Fracture analysis on flexible roll forming process of anisotropic Al6061 using ductile fracture criteria and FLD

In this research, the fracture phenomenon was investigated on flexible roll forming process of channel section using ductile fracture criteria and forming limit diagram (FLD) by considering the effect of anisotropy. For this purpose, a finite element simulation of the process using the ABAQUS software was done. The fracture in this process was evaluated by considering six types of ductile fracture criteria by UMAT subroutine implementation on the FEM software and using FLD criterion. Experimental tests were performed on 27 blanks of Al6061-T6 using flexible roll forming machine made in Shahid Rajaee Teacher Training University (SRTTU). Numerical results were validated by experimental results. In addition, prediction of occurrence and fracture position by ductile fracture criteria and FLD criterion were compared with experimental results; the Argon criterion was chosen as the most appropriate criterion to predict the fracture position and its occurrence. The fracture occurrence was only observed in a 60° bending angle for 1.5- and 2-mm thicknesses, and the fracture position error percentages of the Argon criterion with experiments for these cases were 18.7 and 3.5%, respectively. Also, the effects of parameters such as sheet thickness, bending radius, and bending angle on the fracture phenomenon by using the selected criterion of Argon were studied.