Construction, calibration and application of pseudo-corner models

Previous experimental studies have noted that numerous metals exhibit “corner effects” following an abrupt change in strain-path, characterized by the sharp vertex produced on the subsequent yield surface and the apparent non-normality of the plastic flows. Some advanced models, known as pseudo-corner models, have been introduced to provide reasonable predictions regarding these corner effects, but their complex expressions limited their practical application in the industry. This work presents a simple pseudo-corner model to describe the flow non-normality after abrupt strain-path change and the model has been implemented in ABAQUS. A general parameter calibration method is proposed for the pseudo-corner model class based on the equivalent tangential shear modulus reduction after abrupt strain-path change. Furthermore, we apply the pseudo-corner models and the associated flow rule (AFR) to critical buckling estimation and post-buckling analysis. The results indicate that the pseudo-corner models and AFR offer the same prediction for the onset of buckling in circular tubes under axial compression. AFR apparently overestimates the plastic post-buckling strength, while the pseudo-corner models exhibit superior prediction performance.