20.500.12556/RUL-145731 Napovedovanje dobe trajanja izdelkov z upoštevanjem tehnološke zgodovine in inkrementalnim računanjem poškodbe Fatigue life prediction of products by considering manufacturing history and incremental damage calculation Analiza vpliva zaostalih napetosti na izračun dobe trajanja je pogosto omejena le na površinsko stanje do pojava razpoke. V tej raziskavi obravnavamo celotno dobo trajanja ciklično obremenjenega izdelka. Analiziramo število ciklov do pojava razpoke in spremljamo njeno rast skozi polja zaostalih napetosti, ki niso prisotna le na površini izdelka. Za spremljanje interakcije zaostalih napetosti s ciklično obremenitvijo oz. njene relaksacije smo uporabili kombinacijo konturne metode in digitalne korelacije slik. Za modeliranje materialnega odziva je bil uporabljen kombiniran izotropično-kinematični materialni model. Razvili smo namenski algoritem, ki je sposoben preko vpeljave kohezivnega kontakta modelirati poškodbo v obliki razpoke. Algoritem dobro opisuje trend smeri rasti, na drugi strani pa nekonzervativno podaja gradient hitrosti rasti razpoke. Spoznali smo, da lahko tlačno vnesene zaostale napetosti na mestu stran od pojava razpoke negativno vplivajo na dobo trajanja izdelka. Analysis of the effects of residual stresses on fatigue life is often limited to the product surface. In this study the total fatigue life of dynamically loaded products was studied. Both the number of cycles to crack initiation and the growth of the crack with subsequent cycles was analised. The contour method and digital image correlation techniques are used to validate the interaction between residual stress and fatigue loading. The combined isotropic-kinematic material model was used to model the material response. An algorithm to simulate fatigue crack growth by modelling cracks with cohesive contact was developed. The algorithm correctly predicts the fatigue crack growth trend but cannot capture the crack propagation gradient. A residual compressive stress field away from the crack initiation site has a negative effect on fatigue life. Zaostale napetosti Ciklična obremenitev Rast razpoke Poškodba Kombiniran izotropično-kinematični materialni model Konturna metoda Residual stress Cyclic load Fatigue crack growth Damage Combined isotropic-kinematic material model Contour method Digital image correlation true false false [P. Zobec] Slovenski jezik Neznan jezik Doktorsko delo/naloga 2023-05-11 08:30:24 2023-05-11 08:30:30 2023-11-29 10:05:58 0000-00-00 00:00:00 2023 0 Ljubljana 0 XXVI, 110 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 620.172.21:539.4.012(043.3) 249184 152891907 23120.pdf 23120.pdf 1 14AF1D20342702C5497B79F95A503756 bb22b7f09553d383d8270165d9bd7877d3bd6996177bfeb0b6b77bc85b56fdc5 1703a4cb-efc5-11ed-a314-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=168721 Fakulteta za strojništvo 0 0 0