Effect of Solution Methods for Evolutionary R-Values on the Prediction of Anisotropic Yield Behavior

Background

The anisotropic behavior of sheet metal has a significant influence on the plastic forming process, especially the accurate description of the plastic flow (r-value).

Objective

The purpose of this paper is to reveal the influence of different evolutionary r-value solution methods on yield model prediction.

Methods

Uniaxial and biaxial tensile experiments were carried out for DP590. The principles and results of r-value calculation based on slope method and polynomial fitting method are compared and analyzed. On this basis, the inverse solution method based on exponential function is established. The prediction results of Hill48, Hill48-non and Yld2000-2D yield models based on different r-value solution methods were compared. Furthermore, anisotropic yield models calibrated by different r-value solution methods are used as user material subroutine (VUMAT) to achieve cup-drawing simulation in ABAQUS.

Results

In the theoretical prediction of anisotropic yield model, the prediction accuracy of the three yield models is the best when the new inverse exponential function method is used. The earing height obtained by the three yield models based on inverse exponential function method calibration is more consistent with the physical experiment, while the prediction accuracy of the traditional slope method is the worst.

Conclusions

The appropriate r-value solution method can improve the predictive accuracy of anisotropic yield model. The research results provide a method for the anisotropic parameter calibration strategy of yield model considering anisotropic evolution, and provide an effective reference scheme for improving the prediction accuracy of deformation behavior in sheet metal stamping.

Graphical Abstract