Search

This paper presents a numerical modelling and experimental investigation of the cyclic plasticity behaviour of low carbon steel. In order to improve the accuracy of modelling the material response under cycling loading, a new set of internal variables is proposed. The developed plasticity model is applied to the problem of modelling compressive residual stress inducing methods which are based on a plastic overload of a material. A beneficial influence of induced compressive residual stress is demonstrated on a benchmark problem of autofrettage of a high pressure thick-walled cylinder. Numerical simulation of the cyclic plasticity problems and fatigue assessments are carried out by means of FEM in ANSYS Workbench with FORTRAN user-programmable subroutines for material model incorporating custom equations.

The effect of weld angular distortion on fatigue test specimens cut from butt welded plates is investigated by experimental and numerical methods. The weld specimens are made of a structural steel equivalent to BS 4360 grade 50D. The SN curve obtained from experimental data is used with the fatigue post-processor nCode DesignLife for fatigue life prediction. Mean stress correction is applied using the FKM approach to address the component of bending stress induced by clamping the distorted specimen, which is constant during the fatigue test. A parameter identification procedure for the SN curve and mean stress correction is proposed. The weld SN curve evaluated using the procedure is compared to the generic weld SN curves provided in the material database of nCode DesignLife and discussed.