## Estimating the workpiece-backingplate heat transfer coefficient in friction stirwelding

Publication: Research - peer-review › Journal article – Annual report year: 2012

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**Estimating the workpiece-backingplate heat transfer coefficient in friction stirwelding.** / Larsen, Anders; Stolpe, Mathias; Hattel, Jesper Henri.

Publication: Research - peer-review › Journal article – Annual report year: 2012

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*Engineering Computations*, vol 29, no. 1, pp. 65-82., 10.1108/02644401211190573

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*Engineering Computations*,

*29*(1), 65-82. 10.1108/02644401211190573

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*Engineering Computations*. 2012, 29(1). 65-82. Available: 10.1108/02644401211190573

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TY - JOUR

T1 - Estimating the workpiece-backingplate heat transfer coefficient in friction stirwelding

AU - Larsen,Anders

AU - Stolpe,Mathias

AU - Hattel,Jesper Henri

PB - Emerald Group Publishing Ltd.

PY - 2012

Y1 - 2012

N2 - Purpose - The purpose of this paper is to determine the magnitude and spatial distribution of the heat transfer coefficient between the workpiece and the backingplate in a friction stir welding process using inverse modelling. Design/methodology/approach - The magnitude and distribution of the heat transfer coefficient are the variables in an optimisation problem. The objective is to minimise the difference between experimentally measured temperatures and temperatures obtained using a 3D finite element model. The optimisation problem is solved using a gradient based optimisation method. This approach yields optimal values for the magnitude and distribution of the heat transfer coefficient. Findings - It is found that the heat transfer coefficient between the workpiece and the backingplate is non-uniform and takes its maximum value in a region below the welding tool. Four different parameterisations of the spatial distribution of the heat transfer coefficient are analysed and a simple, two parameter distribution is found to give good results. Originality/value - The heat transfer from workpiece to backingplate is important for the temperature field in the workpiece, and in turn the mechanical properties of the welded plate. Accurate modelling of the magnitude and distribution of the heat transfer coefficient is therefore an essential step towards improved models of the process. This is the first study using a gradient based optimisation method and a non-uniform parameterisation of the heat transfer coefficient in an inverse modeling approach to determine the heat transfer coefficient in friction stir welding. © Emerald Group Publishing Limited.

AB - Purpose - The purpose of this paper is to determine the magnitude and spatial distribution of the heat transfer coefficient between the workpiece and the backingplate in a friction stir welding process using inverse modelling. Design/methodology/approach - The magnitude and distribution of the heat transfer coefficient are the variables in an optimisation problem. The objective is to minimise the difference between experimentally measured temperatures and temperatures obtained using a 3D finite element model. The optimisation problem is solved using a gradient based optimisation method. This approach yields optimal values for the magnitude and distribution of the heat transfer coefficient. Findings - It is found that the heat transfer coefficient between the workpiece and the backingplate is non-uniform and takes its maximum value in a region below the welding tool. Four different parameterisations of the spatial distribution of the heat transfer coefficient are analysed and a simple, two parameter distribution is found to give good results. Originality/value - The heat transfer from workpiece to backingplate is important for the temperature field in the workpiece, and in turn the mechanical properties of the welded plate. Accurate modelling of the magnitude and distribution of the heat transfer coefficient is therefore an essential step towards improved models of the process. This is the first study using a gradient based optimisation method and a non-uniform parameterisation of the heat transfer coefficient in an inverse modeling approach to determine the heat transfer coefficient in friction stir welding. © Emerald Group Publishing Limited.

KW - Friction stir welding

KW - Inverse modelling

KW - Friction welding

KW - Heat transfer coefficient

KW - Optimisation

U2 - 10.1108/02644401211190573

DO - 10.1108/02644401211190573

JO - Engineering Computations

JF - Engineering Computations

SN - 0264-4401

IS - 1

VL - 29

SP - 65

EP - 82

ER -