Bulging Investigation of Cylinder Compression Forming Using Upper Bound Analysis

Bulging deformation during cylinder compression forming results in geometrical imprecision and flow stress prediction error. Consequently, the present study proposes a hybrid technique comprising the Upper Bound Method (UBM) and geometrical fitting method. It is noted that a volume conservation constraint and an elliptical curve-fitting method with UBM for predicting both the compression force and the bulge profile. It is shown that the predicted results for the compression force based on UBM under certain reduction ratios of 30%, 40%, 50% and 60% are in good agreement with those obtained by experiment, Finite Element Method (FEM), and Slab Method (SM). In addition, it is revealed that the use of an elliptical curve-fitting technique provides a reasonable approximation of the bulge profile obtained by experiment and FEM simulations. Generally, the proposed method effectively provides a low-cost, computationally straightforward means of estimating the compression force and bulge profile in cylinder compression forming. Therefore it can be utilized as the widespread applications in the metal forming field.