Browsing by Author "Giusca, Claudiu L."

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    Benchmarking of several material constitutive models for tribology, wear, and other mechanical deformation simulations of Ti6Al4V
    (Elsevier, 2019-05-12) Liu, Cen; Goel, Saurav; Llavori, Iñigo; Stolf, Pietro; Giusca, Claudiu L.; Zabala, Alaitz; Kohlscheen, Joern; Paiva, Jose Mario; Endrino, José L.; Veldhuis, Stephen C.; Fox-Rabinovich, German S.
    Use of an alpha-beta (multiphase HCP-BCC) titanium alloy, Ti6Al4V, is ubiquitous in a wide range of engineering applications. The previous decade of finite element analysis research on various titanium alloys for numerous biomedical applications especially in the field of orthopedics has led to the development of more than half a dozen material constitutive models, with no comparison available between them. Part of this problem stems from the complexity of developing a vectorised user-defined material subroutine (VUMAT) and the different conditions (strain rate, temperature and composition of material) in which these models are experimentally informed. This paper examines the extant literature to review these models and provides quantitative benchmarking against the tabulated material model and a power law model of Ti6Al4V taking the test case of a uniaxial tensile and cutting simulation.
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    Improved and simpler estimation of scale linearity contribution to topography measurement
    (Elsevier, 2019-09-05) Giusca, Claudiu L.; Goel, Saurav
    Instruments measuring surface topography with nanometre accuracy are essential tools for studying nanotechnology. Despite their maturity, erroneous observations due to various error sources are widespread, particularly due to calibration and traceability issues. The current method of vertical scale calibration (which is one of the error sources), relies on the depth standard method that limits the traceability of the instrument to the calibrated range determined by the minimum and maximum discrete values. This paper reports a new method relying on the tilted flat that was aimed at mapping the linearity deviations continuously within the range covered by the tilt angle. The full traceability in this case requires only the measurement of a single depth measuring standard, that can be optimally selected to achieve least uncertainty associated with the amplification coefficient of the scale. The proposed method opens the opportunity for high dynamic range calibration, currently unachievable with conventional calibration techniques.