Prediction of welding-induced distortions in large weld structure through improved equivalent load method based on average plastic strains (original) (raw)
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The welding process is the basic technique of joining in the shipbuilding industry. This method generates welding distortions that cause a lot of problems during the manufacturing process due to both the time and cost of straightening as well as their influence on later stages of production. Proper preparation of welding processes plays a growing role in the shipbuilding industry and the development of calculating tools is being observed. The paper presents a review and critical analysis of numerical methods for the assessment of welding distortion.
Welding in the World, 2013
Fusion welding processes are widely used to assemble large thin plate structures such as ships, automobiles, and passenger trains because of their high productivity. However, welding-induced distortion often inevitably occurs during the assembly process. Welding distortion not only reduces the fabrication accuracy of a welded structure but also decreases productivity due to correction works. If welding distortion can be predicted using a practical method beforehand, the prediction will be helpful for taking appropriate measures to control the dimensional accuracy. In this study, an elastic finite element method to predict the distortion accumulated in large and complex structures during the welding assembly process from cutting through straightening is developed based on inherent strain theory and interface element.
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In this study, the experimental procedure of various welding processes has been explained and the variations in the various properties of weldment due to the influence of several welding parameters were studied. Here, the processes are common to all the conditions such as the welding conditions and material selection criterion. In the present paper, the focus is on presenting and classifying the specified welding process and the changes in the properties of weld in terms of varying parameters applied for welding process. This study allows putting them into proper context based on the new trends in the field of welding. Finally, the variations of the properties of weld with respect to various parameters, defects in weldment and stresses in weldment have been reviewed.
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Prediction of welding residual distortions is more difficult than that of the microstructure and residual stresses. On the one hand, a fine mesh (often 3D) has to be used in the heat affected zone for the sake of the sharp variations of thermal, metallurgical and mechanical fields in this region. On the other hand, the whole structure is required to be meshed for the calculation of residual distortions. But for large structures, a 3D mesh is inconceivable caused by the costs of the calculation. Numerous methods have been developed to reduce the size of models.
Forecasting of Welding Distortions in Large-Sized Structures
Metal ..., 2020
The prevention of welding distortions is one of the most important and, at the same time, most difficult issues in welding engineering. The above-named distortions result from the combined effect of the shrinkage of solidifying weld metal and the shrinkage occurring in the partially melted zone (primarily in the HAZ). Welding distortions often preclude the obtainment of proper joints in large-sized elements and, could even lead to the disqualification of the final product failing to satisfy related standard requirements concerning maximum distortion values. In spite of extensive research focused on welding distortions, they remain the primary issue accompanying the making of steel structures. Various industrial sector organisations express their need for solutions making it possible to forecast the presence of welding distortions. The possibility of forecasting the probable structure imperfections during assembly and the prevention of such imperfections as early as at the design stage and when scheduling assembly make it possible to reduce costs and delays resulting from the removal of distortions. The use of appropriate methods can reduce welding distortions yet it does not ensure their entire elimination. Engineering practice relies on analytical methods involving calculations of total distortions present in elements of welded structures having one and two-sided longitudinal welds, transverse distortions generated during the butt welding of sheets as well as local distortions generated as a result of the loss of stability of thin-walled welded structures. Knowledge concerning possible welding distortions can also be obtained by performing FEM-based numerical analyses concerned with the welding of structures.
This paper presents an investigation of welding sequence based on the effect of distortion induced by gas metal arc welding (GMAW) process. The selected lower arm parts from national car parts manufacturer will be simulated using Virtual Manufacturing and verified through an experiment by means of a real parts production from industry. Distortion happens due to the uneven rate of expansion and contraction during the welding process. Engineers need to prevent or reduce welding distortion since it could be less cost-efficient to be corrected. Distortions affect the accuracy as well as weld quality. In industry, they use a lot of clamps to prevent distortions. However, with proper welding sequence and lower predicted distortion, lesser clamping setup needed to support the welded part. In this study, the distortion of the lower arm due to changing in welding path/sequence will be analyzed. Simufact. welding 4.0 software will be used to simulate the welding process and the result will be verified by an experimental investigation. . Goldak’s double ellipsoidal model was selected to model the heat source of the GMAW process. The specification of lower arm used is obtained from collaboration with one of the biggest stamping company in the industry. The result from the simulation show that welding sequence does contribute to the distortion of welding process. The sequence can be manipulated to get a better welded product which has lower internal stress due to clamping. Simulation is reliable in predicting welding outcome; however, human expertise is still needed to set up proper simulation. Keyword: welding, distortion, welding sequence, lower arm,welding simulation
Hybrid model for prediction of welding distortions in large structures
2011
The paper presents a short overview of the contemporary approaches for calculating welding distortions. In order to meet the existing challenges, an advanced hybrid model for prediction of welding distortions in large structures is described. For the purpose of illustrating the capability of this model, a simulation case is put into discussion. The results are validated by comparison with experimental data, as well as with common simulation technique. Analysis of the calculation costs is also presented. The directions for development of calculation technique, based on the presented model, are also suggested.
Strain-Based Assessment and Modeling for Low-Distortion Welding Procedure
Materials and Manufacturing Processes, 2012
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An Investigation for Introducing Welding Imperfection in Elastic-plastic Large Deformation Analysis
Transactions of J W R I, 2009
When the elastic-plastic finite displacement analysis based on the large deformation theory is carried out for evaluating elastic-plastic mechanical behavior and ultimate strength of a welded steel structural member, the welding imperfection is indispensably considered and introduced as the initial imperfection. However, it is known that the introduced welding imperfection could not be reproduced with fidelity by unbalanced force because the welding imperfection is not legitimate. Therefore, it is anticipated that the welding imperfection can be introduced with fidelity if the legitimate welding imperfection is obtained. In order to investigate the validity of the anticipation, the thermal elastic-plastic analysis for a single-pass butt-welding was carried out and welding distortion and residual stress as the legitimate welding imperfection were obtained in this study. The obtained welding imperfection was introduced into the elastic-plastic finite displacement analysis as the legitimate initial imperfection and it was verified whether the introduced welding imperfection could be reproduced with high accuracy or not. As a result, the introduced welding distortion was changed largely from original value because thin steel plate is easy to bend. Consequently, it was considered that the introduction accuracy of the welding imperfection is dependent on the flexural rigidity of steel plate. Anyway, it is known that there are such case as the introduction accuracy of the welding imperfection falls down when the welding imperfection obtained from the thermal elastic-plastic analysis based on the infinitesimal deformation theory is introduced into the elastic-plastic finite displacement analysis based on the large deformation theory.