Papers by Keyword: Ratcheting Strain

Abstract: The current paper reports the results of a numerical simulation and experiment of ratcheting behavior of pressurized straight pipe under reversed bending. A nonlinear isotropic/ kinematic (combined) hardening model is implemented into finite element program ANSYS by writing own user subroutine in FORTRAN language. The results of the numerical simulation is compared with experimental data. A reasonable agreement is noticed between the experimental and the numerical results for the ratcheting behavior of the pressurized straight pipe subjected to reversed bending.

Abstract: The paper compares numerical simulation with experimental results of pressurized elbow piping subjected to reversed in-plane bending in elastoplastic domain. The modified AbdelKarim-Ohno model is implemented into finite element program ANSYS by writing own user subroutine in FORTRAN language. The modified AbdelKarim-Ohno model may improve the prediction accuracy of ratcheting behavior of pressurized elbow under cyclic loading.

Abstract: A series of ratcheting experiments and finite element analysis simulation under bending loading for Z2CND18.12N stainless steel elbows were carried out. Chaboche and modified Ohno-Wang model are applied to evaluate structural ratcheting response simulations. It is found that ratcheting strain initiates firstly in the hoop direction and increases in the axial direction with the increasing of loading. The Ratcheting strain rate grows with the increase of the reversed in-plane bending load or internal pressure for both specimens with different loadings. Comparison of simulation and experiment showed that modified Ohno-Wang model presented simulation more reasonably.

Abstract: The cyclic deformation behaviors of hotrolled AZ91 magnesium alloy are studied by asymmetrical cyclic stresscontrolled experiments at room temperature. The ratcheting behavior and fatigue failure mechanism are discussed. Results show that: (1) The ratcheting strain increases sharply with the increase of cycle number at the initial stage, and then tends to be a constant after certain cycles. (2) The fatigue crack initiation and stable propagation regions are flat with lamellar structures, while the unstable propagation and rapid fracture regions are coarse with ductile dimples and tearing edges. (3) The residual twins can be seen as potential damage to fatigue failure of the material, due to its irreversibility of cyclic plastic deformation and damage to grain boundaries.