Advanced methods for finite element simulation for part and process design in tube hydroforming
Tube HydroForming (THF) process offers several advantages over the conventional manufacturing via stamping and welding; a) part consolidation, b) weight reduction, c) improved structural stiffness, d) lower tooling cost, e) fewer secondary operations, and f) tight dimensional tolerances. Unfortunately, the current development method of THF processes is plagued with long lead times, which is resulted from much iteration on prototyping. The formability of hydroformed tubular parts is affected by a large number of parameters such as material properties, tube geometry, complex die-tube interface lubrication, and process loading paths. FE simulation is perceived by the industry to be a cost-effective process analysis tool compared to the conventional hard tooling prototyping. However, the prevalent trial-and-error based simulation method becomes very costly when the THF process analyzed is complex. More powerful design methods are needed to help the engineers design better THF part geometries and process parameters, thus reducing lead times and costs. This work was intended to develop methodologies for design of part geometries and process parameters in THF. The methodologies in design of process parameters include analytical equations, FEA modeling, and FEA modeling enhanced with numerical optimization algorithms and a kind of control rules. These tools will enable engineers to quickly and effectively select loading paths (i.e. pressure curve and axial feed curve versus time) optimized for successfully hydroforming of simple to complex tubular part geometries such as T-shapes, Y-shapes, cross members, and engine cradles. The research contributions that are associated with this dissertation work are: • Systematic FEA simulation strategies such as analytical method and self-feeding method to calculate proper THF loading paths, and formability limits for simple to moderate complex part geometries. • Procedure of automatic optimization of THF loading paths using PAM-STAMP and a general optimization code, PAM-OPT, for typical THF complex part geometries such as, simple bulges, Y-shapes, and automotive structural parts. • Adaptive Simulation program that works with a commercial code, PAM-STAMP, to automatically determine feasible loading paths of any given THF parts. The current program can handle only simple part geometries such as axisymmetric bulges.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:tube hydroforming finite element simulation optimization process parameter design
Date of Publication:01/01/2004