A framework to assess and repair pre-fatigued welded steel structures by TIG dressing

Artikel i vetenskaplig tidskrift, 2020

The extension of fatigue life of ageing welded steel structures is an important challenge faced by the industry. Herein, a detailed framework was developed to assess and improve the performance of these aged structures (pre-fatigued) using tungsten inert gas (TIG) dressing. Within this framework, relevant damage theories and models were applied to assess the state of pre-fatigued structures. Based on the results of this assessment and TIG dressing parameters, the extended fatigue life was estimated. Particular attention is paid to the deterministic study of the TIG dressing parameters, which are the fusion depth, weld toe radius, and residual stress. The resulting data, especially longitudinal and transversal attachments, were analysed to verify the proposed framework. The improved fatigue life was found to be at least 3.4 times the as-welded fatigue life when the cracks were completely re-melted. A significant dependency of the extended fatigue life on the remaining crack length after treatment was observed. A comparison of my predictions with experimentally obtained fatigue lives in other studies showed an absolute error of 20%.