An elastic-plastic-creep finite element analysis for small punch creep test specimens

An elastic-plastic-creep finite element model, incorporating a Von Mises plastic flow rule and a creep damage equation, was established based on the small punch creep test on Cr5Mo steel specimens at 550°C and three different loads. Finite element analyses were performed to examine the variation of the central creep deflection and the creep strain with time and the evolution of creep damage. The sensitivity of the creep deflection and equivalent stress at the centre on the disc to mesh size is discussed. Numerical results presented in this paper confirm that the creep damage at the central part is high. The stress gradients are highest near the centre area of the specimen (from 0 to 1 mm). Therefore, accurate stress and strain can be obtained using refined meshes near the specimen center and coarse meshes in other places. The test results are in agreement with those of the numerical simulation and three different stages appearing in the curve of creep deflection, which are quite similar to those observed in conventional creep tests.