 m/s); ii) a crack event (2.7 m/s); and iii) a fracture event (3.3 m/s). Two element sets were created in the locations of the experimental strain gauges (dorsal radial styloid and do...

The authors describe the case of an athlete from the Brazilian national men's basketball team (sub-16) who reported pain in the right iliac region at the end of the season. Clinical and imaging exams revealed an iliac bone stress fracture. A conservative treatment of removing the load from the fracture in combination with physical therapy was chosen. The athlete improved satisfactorily and retu...

Bioabsorbable phosphate glass fibre/polymer composites are being investigated as alternatives to commonly used metal alloy-based bone fracture fixation devices. According to Knowles [1], these ‘Third Generation’ implants remain in the body for the short term necessary for mechanical stabilisation of tissue. In addition the degradation products of the bioabsorbable implants perform an active fun...

An equation was developed from studies of single-pass wear and fracture toughness of filled and unfilled dental restorative resins and dental amalgams relating the sliding frictional force F to the normal load N, fracture toughness, modulus of elasticity, yield strength and slider diameter. This equation was of the same form as that reported for viscoelastic materials (F = KW). Friction was cau...