Browsing by Author "Vial-Edwards, C"

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    Strain rate measurement by Electronic Speckle Pattern Interferometry
    (2006) Guelorget, B; François, M; Vial-Edwards, C; Montay, G; Daniel, L; Lu, J
    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force (epsilon(t) similar or equal to 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements. (c) 2005 Elsevier B.V. All rights reserved.
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    The uncertainty of experimental derivatives
    (2004) Lira, I; Cordero, RR; François, M; Vial-Edwards, C
    A procedure is presented to evaluate the uncertainty of derivatives computed from polynomial curves or surfaces fitted to experimental data. The procedure takes into account the uncertainties in the dependent and independent variables and agrees with international recommendations. It is valid independent of the experimental technique from which data are obtained. The application of the procedure is demonstrated by evaluating the uncertainty of strains calculated by differentiation of whole-field displacement data obtained by moire interferometry.