Uticaj višestrukih grešaka u zavarenom spoju na integritet zavarene konstrukcije
Influence of multiple defects on structural integrity of welded joints
Докторанд
Aranđelović, MihajloМентор
Sedmak, AleksandarЧланови комисије
Radaković, ZoranBakić, Gordana
Petrović, Ana S.
Burzić, Zijah
Метаподаци
Приказ свих података о дисертацијиСажетак
Glavni cilj ovog istraživanja je utvrđivanje kombinacije realnih grešaka koji predstavljaju
potencijalno najveću opasnost po integritet zavarenih spojeva i konstrukcija. Analiziran je uticaj
prisustva više različitih grešaka u zavarenom spoju čelika S275JR na integritet zavarene
konstrukcije. Sa tim ciljem formirani su numerički proračunski modeli i fizički modeli epruveta,
koji su bili ispitivani jednoosnim zatezanjem, a deformacije zona zavarenog spoja su merene
beskontaktnom optičkom metodom. Osnovna ideja je bila da se predvidi ponašanje zavarenih
spojeva u radnim uslovima u prisustvu višestrukih površinskih grešaka numeričkoeskperimentralnim pristupom. Određeni su naponi pri kojima dolazi do pojave prsline u zavarenim
spojevima za sve merodavne kombinacije grešaka, pri čemu je takođe utvrđeno koja greška inicara
početnu prsline za sve slučajeve kombinacije grešaka. Kao rezultat ovog ispitivanja određene su
karakteristike materijala svih zona zavarenog spoja.
Razvijeni su početni m...odeli koji su potom unapređvani. Polja deformacija dobijena
ekperimentalnim istraživanjima, pre svega digitalnom korelacijom slika, su korišćena u ovoj studiji.
Na taj način su iterativno razvijeni novi realni numerički modeli, koji su omogućili određivanje
napona pri kojem dolazi do pojave prsline, kao i naponskog i deformacijskog stanja u zoni uticaja
toplote.
Kombinacije grešaka u zavarenom spoju sa smaknućem ploča su se pokazale kao
najkritičnije u pogledu integriteta zavarene konstrukcije, kao i sama priroda kombinacije pomenutih
grešaka. Usled primetnog “overmatching” efekta, ova studija je pokazala da lomovi “kreću” iz
grešaka smeštenih u zoni uticaja toplote (pre svega na ili blizu linije stapanja).
The main goal of this research was to determine the combination of real defects that
potentially represent the greatest danger to the integrity of welded joints and structures. The
influence of multiple defects in the welded joint of S275JR steel on the integrity of the welded
structure was investigated. For this purpose, numerical calculation models and physical models of
specimens were formed, which were tested by uniaxial tension, and the deformations of the welded
joint zones were measured by the non-contact optical method. The basic idea was to predict the
behavior of welded joints in working conditions with presence of multiple surface defects by
numerical-experimental approach. The stress at which a crack occurs in welded joints with a
combination of defects has been determined, as well as which defect inititates the crack propagation
for all defets combinaction. As a consequence of this test, the material characteristics of all zones of
the welded joint were determined.
Initial... models were developed and then improved. The deformation field obtained by
experimental research was included. Thus, a new real numerical models were iteratively developed,
which enabled both the determination of the stress at which the crack occurs as well as the stress in
the heat affected zone.
Combinations of defets in welded joints with vertical misalignment were recocnized as the
most critical one concerning welded construction integrity, as well as the nature of these defects
combinations. Due to the noticeable "overmatching" effect of the welded joint, this study shown
that the fractures originated from defects located in the heat affected zone (primarily at or near the
fusion line).