Influence of fatigue impact loading on radial carrier and rapping device fillet weld strength

Abstract

Professional paperThe device used to shake off the ash of the steam boiler harp consists of a drive shaft which has radial carriers welded on. During the operation of the waste incinerator steam boiler in Riverside, a fracture of the radial carrier and drive shaft weld occurred. Such a welded T-joint is made as a double fillet weld. It is loaded with the impact loading which causes the fatigue of material because of its repetition. The analytical calculation, with which the loadbearing capacity of the welded joint is determined, is suggested in this paper. The suggested analytical calculation of the mean impact force is based on the law of momentum conservation during the collision of rapping device and elastically deformable heat exchanger harp. The mean impact force is applied for the weld strength calculation. The results showed that the use of double fillet weld loaded with the fatigue impact loading was a bad choice. The suggested analytical calculation model is applicable for the rapping device design. Keywords: double fillet weld; fatigue; impact loading; rapping device; strength Utjecaj udarnog zamornog opterećenja na čvrstoću kutnog zavarenog spoja radijalnog nosača i pogonskog vratila udaračaStručni članak Uređaj za stresanje pepela s izmjenjivačkih harfi parnog kotla sastoji se od pogonskog vratila na koje su zavareni radijalni nosači čekića. U radu parnog kotla spalionice smeća u Riverside-u došlo je do loma zavarenog spoja radijalnog nosača i pogonskog vratila udarača. Zavareni spoj radijalnog nosača i vratila izveden je kao obostrani kutni zavareni spoj. Ovaj zavareni spoj opterećen je udarnim opterećenjem koje zbog ponavljajućeg karaktera prouzrokuje zamor materijala. U radu je predložen analitički proračun kojim je utvrđena nosivost zavarenog spoja. Predloženi analitički proračun srednje sile sudara temelji se na zakonu očuvanja količine gibanja uslijed sudara čekića udarača i elastično deformabilne harfe izmjenjivača topline. Srednja sila sudara primjenjuje se kod proračuna čvrstoće zavarenog spoja. Dobiveni rezultati pokazali su da je primjena kutnog zavarenog spoja opterećenog udarnim zamornim opterećenjem loš izbor. Predloženi model analitičkog proračuna moguće je primijeniti kod dizajna udarača.

Analytical vs Numerical Calculation of Fatigue Life for Different Welded Joint Regions

“…The influence of different microstructures, i.e. different welded joint regions on fracture behaviour of welded joints became an interesting research topic in the field of fracture mechanics [1,[10][11][12][13][14], and this recent interest in it inspired the work presented here. The goal was to expand the methodology developed in [1] to numerical simulations which would involve different types of materials for welded joints.…”

A Double Seam Profile Tracking Automation Method for Cylindrical Welding Technique

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