Database for real-time loading path prediction for tube hydroforming using multidimensional cubic spline interpolation

Tube hydroforming (THF) is a metal-forming process that uses a pressurized fluid in place of a hard tool to plastically deform a given tube into a desired shape. In addition to the internal pressure, the tube material is fed axially toward the die cavity. This process has various applications in the automotive, aerospace, and bicycle industries. Accurate coordination of the fluid pressure and axial feed, collectively referred to as a loading path, is critical to THF. Workable loading paths are currently determined by trial and error, which can be time consuming. This study discusses an innovative technique for developing an interactive, real-time database that would be able to predict loading paths for many THF components and hence reduce the computational time required. By classifying most of the commercial THF parts into families, parameters such as material properties, part geometry, and tribological factors were simulated by category and stored in the database. Multidimensional cubic spline interpolation was implemented to enable an end user to request from the database a loading path for a wide range of conditions. Test results from the database for different THF families were shown to approximate the simulated results. In addition to reducing the computation time, the use of interpolation techniques eliminates the need for carrying out multiple simulations for similar THF parts.