An optimization method of wall thickness distributions in T-shaped tube compound-forming method with unconventional tube blank

Abstract

The thin-walled T-shaped tube is widely applied in aviation pipeline systems with the development of lightweight manufacturing technology. However, the severe wall thickness thickening is a bottleneck problem restricting the application of T-shaped tubes. In order to avoid excessive thickening and improve the overall performance of the formed parts, an optimization method of wall thickness distributions in T-shaped tube compound forming by using optimized unconventional tube blank is proposed. The strain spline method is adopted to investigate the stress-strain state and deformation mechanism of T-shaped compound forming. The optimization model of tube blank is established and includes two parts: the initial optimization based on the geometric analytic method and the iterative optimization based on the incremental finite element method. The optimal tube blank is achieved through two-step optimizations. The numerical simulations and experiments of T-shaped tube compound forming using conventional and optimized tube blanks are carried out to investigate the forming height and the wall thickness distributions. The simulation and experimental results agree with a no more than 20 % relative error. The optimal tube blank could effectively improve the wall thickness distributions compared with the T-shaped tube compound using the conventional tube blank. The final experimental results show that the maximum thickening rate decreases from 48.67 % to 28.67 %, the maximum thinning rate decreases from 25.33 % to 18 %, and the maximum difference in the wall thickness decreases from 1.11 mm to 0.7 mm. The comparison results are further verified to be the correctness of the optimization method and the effectiveness of the T-shaped tube compound forming method with unconventional tube blank in the actual experiments.