十字形試験片を用いた二軸応力試験の
数値解析的検証

抄録

A method of determining stress measurement error in biaxial tensile tests using a cruciform specimen is proposed. The cruciform specimen is assumed to be fabricated from a flat sheet by laser machining and to have uniform thickness and slits in its arms. Using finite element analysis with the von Mises yield function, the optimum dimensions of the cruciform specimen and the strain measurement point that minimize the stress measurement error are determined. The following conclusions are drawn. (i) When the side length of the test area of the cruciform specimen is B, the thickness of the test material should be less than 0.08 B. (ii) The dimensions of the cruciform specimen should be N≥7,L≥B,ω_S≤0.01B and 0.0034≤R/B≤0.1, where N is the number of slits, L is the length of slits in the arms, ω_S is the width of slits and R is the corner radius at the junction of the arm and test area. (iii) Strain components in the test area should be measured on the centerline of the specimen parallel to the maximum principal stress direction at a position approximately 0.35B from the center of the specimen. The stress measurement error is estimated to be less than 2% when the optimum conditions above are adopted.