The Effect of Dynamic Loading on the Ratcheting Behavior of Pressurized Piping Branch

In this study, cyclic loading behavior of carbon steel pressurized piping branch junction are described. Effects of internal pressure and quantity of moments on ratcheting strain are investigated. The nonlinear kinematic hardening model is used to assessment of the plastic behavior of the branch pipes. The constant parameters of the hardening model and stress-strain data have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The results showed that the maximum ratcheting strain occurred on the flanks in the branch hoop stress direction just above the junction. The results show that in low moments, the ratchetting strain rate is very low and near to zero. The ratchetting strain rate increases with increase of average stress and the moment levels in constant pressure. The results show that initial the rate of ratcheting is large and then it decreases with the increasing of cycles. The hoop strain ratchetting rate by FE model give over estimated values comparing with the experimental data.