Welding deformation is one of the most complex problems arising in manufacturing of welded structures and it is impossible to remove or correct it. Welding deformation reduces accuracy in the size and shape of structures and increases the amount of correction work which leads to rise in manufacturing cost. Therefore, predicting and controlling welding deformation is of key importance in manufacturing welded structures. Predicting and controlling of welding deformation can reduce the amount of correction work, thus saving labor and cost and raising productivity.
At present, analysis of welding deformation is conducted by thermal-elastic-plastic (TEP) FEM and inherent strain method. In the past, there were a large number of experiments and numerical models to obtain inherent deformation. Although constraint is, in general, a simple practical method to reduce angle distortion, past researches were focused on numerical analysis of welding deformation, and the control of welding deformation considering the effect of constraint on angle distortion of large structures have not been sufficiently investigated.
Kim Chang Son, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has predicted the welding distortion of a ship panel structure with butt and zigzag joints and determined the reasonable constraint position to reduce fabrication cost by considering the effect of constraint on angle distortion.
First, he investigated the inherent strains of the welded structure by TEP FEM analysis under both constraint and free conditions. Next, through the elastic FEM based on inherent strain, he estimated the welding deformation of ship panel structure under consideration. After that, in order to quantitatively estimate the effect of constraint on angle distortion of welded structure, he performed a numerical analysis in a non-constraint free condition and various constraint positions, and determined the reasonable constraint position. Finally, he compared the angle distortion of ship panel structure under the constraint condition with that under the non-constraint free condition.
The simulation results show that angular distortion can be effectively reduced under a constraint condition.
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