Development of a Practical Straightening Simulation for Welded Structures Using Inherent Strain Method

Welding is the most widely used assembly method available to industries in the construction of metal structures, ships, and offshore platforms. However, this method always produces a certain amount of distortion that will not only degrade the performance but also increase the building cost of the structure, and it should be straightened. Murakawa [1] developed a thermal elastic plastic based and inherent strain based welding simulation FE code JWRIAN. Coarse shell FE models are usually used in the inherent strain based JWRIAN elastic analyses. This drastically reduces the manpower needed for modeling and computer resources needed for the calculation. However, it is not easy to perform straightening analysis using JWRIAN because gas heating’s inherent strain distributes over a range much smaller than element sizes of the shell model.RUIZ [2] modified JWRIAN’s code so that the inherent strain equivalent nodal forces along the heating line are calculated and applied in the elastic shell analysis. However, a discrepancy between 3-dimensional thermal-elastic-plastic analysis and elastic analysis was observed. This is mainly because of the nature of solid and shell elements. RUIZ [3] proposed a linearized inherent strain and applied it to both 3-d and 2d analysis, getting matching results between solid and shell element models. In this study, as a working example, a thin plate panel with an opening is considered utilizing the developed system at the same time a friendly user interface for staffs and workers on a production site is developed.  Keywords: Inherent strain, straightening, finite element method, Gauss-Legendre quadratur

A numerical study of parameters governing an inherent deformation database of plates formed by line heating

As an overall strategy to improve the accuracy of the forming process, the authors pay attention to those factors which may influence the inherent deformation of plates formed by line heating. In order to identify those factors, we numerically analyze the inherent deformation produced by single heating lines and compare it with that obtained by different combination of multi-heating lines under different heating and cooling condition and applied over plates with different geometries. Based on acknowledge obtained from this study, the influential factors in inherent deformation are indentified and its influence clarified.As an overall strategy to improve the accuracy of the forming process, the authors pay attention to those factors which may influence the inherent deformation of plates formed by line heating. In order to identify those factors, we numerically analyze the inherent deformation produced by single heating lines and compare it with that obtained by different combination of multi-heating lines under different heating and cooling condition and applied over plates with different geometries. Based on acknowledge obtained from this study, the influential factors in inherent deformation are indentified and its influence clarified

Analysis and prediction of welding distortion in complex structures using elastic finite element method

The Elastic Finite Element Method based on the inherent strain theory is used to predict the welding distortion of ship structures. In addition, a method to predict welding distortion of complex structures by using elastic FEM is presented. To evaluate the effectiveness of the proposed method, a typical case of a ship's structure is examined and the resulting welding distortion is compared to that obtained by using thermal elastic-plastic finite element method.The Elastic Finite Element Method based on the inherent strain theory is used to predict the welding distortion of ship structures. In addition, a method to predict welding distortion of complex structures by using elastic FEM is presented. To evaluate the effectiveness of the proposed method, a typical case of a ship's structure is examined and the resulting welding distortion is compared to that obtained by using thermal elastic-plastic finite element method

Análisis y predicción de distorsiones en estructuras soldadas por medio de un análisis elástico de elementos finitos

The Elastic Finite Element Method based on the inherent strain theory is used to predict the welding distortion of ship structures. In addition, a method to predict welding distortion of complex structures by using elastic FEM is presented. To evaluate the effectiveness of the proposed method, a typical case of a ship's structure is examined and the resulting welding distortion is compared to that obtained by using thermal elastic-plastic finite element method.Un análisis elástico de elementos finitos basado en la teoría de la deformación unitaria inherente es utilizado para predecir la distorsión causada por la soldadura en estructuras de barcos. Adicionalmente, se propone un nuevo método para predecir la distorsión de estructuras complejas. Los resultados obtenidos son luego comparados con aquellos obtenidos por medio de análisis termo-plástico de elementos finitos