Change in geometry size and thinning rate in single-point incremental forming process of TA1 sheet: evaluation method and finite element analysis

As a mold-less forming technology of sheet materials, single-point incremental forming (SPIF) can efficiently and economically fabricate various protypes and products. Although considerable studies have been conducted on SPIF, further improvement is possible in terms of the analysis method of the forming part quality, such as the accuracy and simplicity of the method. In view of this, this study aimed at establishing a thinning rate evaluation method from a three-dimensional perspective. By taking a titanium alloy sheet as an example, the three-dimensional change in the part size and its thinning rate during the SPIF process were systematically investigated. Furthermore, LS-DYNA software was employed to simulate the forming process. The results showed that the proposed method can effectively evaluate the dimensional changes of any cross-section of the sheet material. With the use of finite element model, a better thinning behavior prediction of the as-formed TA1 titanium sheets was achieved. The finite element simulation results were well comparable to those of the actual forming process. The simulated deformation of the four corners of a square box during the forming process could reach a maximum value of 0.252 mm, which was close to the experimental result of 0.248 mm. The deformation depth from the finite element simulations was 9.01 mm, whereas the actual experimental result was 8.50 mm. This study provided some insight on the development of a forming quality evaluation method and the forming simulation of SPIF.