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Inverse analysis of heat transfer in friction stir welding using generalized extremal optimization
Felipe R. Centeno and Francis H. R. França

Numerical simulations of the transient, three-dimensional conduction equation are carried out to model the heat transfer in the friction stir welding (FSW) of 304L Stainless Steel. Based on temperatures that are artificially measured at several locations on the surface of the workpiece at a given instant of time, an inverse analysis of the thermal process is conducted to determine the heat generated by the friction between the tool shoulder and the workpiece, and the maximum temperature that is reached in the workpiece. This indirectly requires that the inverse analysis estimates the unknown heat transfer coefficients on the top and bottom surfaces of the workpiece. The inverse analysis is formulated as an optimization problem, which is then solved with the generalized extremal optimization (GEO) algorithm. This paper demonstrates that the inverse analysis can be an effective way to evaluate and predict the parameters that govern the complex friction stir welding process, which otherwise would be very difficult to determine from a direct measurement.

Keywords: Friction stir welding, heat source determination, high temperature estimation, inverse analysis, optimization.

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