Effect of welding sequence to minimize fillet welding distortion in a ship’s small component fabrication using joint rigidity method

Abstract

This study was performed to investigate the effect of welding sequence on fillet welding distortion. It proposes a new model of joint rigidity method, which can determine the welding sequence for minimum welding distortion, through a reliability validation done via experiments and welding distortion analysis using the equivalent load method. A new joint rigidity method considers the gap between base plate and stiffener and the fillet welding sequence at left/right bead. Fillet welding sequence at left/right bead could be considered by setting welding beads at left/right as a separate solid element after welding sequence was drawn by new joint rigidity method. Analysis and experiment for welding distortion for the test specimen with different stiffener distances were conducted. It was confirmed that the experimental and analysis results were well-matched. The validity of welding sequence using joint rigidity method was followed after the comparison of the welding distortion for the small components for ship building. Note that the welding sequence by which welding distortion became maximum and minimum was drawn using joint rigidity method for the small assembly components. Welding distortion was also analyzed using equivalent load method. Analysis results revealed that the maximum welding distortion less than 10 mm was generated. Welding distortion less than around 5 mm occurred in welding sequence which minimized welding distortion compared with welding sequence, generating maximum welding distortion.

Modified Equivalent Load Method for Welding Distortion Analysis

“…Based on the derived plane stress element stiffness matrix, the system's stiffness matrix can be derived. Then, the force vector term that generates only transverse shrinkage (δ T ) can be derived as Equation (12):…”

“…These values can directly enter the common FE code as an equivalent nodal load vector that generates the inherent deformation. Equivalent load method directly uses the distortion data so it does not need long computational time for the input variables extraction [11][12][13]. However, the conventional equivalent load method equation cannot precisely predict the longitudinal bending distortion.…”

Finite Element Simulation of Welding Distortion in Dissimilar Joint by Inherent Deformation Method

“…. Q I V η = (9) where I is the current, V is the voltage, and η is the thermal source efficiency assumed to be 0.6. Finally, models with 8300, 9500, 10050, and 10700 elements were designed and analyzed thermally to study the sensitivity of the mesh.…”

“…In another study, he studied the effect of a different welding sequence on out-of-plane buckling distortion [8]. Similar to Wang, Park studied welding of ship panels by equivalent forces method, which is based on inherent deformation, and designed a welding sequence that minimized distortion for a ship [9]. In 2015, Rezaei et al studied a large panel by inherent deformation theory and proposed a welding sequence appropriate to minimize distortion [10].…”

Welding Sequence Optimization using Artificial Intelligence Techniques, an Overview

“…Park et al [22] have proposed a new model of the JRM. This new model considers the gap between plates, effect of the tacking and the welding sequence by changing FEA modeling parameters.…”