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Collagen fibre architecture in articular cartilage is commonly described in terms of the predominant direction of fibre alignment. X-ray scattering has been used to study the distribution of fibre orientations in cartilage. In this paper, a new methodology for the analysis of small-angle X-ray scattering (SAXS) patterns of articular cartilage in order to quantitatively determine the distribution of collagen fibre orientations in the tissue is presented. A simple three-component model was used to fit intensity data from SAXS patterns to separate diffraction maxima from general diffuse scatter. Deconvolution of angular distributions of intensities of diffraction maxima obtained from SAXS patterns of articular cartilage and ligament samples yielded fibre orientation distributions in the cartilage samples. The methodology developed in this study worked reliably on a large set of SAXS patterns collected from native, dehydrated and trypsin-treated articular cartilage samples. The methods can be extended to quantitative analysis of small or wide angle X-ray scattering patterns obtained from other collagenous materials.

Brain tissue modelling has been an active area of research for years. Brain matter does not follow the constitutive relations for common materials and loads applied to the brain turn into stresses and strains depending on tissue local morphology. In this work, a hyperviscoelastic fibre-reinforced anisotropic law is used for computational brain injury prediction. Thanks to a fibrere-inforcement dispersion parameter, this formulation accounts for anisotropic features and heterogeneities of the tissue owing to different axon alignment. The novelty of the work is the correlation of the material mechanical anisotropy with fractional anisotropy (FA) from diffusion tensor images. Finite-element (FE) models are used to investigate the influence of the fibre distribution for different loading conditions. In the case of tensile-compressive loads, the comparison between experiments and simulations highlights the validity of the proposed FA-k correlation. Axon alignment affects the deformation predicted by FE models and, when the strain in the axonal direction is large with respect to the maximum principal strain, decreased maximum deformations are detected. It is concluded that the introduction of fibre dispersion information into the constitutive law of brain tissue affects the biofidelity of the simulations., QC 20140131

Cementitious materials are brittle and have an inherent weakness in resisting in tension. Fibre reinforcement is an effective means of enhancing the fracture characteristics of concrete. The use of low fibre volume fractions in concrete has increased significantly in recent years for the control of opening and slippage of concrete cracks. To understand fully such effects of fibres in concrete, it is important to assess their effects on the various fracture mode of concrete.This study looks at the performance of discrete end-hooked and straight steel fibres crossing a cracking plane at various angles loaded normal to the plane. In addition to discrete fibre tests, uniaxial tension tests are conducted on the dog-bone shaped specimens containing randomly distributed fibres with fibre volumes of 0.5%, 1.0%, 1.5% and 2.0% with end-hooked only and hybrid steel fibres combinations. X-ray imaging is used to investigate the mechanisms of fracture in fibre reinforced concrete and to identify the shape of the discrete fibres at various stages of loading and quantitative mapping of snubbing regions. An increase in fibre volume concentration can have an adverse effect on the tensile performance of a fibre reinforced composite when very high strength, end-hooked, fibres are used in a matrix of moderate strength. The experimental investigation showed that an increase in fibre volume concentration can lead to a decreased in the proportion of end-hooked fibres straightening through the end-hook. In this case, failure of the matrix surrounding the hook follows and significantly influences the behaviour. A relationship between fibre and matrix mechanical properties is developed and the result supports the findings obtained from the tests conducted in this study.X-ray imaging was also undertaken on dog-bone specimens under load. The tests were used to map the cracks around and through the fibre and a statistical model developed to determine fibre distribution.The experimental results o