Research On Simulation Of High Pressure Forming Of TAILOR-Welded Tube And Its Optimization Of Process Parameters

Hydroforming of tailor-welded tube (TWT) is that the tube blank is deformed by hydraulic pressure into the desired shape with dissimilar thickness welded tubes. It combines tailor-welded blank and hydroforing forming which in the dual advantages, a new forming process and innovative, so it needs further study. In this paper,the explicit finite element software DYNAFORM and MATLAB was used to simulate and analyze the Process of internal high pressure forming. The main content of the research in this article:(1) Commoning pipe hydroforming process mechanics theory analysis. Simulation and experiment were conducted on the analysis of geometry character and the effects of weld-seam position and thickness difference on the deforming process.(2) Worked out different position of the weld formability and find out the better formability, in which select the appropriate location of the weld.(3) Then, the rules of internal pressure and axial feeding influencing on the forming were determined. After tube hydroforming, the thickness of tube became thin gradually from both ends to the middle and different thickness bands appeared. The maximum thickness appeared in the bulging highest position. The maximum thickness was mainly determined by axial feeding. The minimum thickness was mainly determined by the maximal internal pressure. And the supplementing material function of axial feeding mainly happened at stage of low pressure of forming.At the same time, the influences of strain hardening exponent(n-value) and thickness on the forming were discussed, too. The bigger n-value is and the relatively thickness, the better the forming property is.(4) Aiming at the optimization of parameters, a new method was proposed, in which uniform design was integrated with neural network and genetic algorithm. This method makes full use of the reliability of uniform design and the nonlinear mapping, network reasoning and predicting of the neural networks, but also the global optimal characteristics of genetic algorithm, and the optimum results were obtained. Finally, it proves experimentally that the computer numerical simulation is reliable and the optimal algorithm is stable.The research results in the thesis provide effective guidance and solid foundation for the application of internal high pressure forming process to automobile tubular parts. They also offer a novel and high-efficient way for parameters optimization. In this way, the trial and error method can be abandoned. Efficiency and competition can be enhanced by shortening the experiment cycle of internal high pressure forming process.