Strain measurement of forming process using digital imaging

Abstract

An understanding of local strain behaviour during a metal forming operation can be important but maybe difficult to measure. A non-invasive digital imaging procedure has been developed to quantify local strain behaviour in metal forming. From digital images obtained during the forming process, discrete spatial data of the object profile was acquired. B-spline curve fitting was then applied to obtain a continuous profile. The deformation strains were calculated from the curvature of the continuous profile. The procedure was applied to an electric resistance welded pipe forming process. Strain gauge data was used to validate the proposed procedure.