Browsing by Author "Hassan, A."

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    Micromechanical modeling of 8-harness satin weave glass fiber-reinforced composites
    (SAGE Publications (UK and US), 2017-03-01) Choudhry, R. S.; Khan, K. A.; Khan, Muhammad; Hassan, A.
    This study introduces a unit cell-based finite element micromechanical model that accounts for correct post cure fabric geometry, in situ material properties and void content within the composite to accurately predict the effective elastic orthotropic properties of 8-harness satin weave glass fiber-reinforced phenolic composites. The micromechanical model utilizes a correct post cure internal architecture of weave, which was obtained through X-ray microtomography tests. Moreover, it utilizes an analytical expression to update the input material properties to account for in situ effects of resin distribution within yarn (the yarn volume fraction) and void content on yarn and matrix properties. This is generally not considered in modeling approaches available in literature and in particular, it has not been demonstrated before for finite element micromechanics models of 8-harness satin weave composites. The unit cell method is used to obtain the effective responses by applying periodic boundary conditions. The outcome of the analysis based on the proposed model is validated through experiments. After validation, the micromechanical model was further utilized to predict the unknown effective properties of the same composite.
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    Optical and AFM study of electrostatically assembled films of CdS and ZnS colloid nanoparticles.
    (Elsevier Science B.V., Amsterdam., 2008-05-30T00:00:00Z) Suryajaya, S.; Nabok, Alexei; Davis, Frank; Hassan, A.; Higson, Seamus P. J.; Evans-Freeman, J.
    CdS and ZnS semiconducting colloid nanoparticles coated with the organic shell, containing either SO3− or NH2+ groups, were prepared using the aqueous phase synthesis. The multilayer films of CdS (or ZnS) were deposited onto glass, quartz and silicon substrates using the technique of electrostatic self- assembly. The films produced were characterized with UV–vis spectroscopy, spectroscopic ellipsometry and atomic force microscopy. A substantial blue shift of the main absorption band with respect to the bulk materials was found for both CdS and ZnS films. The Efros equation in the effective mass approximation (EMA) theoretical model allowed the evaluation of the nanoparticle radius of 1.8 nm, which corresponds well to the ellipsometry results. AFM shows the formation of larger aggregates of nanoparticles on solid surfa