• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.410-417
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• 2017

Hydro-forming is being employed increasingly to realize lightweight vehicular parts. The bumper beam produced by this process weighs 30% less than the conventional products with equal stiffness. However, hydro-forming involves complex parameters to obtain the target geometry and low residual stress. Parametric studies are conducted using finite element analysis to obtain optimized process conditions. Through these numerical approaches, the internal and holding pressures and feeder forward stroke along the extruded direction are optimized to achieve low residual stress and to minimize springback. The numerical results are verified by experimental observations made by employing a three-dimensional laser scanner. The numerical and experimental results are compared in terms of the springback. Both results show similar tendencies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.483-492
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• 1998

An inverse analysis been applied to obtain the flow stress of the material. In this method, a ring-shaped specimen is compressed between two flat tools. This procedure employs, as the object function of inverse analysis, the balance of measured loads and reaction forces calculated by using rigid-plastic finite element method. The balance is explicit scalar function of flow stress which is a function of some unknown constants. For minimizing the balance, Newton-Raphon scheme is used. The friction factor, m, between flat tools and the specimen is determined by using friction area-divided method. The proposed method allows an accurate identification by avoiding the usual assumptions made in order to convert experimental measures into stress-strain relation. In this paper, the proposed method is numerically tested. A commercial pure aluminum was selected, as an example, to apply the method and the results are compared with stress-strain relation obtained by experiments.