PSI - Issue 18

Evgeny Lomakin et al. / Procedia Structural Integrity 18 (2019) 549–555 Evgeny Lomakin and B ris Fedulov / Structural Integrity Proc dia 00 (2019) 000–000

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Fig. 5. The yield limit values of the equivalent Mises stress at biaxial tests (alloy AD33). Fig. 7 shows the deviations of the criteria values in percentage of the applied load at yield limits obtained in the experiments corresponding to Fig. 5. First set of bars shows values obtained by the use of Mises criterion � = , where , which corresponds to the tensile yield stress along the tubular specimen. Second criterion on Fig. 7 corresponds to the equation (2), where the coefficients �� ( are shown in Fig. 6, and the parameter is chosen similarly to the von Mises criterion - .

Fig. 6.Coefficients �� ( for the yielding surface based on experiment from Fig. 5 Deviations obtained using the plasticity criterion (2) are less than one percent, which in practice can be considered as an ideal result. The Mises criterion shows a maximum deviation of ∼ 12%, while the experiment with the maximum deviation shows the minimum plastic deformation prior to failure. It worth to note that the experiments did not involve the ST direction, which is radial for the tubular sample and could make a more significant contribution both to the anisotropy of the properties and to the degree of sensitivity of the material properties to the type of loading.