Elasto-plastic deformation analysis of A1050P aluminum sheet subjected to three-point bending and estimation of the springback of the bent sheet

Abstract

This study describes the three-point bending deformation characteristics of the bent part of an aluminum alloy sheet (A1050P). The elasto-plastic states in the bent zone of the worksheet at bending angles of 0°–90° were simulated using the finite element method (FEM). To develop a simulation bending model, a three-point bending experiment was conducted using a 0.39-mm-thick aluminum sheet. The bending load resistance and deformation profile of the bent part in the FEM model were compared with the experimental results, and the initial punch indentation depth (dP) was varied within a certain range. The FEM model was developed and simulated using isotropic elasto-plastic solid properties. When simulating the three-point bending process, the modification of the plastic coefficient appears to be the primary characteristic that closely matches the experimental results. Through the FEM simulation of the worksheet, the following results were obtained: (1) The contract friction force (c) between the worksheet and the channel die was greater than that between the punch and the worksheet. This may be due to the boundary conditions of the three-point bending apparatus. (2) The pressure dependency of the friction coefficient is important. Further investigation into this pressure dependency, specifically the relationship between contact pressure and frictional resistance, should be considered. (3) The corner radius of the channel dies had a greater impact on the maximum principal compressive stress (P2max) than the maximum principal tensile stress (P1max), primarily because of the abrasive forces encountered during the three-point bending process. The peak maximum ratio of   P2max by P1max was approximately 1.12–1.27. An appropriate round edge of the corner die is important. (4) The number of nonlinear elasto-plastic states at the bending zone appeared to be three. The different separations in the three states may be due to the three different stress distribution patterns. (5) Regarding springback, for large (deep) deformations, Gardiner’s model closely matched the simulation model. This was confirmed by comparing the undefined V-notch with the applied V-notch. However, for small (shallow) deformations, further investigation is required through experimentations.