Development of the slope cutting method for determining the residual stresses in roll formed products

The residual stresses in a roll formed product play a critical role in determining the product quality. They are generally very complex and frequently difficult to predict due to the complicated fabricating process and its parameters. Consequently, they attract many concerns from roll forming scholars and engineers. However, how to inspect the residual stresses in roll formed products efficiently and economically is still a challenge. This paper introduces a novel, highly efficient, operationally simple and accurate residual stresses measurement method for evaluating the residual stresses in roll formed products. It utilizes a modification of the current sectioning methods to firstly obtain the membrane and bending residual stresses components. Then a novel material removal approach, the tapered removal, is employed to determine the layering stresses component by measuring the curvature variations of the remaining sample through its thickness direction. A practical implementation of the method is performed through the residual stresses measurement of a typical roll formed square hollow section (SHS). The method is successfully verified by the neutron diffraction method. The new method is expected to become a routine measuring method to determine the residual stresses distribution in roll formed products, with potentially significant impact on the roll forming industry.