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Tubular bending and hydroforming expansion processes are studied experimentally and numerically in this paper. The experimental results show that the hydroforming process is sensitive to material grades and process variables, and the axial feeding used in this case causes more material deformation near the inner bending surface. Finite element analysis (FEA) was carried out on an S-shape bending and expansion process using the incremental code LS_DYNA. The simulation results successfully explain the phenomena occurring in the experiments. A methodology of analyzing tubular bending process using a One Step FEA code is proposed to improve simulation efficiency. This approach is validated by comparisons with both the incremental FEA predictions and the experimental results. One Step FEA is not only highly efficient but also reasonably accurate in predicting the deformation mode and thickness distributions during the bending operation.

The work describes an approach for a closer interface between product design and manufacturing. Starting from the part print a finite element model of the final part is constructed. The model is used for a one step unfolding of the part to determine the blank shape. In addition, by tracking the shape of the material “finite” elements before and under unfolding, the approximate forming severity of the stamping can be obtained. The one step unfolding solution also provides the thickness distribution together with the yield stress distribution in the stamped part. This information is of great value to product design for the performance of a more realistic fatigue analysis. Since during product design many design alternatives are to be evaluated, the finite element formulation used at this stage is based on a one step approach, with the emphasis on solution speed as opposed to exactness.