Advanced Structural and Technological Method of Reducing Distortion in Thin-Walled Welded Structures

Abstract

The article presents an innovative method of reducing welding distortions of thin-walled structures by introducing structural and technological changes. The accuracy of the method was demonstrated on the example of welding the stub pipes to the outer surface of a thin-walled tank with large dimensions, made of steel 1.4301 with a wall thickness of 1.5 × 10−3 (m). During traditional Gas Tungsten Arc Welding (GTAW), distortions of the base are formed, the flatness deviation of which was 11.9 × 10−3 (m) and exceeded the permissible standards. As a result of structural and technological changes, not only does the joint stiffness increase, but also a favorable stress state is introduced in the flange, which reduces the local welding stresses. Numerical models were developed using the finite element method (FEM), which were used to analyze the residual stresses and strains pre-welding, in extruded flanges, in transient, and post-welding. The results of the calculations for various flanges heights show that there is a limit height h = 9.2 × 10−3 (m), above which flange cracks during extrusion. A function for calculating the flange height was developed due to the required stress state. The results of numerical calculations were verified experimentally on a designed and built test stand for extrusion the flange. The results of experimental research confirmed the results of numerical simulations. For further tests, bases with a flange h = 6 × 10−3 (m) were used, to which a stub pipe was welded using the GTAW method. After the welding process, the distortion of the base was measured with the ATOS III scanner (GOM a Zeiss company, Oberkochen, Germany). It has been shown that the developed methodology is correct, and the introduced structural and technological changes result in a favorable reduction of welding stresses and a reduction in the flatness deviation of the base in the welded joint to 0.39 × 10−3 (m), which meets the requirements of the standards.

Forecasting the Fatigue Strength of DC01 Cold-Formed Angles Using the Anisotropic Barlat Model

“…The stress analysis was performed using the Huber–von Mises–Hencky equivalent stress hypothesis (HMH) [ 27 , 28 , 29 ]. As can be seen in Figure 11 and Figure 12 the change in the θ angle from 0° to 90° influences the stress distribution.…”

Stress Calculations of Heat Storage Tanks

“…Finite element analysis can also be used for weld analysis. This method was used in [ 16 ], the purpose of which was to develop an inexpensive, fast and effective method of welding stub pipes to the shell of a cylindrical tank without the formation of large shell distortions. A description of how to prepare the FEA model for this application can be found in [ 27 ].…”

“…Assuming that element have M nodes, the displacement elements after discretizing are described by Equations ( 14)- (16).…”

“…Thermomechanical properties of metals influence the kinetics of stresses and thermal deformations and, consequently, deformations of the structure. The deformation and stress also depend on the selected welding technology [ 16 ].…”

Application of the FEM Method to Modeling and Analysis of the Cold Thread Rolling Process—Part 1: Conditions for Ensuring a Plane State of Deformations

“…As a result, for successive discrete moments of time τ 0, Δt, 2Δt, … the geometry of the body and the states of incremental displacements, displacement velocities, accelerations, strains, strain rates, and stresses are determined. The concept of incremental description has already been verified by the author and was used to describe other plastic-forming processes: cutting [36][37][38][39][40][41][42], thread rolling [15][16][17]28,29], burnishing rolling [43][44][45][46][47][48][49], drawing [50][51][52], grinding with a single abrasive grain [53], calculating the fatigue strength of products [54][55][56], and diamond sliding burnishing [56].…”