Welding Distortion Analysis of Hull Blocks using Equivalent Load Method Based on Inherent Strain

Welding deformation reduces the dimensional accuracy of ship hull blocks and decreases productivity due to the correction work. Prediction and minimizing of welding distortion at the design stage will lead to higher quality as well as higher productivity. Therefore, the development of an effective method to predict accurately the weld distortion of hull blocks considering the fabrication sequences is required. In the case of hull block welding work in shipyards, the welding process of curved stiffened plates has large amounts of workload. This paper suggests an efficient method for predicting the welding deformation of stiffened curved plates based on the inherent strain theory combined with the finite element method. The equivalent load was determined by integrating inherent strain components which are calculated in the vicinity of heat affected zone using the highest temperature and the degree of restraint. The welding distortion of curved stiffened panels under equivalent load are calculated by elastic analysis and compared with that by intensive elasto-plastic finite element analysis. It is verified that the proposed method has a high efficiency and accuracy.