In this paper the ratchetting behavior of four pairs of stainless steel, long and short radius welding elbows is studied under conditions of steady internal pressure and in-plane, resonant dynamic moments that simulated seismic excitations. The finite element analysis with the nonlinear kinematic hardening model has been used to evaluate ratchetting behavior of the elbow under mentioned loading condition. Stress-strain data and material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The results show that the maximum ratcheting strain occurred mainly in the hoop direction at flanks. Ratcheting strain rate increases with increase of the bending loading level at the constant internal pressure. The results show that the FE method gives over estimated values comparing with the experimental data.
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