ABSTRACT

The main purposes of the present study are to develop an efficient analysis method that can predict the welding distortion of stiffened hull blocks according to fabrication sequences and also to simulate the correction of welding distortions in stiffened hull blocks by line heating. In this paper, the equivalent loading method based on the inherent strain theory was adopted. By the present approach, the welding distortion of a stiffened panel block was calculated according to the assembly sequences and the heat-correction process was simulated. It is verified through the experiments that the present method is effective and efficient for the simulation to predict and to correct the welding distortions of stiffened hull blocks.

INTRODUCTION

Accuracy management in shipbuilding is an essential technique to systematize the work process of fabrication, assembly, pre-erection and erection. In particular, the work efficiency in the erection stage is dependent on the accuracy of the blocks. However, welding deformation accumulated in each assembly stage reduces the accuracy of the blocks and has an adverse effect on productivity. Therefore, an analysis method to estimate welding deformation is essential for proposing error-minimizing guides at the design stage. The requirements for the analysis method are as follows, 1. It should be accurate 2. The shape change of a block according to assembly processes should be considered 3. It should be efficient in time and cost In this paper, a method for predicting the welding deformation of large structures is presented. The method uses both the inherent strain theory and the experimental results combined with the finite element method for accurate and efficient analysis. In the inherent strain theory, the residual plastic strain due to welding is defined as the inherent strain.

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