Sensitivity analysis and parameter estimation of heat transfer and material ow models in Friction Stir Welding

S. PEREYRA; G.A.LOMBERA; FRONTINI, GLORIA; S. URQUIZA

INVERSE PROBLEMS IN SCIENCE AND ENGINEERING

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2011

1741-5977

Although numerical models of heat transfer and material ow have contributed to understand friction stir welding (FSW), there are certain input model parameters that can not be easily determined either from fundamental principles or from the welding conditions. Thus, the model predictions do not always agree with experimental results. In this work, sensitivity analysis and parameter estimation approach were performed to test heat transfer and material ow models. A forward-dierence approximation was used to compute the sensitivity of the solution with respect to the unknown model parameters. The Levenberg-Marquardt (LM) method was applied to solve the nonlinear parameter estimation problem. The numerical models were developed by the nite element method (FEM). The unknown model parameters were: the friction coecient and the amount of material stuck to the tool surface, the heat transfer coecient at the bottom surface and the internal heat generation. In this study, the way in which these parameters independently aect the results and the importance of the location of reference points that take part in the objective function were determined.