Revisiting the wrinkling limits in flexible roll forming

This article presents a new understanding on the deformation mechanics of flexible roll forming and is focused on the occurrence of flange wrinkling. The presentation draws from the experimental and numerical simulation of flexible roll forming to the determination of the wrinkling limits by means of a new theoretical and experimental methodology based on the utilization of rectangular test specimens loaded in axial compression. This research work is performed in mild steel sheets and the results show that the combined evolution of the effective strain with stress triaxiality obtained from finite element modelling of flexible roll forming and from the rectangular test specimens loaded in axial compression can be successfully utilized to predict the occurrence of flange wrinkling in variable cross-sectional profiles produced by flexible roll forming. The proposed methodology can, therefore, be considered an alternative to existing approaches based on simplified analytical and numerical procedures.