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Improvement of characteristics of fatigue resistance of welded joints of light alloys and elements of in-service metal structures using high-frequency mechanical peening

Work number - M 21 FILED

The authors: Dr. Klochkov I.N., Dr. Solovey S.A.

      Presented by the E.O.Paton Electric Welding Institute of the NAS of Ukraine.

      The aim of workis the establishment of regularities for improvement of characteristics of fatigue resistance of welded joints of thin-sheet structures of aluminium alloys and welded joints of in-servuce metal  structures of low-alloyed steels after their long-term operation using high-frequency mechanical peening (HFMP).

     Novelty of obtained results. A number of fundamental results was obtained about the regularities of improvement of cyclic long life of welded joints with fatigue damages after their strengthening by HFMP technology depending on type and sequence of applying loads before and after the strengthening. Formula for summing of fatigue damages in welded joints at multi-step loading was suggested. Revealed was the influence of HFMP on improvement of fatigue resistance of joints, operating under conditions of corrosion environment, containing design lacks of penetration or surface fatigue cracks. The priority results were obtained about the influence of HFMP process on improvement of fatigue resistance of thin-sheet welded joints of aluminium alloys at the established optimum parameters of treatment. The new approaches were offered on application of HFMP as the method of cold straightening to eliminate the structural eccentricity of transition of force load in thin-sheet overlapped welded joints.

      The practical value of the obtained results.New experimental data can be directly used at widening the existing standard base of designing and evaluation of service life of welded aluminium structures which operate under the conditions of alternate loading, and also in working out of recommendations on application of HMP technology for prolongation of residual life of welded elements of  in-service metal structures designed for long term purpose. The experimental investigations found their implementation in real engineering developments: in 2007 during repair-welding works for restoration of integrity of spans of railroad bridge across the  Vorskla river at 333 km of the line Darnitsa-Poltava of the Southern railroad the welds were strengthened by HMP technology according to the specified optimal parameters; the results of work were used during working out of standard document of “Ukrzaliznytsia” TsP-0214 “Service of railroad bridges” acting since 01.12.2009: “Service  of railroad bridges. Technological regulations on repair of elements of span structures of railroad bridges, damaged by cracks, using welding; the established parameters of HMP strengthening of thin-sheet welded joints are used to eliminate residual welding deformations of thin sheet panels of side walls of passenger cars at the  PJSC “Kryukov railway car building plant”, Kremenchug.

     Materials of works are described in 34 publications, including 17 articles in the specialized publicationsof Ukraine, 17 – in the collections of materials and abstracts of the conferences. The specialized journals and collections of Ukraine on welding and related processes and technologies are not included into the Scopus data base.