2008E-G2-2 Measurement of True Stress-Strain and its Application to Assess the Strength and Deformability of Steel Plates with Surface Pits and Replica for General Corrosion

概要

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Strength and deformability of steel plates for marine use are studied both experimentally and numerically. The numerical analysis to solve this problem requires the true stress-strain relationship. We, at first, estimate the true stress-strain of flat steel plate under uniaxial tension by a vision sensor system. The experimental technique consists of the measurement of minimum cross-sectional area and the estimation of a correction factor due to tri-axial stress state after the necking phenomenon by using a flat specimen without any imperfections. The measured true stress-stain is then applied to assess the strength and deformability of steel plates with surface pits and replica for general corrosion. The numerical analyses are carried out with a nonlinear implicit finite element code; LSDYNA. The numerical result is then validated by experimental counterpart. Two types of steels having yield ratios11), 0.657 and 0.841, respectably, are considered to investigate the material effect for corrosion damage. The strength and deformability do not show significant dependence on the yield ratio of these two materials, while they depend on the geometry; i.e., the minimum cross-sectional area of the specimens.