A Practical Estimation Method of the Skin Plate Distortion Caused by Fillet Weld

Abstract

Development of a useful estimation method of the welding deformation about welded built-up structures is developed in this paper. Improvement of matching accuracy of each hull block element is essential to introduce the economical automatic welding machines in an assembly stage. Precise estimation method of the welding deformation is also necessary to achieve the aim. Equivalent inherent strain method is highlighted as a convenient estimation method about welding deformation in large welded built-up structures. Inherent strain can be seen as the deformation source generated by welding and derives from the thermal cycles under welding processes. This deformation source can be given if the amount of welding heat input is known. The deformation can be calculated by elastic finite element analysis. Shell element is applied to simplify the mesh idealization. However, this method did not give a good estimation result in case that out-of-plane deformation such as a skin plate distortion occurs. Improvement of equivalent inherent strain method to advance the accuracy of estimation about the skin plate distortion caused by fillet weld is performed in this paper. Beam element, which expresses the fillet weld bead and has inherent strain along the bead to generate tendon force, is incorporated with former equivalent inherent strain method. The skin plate distortion measured are compared with the calculated one by applying the proposed method. As a result, the validity of the improvement is confirmed.