Springback in beams and plates of work hardening materials due to variable combinations of Stretch-Bending

An exact analytical solution for springback due to variable stretch bending of beams and plates is presented. Three types of materials are investigated, elastic perfectly plastic (EPP), elastic linear work hardening (ELWH) and elastic exponential work hardening (EEWH). The variation of the applied bending moment with the axial force for the fully elastic, elastic-plastic and fully plastic cases for cantilever beam is studied analytically. It was found that the curvature, slope, deflection and final deflection for (ELWH) is greater than that for (EEWH) and smaller than that for (EPP) material, and the springback ratio is smaller than that for EEWH materials and greater than that for EPP material. The presented model was modified to evaluate the springback of flat rectangular plates and circular blanks formed by a hemispherical punch and die. It was found that the curvature increases as the thickness increases for different materials, and that stretching increases as the blank radius increases and/or as thickness decreases.Comparisons with published work for the case of axis-symmetric stretch bending and plane strain sheet bending are presented. It was found that the proposed mechanism provided acceptable predictions of springback due to stretch bending of work hardening materials for all possible stretch bending combinations, for different stress conditions and for different materials

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